CN114482014A - Hammering pile sinking construction method for precast pile in deep foundation pit in offshore super-thick sludge area - Google Patents

Abstract

The invention discloses a construction method for hammering and sinking a precast pile in a deep foundation pit in an offshore ultra-thick silt region, which belongs to the technical field of building construction, and aims to solve the technical problem of ensuring the safety of the foundation pit in the precast pile construction process and simultaneously reducing the influence of the hammering construction vibration and stress extrusion of the precast pile in the deep foundation pit on a supporting pile of the deep foundation pit, wherein the technical scheme is as follows: the method comprises the following steps: s1, mounting an inclinometer and automatic foundation pit detection equipment; s2, constructing a stress release hole and a stress release groove; s3, hammering construction of the precast pile; s4, monitoring and feeding back to dynamically adjust the construction sequence and release stress through the stress release groove and the stress release hole; s5, selecting a proper construction tool according to the detection data theory; and S6, groove cleaning and local pit-sharing excavation.

Description

Hammering pile sinking construction method for precast pile in deep foundation pit in offshore super-thick sludge area

Technical Field

The invention relates to the technical field of building construction, in particular to a construction method for hammering and sinking a precast pile in a deep foundation pit in an offshore ultra-thick sludge area.

Background

The precast pile becomes a preferred scheme of more and more pile foundations by the advantages of high construction speed, simple and convenient field management, good quality control and low construction cost. At present, a method of starting construction from the ground is mostly adopted, namely before a foundation pit is excavated, piling is started from the ground, and a pile feeding technology is adopted to sink a pipe pile into a designed depth. The excavation scope of the deep foundation pit in the offshore ultra-thick silt region is flow-plastic silt silty clay, the precast pile can be flushed down when the precast pile is constructed firstly and then the earthwork is excavated, the large-area precast pile inclination quality accident is caused, and meanwhile, the engineering cost is greatly increased.

How to guarantee the foundation ditch safety in the precast pile work progress so, reduce the influence of precast pile hammering construction vibration, stress extrusion to deep basal pit fender pile in the deep basal pit simultaneously is the technical problem that awaits the solution at present.

Disclosure of Invention

The technical task of the invention is to provide a pile hammering and sinking construction method for a precast pile in a deep foundation pit in an offshore ultra-thick silt region, so as to solve the problems of ensuring the safety of the foundation pit in the precast pile construction process and reducing the influence of pile hammering construction vibration and stress extrusion of the precast pile in the deep foundation pit on a supporting pile of the deep foundation pit.

The technical task of the invention is realized according to the following mode, the construction method for hammering and sinking the precast pile in the deep foundation pit of the offshore ultra-thick sludge area comprises the following steps:

s1, mounting an inclinometer and automatic foundation pit detection equipment;

s2, constructing a stress release hole and a stress release groove;

s3, hammering construction of the precast pile;

s4, monitoring and feeding back to dynamically adjust the construction sequence and release stress through the stress release groove and the stress release hole;

s5, selecting a proper construction tool according to the detection data theory;

and S6, groove cleaning and local pit-sharing excavation.

Preferably, the installation of the inclinometer and the automatic foundation pit detection equipment in the step S1 is specifically as follows:

s101, mounting a deep foundation pit supporting pile in an ultra-thick sludge area;

s102, mounting a static level gauge and an inclination angle sensor for automatic observation on the crown beam;

s103, mounting a dynamometer on the anchor rod, and pre-excavating the earth after the inclinometer pipe is pre-embedded;

s104, observing the influence of excavation of upper soil on lower soil in the earthwork excavation process, detecting soil movement through an inclinometer, theoretically analyzing the influence of the earthwork excavation on the stress of the pile body of the sludge layer precast pile and the influence of machinery on the pile so as to guide construction, and avoiding the inclined damage of the pile foundation caused by mechanical disturbance.

Preferably, the construction stress relief holes and stress relief grooves in step S2 are as follows:

s201, leveling mucky soil within the range of 3m around the foundation pit;

s202, excavating and correcting the stress release trench;

s203, draining accumulated water;

s204, positioning a drilling machine;

s205, forming holes, simultaneously installing a PVC (polyvinyl chloride) plastic pipe with holes punched at the periphery, and pouring coarse sand around the plastic pipe: during the construction of the stress release holes, adopting a jumping mode of three-to-one punching for circle construction, sequentially punching holes in sequence, and punching the stress release holes to timely perform PVC plastic pipe and sand filling treatment;

s206, shifting a drilling machine;

and S207, cleaning the site after construction is finished.

Preferably, the stress relief trench excavation correction in step S202 is as follows:

s20201, in order to ensure that the soil squeezing effect is weakened in the construction process of the civil air defense garage prefabrication engineering square pile and the stress release requirement is met, stress release holes are arranged on the periphery of the inner side of a garage crown beam, the diameter of each stress release hole is 300mm, the distance between every two stress release holes is 1000mm, a PVC plastic pipe with the diameter of 50mm is placed in the garage crown beam, coarse sand is filled between the PVC plastic pipe and the wall of the hole, and the PVC plastic pipe is exposed by 300 mm;

s20202, the width of the stress release groove is 1 meter, and the depth is 1.5 meters; the construction of the stress release holes is adjusted in time according to observation results, and if the soil displacement is still larger than an alarm value in the pile sinking process after construction, the number of the holes is increased on the basis of the original layout. The principle is that the hole positions with multiple times are added between the inner rows of holes close to the construction area, so that the protection effect is guaranteed to be economic and effective to the maximum extent.

