CN113550350B - Construction method and application of single wall of underground station in silt and broken zone stratum - Google Patents

Abstract

The application relates to the technical field of underground station construction, and particularly discloses a construction method and application of a single wall of an underground station with silt and broken zones. The construction method comprises the steps of geological supplement exploration, sludge stratum treatment, wall guide construction and verticality control, pulping, double-wheel milling to form grooves, groove cleaning and wall brushing, groove wall detection, reinforcement cage manufacturing and embedded part installation, steel jogwash joint treatment, secondary hole cleaning, underwater concrete pouring and underground continuous wall quality detection. This application adopts underground continuous wall to do the foundation ditch excavation stage concurrently as the permanent structure side wall of underground station and keeps off the single wall form of stagnant water envelope, has solved the atress problem that underground continuous wall does the permanent structure side wall, has cancelled main body frame structure and additional waterproof layer simultaneously, can reduce engineering cost and practice thrift the time limit for a project. In addition, the rail transit station is basically located in a main urban area of a city, noise in the construction process can be effectively reduced by using double-wheel milling grooving, and the construction quality of the continuous wall can be guaranteed by adopting the process.

Description

Single wall construction method for underground station in silt and broken zone and application

Technical Field

The invention relates to the technical field of underground station construction, in particular to a construction method and application of a single wall of an underground station with silt and crushed zone strata.

Background

Under the environment that green construction and energy conservation and environmental protection are greatly advocated in China, more and more assembly type construction methods are made out of the ground and play a greater and greater role in the actual construction process.

In the prior art, the construction method of the cast-in-situ bored pile and the main concrete frame structure is generally used for the construction of the underground continuous wall of the subway station, but the construction method has the problems that the underground continuous wall cannot be used as a side wall of a permanent structure due to poor stress, and meanwhile, the construction cost is very high due to the maintenance cost of water prevention, leakage stoppage and the like in the later stage of the related technology.

Disclosure of Invention

In order to enable the underground continuous wall to be used as a permanent structure side wall, and effectively reduce the construction cost by canceling a main body frame structure and an additional waterproof layer, the application provides a construction method and application of a single wall of an underground station of a silt and broken zone stratum.

In a first aspect, the application provides a single wall construction method for an underground station of a silt and crushed zone stratum, which adopts the following technical scheme:

a single wall construction method for underground stations with silt and broken zone stratums comprises geological supplement exploration, silt stratum treatment, guide wall construction and verticality control, pulping, double-wheel milling to form grooves, groove cleaning and wall brushing, groove wall detection, reinforcement cage manufacturing and embedded part installation, steel king-shaped joint treatment, secondary hole cleaning, underwater concrete pouring and underground continuous wall quality detection.

By adopting the technical scheme, grooving is carried out by utilizing the hydraulic grab bucket and the double-wheel mill, the verticality deviation is controlled in the grooving process, then the reinforcement cage is manufactured and the embedded part is installed on the ground, the reinforcement cage is lifted and then placed down by the two crawler cranes, and finally the construction of the single wall of the whole underground station can be completed by pouring underwater concrete by adopting a conduit method.

The underground diaphragm wall (or the bored pile and the main concrete frame structure form) of the traditional subway station is replaced by the single wall form of the underground diaphragm wall serving as the permanent structure side wall of the underground station and serving as the retaining and water-stopping enclosure structure in the foundation pit excavation stage. The single wall structure form well solves the problem that the stress of the side wall of the permanent structure made of the underground diaphragm wall is poor, and simultaneously cancels a construction method of a main body frame structure and an additional waterproof layer, so that the construction cost can be effectively reduced, and meanwhile, the subsequent treatment of wall surface bulge, waterproof leakage stoppage at joints, local spot leakage and other common quality problems is not needed in the later stage of the engineering, so that the construction period of the construction method is shortened to a great extent.

Preferably, in the geological supplementary exploration, aiming at geological complex sections with silt and broken zones, a 'one-groove one-drill' treatment mode is adopted to explore underground continuous walls in advance, and the condition of unfavorable geology is known and explored.

