CN110644363A

CN110644363A - Construction method of underwater main tower of cross-river cable-stayed bridge of high-speed railway

Info

Publication number: CN110644363A
Application number: CN201910551986.4A
Authority: CN
Inventors: 高军; 林晓; 盛永东; 杨立云; 申百囤; 王仁明; 汤宇; 李波; 李锐; 袁洪义; 李军; 蔡荣喜
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-06-24
Filing date: 2019-06-24
Publication date: 2020-01-03

Abstract

The embodiment of the invention discloses a construction method of an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway, relates to the technical field of bridge construction, and can be applied to construction of a cross-river bridge in water. The method comprises the following steps: cleaning an original stone protective layer of a first side river bank protective area, and inserting and driving a steel plate protective pile retaining wall; drilling a protective pile; measuring and placing the pile position, inserting and driving the steel pile casing, and drilling a drilled pile to complete the first main tower pile foundation construction; putting the cofferdam in a pieced assembly mode, pouring bottom sealing concrete in a subarea mode, and pumping water; constructing bearing platforms in times after pile inspection; constructing a tower body structure above the bearing platform after the construction of the bearing platform is completed; and finishing the construction of a first main tower, repeating the construction steps of the first main tower, and finishing the construction of a second main tower, wherein the center distance between the first main tower and the second main tower is 672 m. The invention is suitable for the construction of the river-crossing bridge of the high-speed railway.

Description

Construction method of underwater main tower of cross-river cable-stayed bridge of high-speed railway

Technical Field

The invention relates to the technical field of bridge construction, in particular to a construction method of an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway.

Background

With the construction of the river-crossing high-speed railway, the river-crossing bridge becomes a necessary link in the construction of the high-speed railway. Due to the fact that the river-crossing bridge is built at a position, such as hydrological and geological characteristics near a water area of a Yangtze river, water sources are rich, the surface of a covering layer is mainly plastic cohesive soil, the pile foundation of a main tower foundation is covered by a cohesive soil stratum which is easy to collapse in the water during the construction process of the bridge, and quality requirements on stability and the like of the bridge cannot be reduced due to the fact that the pile foundation of the main tower foundation is in the water, and therefore the construction method for the main tower of the river-crossing cable-stayed bridge of the high-speed railway applicable to the water is needed.

Disclosure of Invention

In view of this, the embodiment of the invention provides a method for constructing an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway, which can be applied to construction of a cross-river bridge in water.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

on one hand, the embodiment of the invention provides a construction method of an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway, the main tower comprises a first main tower and a second main tower, the center distance between the first main tower and the second main tower is 672m, the first main tower is close to a first side dike, the second main tower is close to a second side dike opposite to the first side dike, the pile foundations of the first main tower and the second main tower are formed by arranging 45 pile arrays with the diameter of 3 meters, the pile length of the pile foundation of the first main tower is 49.5-67.5, the pile length of the pile foundation of the second main tower is 38.5-55 m, the first main tower pile foundation and the second main tower pile foundation are provided with bearing platforms which are rectangular, the transverse length of each bearing platform is 55.2m, the longitudinal width of each bearing platform is 36.4m, the thickness of each bearing platform is 7.5m, the elevation of the top of a bearing platform on the first main tower pile foundation is +0.000m, the elevation of the top of a bearing platform on the second main tower pile foundation is +10.000m, and two bearing platforms are respectively provided with a 4m high tower;

wherein, to first main tower construction include: cleaning an original stone protective layer of a first side river bank protective area;

after the field is leveled, inserting and driving a steel plate protecting pile retaining wall;

drilling a first row of protective piles on the first side river bank and at a position close to the first main tower pile foundation by using a rotary drilling rig;

after the first row of protective piles are constructed, a long-arm excavator and a grab ship are used for cleaning the first main tower pile foundation construction position and nearby rubbles;

performing high-pressure rotary jet grouting and sleeve valve flower tube layered grouting on the first side dike;

drilling a second row of protective piles on the first side river bank at a position which is far away from the first main tower pile foundation than the first row of protective piles by using a rotary drilling rig;

arranging crown beams on the first row of protective piles and the second row of protective piles, and connecting the first row of protective piles and the second row of protective piles by using tie beams;

erecting a first drilling platform at the position of a first main tower pile foundation, and erecting a crane pier near the first drilling platform;

arranging a gantry crane on the first drilling platform, and arranging four rotary drilling rigs and a floating crane on the hoisting wharf;

measuring the coordinates of the central point of the pile position by using a total station;

inserting and beating the steel casing by using the gantry crane based on the central point coordinate;

after the steel casing is inserted and driven, drilling piles are respectively drilled at corresponding positions by using 4 rotary drills to complete the construction of a first main tower pile foundation;

and after the construction of the drilled pile is finished, mounting a bracket on the steel pile casing, and connecting the steel pile casing to a high position.

Dismantling the first drilling platform, and assembling the cofferdam in blocks by using a floating crane on the hoisting wharf;

hanging the bottom cofferdam on the bracket;

mounting a hanging beam and a hanging system on the heightened pile casing;

the cofferdam is raised by 1m, and then the bracket on the steel casing is dismantled;

arranging sinking guide on the cofferdam;

synchronously lowering the bottom section cofferdam through 8 continuous jacks of 250 t;

pouring concrete into the bottom cofferdam after the bottom cofferdam enters water and is balanced by self-floating;

dismantling the hanging system;

connecting high top section cofferdams in blocks by using 400t floating cranes;

continuously lowering the cofferdam and the cofferdam to be implanted, and injecting water into the cofferdam wall bin in the process of implantation;

arranging a cofferdam mud sucking platform on the top surface of the steel casing; 8 sludge suction machines are arranged on the cofferdam sludge suction platform;

utilizing the suction dredge to suck mud so that the cofferdam sinks to 2m below the river bed surface;

carrying out concrete construction on the cofferdam wall bin;

and continuously sucking mud in the cofferdam bin, and sinking to the designed elevation.

Leveling the substrate;

and lowering the installation compartment plate along the guide.

Pouring bottom sealing concrete in a subarea manner;

removing the mud suction platform;

pumping water after the bottom sealing concrete reaches the strength;

leveling and cutting off the steel casing;

breaking the pile head and carrying out pile inspection;

constructing a bearing platform twice;

constructing a tower base and a tower column in the cofferdam, and beginning to dismantle the cofferdam after the tower column is higher than the cofferdam to finish the construction of a first main tower;

and repeating the steps of the first main tower construction to finish the construction of the second main tower.

Preferably, the step of erecting a first drilling platform at the position of the first main tower pile foundation and erecting a crane pier near the first drilling platform comprises the steps of:

an overwater pile driving boat is adopted to be matched with a vibration pile driving hammer to insert and drive the overwater positioning steel pipe pile, and other steel pipe piles of the platform are gradually inserted and driven;

the floating crane is used for respectively installing an inter-pile connecting tie beam, a pile top distribution beam, a Bailey beam, a steel bridge deck, a railing and a matched structural device to form a drilling platform;

and a gantry crane is arranged on the drilling platform in the direction of the cross bridge to the cross pier.

Preferably, the assembling of the cofferdam by the floating crane on the crane terminal in blocks comprises the following steps:

determining the type and height of the cofferdam according to the hydrology of the pile position of the first main tower and the stratum condition; the hydrographic and formation conditions include: rainfall and stratum soil texture; the cofferdam is a rectangular double-wall steel boxed cofferdam, the top elevation is +22.350m, the bottom elevation of the cofferdam is-6.600 m, the total height of the cofferdam is 28.95m, the top 3.5m is designed to be a single-wall structure, the thickness of a wall cabin is 2.0m, the wall cabin is filled with 14m high C25 underwater concrete, the water head difference between walls is not more than 7.5m, and three layers of inner supports are arranged in the cofferdam;

according to the determined cofferdam type and height, dividing the cofferdam into two sections in the vertical direction in a factory according to the height of the cofferdam; the height of each section is 13.0 m;

the cofferdam is divided into three parts in the long side direction of the plane and two parts in the short side direction, and the weight of a single cofferdam is 130 t;

after the blocks are prefabricated, the blocks are transported to a first main tower pile position on a construction site by a ship;

after the construction of the cofferdam assembly platform is completed, leveling the base;

marking and lofting on the assembly platform according to the plane position of the cofferdam, and assembling the cofferdam of the bottom section;

during assembly, four corners are positioned firstly, then the four corners are symmetrically assembled by taking the four corners as a reference, and finally the four corners are folded at one side;

and after the assembly is finished, the suspension device arranged on the steel casing is lowered in times.

Preferably, communicating pipes are pre-embedded in a cofferdam wall and a partition wall at the position 20m away from the edge foot surface on the cofferdam, one end of each communicating pipe is positioned in the cofferdam, the other end of each communicating pipe is positioned in a water area outside the cofferdam, and a flange joint for plugging is reserved at the position where the communicating pipe is pre-embedded in the cofferdam wall;

an air supply pipeline and a water supply pipeline are arranged on the cofferdam compartment, and the air supply pipeline and the water supply pipeline are respectively connected with each pipeline on the mud suction machine through rubber pipes.