More preferably, the accumulated water removal in step S203 is specifically as follows:

s20301, excavating along the side of the foundation pit to a position 50cm lower than the garage cushion layer, laying a circle of stones, and placing a drainage pipe to block soil;

s20302, placing the PVC-U corrugated pipes with the holes on the pipe walls along a ditch, and reserving 11 water collecting well building positions in the middle;

s20303, after the water collecting well is built, covering a 850mm stone water filtering layer on the PVC-U corrugated pipe, and backfilling gravel soil to-2.61 m;

s20304, placing a water pump in the water collecting pit to pump water, and discharging the extruded water after piling in time.

Preferably, the precast pile hammering pile sinking construction in the step S3 is specifically as follows:

s301, backfilling gravel soil;

s302, leveling the field;

s303, measuring and lofting;

s304, pile foundation in place;

s305, pile sinking; the method comprises the following specific steps:

s30501, a hammer is lifted and tapped, the pile is kept vertical under the checking of the two theodolites, and the pile can be formally sunk when no abnormality exists;

s30502, when hammering is started, the drop distance is small, and after the pile is stably placed at a certain depth, the pile is sunk according to the required drop distance; the piling is preferably carried out by a heavy hammer, and the weight of the heavy hammer is selected according to geological conditions, types, structures, density and construction conditions of the piles; according to the density of piles, the piling sequence can be symmetrically driven from the middle to two sides or from the middle to the periphery;

s30503, hammering and sinking the pile, and applying a vertical-line hardwood or a steel wire rope stacked in a disc circle as a hammer pad between a pile cap and a pile hammer, wherein the thickness of the hammer pad is 150-200 mm;

s306, sinking the pile in place;

s307, pile splicing or pile cutting;

and S308, pile testing.

More preferably, the pile sinking in step S305 is specifically as follows:

s30501, a hammer is lifted and tapped, the pile is kept vertical under the checking of the two theodolites, and the pile can be formally sunk when no abnormality exists;

s30502, when hammering is started, the drop distance is small, and after the pile is stably placed at a certain depth, the pile is sunk according to the required drop distance; the piling is preferably carried out by a heavy hammer, and the weight of the heavy hammer is selected according to geological conditions, types, structures, density and construction conditions of the piles; according to the density of piles, the piling sequence can be symmetrically driven from the middle to two sides or from the middle to the periphery;

s30503, hammering and sinking the pile, and using a vertical-line hardwood or a steel wire rope with stacked discs as a hammer pad between the pile cap and the pile hammer, wherein the thickness of the hammer pad is 150-200 mm.

Preferably, the monitoring feedback in step S4 dynamically adjusts the construction sequence and the stress relief through the stress relief grooves and holes is as follows:

s401, carrying out deformation observation in real time from excavation to precast pile construction completion by adopting an automatic foundation pit deformation monitoring system;

s402, the automatic foundation pit deformation monitoring system sends data acquired by a sensor to a cloud platform in real time through an intelligent node by using a 4G/5G network, so that real-time early warning and alarming are realized, and monitoring data are counted and processed to automatically generate corresponding curves and reports;

and S403, adjusting the construction sequence and the drainage in the stress release holes in time through the detection data to ensure the stability of the supporting structure.

Preferably, the step S5 of selecting a proper construction tool according to the detection data theory means that the selected mechanical equipment is used to reversely push the precast pile in the excavation process of the clear groove, the water collecting pit and the local pit of the reclaimed water treatment station, so as to avoid the toppling of the pile foundation caused by the earth excavation; the method comprises the following specific steps:

s501, excavating machine: a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator are adopted;

when a creep-working XE215CA excavator is used in a foundation pit, the total weight of the excavator is 21750kg, the total length is 9565mm, the track wheel base is 3462mm, the minimum turning radius is 3.5m, and the estimated excavator load is as follows:

s502, earthwork vehicle: the earthwork external transportation adopts a front four-rear eight-self-dumping truck for external transportation, and the total axle weight of a rear wheel double axle is 600 kN; setting the distance between the wheel outside the automobile and the slope top line of the foundation pit to be 3.5m, and calculating the equivalent distributed load action of the automobile, wherein the diffusion angle of the wheel diffusion pressure is 30 degrees, and the diffusion area of the wheel pressure of the rear wheel double axle is (2.4+2 x 3.5) × (1.6+2 x 3.5) ═ 71.44m²；

Then the equivalent distributed load of the automobile is as follows:

therefore, the minimum turning radius of the 21t excavator is 3.5m, and the equivalent load of the excavator is 6.34 kPa; if the outer side wheel of the earthwork vehicle is 3.5m away from the slope top line of the foundation pit, the equivalent load of the automobile is 8.4 kPa; the depth of the socketed rock is L because the automobile and the excavator can not act on one at the same time_d1.5b can meet the requirement; the construction machinery comprises a large excavator and a earthwork vehicle which are fully loaded, and is matched with a steel plate for operation in mucky soil, and the size of the steel plate is 6000 x 2000 x 20 mm; paving the pattern steel plate with the size of 4000 x 2000 x 5mm to meet the requirement;

s503, determining that the construction excavator adopts a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator; the earth transporting vehicle adopts four front and eight rear earthwork muck vehicles and is equipped with a small-sized agricultural vehicle for emergency cooperation.