By adopting the technical method, aiming at geological complicated sections, such as silt, broken zones and the like, the geological advanced drill is adopted to drill one groove for one underground diaphragm wall, unfavorable geological conditions are detected in advance, and reliable theoretical basis is provided for the selection of groove wall reinforcement, slurry proportion, grooving process and the like of the underground diaphragm wall.

Preferably, in the sludge stratum treatment, the underground continuous wall slot wall is reinforced by adopting a grid type cement soil wall as a temporary supporting structure, and the foundation of the deformation area is reinforced by adopting a single-shaft stirring pile form.

By adopting the technical method, the groove wall of the underground continuous wall and the traveling area of the double-wheel milling and grooving machine are reinforced before construction, so that the stability of the groove wall in the grooving process is improved, the hole collapse condition of weak strata (namely the strata with high softness such as silt, miscellaneous filling soil and the like) in the grooving process is reduced, the probability of quality common faults such as bulges, guide wall inclination to the groove and the like in the position after concrete pouring can be reduced, and the surface flatness and the verticality of the underground continuous wall in the strata are effectively improved. In addition, through adopting unipolar stirring stake to the continuous wall upper portion weak stratum cell wall of underground, the double round mills and the weak soil layer is consolidated in the crawler crane walking area, can effectively avoid the hole condition of collapsing in silt layer, muck layer grooving process, has effectively reduced a large amount of concrete and has surpassed the phenomenon of irritating when guaranteeing the quality of cell wall.

Preferably, in pulping, a high-quality bentonite slurry is adopted for protecting the wall, and the bentonite slurry has the use requirements that: the bentonite slurry is observed to have stable property after standing for 24 hours, and can be used after the bentonite slurry is fully hydrated.

Preferably, after slurrying, the slurry properties in the tank are measured at intervals of 2-4 hours, when the specific gravity of the slurry in the fractured zone is found to be less than 1.25g/cm ³ When the slurry is changed, the slurry circulation system is immediately driven to change the slurry; the mud circulation system comprises a mud pump, a mud separation purifier and a mud storage area; wherein, according to the treatment sequence of the mud, the mud separating and purifying device consists of a sedimentation tank, a cyclone and a vibrating screen in turn.

By adopting the technical method, the quality of the slurry determines the quality of the wall protection effect, and the quality of the slurry is monitored in real time to play an important role in the stability of the wall of the tank.

Preferably, in the double-wheel milling grooving process, a grooving machine is adopted for grooving operation, and a hydraulic motor of the grooving machine is adopted to drive a plurality of milling wheels to rotate so as to cut and crush the rock stratum; discharging the milled residue soil to a slurry separation purifier for purification by using a pumping or gas-lift slag discharging mode; then, the purified slurry is delivered into the tank again by a slurry pump for recycling; a flat gear is adopted in the soil layer and the stratum of a broken zone, and a bevel gear is adopted in the stratum to rotate so as to cut and break the stratum.

By adopting the technical scheme, the grooving operation is carried out by adopting the hydraulic grab grooving machine and the double-wheel milling machine, and the stratum applicability is strong. Meanwhile, flat gears are adopted in the soil layer and the stratum of the broken zone, and bevel gears are adopted in the rock stratum, so that the efficiency of double-wheel milling construction can be further improved.

Preferably, in the double-wheel grooving process, the cutting transmission chain of the grooving machine is provided with a plurality of convex guide blocks on the side walls which are far away from each other, and the cutting transmission chain simultaneously forms a triangular guide groove on two sides of the grooving while performing transmission cutting.

By adopting the technical scheme, the cutting transmission chain adopts an outward convex design, and at the moment, the guide blocks on two sides of the double-wheel milling main body slide downwards along the guide grooves in the sinking process of the double-wheel milling, so that the vertical accuracy of the formed grooves is improved.

Preferably, a plurality of deviation correcting plates controlled by a hydraulic jack are arranged on a double-wheel mill of the slot milling machine, the hydraulic jack is connected with the touch screen controller through an electric signal, and the touch screen controller controls the hydraulic jack to extend out of or retract into the deviation correcting plates.