Preferably, the method comprises the following steps of utilizing the suction dredge to suck mud so that the cofferdam sinks to 2m below the river bed surface or the cofferdam bin to continuously suck mud, and sinking to the designed elevation further comprises the following steps: measuring a reference surface for cofferdam sinking measurement control, arranging four control points on the longitudinal and transverse axes of the cofferdam, and measuring the plane coordinates and elevations of the four control points to determine the center coordinates of the top and bottom surfaces of the cofferdam;

calculating the sinking amount, the angle height difference and the plane torsion angle of the cofferdam based on the central coordinates;

and controlling the sludge suction sinking of the cofferdam according to the sinking amount, the angle height difference and the plane torsion angle of the cofferdam.

Preferably, scale marks are marked on the visible positions of the cofferdam wall plates.

Preferably, the zone-cast closed-bottom concrete comprises:

checking whether the perpendicularity, the plane position and the elevation of the cofferdam are within the range of a design threshold value;

if the cofferdam is not in the design threshold range, continuously sucking mud to adjust the perpendicularity, the plane position and the elevation of the cofferdam;

if the height is within the design threshold range, the vertical guide pipe is distributed underwater at multiple points for perfusion;

in the pouring process, the communicating pipe is utilized to ensure that the height of the water level inside and outside the cofferdam is consistent so as to balance the water pressure.

Preferably, the twice-construction bearing platform comprises:

measuring and releasing the cross axis and the elevation line of the bearing platform after the bored pile is completed and checked, marking, and popping out the outline dimension line of the bearing platform by using an ink line;

manufacturing bearing platform reinforcing steel bars in a factory workshop, and transporting the bearing platform reinforcing steel bars to a construction site;

arranging erection steel bars, a main reinforcement framework and steel bars at the top of the bearing platform at the top of the drilled pile, and binding and fixing;

according to the concrete pouring sequence of the bearing platform, the cooling pipes are independently arranged in different areas along the longitudinal and transverse axes of the bearing platform; the cooling water pipe network is arranged according to the principle that cooling water flows from the central area to the edge area, the water inlets and the water outlets of the cooling pipes of each layer are arranged in a staggered mode, the staggered distance is more than 1.0m, and the cooling pipes are bound and fixed on the erection steel bars and the main steel bar framework;

the cooling water pipes are black-skin steel pipes or seamless steel pipes with the wall thickness of 2.5mm and the diameter of 42mm, 6 layers of horizontal cooling water pipe networks are arranged along the height direction of the bearing platform, the layer spacing is 1.0m, and the distance from the top layer pipe network to the upper surface of the bearing platform and the distance from the bottom layer pipe network to the lower surface of the bearing platform are 1.25 m; the pipe spacing in the pipe network of the same layer is 1.0m, and the outer layer cooling water pipe close to the periphery of the bearing platform is 1m away from the peripheral surface of the bearing platform; after concrete is poured, the water inlet and the water outlet of the pipe network are vertically led out of the top surface of the concrete by more than 0.5m, and a throttle valve and a flowmeter are arranged at the water outlet;

binding and fixedly mounting a temperature sensor on the horizontal steel bar of the bearing platform, and monitoring the temperature of the concrete;

connecting the temperature sensor to a digital display patrol instrument through a cable;

after the embedded parts including the steel bars, the cooling water pipes and the temperature sensors are qualified, carrying out concrete pouring construction;

determining the proportion of concrete for pouring according to the performances of the adopted sandstone materials, cement, fly ash and additives; the initial setting time of the concrete is not less than 20 h; the slump is 16-20 cm;

calculating the concrete consumption of the bearing platform, and pouring concrete twice based on the consumption;

laying a scaffold on the erected steel reinforcement framework as a pouring platform;

arranging two HBT-80 type ground pumps on a platform, and pouring for the first time by two HG28F1-A1 material distributors, wherein the height of the concrete poured for the first time is 4m, and the square amount is 8110.56 m;

arranging a chute and a stringing barrel on a bearing platform according to the flowing radius of the concrete;

when concrete poured by the distributing machine for the first time enters the template, the free falling height of the concrete is not more than 2 m;

the concrete is poured in an inclined layered mode, and the pouring sequence is from the upstream to the downstream and from two sides

The concrete is obliquely layered towards the middle and gradually pushed, the thickness of the layering is 30cm, and continuous construction is not interrupted in the construction process;

in the concrete pouring process, a ZN50 vibrating spear and a ZN70 vibrating spear are adopted to be matched with the concrete in the vibrating cofferdam, a ZN35 vibrating spear is prepared, and the vibration is strengthened at the position with a small steel bar gap;

when the concrete is vibrated, the vibrating rod is inserted into the next layer to a preset depth; the preset depth is 5-10 cm;

the vibrating rod needs to be quickly inserted and drawn out, and the movement distance is not more than 1.5 times of the action radius of the vibrating rod;

the insertion points move uniformly, in a row or in a staggered manner during vibration so as to avoid leakage vibration;

each vibration time is about 30s to avoid under vibration or over vibration, and after the vibration is finished, the vibrating rod is pulled out while vibrating;

stopping vibrating when the concrete does not sink any more, bubbles do not appear any more and the surface begins to be flooded;

after the concrete pouring of the first bearing platform is finished and the strength of the concrete reaches 2.5MPa, chiseling the surface of the concrete to expose fresh and hard stones, binding reinforcing steel bars of the second bearing platform after cleaning, embedding a tower seat and lower tower column embedded ribs, and installing a bracket beside a pier, a cooling water pipe, a temperature sensor and a measurement control point;

after acceptance, repeating the steps, and pouring concrete of the bearing platform for the second time to complete the construction of the bearing platform; the second bearing platform concrete pouring height is 3.5m, and the square amount is 7096.74 m.

Preferably, short steel bars are welded on the top surface of the vertically arranged temperature sensor;

when the concrete is vibrated, the distance between the vibrating rod and the inner wall is kept between 5 and 10cm when the vibrating rod vibrates around the inner wall of the cofferdam;

the distance between the cooling water pipe and the temperature measuring element is kept at 20cm, so that the cooling water pipe and the temperature sensor cannot be collided;

during the concrete pouring process, the method further comprises the following steps: when the cooling water pipe of a certain area is completely covered by concrete for 50cm, the cooling water pipe of the area is filled with water for curing.

Preferably, the construction of the tower base and the tower column in the cofferdam comprises the steps of:

respectively installing a 480t.m tower crane on the upstream and downstream of a tower column, a hoisting device for main tower and tower column construction, arranging an elevator on a single main tower, and arranging two tower cranes according to the diagonal line of the central line of a bridge;

pouring to finish the construction of the first main tower base and the second main tower base;

the positions and the center distances of the two towers are measured in a combined mode, the measured positions and the center distances are checked with completion data, accurate positions are determined, and measuring points are released;

cleaning the concrete surface of the tower base according to the position and the elevation of the measuring point, and adjusting the connecting steel bar;

manufacturing a stiff framework according to tower column sections in sections, and installing a bottom section stiff framework on an embedded part of a tower base;

the other sections of stiff frameworks are installed in a butt joint mode according to the inclination of the tower column, so that the stiff frameworks and the tower column are consistent in inclination;

prefabricating reinforcing steel bars in a reinforcing steel bar workshop on the bank, transporting the reinforcing steel bars to a construction site, sleeving stirrups on reserved vertical bars at the top of a tower column, connecting tower column connecting long bars with tower column extending reinforcing steel bar joints, and staggering the joints up and down;

when the stirrups are bound, a plurality of concrete cushion blocks are bound on the outer sides of the vertical reinforcements;

the outer mold of the lower tower column is constructed in sections by adopting a hydraulic creeping formwork method, the inner mold is constructed in sections by adopting a wood mold reverse mold method, and the section height is 4.5 m;

the inner and outer molds of the hollow section of the lower tower column are connected into a whole by pulling the stiff frameworks of the tower column through pull rods, the pull rods of the template of the solid mixed section are connected and fixed with the stiff frameworks, the stiff frameworks of the tower column are connected into a whole, and the stiff frameworks are used for bearing the lateral pressure during concrete pouring;

pouring to finish the construction of the lower tower column, dismantling the template and storing in a classified manner;

a metal corrugated pipe and a steel strand are arranged in the lower cross beam in a penetrating way, and the lower cross beam is cast twice by adopting a floor type support;

pouring the mixture to the middle of the lower cross beam for the first time, and pouring the mixture to an upper chamfer of the lower cross beam for the second time;

after pouring is finished, prestress tensioning is carried out on the lower cross beam;

after tensioning is finished, carrying out vacuum auxiliary grouting on a prestressed duct formed by the metal corrugated pipe;

connecting two ends of the prestressed duct with sealing valves, connecting a vacuum pump to the non-grouting end of the prestressed duct, connecting a grouting pump to the grouting end of the prestressed duct, and connecting a negative pressure container, a three-way valve and an anchor device cap in series, wherein the anchor device cap and the three-way valve are connected by a transparent throat pipe;