Preferably, the groove cleaning and the local pit excavation in the step S6 are as follows:

s601, determining an excavation sequence: 1-1, 2-1, 1-2 → 2-2, 1-3, 2-3 → 1-4, 2-4, 1-5 → 2-5, 1-6, 2-6 → 1-7, 2-7 → 1-8;

and S602, simultaneously constructing the two excavators.

The construction method for hammering and sinking the precast pile in the deep foundation pit in the offshore ultra-thick sludge area has the following advantages:

when the foundation pit support in the sludge area is constructed, the static level gauge and the inclination angle sensor are arranged on the top beam, the anchor dynamometer is arranged on the self-propelled anchor rod, and the Huazhu automatic online monitoring system is adopted, so that the continuous, real-time and online monitoring is realized, the warning is given in advance in time, and the safety of the foundation pit in the process of hammering the precast pile in the deep foundation pit and excavating the earthwork is ensured;

the method comprises the following steps of (1) analyzing the influence of excavation unloading on the displacement and the change rate of a soil body by utilizing an installation inclined pile test, quantitatively analyzing the influence of the excavation unloading on a precast pile according to the displacement change rule of the soil body around the pile, and verifying the excavation construction method of the mucky soil precast pile through theoretical calculation; arranging stress release grooves and stress release holes on the periphery of the deep foundation pit; the stress release is completed while the precast pile is constructed, so that the problem of the influence of the soil squeezing effect and the vibration impact on the supporting structure caused by hammering pile sinking is solved;

thirdly, the construction of the stress release holes of the invention is adjusted in time according to observation results, if the displacement of the soil body is still larger than the alarm value in the pile sinking process after the construction, the number of the holes is increased on the basis of the original layout; the principle is that the hole positions with multiple times are added between the inner rows of holes close to a construction area, so that the protection effect is guaranteed to be economic and effective to the maximum extent;

the automatic online monitoring system, the stress release ditch and the stress release hole technology are adopted, the horizontal displacement of the top of the supporting structure, the tension of the anchor rod and the underground water level are monitored in real time, the safety of the foundation pit in the precast pile construction process is ensured, and the influence of the hammering construction vibration and the stress extrusion of the precast pile in the deep foundation pit on the supporting pile of the deep foundation pit is effectively reduced;

the method comprises the following steps of (V) automatically monitoring deformation, strength and stability of a foundation pit supporting structure when the precast pile is in use in the construction process, timely knowing the deformation of the foundation pit supporting structure on a construction site through monitoring data, carrying out safety assessment on the integral stability and deformation of the foundation pit, analyzing the reason of deformation, feeding back construction in time, adjusting construction steps and stress release holes to reduce water and release stress, and further ensuring construction safety;

and finally, analyzing the influence of excavation unloading on the displacement and the change rate of a soil body by relying on an inclined pile test for installation, verifying an excavation construction method of the mucky soil precast pile through theoretical calculation, and selecting the optimal mucky soil excavation scheme.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of a construction method for hammering and sinking a pile by a precast pile in a deep foundation pit in an offshore ultra-thick sludge area;

FIG. 2 is a construction schematic diagram of a civil air defense garage prefabrication engineering square pile;

FIG. 3 is a schematic view of 240X 115X 53 small lime brick masonry sump phi 2000;

FIG. 4 is a schematic view of 240X 115X 53 small lime brick masonry sump phi 1000;

FIG. 5 is an interface screenshot of a report when the variance is accumulated;

FIG. 6 is an interface screenshot of a report at a single change;

FIG. 7 is a line graph of lateral displacement and burial depth;

FIG. 8 is a line graph of side shift versus time;

fig. 9 is a schematic view of the excavation sequence.

In the figure: 1. the device comprises a static force level gauge, 2, a water level observation instrument, 3, an axial force gauge, 4, an inclination angle sensor, 5, a stress release hole, 6, a stress release ditch, 7, coarse sand, 8, an engineering pile, 9, a PVC plastic pipe, 10, a drainage ditch, 11, a stone filter layer, 12, gravel soil, 13, a garage main body structure, 14 and a PVC-U corrugated pipe.