By adopting the technical scheme, an operator controls the hydraulic jack to extend out or retract into the deviation correcting plate through the touch screen controller, can also control the hydraulic jack to extend out or retract into the guide frame, adjusts the posture of the milling head, and slows down the descending speed of the milling head, so that the verticality of the slotted hole is effectively controlled, and meanwhile, the conditions of hole depth, hole inclination and the like can be automatically recorded through the probe and displayed through the touch screen. In addition, an operator can know the pressure and the rotating speed of the milling wheel, the rotating speed and the discharge capacity of the slag discharge pump, the depth and the straightness of the milling head in the milling groove and the tension parameter of the milling chain through a display system of the touch screen controller, and can timely regulate and control the working state of the double-wheel milling.

Preferably, the joints of the underground diaphragm wall are steel joints in the shape of Chinese character 'wang', the steel joints are assembled and welded on the ground into a whole, the steel joints are welded on two sides of the reinforcement cage, and meanwhile, a joint box is placed on the back of the steel joints.

Through adopting above-mentioned technical scheme, place two joint casees (the case that is used for the joint) respectively in the steel back of the Chinese character ' wang ', lie in two half surrounding structures that the steel of the Chinese character ' wang encloses promptly, guarantee that the concrete placement in-process can not appear the phenomenon of streaming, improved construction quality.

In a second aspect, the application of the construction method for the single wall of the underground station with the silt and the crushed zone stratum is applied to manufacturing of underground continuous walls with higher quality, perpendicularity and embedded part installation accuracy.

In summary, the present application has the following beneficial effects:

1. this application adopts underground continuous wall to do the foundation ditch excavation stage concurrently as the permanent structure side wall of underground station and keeps off the single wall form of native stagnant water envelope, and this structural style has solved underground continuous wall and has done the atress problem of permanent structure side wall, has improved the quality of the single wall of underground station greatly.

2. The construction method has the advantages that the underground diaphragm wall is used as the side wall of the permanent structure of the underground station and is also used as the single wall form of the retaining and water stopping enclosure structure in the foundation pit excavation stage, the construction form of a main frame structure and an additional waterproof layer is omitted, the construction cost is reduced, the construction period is shortened, and certain advantages are achieved. Meanwhile, the rail transit station is basically located in a main urban area of a city, citizens have high attention, noise in the construction process can be effectively reduced by milling grooves with two wheels, and the construction quality of the continuous wall can be guaranteed by adopting the process.

3. The grooving operation is preferably carried out by adopting a hydraulic grab grooving machine and a double-wheel milling machine, and the stratum applicability is strong. Meanwhile, flat gears are adopted in the soil layer and the stratum of the broken zone, and bevel gears are adopted in the rock stratum, so that the efficiency of double-wheel milling construction can be further improved.

Drawings

FIG. 1 is a process flow chart of a single wall construction method of an underground station of a silt and crushed zone stratum according to the application.

FIG. 2 is a top view of the grooved shape obtained by the hydraulic grab grooving machine and the double-wheel milling grooving machine of the present application, which is mainly used for embodying the shape and relative position of the Chinese character pin-shaped guide groove in the grooved shape.

FIG. 3 is an ultrasonic inspection of the walls of the tank after cleaning and brushing of the walls of the tank of the present application.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples.

Example 1: a single wall construction method for underground stations in the ground layer of silt and broken zones is suitable for underground continuous wall construction operation with high requirements on the quality, verticality and installation accuracy of embedded parts of the underground continuous wall. As shown in fig. 1, the single wall construction method for the underground station specifically comprises the following steps:

s001, preparation for construction

0011. Before construction, preparation work of technologies such as drawing consultation, editing and reviewing of construction schemes, technical background settlement, personnel training and the like is made;

0012. site preparation work such as tee joint leveling is well done on a construction site (namely, before formal construction of a construction project, the construction site needs to reach the conditions of water circulation, electricity circulation, road communication, site leveling and the like), construction enclosure, construction bulletin and the like;

0013. before construction, the inspection and acceptance work of machines, materials and the like in the field is well done.