testing the evacuation, comprising: closing the mud jacking valve and the exhaust valve, opening the vacuumizing valve, starting the vacuum pump to vacuumize the prestressed duct, observing the reading of a vacuum pressure gauge, stopping the pump for about 1min when the vacuum degree in the prestressed duct is maintained at 0.08MPa, and determining that the duct can reach the preset vacuum degree if the pressure can be kept unchanged;

stirring the weighed concrete raw materials for about 2min, deducting water of the water reducing agent, pouring the mixture into a stirrer for stirring, discharging the cement paste, pumping, and continuously stirring the cement paste which is not pumped;

adding cement slurry into a slurry storage tank, leading the cement slurry to a grouting pump, grouting slurry at an outlet of a high-pressure rubber pipe of the grouting pump, turning off the grouting pump when the concentration of the slurry is the same as that of the grouting pump, connecting the high-pressure rubber pipe end to a grouting pipe of a pore passage, fastening and closing a grouting valve;

starting a vacuum pump, opening a grouting valve when the vacuum value reaches and is maintained at a value of 0.06-0.1 MPa, starting a grouting pump, and starting grouting, wherein the vacuum pump keeps continuously working in the grouting process;

when slurry passes through the transparent throat pipe at the vacuumizing end, closing a vacuum valve at the front end of the vacuum machine, closing the vacuum machine, enabling the cement slurry to automatically and smoothly flow out of the non-return exhaust valve, observing whether the corrugated pipe is filled with the cement slurry or not from the transparent throat pipe, closing a valve at the vacuumizing end when the consistency of the cement slurry is consistent with that of the injected slurry, and keeping the pressure at 0.4MPa to continue grouting for half a minute;

closing a valve arranged at the pulp outlet of the grouting pump, and closing the grouting pump;

after grouting, sealing the anchor, and adopting concrete with the same grade as the tower column;

after the anchor is sealed, the external pipeline is disassembled, an air filter and a pipeline valve of the vacuum machine are cleaned, a grouting pump, a stirrer, equipment and accessories which are stained with cement paste are cleaned, and the construction of the lower cross beam is completed;

repeating the construction step of the lower tower column, and constructing the centering tower column sections by adopting an automatic hydraulic creeping formwork;

assembling three steel pipe cross braces between the middle tower column of the first main tower and the middle tower column of the second main tower by using steel members;

a jack is arranged at the end part of the cross brace to jack the cross brace to the designed internal force and tightly fill the cross brace so as to control the bending moment and the deformation of the tower column;

the upper cross beam is constructed by adopting a bracket, brackets are embedded in the tower when a tower column is constructed, two ends of the bracket are supported on the bracket embedded parts, and the construction step of the lower cross beam is repeated to finish the construction of the upper cross beam;

constructing the upper tower column by adopting a creeping formwork construction method, observing the deformation condition of the tower column in the construction process, and well recording the compression deformation of the tower column and the foundation settlement;

based on the compression deformation of the tower column and the foundation settlement record, the elevation of the tower column is adjusted when the tower column is constructed to the bottom of the first section of steel anchor box;

positioning and measuring the first section of steel anchor box, and assembling the first section of steel anchor box based on the measured positioning points;

after the construction of the first section of steel anchor box is completed, connecting the upper part of the tower column to the upper part of the tower column, and repeating the construction steps of the lower tower column to complete the construction of other structures of the upper tower column;

and anchoring the stay cables on the upper tower columns of the first main tower and the second main tower, and grouting and fixing the stay cable anchoring areas.

The embodiment of the invention provides a construction method of an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway, wherein the main tower comprises a first main tower and a second main tower, and the construction of the first main tower comprises the following steps: cleaning an original stone protective layer of a first side river bank protective area; after the field is leveled, inserting and driving a steel plate protecting pile retaining wall; drilling a first row of protective piles on the first side river bank and at a position close to the first main tower pile foundation by using a rotary drilling rig; after the first row of protective piles are constructed, a long-arm excavator and a grab ship are used for cleaning the first main tower pile foundation construction position and nearby rubbles; performing high-pressure rotary jet grouting and sleeve valve flower tube layered grouting on the first side dike; drilling a second row of protective piles on the first side river bank at a position which is far away from the first main tower pile foundation than the first row of protective piles by using a rotary drilling rig; arranging crown beams on the first row of protective piles and the second row of protective piles, and connecting the first row of protective piles and the second row of protective piles by using tie beams; erecting a first drilling platform at the position of a first main tower pile foundation, and erecting a crane pier near the first drilling platform; arranging a gantry crane on the first drilling platform, and arranging four rotary drilling rigs and a floating crane on the hoisting wharf; measuring the coordinates of the central point of the pile position by using a total station; inserting and beating the steel casing by using the gantry crane based on the central point coordinate; after the steel casing is inserted and driven, drilling piles are respectively drilled at corresponding positions by using 4 rotary drills to complete the construction of a first main tower pile foundation; after the construction of the drilled pile is finished, a bracket is arranged on the steel casing, and the casing is connected with the high part; dismantling the first drilling platform, and assembling the cofferdam in blocks by using a floating crane on the hoisting wharf; hanging the bottom cofferdam on the bracket; mounting a hanging beam and a hanging system on the heightened pile casing; the cofferdam is raised by 1m, and then the bracket on the steel casing is dismantled; arranging sinking guide on the cofferdam; synchronously lowering the bottom section cofferdam through 8 continuous jacks of 250 t; pouring concrete into the bottom cofferdam after the bottom cofferdam enters water and is balanced by self-floating; dismantling the hanging system; connecting high top section cofferdams in blocks by using 400t floating cranes; continuously lowering the cofferdam and the cofferdam to be implanted, and injecting water into the cofferdam wall bin in the process of implantation; arranging a cofferdam mud sucking platform on the top surface of the steel casing; 8 sludge suction machines are arranged on the cofferdam sludge suction platform; utilizing the suction dredge to suck mud so that the cofferdam sinks to 2m below the river bed surface; carrying out concrete construction on the cofferdam wall bin; and continuously sucking mud in the cofferdam bin, and sinking to the designed elevation. Leveling the substrate; a cabin separation plate is arranged along the guide downward placement; pouring bottom sealing concrete in a subarea manner; removing the mud suction platform; pumping water after the bottom sealing concrete reaches the strength; leveling and cutting off the steel casing; breaking the pile head and carrying out pile inspection; constructing a bearing platform twice; constructing a tower base and a tower column in the cofferdam, and beginning to dismantle the cofferdam after the tower column is higher than the cofferdam to finish the construction of a first main tower; the step of the first main tower construction is repeated to complete the construction of the second main tower, and the method can be applied to the construction of the river-crossing bridge in water; further, because the original stone protective layer in the river levee protecting region is cleaned before the pile foundation construction, the construction of the steel plate protective pile retaining wall is carried out, the collision of external force in the construction process of the main tower pile foundation can be avoided, the cofferdam is arranged, water or silt and the like in the construction region are prevented from entering the pile foundation construction region, so that the quality of the constructed pile foundation is ensured, grouting layering is further carried out on the foundation near the pile foundation, grouting can be carried out aiming at the geological characteristics of different soil layers to harden the foundation, bottom sealing hardening treatment is carried out after the cofferdam foundation is leveled, and the stability of the constructed main tower after completion can be ensured to a certain extent.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a construction process of an underwater main tower of a cross-river cable-stayed bridge of a high-speed railway according to an embodiment of the invention;

FIG. 2 is a schematic diagram of a construction layout structure of a guard wall of steel sheet pile inserted and driven according to an embodiment of the invention;

FIG. 3 is a schematic diagram of a cofferdam assembly construction layout structure according to an embodiment of the invention;

FIG. 4 is a schematic structural view illustrating a process of lowering a cofferdam according to the present invention;

FIG. 5 is a schematic view of a top cofferdam elevation and implantation construction structure according to an embodiment of the present invention;

FIG. 6 is a schematic view of the structure of the cofferdam for absorbing sludge and sinking the cofferdam of the present invention;

FIG. 7 is a schematic view of the construction of pumping water from the bottom cover after the cofferdam is sunk in place;

FIG. 8 is a schematic view of a construction structure of a bearing platform according to an embodiment of the present invention;

fig. 9 is a schematic view of a tower base and a tower column according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The method for constructing the underwater main tower of the high-speed railway cross-river cable-stayed bridge can be suitable for construction of a cross-river bridge in water, and is particularly suitable for construction of the cross-river bridge of the high-speed railway.

The king-tower includes first king-tower and second king-tower, the centre-to-centre spacing of first king-tower and second king-tower is 672m, first king-tower is close to first side river dike, the second king-tower is close to the second side river dike relative with first side river dike, the pile foundation of first king-tower and second king-tower is arranged by 45 root diameters for 3 meters's pile array and is formed, and the pile length of constituteing first king-tower pile foundation is 49.5 ~ 67.5, and the pile length of constituteing second king-tower pile foundation is 38.5 ~ 55m be equipped with the pile foundation cushion cap on first king-tower and the second king-tower, the cushion cap is the rectangle, and cushion cap horizontal length 55.2m, vertical wide 36.4m, thick 7.5m, cushion cap top elevation on the first king-tower pile foundation is +0.000m, and the cushion cap top elevation on the second king-tower is +10.000m, establishes the high tower of 4m respectively on two cushion caps.