Detailed Description

The method for driving and sinking the pile by hammering the precast pile in the deep foundation pit in the offshore ultra-thick sludge zone according to the present invention will be described in detail with reference to the drawings and the specific embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description. And are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example (b):

as shown in the attached drawing 1, the method for pile hammering and pile sinking construction of the precast pile in the deep foundation pit of the offshore ultra-thick sludge area comprises the following steps:

s1, mounting an inclinometer and automatic foundation pit detection equipment;

s2, constructing a stress release hole and a stress release groove;

s3, hammering construction of the precast pile;

s4, monitoring and feeding back to dynamically adjust the construction sequence and release stress through the stress release groove and the stress release hole;

s5, selecting a proper construction tool according to the detection data theory;

and S6, groove cleaning and local pit-sharing excavation.

In this embodiment, the installation of the inclinometer and the automatic detection equipment for the foundation pit in step S1 is specifically as follows:

s101, mounting a deep foundation pit supporting pile in an ultra-thick sludge area;

s102, mounting a static level 1 for automatic observation and an inclination sensor 4 on the crown beam;

s103, installing a dynamometer 3 on the anchor rod, and pre-excavating the earth after embedding the inclinometer;

s104, observing the influence of excavation of upper soil on lower soil in the earthwork excavation process, detecting soil movement through an inclinometer, theoretically analyzing the influence of the earthwork excavation on the stress of the pile body of the sludge layer precast pile and the influence of machinery on the pile so as to guide construction, and avoiding the inclined damage of the pile foundation caused by mechanical disturbance.

The construction stress relief holes and stress relief grooves in step S2 in this embodiment are as follows:

s201, leveling mucky soil within the range of 3m around the foundation pit;

s202, excavating and correcting the stress release trench 6;

s203, draining accumulated water: the water level depth is measured by the water level observation instrument 2, so that the drainage can be ensured in time;

s204, positioning a drilling machine;

s205, forming holes, simultaneously installing a PVC (polyvinyl chloride) plastic pipe 9 with holes punched at the periphery, and pouring coarse sand 7 around the plastic pipe: when the stress release holes 5 are constructed, the jumping beating mode of three-for-one beating is adopted for rotating construction, holes are sequentially punched in sequence, and the stress release holes 5 are punched to timely carry out the PVC plastic pipes 9 and sand filling treatment;

s206, shifting a drilling machine;

and S207, cleaning the site after construction is finished.

The stress relief trench excavation correction in step S202 in this embodiment is specifically as follows:

s20201, in order to ensure that the soil squeezing effect is weakened in the construction process of the civil air defense garage prefabrication engineering square pile and the stress release requirement is met, stress release holes 5 are arranged on the periphery of the inner side of a garage crown beam, the diameter of each stress release hole 5 is 300mm, the distance between every two stress release holes is 1000mm, a PVC plastic pipe 9 with the diameter of 50mm is placed in the center, coarse sand 7 is filled between each PVC plastic pipe 9 and the wall of the hole, and the PVC plastic pipe 9 is exposed by 300 mm;

s20202, the width of the stress release groove 6 is 1 meter, and the depth is 1.5 meters, as shown in the attached figure 2; the depth of the stress release holes 5 is the same as that of the engineering piles 8, and the depth of the stress release holes 5 is 13.5 meters. The construction of the stress release holes 5 should be adjusted in time according to observation results, and if the soil displacement is still greater than an alarm value in the pile sinking process after construction, the number of holes should be increased on the basis of the original layout. The principle is that the hole positions with multiple times are added between the inner rows of holes close to the construction area, so that the protection effect is guaranteed to be economic and effective to the maximum extent.

The accumulated water drainage in step S203 in this embodiment is specifically as follows:

s20301, excavating along the side of the foundation pit to a position 50cm lower than the garage cushion layer, laying a circle of stones, and placing a drainage pipe to block the drainage pipe with soil;

s20302, placing the PVC-U corrugated pipes 14 with the holes on the pipe walls along the ditch, and reserving 11 water collecting well building positions in the middle;

s20303, after the water collecting well is built, covering a 850mm stone water filtering layer 11 on a PVC-U corrugated pipe 14, and then replacing and filling gravel soil 12 to-2.61 m;

s20304, placing a water pump in the water collecting pit to pump water, and discharging the extruded water after piling in time.

As shown in the attached figure 3, the depth of a stone-filling filter layer 11 at the position of a garage main body structure 13 along the periphery of a foundation pit is 650mm, and phi 200mm PVC-U corrugated pipes 14 (holes with the distance of 100mm phi 10mm around the pipes) are embedded; the depth of the stone replacement and filling sub filter layer 11 mm along the periphery of the foundation pit is 850 mm; and excavating a drainage ditch 10 along the periphery of the foundation pit, wherein the size of the drainage ditch is 1500 mm/2000 mm.

As shown in figure 4, 240X 115X 53 small lime bricks build the sump well with a diameter of 1000mm and a depth of 2 m.