S002, geological supplementary investigation

Before construction, according to a detailed engineering geological survey report, contacting a qualified survey unit, determining unfavorable geological conditions such as silt, a sand layer, a broken zone and the like by adopting a 'one-trough one-drill' treatment mode, forming a 'one-trough one-drill' geological supplementary survey report, and reporting the report to a design institute for scheme optimization; and meanwhile, the specific grooving scheme and slurry performance are selected according to data such as 'one-groove one-drill' geological supplementary survey report and the like. The final hole depth of the processing mode of 'one groove and one drill' is 3d below the continuous wall (namely, the anchoring length which is designed to bear the length value of 3 times of the diameter of the steel bar is reached), and the hole penetrates 3m behind the crushing belt.

S003, sludge stratum treatment

0031. Underground continuous wall groove wall reinforcement

Aiming at the weak strata such as silt, miscellaneous filling soil and the like existing on the surface layer, hole collapse is easy to occur in the grooving process, and common quality problems such as bulging and the like are easy to occur at the position after concrete pouring, in order to ensure the surface flatness of the underground continuous wall on the stratum and prevent the hole collapse of the underground continuous wall, the grid type cement soil wall is used as a temporary supporting structure. The diameter of deep stirring is phi 600, and the lapping length between piles is not less than 150 mm. The pile body adopts 42.5-grade ordinary portland cement, and the mixing amount of the ordinary portland cement is 20%; the water cement ratio of the cement paste is 0.45-0.55, and the water cement ratio of the cement paste in the embodiment can be 0.5.

0032. Double-wheel milling walking area foundation reinforcement

Because the double-wheel milling machine weighs about 175 tons, the grounding area is 11.6 square, the required bearing capacity of the foundation reaches 150KPa, the bearing capacity of a soft layer on the surface layer of a general foundation is lower, and the position of the double-wheel milling machine station is closer to the groove wall, so that the guide wall can incline towards the groove due to overlarge pressure, and therefore the groove can not be formed normally. The foundation of the deformation area is reinforced by adopting a single-shaft stirring pile form, the diameter phi is 600, and the lap joint length between piles is not less than 150 mm. The pile body adopts 42.5-grade ordinary portland cement, and the mixing amount of the ordinary portland cement is 20%; the water cement ratio of the cement paste is 0.45-0.55, and the water cement ratio of the cement paste in the embodiment can be 0.5.

S004, wall guiding construction and verticality control

The guide wall is of a cast-in-place reinforced concrete structure, wherein the guide wall is of a structure

The depth and the thickness of the guide wall of the structural type need to meet design requirements, the guide wall is placed 5cm (single side 2.5cm) outside the clear distance according to the standard requirements, and the underground continuous wall needs to be placed outside the center line of the guide wall.

And (3) conducting wall verticality control measures: the guide wall adopts a large steel mould (namely a guide wall steel template component) for auxiliary construction, and concrete at two sides of each section of guide wall needs to be symmetrically poured simultaneously in the pouring process, so that the offset of the wall template is reduced. If the construction of the guide wall is not timely after the construction of the guide wall is finished (for example, the construction of the guide wall can be continued after 3-7 days), the guide wall groove needs to be backfilled to prevent the guide wall groove from deforming. In addition, when the ground nearby has a large load or the machine is running, the support of the guide wall needs to be strengthened to prevent the guide wall from displacing and deforming.

S005, single wall grooving construction of broken zone stratum

0051. Device model selection

At the present stage, main grooving equipment mainly comprises a double-wheel grooving machine (namely an FD60HD grooving machine, which is called a grooving machine for short), a hydraulic grab grooving machine (namely an SG60 hydraulic grab, which is called a hydraulic grab for short) and an impact drill. Wherein, the hydraulic grab grooving machine is only suitable for soil layer construction; and the impact drilling grooving easily causes the irregular groove shape and the poor grooving precision. Because of single wall construction requires continuous wall body straightness that hangs down, surface smoothness are high, simultaneously at broken zone stratum grooving in-process, if there is great impact then can cause broken zone part to collapse the groove, consequently the embodiment of this application adopts the construction scheme of "hydraulic grab grooving machine for the soil layer and rock stratum are with double round milling grooving machine", and it has the cell type rule, and the grooving precision is high, does not have the advantage of impact and vibrations basically to the cell wall.