As shown in fig. 1 to 9, the construction of the first main tower includes: cleaning an original stone protective layer 01 in a protective area of a first side river dike J; after the field is leveled, inserting and driving a steel plate protecting pile retaining wall; drilling a first row of fender piles 1 on a first side dike J and at a position close to a first main tower pile foundation by using a rotary drilling rig; after the first row of protective piles are constructed, a long-arm excavator and a grab ship are used for cleaning the first main tower pile foundation construction position and nearby rubbles; performing high-pressure rotary jet grouting and sleeve valve flower tube layered grouting on the first side dike; and drilling a second row of fender piles 2 on the first side river bank at a position far away from the first main tower pile foundation than the first row of fender piles by using the rotary drilling rig.

And arranging crown beams 3 on the first row of fender piles and the second row of fender piles, and connecting the first row of fender piles and the second row of fender piles by using tie beams 4.

Erecting a first drilling platform at the position of a first main tower pile foundation, and erecting a crane pier near the first drilling platform; and a gantry crane is arranged on the first drilling platform, and four rotary drilling rigs and a floating crane are arranged on the hoisting wharf.

Measuring the coordinates of the central point of the pile position by using a total station; and inserting and beating the steel casing by using the gantry crane based on the central point coordinate.

And after the steel casing is inserted and driven, drilling piles are respectively drilled at corresponding positions by using 4 rotary drilling rigs so as to complete the construction of the first main tower pile foundation.

In this embodiment, 4 rotary drilling rigs are respectively configured for drilled pile construction, the number of each rotary drilling rig is 2, namely, BG 46 type and TR550 type, drilled pile construction is synchronously performed, and 45 drilled piles in a pier position (pile foundation) are completed in 12 cycles.

The construction of the concrete bored pile comprises the following steps: building a drilling platform, measuring and paying off the pile foundation, inserting and drilling a steel casing, and retesting whether the drilling position is consistent with the design of the pile foundation or within the allowable range of the design tolerance after the drilling machine is in place; and after the retest is finished, if the drilling position is consistent with the pile foundation design standard, preparing the drilling mud by adopting 2 mixers in the 6 halls. After being mixed, the mud is stored in a mud boat for standby, and the mud boat is provided with a plurality of 3PN mud pumps for pumping the mud to each required point; before opening the hole, adopting hole to make slurry; in the drilling process: directly replenishing slurry by a slurry ship or a slurry mixing tank; cleaning holes and replacing pulp; hole shape detects, accomplishes the back and makes and transfer the steel reinforcement cage, and the steel reinforcement cage is transferred to design position department, transfers the pipe, and the pipe is demolishd to the cast-in-place concrete, and pile foundation detects, accomplishes the bored pile construction.

After the construction of the drilled pile is finished, a bracket is arranged on the steel casing, and the casing is connected with the high part; and (4) dismantling the first drilling platform, and assembling the cofferdam in blocks by using a floating crane on the hoisting wharf.

In this embodiment, after the bored pile construction is completed, part of the bored platform structure affecting the subsequent construction is removed, a steel cofferdam assembly platform is arranged, the cofferdam is assembled in sections at pier positions by utilizing the platform, meanwhile, a high steel pile casing is connected, a cofferdam transfer system is arranged, and guiding and positioning are arranged on the cofferdam. After the bottom cofferdam is assembled, the cofferdam is lowered by a certain height and edge concrete is poured, so that the top cofferdam is hoisted and connected, the cofferdam is assembled in a floating state, the top cofferdam is continuously connected, the top cofferdam is assembled and is free of errors after being checked, the cofferdam is lowered to be implanted, the cofferdam is supported in a riverbed stably by means of dead weight through preliminary adjustment, wall cabin concrete is poured, and then the cofferdam is lowered to the designed elevation through measures such as symmetrical mud suction and water jetting.

The partitioned assembled cofferdam specifically comprises:

hanging the bottom cofferdam on the bracket; mounting a hanging beam and a hanging system on the heightened pile casing;

the cofferdam is raised by 1m, and then the bracket on the steel casing is dismantled; arranging sinking guide on the cofferdam;

dismantling the hanging system; connecting high top section cofferdams in blocks by using 400t floating cranes;

carrying out concrete construction on the cofferdam wall bin;

Leveling the substrate; and lowering the installation compartment plate along the guide.

Pouring bottom sealing concrete in a subarea manner; removing the mud suction platform;

pumping water after the bottom sealing concrete reaches the strength;

leveling and cutting off the steel casing;

breaking the pile head and carrying out pile inspection;

constructing a bearing platform twice; constructing a tower base and a tower column in the cofferdam, and beginning to dismantle the cofferdam after the tower column is higher than the cofferdam to finish the construction of a first main tower; and repeating the steps of the first main tower construction to finish the construction of the second main tower.

The method further comprises the steps of: chiseling the part of the bottom sealing concrete higher than the elevation of the bottom surface of the bearing platform, filling broken stones in the part lower than the elevation of the bottom surface of the bearing platform, and leveling by using mortar, wherein the thickness of the mortar is not less than 2 cm;

in this embodiment, the construction of first main tower pile foundation specifically includes: measuring and lofting; the measurement lofting specifically comprises: building a drilling platform, determining a pile position by using a total station coordinate lofting method, and setting a leveling point; and measuring the central point of the pile position by using a total station, arranging four-point guide piles, and measuring the elevation of the leveling point by using a triangular elevation method.

Inserting and beating a protective cylinder; the method specifically comprises the following steps: based on the central point of the pile position and the guide pile, arranging a guide frame on the drilling platform, wherein the guide frame is used for guiding and positioning the pile casing; the guide frame comprises an upper guide frame and a lower guide frame.

During specific construction, the lower guide frame can be manufactured in a larger number, for example, 45 sleeves, due to more than one pile position. The upper guide frame can be made into a small number and can be recycled, for example, 6 sets.

According to the hoisting construction sequence when the steel casing is sunk, the steel casing is loaded and transported to the position near the drilling platform layer by layer; this can reduce secondary dumping. The cross supports are arranged at the two ends and the middle part in each section of steel casing to ensure that the steel casing is not deformed in the manufacturing, transporting and hoisting processes; and lifting rings are arranged at the positions of the steel pile casings, which are 0.5-0.8 m away from the two ends, so that the steel pile casings can be lifted conveniently. The crane ship horizontally lifts the steel casing from the transport ship and places the steel casing on the drilling platform; the shipping steel protective cylinder is fixed by adopting a transportation jig frame, is provided with a skid and is fastened by a steel wire rope to prevent rolling; and the carrier is strictly inspected and necessary reinforcement measures are taken. The length of the steel pile casing can be determined according to the water depth, geology, scouring condition and drilling requirement at the pile position, the inner diameter of the steel pile casing is 35cm larger than the pile diameter, for example, when the pile diameter is 3m, the inner diameter of the steel pile casing is 3.35 m; the steel casing is made by rolling a steel plate with the thickness of 24mm, and a single steel casing weighs about 88 tons. In one embodiment, the length of the bottom section of the steel casing is 18m, the length of the middle section of the steel casing is 18m, and the length of the top section of the steel casing is 8 m; in another combination, the length of the bottom section of the steel casing is 16 or 18m, the length of the middle section is 16m, and the length of the top section is 12m or 10 m; the design elevation of the bottom of the steel casing is-19.16 m so as to enter a stable fine gravel soil layer and ensure the stability of a pile foundation.

In one embodiment of the invention, as the steel casing has a large diameter and a long penetration depth, in order to ensure that the top opening and the bottom opening of the steel casing are not damaged in the insertion and driving process, a 10mm thick steel plate is respectively adhered and welded in the height range of 50cm of the top opening of the steel casing, and a 20mm thick steel plate is adhered and welded in the range of 100cm of the bottom opening of the steel casing for reinforcement, so that the smooth construction of the large-diameter cast-in-place pile can be better ensured.

The 200t floating crane is matched with 1 crawler crane or 2 crawler cranes, and the first section of steel casing is lifted and erected through the lifting rings at the two ends of the top end and the bottom; wherein the steel casing is transported to the drilling platform and is responsible for 200t of floating crane; the erection is carried out by 200t floating crane and 1 crawler crane or 2 crawler cranes; in the process of height connection and inserting driving, a 130t crawler crane, a 100t gantry crane or a 200t floating crane are used for hoisting; before hoisting and erecting or transporting, the quality, particularly the diameter, the line shape and the ovality of the steel casing are required to be checked, and a lifting lug at the top of the casing is checked.

And lifting and erecting the first section of steel pile casing to keep the bottom of the pile casing to be higher than the drilling platform by a preset distance, such as about 1.0 m. Cutting off the lower part of the cross-shaped support at the bottom of the first section of the protective cylinder; and hanging a first section of steel protecting cylinder to slowly sink into the annular guide hole of the guide frame until a lifting lug at the upper end of the first section of steel protecting cylinder touches a guide positioning frame at the top end of the annular guide hole.