The pile hammering and sinking construction of the precast pile in step S3 in this embodiment is specifically as follows:

s301, backfilling the gravel soil 12;

s302, leveling the field;

s303, measuring and lofting;

s304, pile foundation in place;

s305, pile sinking; the method comprises the following specific steps:

s30501, a hammer is lifted and tapped, the pile is kept vertical under the checking of the two theodolites, and the pile can be formally sunk when no abnormality exists;

s30502, when hammering is started, the drop distance is small, and after the pile is stably placed at a certain depth, the pile is sunk according to the required drop distance; the piling is preferably carried out by a heavy hammer, and the weight of the heavy hammer is selected according to geological conditions, types, structures, density and construction conditions of the piles; according to the density of piles, the piling sequence can be symmetrically driven from the middle to two sides or from the middle to the periphery;

s30503, hammering and sinking the pile, and applying a vertical-line hardwood or a steel wire rope stacked in a disc circle as a hammer pad between a pile cap and a pile hammer, wherein the thickness of the hammer pad is 150-200 mm;

s306, sinking the pile in place;

s307, pile splicing or pile cutting;

and S308, pile testing.

The pile sinking in step S305 in this embodiment is specifically as follows:

s30501, a hammer is lifted and tapped, the pile is kept vertical under the checking of the two theodolites, and the pile can be formally sunk when no abnormality exists;

s30502, when hammering is started, the drop distance is small, and after the pile is stably placed at a certain depth, the pile is sunk according to the required drop distance; the piling is preferably carried out by a heavy hammer, and the weight of the heavy hammer is selected according to geological conditions, types, structures, density and construction conditions of the piles; according to the density of piles, the piling sequence can be symmetrically driven from the middle to two sides or from the middle to the periphery;

s30503, hammering and sinking the pile, and using a vertical-line hardwood or a steel wire rope with laminated discs as a hammer pad between the pile cap and the pile hammer, wherein the thickness of the hammer pad is 150-200 mm.

As shown in fig. 5 and 6, the monitoring and feedback in step S4 in this embodiment dynamically adjusts the construction sequence and completes stress relief through the stress relief grooves and holes as follows:

s401, carrying out deformation observation in real time from excavation to precast pile construction completion by adopting an automatic foundation pit deformation monitoring system;

s402, the automatic foundation pit deformation monitoring system sends data acquired by a sensor to a cloud platform in real time through an intelligent node by using a 4G/5G network, so that real-time early warning and alarming are realized, and monitoring data are counted and processed to automatically generate corresponding curves and reports;

and S403, adjusting the construction sequence and the drainage in the stress release holes in time through the detection data to ensure the stability of the supporting structure.

In step S5 in this embodiment, a suitable construction machine is selected based on the theoretical calculation of the detection data as follows:

the change curve of the displacement along with the increase of the burial depth can be seen by installing 6 measuring points on the supporting piles, as shown in the attached figure 7, a change curve graph of the displacement along with time when each mark is inserted into the measuring points and is respectively 4m, 6m, 7m, 7.5m and 8m is inserted into the measuring points, the data of the measuring points on the first day is the initial offset of the inclinometer, and the displacement of the first day is subtracted from the displacement measured on each day later to obtain the final sliding displacement of the soil. And taking a characteristic point as a representative.

The displacement change in the lower 4m of the excavation surface is obvious, the influence of soil unloading and construction is large, the influence of the outside of the lower 4m of the excavation surface is small and mainly influenced by foundation pit excavation, and the displacement of the soil body below 4m is small and basically unchanged. Wherein the general regularity of the shifts from the 4 th to 25 th day indices 2, 4, 6 at 4m, 6m, 7m, 7.5m, 8m is the same, as is the regularity of 1, 3, 5. The data for these plots from day 4 to day 25 show a distinct change at 4m, 6m, then gradually plateauing, with the displacement being essentially constant at 8m, approximately 0.

As shown in fig. 8, as the foundation pit is excavated, the soil body may be displaced, the depth of influence on the soil body is within the range of 8m, and as the excavation depth is increased at 0-6m, the soil body is greatly influenced by excavation, the displacement is increased, the soil body gradually tends to be stable after 6m, and is substantially stable at 8m, and the influence of excavation on the soil body is reduced.

In the embodiment, the step S5 of selecting a suitable construction tool according to the detection data theory is to reversely push the precast pile through the selected mechanical equipment in the process of digging the clean groove, the water collecting pit and the local pit of the reclaimed water treatment station, so as to avoid the toppling of the pile foundation caused by the earth excavation; the method comprises the following specific steps:

s501, excavating machine: a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator are adopted;

when a creep-working XE215CA excavator is used in a foundation pit, the total weight of the excavator is 21750kg, the total length is 9565mm, the track wheel base is 3462mm, the minimum turning radius is 3.5m, and the estimated excavator load is as follows:

s502, earthwork vehicle: the earthwork external transportation adopts a front four-rear eight-self-dumping truck for external transportation, and the total axle weight of a rear wheel double axle is 600 kN; setting the distance between the wheel outside the automobile and the slope top line of the foundation pit to be 3.5m, and calculating the equivalent distributed load action of the automobile, wherein the diffusion angle of the wheel diffusion pressure is 30 degrees, and the diffusion area of the wheel pressure of the rear wheel double axle is (2.4+2 x 3.5) × (1.6+2 x 3.5) ═ 71.44m²；

Then the equivalent distributed load of the automobile is as follows:

therefore, the minimum turning radius of the 21t excavator is 3.5m, and the equivalent load of the excavator is 6.34 kPa; if the outer side wheel of the earthwork vehicle is 3.5m away from the slope top line of the foundation pit, the equivalent load of the automobile is 8.4 kPa; the depth of the socketed rock is L because the automobile and the excavator can not act on one at the same time_d1.5b can meet the requirement; the construction machinery comprises a large excavator and a earthwork vehicle which are fully loaded, and is matched with a steel plate for operation in mucky soil, and the size of the steel plate is 6000 x 2000 x 20 mm; paving the pattern steel plate with the size of 4000 x 2000 x 5mm to meet the requirement;

s503, determining that the construction excavator adopts a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator; the earth transporting vehicle adopts a front four and a rear eight earthwork residue soil vehicle and is equipped with a small agricultural vehicle for emergency coordination.