0052. Dado mud system

According to engineering characteristics and geological conditions, high-quality slurry is adopted for wall protection, the high-quality slurry mainly adopts bentonite slurry, the bentonite slurry does not change in properties or precipitate after being kept stand for 24 hours, and the bentonite slurry can be used after the slurry material is fully hydrated. In the construction process, the liquid level of the slurry is ensured to be higher than the ground water level by more than 1.5m and not lower than the top surface of the guide wall by 0.5 m; and circulating the slurry by a slurry circulating system of a double-wheel milling and grooving machine.

The mud recycling system comprises a mud pump, a mud separation purifier and a mud storage area. Wherein, according to the treatment sequence of the mud, the mud separating and purifying device consists of a sedimentation tank, a cyclone and a vibrating screen in turn. The cyclone is a dehydration cyclone. An operator extracts and recovers the slurry in the tank into the slurry separation purifier by using a slurry pump, the slurry is kept stand and layered in a sedimentation tank, the concentrated lower-layer slurry is guided into the cyclone after an upper-layer water body is removed, the three-dimensional elliptic strong-rotation shearing turbulent motion is carried out by using the centrifugal sedimentation principle, most of coarse particles are discharged through a bottom flow port of the cyclone, and most of fine particles are discharged through the overflow pipe, so that the separation and classification purposes are achieved. Then respectively introducing the coarse particles and the fine particles into corresponding vibrating screens for secondary screening operation, and screening according to the particlesAnd storing the screened soil in a mud storage area in a partition mode according to the size. Then extracting soil with relative particle size according to construction requirements and supplementing the soil into the tank, so that the slurry in the tank is stabilized within a standard range, for example, the stability of the stratum in a fractured zone is poor, and the specific gravity of the slurry in the zone should be controlled to be 1.25g/cm ³ Left and right. And (3) detecting the specific gravity of the slurry every 2 hours at intervals of the performance of the slurry, and immediately driving a slurry circulating system to perform slurry changing treatment if the performance of the slurry cannot meet the requirement.

0053. Dual-wheel milling grooving and verticality control

The double-wheel milling machine is characterized in that a groove is formed in the first groove of the standard groove section by adopting three-digging groove forming, two sides are dug firstly, then the middle is dug, and a concave groove structure with a hollow inner part is obtained; the closing width is reasonably adjusted according to the width.

00531 grooving construction

The length of a double-wheel milling wheel of an FD60HD slot milling machine is 3150mm, the wiping thickness can be adjusted between 650-1200 mm, before the double-wheel milling machine is placed into a guide wall, the outermost edge of the milling wheel teeth of the double-wheel milling machine is aligned with a slot section construction lofting line of a guide wall top, two sides of the milling wheel are parallel to the guide wall surface of a continuous wall, the milling wheel to be milled is vertically placed into the guide wall slot, and a guide frame of the double-wheel milling machine is fixed by a hydraulic fixing frame, wherein the hydraulic fixing frame is in a rectangular frame structure and comprises two long rods and two short rods which are connected end to end, the long rods are horizontally placed on the wall top of the guide wall and are often fixed by a hydraulic jack, the short rods are transversely erected on the guide wall slot, two ends of the short rods are respectively fixedly connected with the two long rods by bolts, and the long rods and the short rods are in a right angle, therefore, the area enclosed by the long rods and the short rods is the area of the construction slot, an operator fixes the hydraulic pressure on the top of the guide wall, the upper part of the milling cutter frame can be effectively prevented from deviating, and the verticality in the groove milling process is ensured.

The double-wheel milling grooving drives two milling wheels to rotate through a hydraulic motor, and cuts and crushes rock strata; discharging the milled residue soil to a slurry separation purifier for purification by using a pumping or gas-lift slag discharging mode; after the purification is finished, an operator can send the purified slurry into the tank again by using a slurry pump for recycling.

The double-wheel milling machine has strong adaptability to stratum, flat gears are adopted in the stratum and the stratum of a broken zone, and bevel gears are adopted in the stratum, so that the construction efficiency of the double-wheel milling machine is accelerated.