In this embodiment, the pile casing is hung and is put into the stake hole and will slowly transfer, because the space between annular guiding hole and the steel casing is little, when the steel casing is put down to annular guiding hole top surface, if the position is not adjusted well, should rotate the steel casing and make it automatic entering guiding hole in, strictly forbid the high-rise impactedly drop and protect a section of thick bamboo.

Supporting the first section of steel casing at the top end of the annular guide hole through the lifting lug; and a plumb bob is vertically hung on the first guide wheel assembly and the second guide wheel assembly arranged at the tops of the guide piles or the guide frames in the 4 vertical directions so as to detect the verticality of the first section of pile casing. And if the verticality of the first section of steel casing is detected not to be in the verticality range required by the design, adjusting the verticality of the first section of steel casing to be in the verticality range required by the design, for example, adjusting the verticality of the steel casing to be within 1/250, and continuing to be supported at the top end of the annular guide hole through the lifting lug. The method for hoisting the first section of steel casing is repeated, and a second section of steel casing (namely the middle section of steel casing) is hoisted to be aligned to the top end of the first section of steel casing and is welded with the top end of the first section of steel casing into a whole in an alignment way; after welding, cutting off a lifting lug and an inner cross-shaped support of a first section of protective cylinder, adjusting the verticality of the welded steel protective cylinder, and controlling the plane position and the vertical position of the steel protective cylinder by using a total station and a plumb bob so as to control the level and the verticality of the steel protective cylinder; after welding is completed, ultrasonic flaw detection of the weld is also required. Slowly lowering the casing, inserting the casing into a riverbed stable soil layer, and supporting the casing at the top end of the annular guide hole by using a second section of lifting lug; the APE400B is lifted by the loose hook to vibrate the pile driver to drive the pile casing downwards until the top surface of the steel pile casing is 1.0m higher than the drilling platform. The APE400 twin hydraulic vibratory pile driver suspended weight was 55 tons, maximum power (738 x 2) kW, maximum excitation force 640.6 t. Repeating the processes of lifting, inserting and piling of the second section of steel casing, aligning the top end of the second section of steel casing, welding a third section of steel casing, and inserting and beating to the preset design depth of the riverbed; and connecting the steel casing which is inserted and drilled to the preset design depth with the drilling platform.

In this embodiment, after the first pile position steel casing is constructed, the above steps are repeated to complete the construction of other pile position steel casings. The following quality requirements need to be met after the construction of the steel casing at each pile position is completed: the perpendicularity of the steel casing must meet the following requirements: meeting the requirements of bored pile construction, namely the perpendicularity of the bored pile does not exceed 1/250, and the deviation of the plane position of the bored pile does not exceed 50 mm; and secondly, inserting and punching perpendicularity precision of the steel casing can not prevent the steel pouring jacket cofferdam from being lowered, and mainly the relationship between the fixed guide ring adjustment amount of the cofferdam and casing deviation is realized.

The quality of the steel casing can meet the design requirement: deviation of outer perimeter: +10mm, -0 mm; ovality: not more than 5 mm; ③ the inclination of the end plane: not greater than 2 mm; fourthly, flatness of the end part: not greater than 2 mm; welding seams: the undercut depth is less than 0.5mm, and the height of the butt weld is increased by 1-3 mm; covering the butt weld seam by 3-4 mm of the width of the groove; sixthly, edge joint dislocation of the butt joint plates: not greater than 2 mm; seventh, joint groove deviation: 5 degrees; eighthly, pipe diameter deviation of adjacent pile positions: not greater than 2 mm; ninthly, the longitudinal bending rise of the protective cylinder is not more than 1/1000 of the length and not more than 10 mm; e, checking weld quality of casing in red (R): and (4) performing ultrasonic flaw detection spot check on the sample by 40 percent. Polishing a smooth circle for drilling a steel casing; drilling holes are needed for punching the lug plates of the lifting lugs, and the holes are strictly forbidden; the sinking process of the steel casing and various technical data after sinking are not more than the allowable deviation of design and specification.

Positioning a drilling machine; driving the rotary drilling rig to a hole site to be constructed, adjusting the angle of a drill rod, aligning the center of a drill bit with the center of a hole channel surrounded by a steel casing, putting the drill bit into the hole channel surrounded by the steel casing, adjusting the horizontal and vertical parameters of a platform of the drilling rig to enable the drill rod to be vertical, and simultaneously lifting the drilling tool; in one embodiment, the rotary drilling rig is provided with 5 stations for circularly drilling a plurality of pile positions of the tower pier.

Measuring and releasing the elevation of the top of the protective cylinder, the ground and the level point of the drilling machine platform, and adjusting the deviation between the center of the drill bit and the center of the top surface of the protective cylinder within a design tolerance range; drilling to form a hole; drilling a hole by adopting a slurry protection wall; the drilling mud is PHP high-quality bentonite chemical mud with non-dispersion, low solid phase and high viscosity. The slurry is composed of raw materials such as high-quality bentonite, alkali (1) aaG03, carboxymethyl cellulose (GMG) and polyacrylamide CPHP), and the water for pulping is river water nearby. The drilling holes are formed by adopting slurry to protect the wall, and the slurry plays a wall protecting role in the drilling process.

In one embodiment of the present invention, the step of supporting a first drilling platform at a first main tower pile foundation position, wherein a crane pier is supported near the first drilling platform comprises the steps of: an overwater pile driving boat is adopted to be matched with a vibration pile driving hammer to insert and drive the overwater positioning steel pipe pile, and other steel pipe piles of the platform are gradually inserted and driven; the floating crane is used for respectively installing an inter-pile connecting tie beam, a pile top distribution beam, a Bailey beam, a steel bridge deck, a railing and a matched structural device to form a drilling platform; and a gantry crane is arranged on the drilling platform in the direction of the cross bridge to the cross pier.

In this embodiment, as an optional embodiment, the assembling the cofferdam by the floating crane on the crane pier in blocks includes the steps of: determining the type and height of the cofferdam according to the hydrology of the pile position of the first main tower and the stratum condition; the hydrographic and formation conditions include: rainfall and stratum soil texture; the cofferdam is a rectangular double-wall steel boxed cofferdam, the top elevation is +22.350m, the bottom elevation of the cofferdam is-6.600 m, the total height of the cofferdam is 28.95m, the top 3.5m is designed to be a single-wall structure, the thickness of a wall cabin is 2.0m, the wall cabin is filled with 14m high C25 underwater concrete, the water head difference between walls is not more than 7.5m, and three layers of inner supports are arranged in the cofferdam; according to the determined cofferdam type and height, dividing the cofferdam into two sections in the vertical direction in a factory according to the height of the cofferdam; the height of each section is 13.0 m. In a specific embodiment, the type and height of the cofferdam are determined according to construction parameters and characteristics.

The cofferdam is divided into three parts in the long side direction of the plane and two parts in the short side direction, and the weight of a single cofferdam is 130 t; after the blocks are prefabricated, the blocks are transported to the first main tower pile position on a construction site by a ship. How to divide blocks on a plane needs to be comprehensively considered in combination with hoisting capacity, hoisting requirements and manufacturing and transportation requirements. In one embodiment, the plane is divided into 10 blocks, the long side direction is divided into 3 blocks (including right-angle sections), the short side direction is divided into 2 blocks, the weight of each block of cofferdam is about 130t, and 400t of full-rotation floating crane assembly is adopted in the construction process, so that the construction speed can be increased. Cofferdam plane block

After the construction of the cofferdam assembly platform is completed, leveling the base; marking and lofting on the assembly platform according to the plane position of the cofferdam, and assembling the cofferdam of the bottom section; during assembly, four corners are positioned firstly, then the four corners are symmetrically assembled by taking the four corners as a reference, and finally the four corners are folded at one side; after the assembly is completed, the suspension device arranged on the steel casing is used for lowering the steel casing in times.

When the top cofferdam is connected to be high, the cofferdam is not bedded, assembly is carried out in a floating state, namely the assembly weight of the top cofferdam is borne by the buoyancy of the bottom cofferdam, and the hanging and lowering system is used for auxiliary guiding adjustment. And (4) assembling the top section cofferdam, putting the cofferdam down to a bed, and supporting the cofferdam in the riverbed stably by means of self weight through preliminary adjustment.

In one embodiment of the invention, communicating pipes are pre-embedded on the cofferdam, the cofferdam wall and the partition wall at the position 20m away from the edge foot surface and used for supplementing water in the cofferdam, one end of each communicating pipe is positioned in the cofferdam, the other end of each communicating pipe is positioned in a water area outside the cofferdam, and a flange joint for plugging is reserved at the position where the communicating pipe is pre-embedded on the cofferdam wall; an air supply pipeline and a water supply pipeline are arranged on the cofferdam compartment, and the air supply pipeline and the water supply pipeline are respectively connected with each pipeline on the mud suction machine through rubber pipes.