In this embodiment, the groove cleaning and the local pit-sharing excavation in step S6 are specifically as follows:

s601, determining an excavation sequence: 1-1, 2-1, 1-2 → 2-2, 1-3, 2-3 → 1-4, 2-4, 1-5 → 2-5, 1-6, 2-6 → 1-7, 2-7 → 1-8, as shown in FIG. 9;

and S602, simultaneously constructing the two excavators.

The invention relates to a material and a device, comprising:

1. the main construction machines and tools:

2. main measuring device

Levels, theodolites, total stations, tape measures, and the like;

3. main construction material

The quality control of the invention is as follows:

1. the construction quality acceptance standard GB50300-2013, the construction foundation support technical regulation JGJ120-2012, the construction foundation engineering construction quality acceptance standard GB50202-2018, the construction foundation engineering inspection technical regulation GB50497-2009, the construction engineering supervision standard GB/T-5039 + 2013 and other relevant regulations and regulations are met.

2. Material quality control

201. Material assurance measures

The previous-stage preparation of the materials and related inspection work are made by all the people according to the required time, and the materials are ensured to enter the field and to be qualified through inspection in time.

202. Construction quality requirement of engineering material

A. Materials, specifications, models and the like of the equipment are checked before construction, and construction is carried out strictly according to design requirements and construction specifications after the materials, the specifications, the models and the like are checked to be correct.

B. During engineering construction, construction preparation work needs to be fully made, and the work is closely matched with each professional to coordinate construction, so that the work procedure crossing and lapping work is conveniently made, the normal operation of foundation pit support is ensured, and the rework is avoided.

3. Construction quality control

301. And (3) precast pile construction: construction is carried out according to the acceptance criteria of construction quality of foundation engineering of building foundations and the drawing set L15G329 of prefabricated high-strength concrete square piles. The elevation deviation of the pile top is +/-100 mm, and the deviation of the axis and the direction of the vertical axis is +/-50 mm. The perpendicularity deviation is 1%.

302. Foundation pit earthwork construction: construction in a mode of supporting after excavation once is not required to be carried out according to the principle of sectional excavation and sectional supporting; before construction, the position, drilling depth, diameter, angle length, grouting proportion, pressure, grouting amount, strength and the like of the anchor are checked to ensure that the design requirements are met.

The safety measures of the invention are as follows:

1. in the construction process, the near-edge protection of the foundation pit opening is made in time, and high-altitude object throwing and drop prevention are forbidden.

2. The excavation of the foundation pit should be carried out in layers, and the height difference should not be too large. The softer the soil texture, the smaller the height difference should be.

3. The special operating personnel must pass through the training examination to be certified and put on duty.

4. The stability and the safety of the hoisting point and the field storage are noticed during the pile entering, unloading and hoisting.

5. The position of an operator below is noticed in the pile body butt joint process, and the condition that the position is not in the range of the hydraulic pipe is guaranteed.

6. The electric welding machine and the mechanical equipment are protected by one machine, one brake and one protection by using electricity on site. And a professional electrician is responsible for the electricity utilization safety during construction and regularly organizes the inspection of related personnel.

7. The piling is strictly forbidden to carry out overload operation, the moment is not over, and the elevation angle cannot exceed the limit, so as to prevent the 'overturning' accident.

8. The occurrence of fighting events on the drunk work is prohibited, and the people can quit the fighting event immediately after finding the fighting events.

9. Personnel entering the site must wear safety helmets and do not work against the regulations at any time. Smoking is strictly prohibited in construction sites.

The benefit analysis of the invention is as follows: taking the project as an example, compared with a cast-in-place pile in a deep foundation pit, the economic benefit analysis of precast pile construction is shown in the table:

one prefabricated square pile is 16 meters long, and 1150 piles are 18400 meters long.

Through the comparison and analysis of the table, compared with the construction of the common precast pile, the method saves the cost by 1150 x 15% by 256 x 16+900000 yuan for 42100 yuan 12520 yuan 1551940 yuan, and has better economic benefit.

10.2 social and environmental benefits:

by adopting the construction method, the construction problems of large-area toppling, shifting and the like of the precast pile in the deep foundation pit in the offshore ultra-thick silt region in the excavation process are effectively solved, the adverse effect of the soil squeezing effect of the precast pile in the foundation pit on the foundation pit support is also solved, the effect of drainage and precipitation is indirectly achieved, and the construction quality of the precast pile is ensured. Meanwhile, the construction method can realize hammering and conveying the precast engineering pile, ensure the verticality and ensure the bearing capacity of the pile body and the bearing platform without adopting other measures. The perfect combination of the construction progress and the quality can be accelerated, and meanwhile, the cost and the mineral resources are saved; saving auxiliary steel and the like. The construction is quick, the construction procedures are reduced, the construction period is shortened, and the unit cost is reduced. Has good social and economic benefits.