0054. Double-wheel milling groove perpendicularity guarantee measure

00541 high-strength double-wheel milling machine, a main body frame structure, cutting transmission chains of FD60HD slot milling machines all adopt an outward-convex design, namely 6-8 convex guide blocks are arranged on the side walls of the cutting transmission chains far away from each other, namely, the cutting transmission chains simultaneously form a triangular convex groove (namely, the cutting transmission chains have the groove forming shape of two oppositely-arranged guide grooves and are communicated with the grooves) on two sides of the groove while performing transmission cutting, and the guide blocks on the two sides of the double-wheel milling machine main body slide along the convex groove (namely, the guide groove) in the sinking process of double-wheel milling, so that the vertical precision of the groove is improved.

00542 in the vertical milling process, due to different geological conditions, stratum changes, excavation speed changes, cutter tooth abrasion conditions, different cutting head stress and other conditions, the milling head may be inclined, so that the slot hole is inclined to cause the verticality deviation. 8 deviation rectifying plates controlled by a hydraulic jack are arranged on a double-wheel mill of the FD60HD slot milling machine, the hydraulic jack is connected with a touch screen controller through an electric signal, an operator can effectively control a hydraulic jack system to extend out of or retract into a guide frame and the deviation rectifying plates through the touch screen controller, the posture of a milling head is adjusted, the descending speed of the milling head is slowed down, the verticality of a slot hole is effectively controlled, the conditions of the depth, the inclination and the like of the hole can be automatically recorded through a probe (namely a position sensor), and the situations can be displayed through the touch screen controller. Meanwhile, an operator can know the pressure and the rotating speed of the milling wheel, the rotating speed and the discharge capacity of the slag discharge pump, the depth and the straightness of the milling head in the milling groove and the tension parameter of the milling chain through a display system of the touch screen controller, and the working state of the double-wheel milling is regulated and controlled in time.

0055. Cleaning groove and brushing wall

00551 cleaning tank

The groove cleaning by adopting a precipitation method is completed by double-wheel milling because each groove section is completed by double-wheel milling, and a double-wheel milling cutter head is provided with a slurry pump, so that the first groove cleaning after groove forming is completed by double-wheel milling, and soil residue sludge deposited at the bottom of the groove is absorbed and removed by a slurry absorption reverse circulation method. In the process of cleaning the tank, high-quality slurry is continuously pumped into the tank to keep the liquid level height and prevent the occurrence of hole collapse.

00552 Brush wall

The joint connection construction quality is directly related to the waterproof effect of the underground diaphragm wall, when the diaphragm wall is constructed, joint treatment is carried out on the closed diaphragm section and the connection diaphragm section, a wall brushing device is used for brushing the wall, and the reciprocating times of wall brushing are not less than 20 times. The brush wall is firstly brushed coarsely by using the steel plate surface and then brushed finely by using the steel wire surface, the reciprocating times of the brush wall are not less than 20 times, and the times of brushing the wall are increased according to the actual situation and are not easy to be brushed cleanly individually until no mud skin exists.

0056. Cell wall detection

After the groove is cleaned and the wall is brushed, the wall of the groove needs to be detected by an ultrasonic side wall instrument before the steel reinforcement cage is placed downwards, and the groove width, the groove thickness, the groove depth and the perpendicularity of the groove wall all meet the design requirements, which is shown in an ultrasonic detection diagram of the groove wall in fig. 3.

S006 steel reinforcement cage manufacturing and embedded part installation

0061. Binding of reinforcing steel bars of reinforcing cage

The steel reinforcement cage adopts whole preparation, integral hoisting to go into the groove, shortens the process time. The reinforcement cage is integrally hoisted once according to a unit groove section and is manufactured on site.

0062. Installation of embedded parts

00621 controlling the elevation of the embedded part: after the grooving is finished, the elevation is respectively measured on the guide wall according to the positions of 4 lifting ribs, the length of the lifting rib is calculated and manufactured on the basis of the elevation, and the position of the embedded rib (member) is determined by taking the elevation of the cage top as a datum point.

00622 acoustic pipe installation control: the sounding pipe is a 3.5mm seamless steel pipe, iron wires are used for binding and fixing the sounding pipe with main ribs of the continuous wall at intervals of 2m in a crossed mode, the extension joint of the sounding pipe is clamped by a special clamp, and the bottom of the sounding pipe is sealed by a cover. After the steel bar cage is arranged in the groove, clear water is needed to be filled into the acoustic pipe, and then the top end is sealed.