In another embodiment of the present invention, the sinking of the cofferdam to 2m below the river bed surface or in the cofferdam chamber by using the suction dredge to suck the mud further comprises the following steps: measuring a reference surface for cofferdam sinking measurement control, arranging four control points on the longitudinal and transverse axes of the cofferdam, and measuring the plane coordinates and elevations of the four control points to determine the center coordinates of the top and bottom surfaces of the cofferdam; calculating the sinking amount, the angle height difference and the plane torsion angle of the cofferdam based on the central coordinates; and controlling the sludge suction sinking of the cofferdam according to the sinking amount, the angle height difference and the plane torsion angle of the cofferdam.

In the embodiment, the mud suction is carried out according to the principles of 'first middle and then back, layered symmetrical ground breaking, first high and then low, and timely deviation correction'. In order to meet the requirement of 0.5m/d sinking progress, the soil output is not less than 1400 jin each day, and 4-6 mud suction machines are suitable to be started.

Wherein, inhale mud equipment includes: air suction dredge, mud pipe, air pipe and its fittings. And a high-pressure air supply pipeline and a high-pressure water supply pipeline are also arranged on the cofferdam compartment and are connected with each pipeline on the sludge suction machine through rubber pipes. When the mud is sucked, the high-pressure water jet pipe and the air mud sucking device are fixed together, and water jet and mud sucking are carried out synchronously. The water injection pipe and the mud suction pipe move up and down together, and the mud suction pipe sucks water while flushing, so that the mud suction effect can be ensured, and the water injection pressure is controlled to be 1.5-2.5 MPa. When the cofferdam is inclined very little, the height difference of the soil surface in each compartment is controlled within 1 m. The depth of the bottom of the cofferdam bulkhead in the middle of the cofferdam bulkhead should be controlled within 0.5-1.5 m to prevent the bottom of the cofferdam from being deep and sinking. If the cofferdam is inclined, deviated or twisted in the sinking process of the cofferdam, the cofferdam is processed by adopting modes of bias voltage, eccentric mud suction and the like.

In order to facilitate direct observation of the sinking amount, measuring ropes are arranged in the sinking process of the cofferdam, and scale marks are marked on the visible positions of the cofferdam wall plates.

In yet another embodiment of the present invention, the zone cast closed-bottom concrete comprises: checking whether the perpendicularity, the plane position and the elevation of the cofferdam are within the range of a design threshold value; if the cofferdam is not in the design threshold range, continuously sucking mud to adjust the perpendicularity, the plane position and the elevation of the cofferdam; if the design threshold value range is within the range, adopting vertical guide pipes to perform multipoint underwater arrangement to pour concrete; in the pouring process, the communicating pipe is utilized to ensure that the height of the water level inside and outside the cofferdam is consistent so as to balance the water pressure.

In this embodiment, at the final stage of cofferdam bottom sealing concrete, concrete is sampled, and a same-condition maintenance test piece is manufactured in a laboratory for monitoring the concrete strength development condition.

In yet another embodiment of the present invention, the water is pumped from the cofferdam when the strength of the back cover concrete is monitored to reach the predetermined design strength. And (4) accurately releasing the height of the bottom of the bearing platform on the steel casing by a measurer, and marking.

And (4) cutting off the steel casing above the pile top, and cleaning the surface of the bottom sealing concrete. And chiseling the part of the bottom sealing concrete higher than the elevation of the bottom surface of the bearing platform, filling broken stones into the part lower than the elevation of the bottom surface of the bearing platform, and leveling by using mortar (the thickness is not less than 2 cm). And the top surface elevation of the leveled foundation pit reaches the design requirement.

In one embodiment of the present invention, the two-time construction bearing platform includes: measuring and releasing the cross axis and the elevation line of the bearing platform after the bored pile is completed and checked, marking, and popping out the outline dimension line of the bearing platform by using an ink line; and manufacturing bearing platform reinforcing steel bars in a factory workshop, and transporting the bearing platform reinforcing steel bars to a construction site.

Arranging erection steel bars, a main reinforcement framework and steel bars at the top of the bearing platform at the top of the drilled pile, and binding and fixing; the steel bar is bound by adopting a binding wire with the diameter of 0.7-1.2 mm and bound at intervals, and the main reinforcement framework is bound firmly. When the reinforcing steel bars of the bearing platform collide with the pile head reinforcing steel bars of the drilled pile, the position of the bearing platform reinforcing steel bars can be properly moved. Steel bar protective layer: concrete cushion blocks are bound outside the steel bars on the side surface and the top of the bearing platform, the strength of the concrete cushion blocks is not less than the design strength of the concrete of the bearing platform, the cushion blocks of the protective layer are arranged in a staggered mode, the distance is about 1.0m, and the cushion blocks are arranged in a quincunx mode; the bottom of the bearing platform adopts erecting steel bars to reserve a concrete protective layer.

the cooling water pipes are black-skin steel pipes or seamless steel pipes with the wall thickness of 2.5mm and the diameter of 42mm, 6 layers of horizontal cooling water pipe networks are arranged along the height change direction of the bearing platform, the layer spacing is 1.0m, and the distance from the top layer pipe network to the upper surface of the bearing platform and the distance from the bottom layer pipe network to the lower surface of the bearing platform are 1.25 m; the pipe spacing in the pipe network of the same layer is 1.0m, and the outer layer cooling water pipe close to the periphery of the bearing platform is 1m away from the peripheral surface of the bearing platform; after concrete is poured, the water inlet and the water outlet of the pipe network are vertically led out of the top surface of the concrete by more than 0.5m, and a throttle valve and a flowmeter are arranged at the water outlet;

binding and fixedly mounting a temperature sensor on the horizontal steel bar of the bearing platform, and monitoring the temperature of the concrete; the temperature change sensor is used as a temperature measuring element to monitor the temperature of the concrete and aims to improve the temperature control effect.

A thermocouple is used as a temperature sensor, the temperature sensor is sealed and firmly bound on a horizontal steel bar of a bearing platform, and the temperature sensor is connected to a digital display inspection instrument through a cable, so that engineering personnel can know the real-time temperature of concrete and take corresponding temperature control measures; considering the symmetry of the bearing platform structure and the cooling system, the temperature of the whole concrete of the bearing platform can be known only by carrying out temperature monitoring on 1/4 volumes of the bearing platform.

After the embedded parts including the steel bars, the cooling water pipes and the temperature sensors are qualified, carrying out concrete pouring construction; determining the proportion of concrete for pouring according to the performances of the adopted sandstone materials, cement, fly ash and additives; the initial setting time of the concrete is not less than 20 h; the slump is 16-20 cm.

two HBT-80 type ground pumps are arranged on a platform, first pouring is carried out through two HG28F1-A1 material distributors, the height of first pouring concrete is 4m, and the square amount is 8110.56m³；

Arranging a chute and a stringing barrel on a bearing platform according to the flowing radius of the concrete; in the concrete pouring process, the chute and the string barrel are used for preventing concrete from segregation, and the scaffold board is laid on the erected steel reinforcement framework to serve as a pouring platform. The distributing machine is arranged on the inner support of the cofferdam, and when concrete poured by the distributing machine for the first time enters the formwork, the free falling height of the concrete is not more than 2 m;

pouring concrete in an oblique layering mode, wherein the pouring sequence is obliquely layered from upstream to downstream and from two sides to the middle, the pouring sequence is gradually promoted, the layering thickness is 30cm, and continuous construction is not interrupted in the construction process; in the concrete pouring process, a ZN50 vibrating spear and a ZN70 vibrating spear are adopted to be matched with the concrete in the vibrating cofferdam, a ZN35 vibrating spear is prepared, and the vibration is strengthened at the position with a small steel bar gap;

when the concrete is vibrated, the vibrating rod is inserted into the next layer to a preset depth; the preset depth is 5-10 cm; the vibrating rod needs to be inserted and drawn out quickly, and the moving distance is not more than 1.5 times of the acting radius of the vibrating rod.

The insertion points move uniformly, in a row or in a staggered manner during vibration so as to avoid leakage vibration; each vibration time is about 30s to avoid under vibration or over vibration, and after the vibration is finished, the vibrating rod is pulled out while vibrating; and stopping vibrating when the concrete does not sink any more, bubbles do not appear any more and the surface begins to be flooded.

After the first bearing platform concrete pouring is finished and the concrete strength reaches 2.5MPa, chiseling is conducted on the surface of the concrete, fresh and hard stones are exposed, the second bearing platform steel bars are bound after the concrete is cleaned up, the tower seat and the lower tower column embedded bars are embedded in advance, and a bracket beside a pier, a cooling water pipe, a temperature sensor and a measurement control point are installed.

After acceptance, repeating the steps, and pouring concrete of the bearing platform for the second time to complete the construction of the bearing platform; the concrete pouring height of the second bearing platform is 3.5m, and the square amount is 7096.74m³. When the first concrete pouring reaches over 75 percent of the design strength and the age is not less than 7 days, the second concrete pouring can be carried out, and a construction platform needs to be erected before the concrete is poured for personnel walking, later-stage slurry collection, plastering and maintenance. In order to prevent the generation of shrinkage cracks, after the top concrete is poured, the top concrete is timely subjected to slurry collection and plastering after initial setting and before final setting.