Application example:

3.1 Qingdao teaching project for children

3.1.1 engineering overview: the engineering of the specialized schools (first period) such as Qingdao children teachers and professions is located in south of the yellow river road and north of the Huaihe road in the Guzhou economic and technical development area of the Guzhou city. The excavation scope of the engineering foundation pit is the flow-molding silt silty clay, and if the precast pile is constructed firstly and then the earthwork is excavated, the precast pile can be flushed down, so that the inclined quality accident of the large-area precast pile is caused, and the engineering cost is greatly increased.

3.1.2 construction effect: an automatic on-line monitoring system, a stress release groove and a stress release hole technology are applied. Stress release holes and stress release holes are formed in the periphery of the foundation pit after the foundation pit is excavated. The influence of excavation unloading on the displacement and the change rate of the soil body is analyzed by relying on an inclined pile test for installation, the excavation construction method of the mucky soil precast pile is verified through theoretical calculation, and the optimal mucky soil excavation scheme is selected.

3.1.3 application effects: by adopting the construction method, the construction progress is accelerated, the construction quality of the main body structure is ensured, the construction cost is reduced, and the social reputation of our company is improved.

3.2 billow Wenyuan project

3.2.1 engineering overview: the second-stage project of the Shanlan Wenyuan located in the West of the great deal of the economic and technical development area of the Guzhou province, the south of the Minjiang river, the north of the Zhujiang river and the east of the Huiying street consists of 6#, 7#, 8#, 9#, 10#, B1#, B2# and an underground garage. The construction method is used for precast pile foundation construction in a deep foundation pit in an offshore super-thick sludge area.

3.2.2 construction effect: the inclination measurement is adopted, the influence caused by the displacement of the pile body is analyzed, the application control of the pile feeder is proper, and the perfect combination of the pile in the pile feeding process is ensured. The pile body does not have large deflection after excavation.

3.2.3 application effects: by adopting the method, quality accidents of precast pile foundation construction toppling, damage, large-area inclination and the like in the deep foundation pit of the offshore ultra-thick sludge area are solved, the supervision and the consistent good comment of Party A are obtained, the application prospect is wide, and the method has good popularization significance.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A pile hammering and sinking construction method for precast piles in deep foundation pits in offshore ultra-thick sludge areas is characterized by comprising the following steps:

s1, mounting an inclinometer and automatic foundation pit detection equipment;

s2, constructing a stress release hole and a stress release groove;

s3, hammering construction of the precast pile;

s4, monitoring and feeding back to dynamically adjust the construction sequence and release stress through the stress release groove and the stress release hole;

s5, selecting a proper construction tool according to the detection data theory;

and S6, groove cleaning and local pit-sharing excavation.

2. The pile hammering and sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 1, wherein the step S1 of installing an inclinometer and an automatic detection device of the foundation pit is as follows:

s101, mounting a deep foundation pit supporting pile in an ultra-thick sludge area;

s102, mounting a static level gauge and an inclination angle sensor for automatic observation on the crown beam;

s103, mounting a dynamometer on the anchor rod, and pre-excavating the earth after the inclinometer pipe is pre-embedded;

s104, observing the influence of excavation of upper soil on lower soil in the earthwork excavation process, and theoretically analyzing the influence of the earthwork excavation on the stress of the pile body of the sludge layer precast pile and the influence of machinery on the pile by detecting the movement of the soil through an inclinometer so as to guide construction.

3. The pile hammering and sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 1 or 2, wherein the construction stress release holes and the stress release ditches in the step S2 are as follows:

s201, leveling mucky soil within the range of 3m around the foundation pit;

s202, correcting the stress release trench excavation;

s203, draining accumulated water;

s204, positioning a drilling machine;

s205, forming holes, simultaneously installing a PVC plastic pipe and pouring coarse sand around the plastic pipe: during the construction of the stress release holes, adopting a jumping mode of three-to-one punching for circle construction, sequentially punching holes in sequence, and punching the stress release holes to timely perform PVC plastic pipe and sand filling treatment;

s206, shifting a drilling machine;

and S207, cleaning the site after construction is finished.

4. The pile hammering and sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 3, wherein the stress relief trench excavation correction in the step S202 is as follows:

s20201, arranging stress release holes around the inner side of the garage crown beam, wherein the diameter of each stress release hole is 300mm, the distance between every two stress release holes is 1000mm, placing a PVC plastic pipe with the diameter of 50mm in the middle, filling coarse sand between the PVC plastic pipe and the wall of a hole, and exposing the PVC plastic pipe for 300 mm;

s20202, the width of the stress release groove is 1 meter, and the depth is 1.5 meters.