00623 controlling precision of the pre-embedded connector: the connector adopts 2 fixed points, two-layer spot welding and main muscle spot welding respectively about the steel reinforcement cage, adopts 2 phi 14 reinforcing bars to press from both sides tightly fixedly simultaneously, prevents to hoist and mount and the built-in fitting condition of droing that appears in the concreting process. Meanwhile, grease is filled in the pre-buried connector and then the connector cover is screwed up to seal the connector, so that the connector is prevented from being filled with water slurry and mud slurry.

0063. Steel reinforcement cage hoist and mount

The underground continuous wall steel reinforcement cage adopts integral hoisting, crane type selection is carried out according to the steel reinforcement cage with the longest standard section and the heaviest standard section, and double-crane lifting and hoisting are adopted for hoisting the underground continuous wall steel reinforcement cage, so that the underground continuous wall steel reinforcement cage returns to be straight in the air. 1 400t crawler crane is used as a main crane and 1 180t crawler crane is used as a secondary crane.

S007 king steel joint treatment

The joints of the underground diaphragm wall adopt steel joints in the shape of Chinese character 'wang', the steel joints are assembled and welded on the ground into a whole and are welded on two sides of a reinforcing cage of the first-stage groove section. The external dimension and the widths of the filling joint box and the soil bag are considered when the first opening width excavation is carried out. For the steel joint with the shape of the Chinese character 'wang', a joint box is placed on the back of the steel joint with the shape of the Chinese character 'wang' to ensure that the phenomenon of streaming can not occur in the concrete pouring process.

S008 secondary hole cleaning and underwater concrete pouring

Before concrete pouring, the sediment thickness and the slurry performance at the bottom of the tank are detected, and if the sediment thickness and the slurry performance do not meet the requirements, gas lift reverse circulation secondary slurry exchange and secondary tank cleaning are carried out.

Commercial concrete is adopted for the construction of the continuous wall, the slump of entering the groove is preferably 180-220 mm, and the workability is good. 2 sets of guide pipes are arranged on the 6m standard section-shaped groove section, the distance between the two sets of guide pipes is not more than 3m, the distance between the guide pipe and the end of the groove is not more than 1.5m, the guide pipe is lifted to be about 30-50 cm away from the bottom of the groove, and concrete pouring is symmetrically carried out.

S009 underground continuous wall quality testing

Due to the high quality requirement of the single wall, when each underground continuous wall reaches the detection age, detection personnel are arranged to enter the underground continuous wall and are detected by the ultrasonic detector, and the construction step is optimized in time or targeted measures are taken according to the ultrasonic detection result.

Application example 1: the construction method for the single wall of the underground station in the silt and broken zone stratum is applied to the 11-number online Yongpark station of Guangzhou subway from 9 months to 1 month in 2019 in 2018, and is a first assembly type station in south China. The Guangzhou city track traffic No. eleven-line upwelling park station is an underground three-layer island type platform station, the total length is 221.7m, the standard section width is 22.3m, the standard section foundation pit depth is 24.48m, and the shield well foundation pit depth is 25.27 m. The station adopts a single wall assembly type structure, the underground continuous wall is also used as a permanent structure side wall, and the concrete support is also used as a permanent structure cross beam, so that the stress problem that the underground continuous wall is used as the permanent structure side wall is effectively overcome.

The standard wall width of the continuous wall of the station enclosure structure is divided into widths according to the width of 6m, and joints of the underground continuous wall are all steel joints shaped like Chinese character 'wang'. The station main structure comprises 82 underground continuous walls in total, the average depth of the underground continuous walls is 38m, and the deepest part of the underground continuous walls is 51.27 m. By adopting the construction method, the problems of the perpendicularity, the flatness and the like of the underground continuous wall body are successfully solved, the construction quality of the underground continuous wall is further ensured, and greater economic benefits are obtained, and the data in the table 1 are referred.