Specifically, after concrete pouring is finished, plastering and collecting slurry in time, and curing is started after concrete is finally set. The maintenance adopts a heat preservation and storage method: and covering geotextile and a plastic film on the surface of the concrete to form a good heat insulation layer, keeping the surface of the concrete moist, and monitoring the temperature of the concrete in real time through the temperature sensor in the curing process.

In another embodiment of the invention, short steel bars are welded on the top surface of the vertically arranged temperature sensor; when the concrete is vibrated, the distance between the vibrating rod and the inner wall is kept between 5 and 10cm when the vibrating rod vibrates around the inner wall of the cofferdam; the distance between the cooling water pipe and the temperature measuring element is kept at 20cm, so that the cooling water pipe and the temperature sensor cannot be collided; during the concrete pouring process, the method further comprises the following steps: when the cooling water pipe of a certain area is completely covered by concrete for 50cm, the cooling water pipe of the area is filled with water for curing.

In the river-crossing cable-stayed bridge construction, the size of the tower base top as a first main tower is 49.0m (transverse direction) 25.0m (forward direction) 4.0m (height), and the volume of C40 concrete is 5513.3 m'. According to the structural characteristics of the main tower, in order to accelerate the construction progress of the main tower and meet the requirements of large-volume concrete temperature control, concrete distribution radius and the like, the 4m high tower base is constructed at one time. The construction method of the tower base is the same as that of the bearing platform, the formwork is constructed by adopting a wood formwork according to a large-volume concrete construction method, and the construction is not repeated.

The tower column is a main component of a first main tower of a cross-river cable-stayed bridge and is formed by casting section by section. In the construction process of the tower column, before and after concrete of each section is poured, three-dimensional coordinates of the top of the section are measured, and the inclination error of the tower column needs to be strictly controlled. In yet another embodiment of the present invention, constructing the foundation and the tower column in the cofferdam comprises the steps of: respectively installing a 480t.m tower crane on the upstream and downstream of a tower column, a hoisting device for main tower and tower column construction, arranging an elevator on a single main tower, and arranging two tower cranes according to the diagonal line of the central line of a bridge; pouring to finish the construction of the first main tower base and the second main tower base; the positions and the center distances of the two towers are measured in a combined mode, the measured positions and the center distances are checked with completion data, accurate positions are determined, and measuring points are released; cleaning the concrete surface of the tower base according to the position and the elevation of the measuring point, and adjusting the connecting steel bar; manufacturing a stiff framework according to tower column sections in sections, and installing a bottom section stiff framework on an embedded part of a tower base;

the other sections of stiff frameworks are installed in a butt joint mode according to the inclination of the tower column, so that the stiff frameworks and the tower column are consistent in inclination; prefabricating reinforcing steel bars in a reinforcing steel bar workshop on the bank, transporting the reinforcing steel bars to a construction site, sleeving stirrups on reserved vertical bars at the top of a tower column, connecting tower column connecting long bars with tower column extending reinforcing steel bar joints, and staggering the joints up and down;

when the stirrups are bound, a plurality of concrete cushion blocks are bound on the outer sides of the vertical reinforcements; the outer mold of the lower tower column is constructed in sections by adopting a hydraulic creeping formwork method, the inner mold is constructed in sections by adopting a wood mold reverse mold method, and the section height is 4.5 m;

pouring to finish the construction of the lower tower column, dismantling the template and storing in a classified manner; the metal corrugated pipe and the steel stranded wire penetrate through the lower cross beam, and the lower cross beam is cast twice by adopting a floor type support.

In this embodiment, because of the column camber, set up two counter-pulling structures before the crossbeam construction to the additional moment of bending of column bottom that produces when balancing lower column concrete dead weight and crossbeam construction.

Pouring the mixture to the middle of the lower cross beam for the first time, and pouring the mixture to an upper chamfer of the lower cross beam for the second time; after pouring is finished, prestress tensioning is carried out on the lower cross beam; and after tensioning is finished, performing vacuum auxiliary grouting on a prestressed duct formed by the metal corrugated pipe.

The vacuum auxiliary grouting specifically comprises the following steps: connecting two ends of the prestressed duct with sealing valves, connecting a vacuum pump to the non-grouting end of the prestressed duct, connecting a grouting pump to the grouting end of the prestressed duct, and connecting a negative pressure container, a three-way valve and an anchor device cap in series, wherein the anchor device cap and the three-way valve are connected by a transparent throat pipe;

when slurry passes through the transparent throat pipe at the vacuumizing end, closing a vacuum valve at the front end of the vacuum machine, closing the vacuum machine, enabling the cement slurry to automatically and smoothly flow out of the non-return exhaust valve, observing whether the corrugated pipe is filled with the cement slurry or not from the transparent throat pipe, closing a valve at the vacuumizing end when the consistency of the cement slurry is consistent with that of the injected slurry, and keeping the pressure at 0.4MPa to continue grouting for half a minute; closing a valve arranged at the pulp outlet of the grouting pump, and closing the grouting pump;

after grouting, sealing the anchor, and adopting concrete with the same grade as the tower column; after the anchor is sealed, an external pipeline is disassembled, an air filter and a pipeline valve of the vacuum machine are cleaned, a grouting pump, a stirring machine, equipment and accessories which are stained with cement paste are cleaned, and the construction of the lower cross beam is completed.

assembling three steel pipe cross braces between the middle tower column of the first main tower and the middle tower column of the second main tower by using steel members; a jack is arranged at the end part of the cross brace to jack the cross brace to the designed internal force and tightly fill the cross brace so as to control the bending moment and the deformation of the tower column; the upper cross beam is constructed by adopting a bracket, brackets are embedded in the tower when a tower column is constructed, two ends of the bracket are supported on the bracket embedded parts, and the construction step of the lower cross beam is repeated to finish the construction of the upper cross beam; constructing the upper tower column by adopting a creeping formwork construction method, observing the deformation condition of the tower column in the construction process, and well recording the compression deformation of the tower column and the foundation settlement; and based on the compression deformation of the tower column and the foundation settlement record, adjusting the elevation of the tower column when the tower column is constructed to the bottom of the first section of steel anchor box.

Positioning and measuring the first section of steel anchor box, and assembling the first section of steel anchor box based on the measured positioning points; after the construction of the first section of steel anchor box is completed, connecting the upper part of the tower column to the upper part of the tower column, and repeating the construction steps of the lower tower column to complete the construction of other structures of the upper tower column; and anchoring the stay cables on the upper tower columns of the first main tower and the second main tower, and grouting and fixing the stay cable anchoring areas.

In this embodiment, in the creeping formwork construction, a creeping formwork system needs to be constructed, and the creeping formwork system is a hydraulic creeping formwork system and mainly comprises a hydraulic creeping frame and a formwork system. The climbing frame mainly comprises a suspension part, an embedded part, a climbing guide rail, hydraulic jacking equipment, 2 upper operation platforms, 1 main working platform, 2 lower operation platforms and an elevator entrance platform. The main working platform consists of a triangular support frame and connecting section steel, and load is transmitted to concrete through embedded parts. A climbing operation platform, a decoration platform, an elevator entrance platform, a supporting template operation platform and a steel bar binding platform are hung below the main working platform.

Adopt hydraulic jacking equipment to climb a whole promotion, respectively arrange 2 sets of hydraulic jacking equipment in pile body along the bridge to both sides, respectively arrange 2 sets of hydraulic jacking equipment in pile body cross bridge to both sides, realize climbing the normal climbing of frame through operating electronic control board.

The inner climbing frame system of the tower column is basically similar to the outer climbing frame and comprises a hanging piece, an embedded part, 2 upper operation platforms, a main working platform and 2 lower operation platforms. The main platform is composed of profile steel, and load is transmitted to concrete through embedded parts. The inner climbing frame is integrally lifted by a chain block, and the climbing frame is synchronously and integrally lifted by manual operation.

Assembling and installing a climbing frame: after the frame body is transported to the site, before the climbing template is installed, whether the hole diameter and the position of the embedded bolt on the engineering structure are correct or not is checked, and if deviation exists, the climbing template can be installed at the rear part by correcting; the climbing frame is assembled in sections and mainly comprises a wall attaching section and a working section. And partitioning according to the climbing frame structure and numbering according to the figures. The bearing frame sections are combined into the climbing frame assembly on the ship, the size error between holes on the climbing frame should meet the requirement, and the stability and firmness of the combined frame are checked.

Firstly, the guide rail is hoisted to the tower body of the installation layer, and is fixed on the tower body by a special bolt, and then the wall attaching section is hoisted to the guide rail for installation. The hoisting is realized by adopting a four-point crane, a bolt at one end of the tower body is temporarily fixed according to the inclination direction after the four-point crane is close to the tower body, a bolt at the other end is shifted and fixed, and finally the four-point crane is simultaneously screwed. After the wall attaching frame is fixed in place, the working frame is lifted to the upper part of the wall attaching section, the upper splicing point and the lower splicing point are fixed in a crossed mode, and the bolts must be completely screwed down, so that the screwing is not missed and less is screwed down. Adjusting and fixing the scaffold connecting rods of the upper and lower frame bodies, wherein the error of the mounted scaffold climbing frame does not exceed the specified requirement; after the assembly is completed, a seabed cage is laid, and a safety net is arranged at the periphery of the seabed cage in a closed mode.