5. The hammering pile-sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 4, wherein the accumulated water removal in the step S203 is as follows:

s20301, excavating along the side of the foundation pit to a position 50cm lower than the garage cushion layer, laying a circle of stones, and placing a drainage pipe to block soil;

s20302, placing the PVC-U corrugated pipes with the holes on the pipe walls along a ditch, and reserving 11 water collecting well building positions in the middle;

s20303, after the water collecting well is built, covering a 850mm stone water filtering layer on the PVC-U corrugated pipe, and backfilling gravel soil to-2.61 m;

s20304, placing a water pump in the water collecting pit to pump water, and discharging the extruded water after piling in time.

6. The hammering pile sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 5, wherein the hammering pile sinking construction method for the precast pile in the step S3 is as follows:

s301, backfilling gravel soil;

s302, leveling the field;

s303, measuring and lofting;

s304, pile foundation in place;

s305, pile sinking;

s306, sinking the pile in place;

s307, pile splicing or pile cutting;

and S308, pile testing.

7. The hammering pile-sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 6, wherein the pile sinking in the step S305 is as follows:

s30501, a hammer is lifted and tapped, the pile is kept vertical under the checking of the two theodolites, and the pile can be formally sunk when no abnormality exists;

s30502, when the hammer is hammered, the hammer is preferably hammered, and the hammer weight is selected according to geological conditions, pile types, structures, density and construction conditions; according to the density of piles, the piling sequence can be symmetrically driven from the middle to two sides or from the middle to the periphery;

s30503, hammering and sinking the pile, and using a vertical-line hardwood or a steel wire rope with stacked discs as a hammer pad between the pile cap and the pile hammer, wherein the thickness of the hammer pad is 150-200 mm.

8. The hammering pile sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 7, wherein the monitoring feedback in the step S4 dynamically adjusts the construction sequence and the stress release through the stress release channels and the stress release holes is as follows:

s401, performing real-time deformation observation from the beginning of excavation to the completion of precast pile construction by adopting an automatic foundation pit deformation monitoring system;

s402, the automatic foundation pit deformation monitoring system sends data acquired by a sensor to a cloud platform in real time through an intelligent node by using a 4G/5G network, so that real-time early warning and alarming are realized, and monitoring data are counted and processed to automatically generate corresponding curves and reports;

and S403, adjusting the construction sequence and the drainage in the stress release holes in time through the detection data to ensure the stability of the supporting structure.

9. The offshore ultra-thick sludge area deep foundation pit precast pile hammering pile sinking construction method as claimed in claim 8, wherein the step S5 of selecting a suitable construction machine according to the detection data theory is to push back the precast pile by the selected mechanical equipment in the process of cleaning the groove, collecting pit and excavating local pit of the reclaimed water treatment station, so as to avoid pile foundation toppling caused by earth excavation; the method comprises the following specific steps:

s501, excavating machine: a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator are adopted;

when a creep-working XE215CA excavator is used in a foundation pit, the total weight of the excavator is 21750kg, the total length is 9565mm, the track wheel base is 3462mm, the minimum turning radius is 3.5m, and the estimated excavator load is as follows:

s502, earthwork vehicle: the earthwork external transportation adopts a front four-rear eight-self-dumping truck for external transportation, and the total axle weight of a rear wheel double axle is 600 kN; setting the distance between the wheel outside the automobile and the slope top line of the foundation pit to be 3.5m, and calculating the equivalent distributed load action of the automobile, wherein the diffusion angle of the wheel diffusion pressure is 30 degrees, and the diffusion area of the wheel pressure of the rear wheel double axle is (2.4+2 x 3.5) × (1.6+2 x 3.5) ═ 71.44m²；

Then the equivalent distributed load of the automobile is as follows:

21t excavatorThe minimum turning radius of the excavator is 3.5m, and the equivalent load of the excavator is 6.34 kPa; if the outer side wheel of the earthwork vehicle is 3.5m away from the slope top line of the foundation pit, the equivalent load of the automobile is 8.4 kPa; the depth of the socketed rock is L because the automobile and the excavator can not act on one at the same time_d1.5b can meet the requirement; the construction machinery comprises a large excavator and a earthwork vehicle which are fully loaded, and is matched with a steel plate for operation in mucky soil, and the size of the steel plate is 6000 x 2000 x 20 mm; paving the pattern steel plate with the size of 4000 x 2000 x 5mm to meet the requirement;

s503, determining that the construction excavator adopts a large 300-type backhoe excavator, a 260-type long arm excavator and a small 60-type excavator; the earth transporting vehicle adopts four front and eight rear earthwork muck vehicles and is equipped with a small-sized agricultural vehicle for emergency cooperation.

10. The pile hammering and sinking construction method for the precast pile in the deep foundation pit in the offshore ultra-thick sludge area according to claim 9, wherein the groove cleaning and the local pit co-pit excavation in the step S6 are as follows:

s601, determining an excavation sequence: 1-1, 2-1, 1-2 → 2-2, 1-3, 2-3 → 1-4, 2-4, 1-5 → 2-5, 1-6, 2-6 → 1-7, 2-7 → 1-8;

and S602, constructing the two excavators simultaneously.

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