TABLE 1 economic profit statistical table of upwelling park station project in 2018-

The upwelling park station project adopts the construction method in the embodiment 1, so that the construction quality of the underground diaphragm wall can be effectively guaranteed, and meanwhile, compared with the traditional diaphragm wall construction method, the subsequent common quality treatment such as wall surface bulge treatment, seam waterproof and leakage stoppage, local point leakage and the like is reduced, the quality of the diaphragm wall is well controlled, and the cost is well saved. During construction, the upwelling park station project saved about 17.5 ten thousand dollars, for a specific comparison see Table 2.

TABLE 2 statistical table of saved construction cost expenses

The specific embodiments are merely illustrative of the present application and not restrictive, and those skilled in the art who review this disclosure may make modifications to the embodiments as needed without any inventive contribution, but fall within the scope of the claims of the present application.

Claims (8)

1. A single wall construction method for underground stations in the ground of silt and broken zones is characterized by comprising geological supplement exploration, silt ground treatment, guide wall construction and verticality control, pulping, double-wheel milling to form grooves, groove cleaning and wall brushing, groove wall detection, reinforcement cage manufacturing and embedded part installation, steel king-shaped joint treatment, secondary hole cleaning and underwater concrete pouring and underground continuous wall quality detection;

in the geological supplementary exploration, aiming at geological complex sections with silt and broken zones, a 'one-groove one-drill' processing mode is adopted to explore underground continuous walls in advance, and the condition of unfavorable geology is known and explored;

in the silt stratum processing, carry out underground continuous wall cell wall reinforcement through adopting grille-type soil cement wall as temporary support structure, adopt the unipolar stirring stake form to walk the regional ground of shape and consolidate simultaneously.

2. The method for constructing the single wall of the underground station of the silt and crushed zone stratum as claimed in claim 1, wherein the slurry is prepared by using high-quality bentonite slurry to protect the wall, and the bentonite slurry has the use requirements that: and (3) standing the bentonite slurry for 24 hours, observing the stable property of the bentonite slurry, and using the bentonite slurry after the bentonite slurry is fully hydrated.

3. The single wall construction method for the underground station with the sludge and the crushed zone stratum according to claim 2, characterized in that after pulping, the performance of the slurry in the tank is detected at intervals of 2-4 hours, and when the specific gravity of the slurry in the crushed zone stratum is found to be lower than 1.25g/cm, a slurry circulating system is immediately driven to carry out slurry changing treatment; the mud circulation system comprises a mud pump, a mud separation purifier and a mud storage area; wherein, according to the treatment sequence of the mud, the mud separating and purifying device consists of a sedimentation tank, a cyclone and a vibrating screen in turn.

4. The construction method of a single wall of an underground station of a sludge and crushed zone as claimed in claim 1, wherein in the double-wheel grooving, a grooving operation is performed by using a groove milling machine, and a hydraulic motor of the groove milling machine is used to drive a plurality of milling wheels to rotate, cut and crush rock strata; discharging the milled residue soil to a slurry separation purifier for purification by using a pumping or gas-lift slag discharging mode; then, a slurry pump is adopted to send the purified slurry into the tank again for recycling;

a flat gear is adopted in the soil layer and the stratum of a broken zone, and a bevel gear is adopted in the rock stratum to rotate so as to cut and break the rock stratum.

5. The method as claimed in claim 4, wherein a plurality of protruding guide blocks are provided on the side walls of the cutting transmission chain of the slot milling machine, and a triangular guide groove is formed on both sides of the slot milling machine while the cutting transmission chain performs transmission cutting.

6. The method as claimed in claim 5, wherein a plurality of deviation correction plates controlled by hydraulic jacks are arranged on the double-wheel mill of the slot milling machine, the hydraulic jacks are connected with a touch screen controller through electric signals, and the touch screen controller controls the hydraulic jacks to extend out of or retract into the deviation correction plates.

7. The method for constructing the single wall of the underground station of the silt and crushed zone stratum as claimed in claim 6, wherein the joints of the underground continuous wall are steel joints with the shape of Chinese character 'wang', the steel joints are assembled and welded on the ground into a whole, and are welded on two sides of the reinforcement cage, and meanwhile, the joint boxes are placed on the back of the steel joints.

8. Use of the method for constructing a single wall of an underground station of a silt and crushed zone stratum according to any one of claims 1 to 7 for manufacturing underground continuous walls with higher quality, verticality and installation accuracy of embedded parts.

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