The working process of the climbing system is as follows: and opening an oil inlet valve of the hydraulic oil cylinder, starting the hydraulic control cabinet, removing the wedge-shaped bolt at the top of the guide rail, and starting the climbing of the guide rail. After the hydraulic oil cylinder finishes the jacking of one stroke, after confirming that the upper jacking device and the lower jacking device are in place, starting the jacking of the next stroke. After the guide rail is lifted to the proper position, a wedge-shaped bolt at the top of the climbing guide rail is inserted from right to left to ensure that the bolt locking device is in the proper position. The top wedge-shaped latch of the drop rail is in full contact with the hanger. When the climbing frame is jacked in place, the hanging bolt and the safety bolt are inserted in time. Closing the oil inlet valve of the oil cylinder, closing the control cabinet and cutting off the power supply.

Specifically, the lower tower column inner cavity template is constructed by adopting a rollover method, and a steel pipe support is erected in the tower column inner cavity to serve as an inner mold supporting platform and a construction operation platform. Because the work load of inner mould transformation is very huge in the lower tower column construction process, in order to accelerate the construction progress, two sets of inner moulds are prepared for alternative use, namely, after one section construction is completed, the inner mould of the section is dismantled, meanwhile, the other set of inner mould is installed to the next section construction, and the dismantled inner mould is transported to a barge to be transformed and used.

The inner and outer molds of the hollow section of the lower tower column are pulled oppositely by utilizing the pull rod, the pull rod of the template of the solid mixed section is connected with the stiff framework of the tower column into a whole, and the stiff framework is used for connection and fixation, so that the rib framework bears the lateral pressure during concrete pouring.

The prestressed duct forming process comprises the following steps: arranging steel strands in the cross beam, and forming a pore channel when pouring cross beam concrete; the pore canal material adopts metal corrugated pipes with the inner diameters of 100 mm and 120 mm. The metal corrugated pipe is required to be checked for the phenomena of no air hole, tripping, slotting, dead bend and the like before installation, and the corrugated pipe is sealed by a sealing adhesive tape after connection, so that the pipeline blockage caused by the fact that cement slurry permeates into the pipe during concrete pouring is avoided. The corrugated pipe is positioned by adopting a positioning net to ensure that the prestressed pipeline does not deviate in the concrete pouring process, the spacing of the positioning reinforcing steel bar nets is arranged according to the straight line section of not more than 50cm and the curve section of not more than 10cm, and the diameter of the reinforcing steel bar of the positioning net is 12 mm. The horizontal rib of the web plate of the positioning net and the vertical rib of the bottom plate are strictly welded with the structural stressed steel bar firmly, the position accuracy of the steel bar of the positioning net must be ensured, and when the steel bar of the positioning net collides with other common steel bars, the common steel bar can be properly moved. In the concrete pouring process, the prestressed pipeline is ensured not to deviate, and the allowable deviation requirement of the reserved hole channel position is not more than 5 mm. After the positioning net is installed and adjusted to be qualified, the corrugated pipe can be penetrated, the corrugated pipe cannot be penetrated through by a hard puller, cracks or fractures of the corrugated pipe are avoided, the hole position of the positioning net is required to be noticed during penetration, and the mistaken penetration is avoided; the corrugated pipe can be segmented from two ends to the middle, and is finally connected with a connector in the middle, the connector and the horn pipe joint of the end anchor backing plate are sealed by using an electrical adhesive tape, and the spiral steel bar under the anchor is welded on the anchor backing plate in a spot mode, so that the position is guaranteed to be centered. The corrugated pipe is directly sleeved in a horn pipe of a section anchoring pore passage matched with the diameter of the corrugated pipe; in order to prevent slurry leakage, a foam rubber plug is used for sealing the corrugated pipe orifice in the horn pipe and the rubber tape.

In an alternative embodiment, to prevent the prestressed pipe from deforming or becoming clogged, a mandrel with a diameter of 90mm is inserted into the corrugated pipe.

Referring to fig. 5, in still another embodiment of the present invention, the cast-in-place concrete includes: calculating the first concrete pouring amount; the calculation formula is as follows:

in the formula: v is the quantity of the first concrete, and the unit is m³(ii) a H1 is the high layer needed by the concrete in the guide pipe to balance the external water (or slurry) pressure of the guide pipe when the height of the concrete surface in the hole reaches Hc, namely H1 is more than or equal to Hw r w/rc; hc is the height Hc from the concrete surface to the bottom of the hole in the well hole, which is h2+ h3, required when the first batch of concrete is poured; hw is the depth of water or slurry above the concrete surface in the hole, and 81m is taken; d is the diameter phi 3m of the hole; d is the diameter phi of the catheter 0.305 m; rc is the concrete mix capacity, which in one embodiment is 23.97kN/m³(ii) a rw is the volume weight of water or slurry in the borehole, and in one embodiment is 10.3 to 11kN/m 3; h2 is the primary embedment depth of the conduit, measured as 1.5 m; h3 is the bottom end of the catheterThe gap at the bottom of the hole is 0.3m in one embodiment.

The construction method of the main tower in the water of the high-speed railway cross-river cable-stayed bridge can be suitable for the construction of the main tower of the cross-river bridge in the water.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A construction method of a main tower of a high-speed railway river-crossing cable-stayed bridge is characterized in that the main tower comprises a first main tower and a second main tower, the center distance between the first main tower and the second main tower is 672m, the first main tower is close to the first side dike, the second main tower is close to a second side dike opposite to the first side dike, pile foundations of the first main tower and the second main tower are formed by arranging 45 pile arrays with the diameter of 3 meters, the pile length of the pile foundation of the first main tower is 49.5-67.5, the pile length of the pile foundation of the second main tower is 38.5-55 m, the first main tower pile foundation and the second main tower pile foundation are provided with bearing platforms which are rectangular, the transverse length of each bearing platform is 55.2m, the longitudinal width of each bearing platform is 36.4m, the thickness of each bearing platform is 7.5m, the elevation of the top of a bearing platform on the first main tower pile foundation is +0.000m, the elevation of the top of a bearing platform on the second main tower pile foundation is +10.000m, and two bearing platforms are respectively provided with a 4m high tower;

after the construction of the drilled pile is finished, a bracket is arranged on the steel casing, and the casing is connected with the high part;

hanging the bottom cofferdam on the bracket;

mounting a hanging beam and a hanging system on the heightened pile casing;

arranging sinking guide on the cofferdam;

dismantling the hanging system;

connecting high top section cofferdams in blocks by using 400t floating cranes;

carrying out concrete construction on the cofferdam wall bin;

continuously sucking mud in the cofferdam bin, and sinking to the designed elevation;

leveling the substrate;

a cabin separation plate is arranged along the guide downward placement;

pouring bottom sealing concrete in a subarea manner;

removing the mud suction platform;

pumping water after the bottom sealing concrete reaches the strength;

leveling and cutting off the steel casing;

breaking the pile head and carrying out pile inspection;

constructing a bearing platform twice;

2. The method of claim 1, wherein the step of supporting a first drilling platform at a first main tower piling location, and wherein the step of supporting a crane pier adjacent the first drilling platform comprises the steps of:

3. The method of claim 2, wherein the step of assembling the cofferdam in blocks by using the floating crane on the crane pier comprises the steps of:

during assembly, four corners are positioned firstly, then the assembly is carried out symmetrically by taking the positioning as a reference, and finally the assembly is carried out on one side:

4. The method according to claim 1, characterized in that communicating pipes are pre-embedded on the cofferdam, the cofferdam wall and the partition wall at a position 20m high from the edge foot surface, one end of each communicating pipe is positioned in the cofferdam, the other end of each communicating pipe is positioned in the water area outside the cofferdam, and flange joints for plugging are reserved at the positions of the pre-embedded communicating pipes on the cofferdam wall;

5. The method of claim 1, wherein the step of sinking the cofferdam to 2m below the river bed surface or the cofferdam cabin by using the suction dredge to suck the mud continuously comprises the following steps: measuring a reference surface for cofferdam sinking measurement control, arranging four control points on the longitudinal and transverse axes of the cofferdam, and measuring the plane coordinates and elevations of the four control points to determine the center coordinates of the top and bottom surfaces of the cofferdam;

6. The method of claim 5 wherein a scale mark is marked on the cofferdam panel at a visible position.

7. The method of claim 4, wherein the zonal casting of the closed-bottom concrete comprises:

8. The method of claim 7, wherein the double construction of the cap comprises:

pouring concrete in an oblique layering mode, wherein the pouring sequence is obliquely layered from upstream to downstream and from two sides to the middle, the pouring sequence is gradually promoted, the layering thickness is 30cm, and continuous construction is not interrupted in the construction process;

after acceptance, repeating the steps, and pouring concrete of the bearing platform for the second time to complete the construction of the bearing platform; the concrete pouring height of the second bearing platform is 3.5m, and the square amount is 7096.74m³。

9. The method of claim 8, wherein short steel bars are welded on top of the vertically disposed temperature sensor;

10. The method of claim 1, wherein constructing the foundation and the tower column within the cofferdam comprises the steps of: