CN110029680B - Deep foundation pit dewatering construction method - Google Patents

Deep foundation pit dewatering construction method Download PDF

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Publication number
CN110029680B
CN110029680B CN201910320044.5A CN201910320044A CN110029680B CN 110029680 B CN110029680 B CN 110029680B CN 201910320044 A CN201910320044 A CN 201910320044A CN 110029680 B CN110029680 B CN 110029680B
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pipe
foundation pit
water
dewatering
filter
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CN110029680A (en
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高清洁
梁栋
谭玉春
肖文德
龚凯
杨华
周林晟
陈干
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23th Metallurgical Construction Group Co ltd Of Minmetals
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23th Metallurgical Construction Group Co ltd Of Minmetals
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D19/00Keeping dry foundation sites or other areas in the ground
    • E02D19/06Restraining of underground water
    • E02D19/10Restraining of underground water by lowering level of ground water

Abstract

A deep foundation pit dewatering construction method comprises the following steps: 1) carrying out overall precipitation design around the basement elevation area by combining engineering geological survey data, and preparing a well point pipe and a self-sucking pump; 2) positioning and paying off; accurately positioning the position of the core barrel according to a design drawing, and arranging a drainage ditch at the outer side of the top of the foundation pit; 3) enlarging each side of the core cylinder along the side line by not less than 2500mm, and excavating to 1-2 m below the underground water level; 4) and uniformly distributing pumping wells for draining and reducing the water level of the diving and confined water in the foundation pit according to the calculated number of the dewatering wells, and arranging dewatering well points in a closed manner around the periphery of the foundation pit of the core barrel, wherein the dewatering well points are inserted into the foundation pit by adopting PVC vertical pipes which are arranged at intervals and in a staggered manner to form a continuous dewatering closed ring. The invention adopts the PVC pipe to arrange the closed type dewatering well points around the foundation pit, has low investment cost, balanced water pressure during dewatering, obvious effect and less influence on the construction period.

Description

Deep foundation pit dewatering construction method
Technical Field
The invention relates to the field of building construction, in particular to a deep foundation pit dewatering construction method.
Background
Along with the rapid development of novel urbanization construction, the building scale is rapidly enlarged, more and more underground facilities are continuously emerged, oversized and ultra-deep basements are more and more, and more large buildings are located along rivers and coastal places. The soil layer with good underground permeability is often communicated with river water, geological data sometimes cannot completely and accurately reflect geological conditions, sand water emerges from the foundation pit along with the excavation of the foundation pit, even piping phenomenon can occur, and at the moment, rapid drainage measures need to be taken. In actual construction, steel sheet piles, cement mixing piles or water interception curtains are often adopted to control underground water before foundation pit excavation, but the method can only meet the projects with smaller water inflow and shallower precipitation depth, and has limited effect on the projects of deep foundation pits near the bank.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a deep foundation pit dewatering construction method which adopts PVC pipes to arrange closed dewatering well points around a foundation pit, has low investment cost, balanced water pressure during dewatering, obvious effect and small influence on the construction period.
In order to solve the technical problems, the technical scheme provided by the invention is as follows: a deep foundation pit dewatering construction method comprises the following steps:
1) the whole precipitation design prepares well point pipe and self priming pump: carrying out integral precipitation design around the basement elevation area by combining engineering geological survey data, and preparing a well point pipe and a self-sucking pump for precipitation;
2) positioning and paying off: after the foundation pit is excavated, accurately positioning the position of the core barrel according to the planar arrangement of the design drawing and marking; arranging a drainage ditch at the outer side of the top of the foundation pit;
3) excavating a core barrel part of the foundation pit: firstly, enlarging each side of the edge of a water collecting well and/or an elevator well which is positioned at the deepest part of the excavation by not less than 2500mm and excavating to the position 1-2 m below the underground water level;
4) arranging dewatering well points: uniformly distributing pumping wells for draining and reducing the level of the diving and confined water in the foundation pit according to the calculated number of the dewatering wells, and arranging dewatering well points in a closed manner around the water collecting well and/or the foundation pit of the elevator shaft, wherein the dewatering well points are formed by inserting PVC vertical pipes into the foundation pit, the interval between every two PVC vertical pipes is 0.8-1 m, every 6-8 PVC vertical pipes are connected into a whole, and the PVC vertical pipes are staggered front and back according to the pumping influence radius to form a continuous dewatering closed ring;
5) communicating a PVC vertical pipe with a water collecting main pipe: the lower end of a PVC vertical pipe is connected with a filter pipe, the upper end of the PVC vertical pipe is connected with a transverse pipe, the transverse pipe is communicated with a water collecting main pipe, and water in the water collecting main pipe is pumped out by a self-sucking pump;
6) draining the foundation pit: and (3) pumping the open water to a drainage ditch at the top of the foundation pit by adopting a submersible pump in the foundation pit, lowering the underground water level in the pit until the underground water level is below 0.5m of the bottom of the cushion layer of the bearing platform, keeping the soil surface at the bottom of the pit in a water-free state, determining the pumping drainage dewatering time according to the foundation construction requirement, and dismantling the dewatering system after the foundation construction is finished.
As a further improvement of the above technical solution: the diameter of the PVC vertical pipe in the step 4) is 30-40 mm, the insertion depth of the PVC vertical pipe is 4-6 m, and the spacing distance of the PVC vertical pipe is 0.8-1 m.
Further, when the PVC vertical pipe in the step 4) is inserted into a sand layer of the foundation pit, the PVC vertical pipe is repeatedly inserted in a rotating mode, when soil is hard, the conical head steel pipe can be firstly pressed in by an excavator and then pulled out, so that a dewatering well with the diameter the same as that of the conical head steel pipe is formed, and then the PVC vertical pipe with the end part blocked by a filter screen is inserted.
Further, the PVC standpipe bottommost that inserts the foundation ditch in step 4) is the chimney filter, the chimney filter is diameter 50 mm's stereoplasm plastic tubing, and the chimney filter side is slotted with the paper cutter drilling, forms the filtration pore that the bar form was arranged, is connected with the PVC standpipe, and the filter screen shutoff is applied to the chimney filter tip, and the inlayer wraps up with net cloth, and the skin is wrapped up with geotechnological cloth, places the chimney filter in the soil layer that the water permeability is good, sinks to below the minimum water level when absorbing water to installation floater liquid level switch on the chimney filter.
Further, the length of the filter tube is more than or equal to 500mm, the mesh cloth is 30-40 holes/cm, the length of the filter holes of the filter tube is 40-50 mm, the width of the filter holes of the filter tube is 5-10 mm, one end of the filter tube is buried underground, the other end of the filter tube is connected with the PVC vertical tube through a reducing direct connector, and the filter tube is placed in a proper range of a water-bearing stratum according to geological survey data and the original site underground water level condition.
Furthermore, the arrangement of the dewatering well in the step 4) needs to divide areas according to the excavation elevation condition, avoid sand blasting points and cover soil on the original sand blasting positions.
Further, every 6-8 PVC vertical pipes in the step 5) are connected into a whole.
Further, the arrangement of the PVC vertical pipes in the step 4) is to comprehensively carry out well point arrangement according to the requirements of the size, the plane size and the precipitation depth of the foundation pit, the permeability of a water-bearing layer and the flow direction of underground water, and during construction in winter, the water collecting main pipe needs to be subjected to heat preservation treatment.
Furthermore, the water leakage caused by various factors is fully considered during the water drainage design in the step 5), a tee joint and a valve are arranged at the wellhead section of the water outlet pipe of each pipe well, a hose is arranged, so that the drainage pipeline can be repaired without stopping a pump, and the drainage pipeline is arranged to avoid a construction access as much as possible.
Further, when local open water exists in the precipitation foundation pit in the step 6), a small excavator is used for digging a water collecting pit at the middle position in the pit, hollow oil drums with the diameter of 550mm and the height of 4000mm are placed, holes are drilled at the intervals of 100mm on the side surfaces of the oil drums, the part, which is sunk below the digging surface, is blocked by a filter screen, a submersible pump is placed in the oil drums during water pumping, and the automatic water pumping controller realizes the discharge of the open water; according to precipitation design, precipitation all needs to be dredged the dive aquifer of excavation within range, nevertheless because receive the influence of dive aquifer bottom plate unevenness, can appear oozing the waterline in local cohesive soil intermediate layer or dive aquifer bottom plate department, consequently can form a large amount of stagnant water in the foundation ditch, this part of water if handle a large amount of fine particle material in will taking out the stratum well, make foundation ditch side slope soil disturbance appear collapsing, influence foundation ditch excavation and foundation construction. When the situation occurs, in order to prevent the pit wall from collapsing, the speed of digging the groove is reduced, a blind pipe is arranged on the pit wall in time for diversion, a blind ditch is dug at the edge of the groove for water collection, the collected water is drained away, the diversion pipe is generally made of a plastic pipe with the diameter of 25mm and the length of 0.5m, is made into a flower pipe and is wound with a nylon gauze with the mesh of 80 meshes, and the blind ditch is generally dug by being attached to the pit wall, and is 300mm wide and 300mm deep.
Before the precipitation construction method is used, settlement monitoring points are distributed according to a water pumping influence range calculated in precipitation design and typical buildings in the range, continuous settlement monitoring is carried out during water pumping, and necessary measures are taken in time if the accumulated settlement is close to an early warning value (different early warning values determined according to different types of buildings).
Compared with the prior art, the invention has the advantages that:
1. the construction method can realize larger depth reduction, is convenient for engineering construction, and can reduce the influence on excavation construction to the maximum extent when the signs of sand overflowing and piping are found in the earth excavation process in a foundation pit at a position close to a river bank or a part of soil layer for super-large and ultra-deep basement engineering;
2. the construction method is simple and easy to operate, high in construction speed, high in efficiency, low in noise, short in construction period and high in civilized construction degree, and can well meet the requirement of environmental protection, wherein for Shenzhou peninsula project basic construction in Wanning city, 1960 square meters are respectively arranged on 6# building and 7# building in a dewatering area, the basic construction period is 60 days, if a hole forming and well pipe installing mode of an impact drilling machine is adopted, 15 holes are required, the well digging cost is 6720 yuan/one, the labor cost of drilling machine operators is 5 yuan in dewatering construction and operation stages, the equipment cost is 230 yuan/set every day, the total cost is 15.4 yuan, the construction method is adopted for construction, about 3.2 yuan is put into a project part at the early stage, the subsequent other costs are 3 yuan, the PVC pipes and the water pumps can be used, the dewatering construction is completed within 7 days, and the basic construction period is greatly advanced;
3. for the problem of sand water leakage of the deep foundation pit at the bank side, probably because of geological fluctuation, the water-stop curtain does not completely cut off the connection between the underground soil layer and the river water, so that the water level is always supplemented by the peripheral river water after the foundation pit is excavated and does not decline along with the excavation of the earth. According to the past engineering experience, a method of lengthening a waterproof curtain or grouting a base is generally adopted, but the construction method can reduce the hole forming cost of a rotary drilling rig, a pipe well is not needed, the rotary drilling rig can be easily pulled out after the operation is finished, materials can be recycled, and the cost is only 1/3-1/5 of other schemes.
Drawings
FIG. 1 is a schematic structural view of the construction of the present invention;
FIG. 2 is a plan view of the precipitation system of the present invention;
FIG. 3 is a cross-sectional view of the precipitation practice of the present invention;
fig. 4 is a schematic view of the precipitation filter tube connection of the present invention.
Illustration of the drawings:
1. a transverse tube; 2. a PVC standpipe; 3. a filter tube; 4. a self-priming pump; 5. reducing the direct joint; 6. filtering holes; 7. geotextile; 8. the original groundwater level line; 9. lowering the post groundwater level; 10. a sump well and/or an elevator well; 11. a submersible pump.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
As shown in fig. 1 to 4, a deep foundation pit dewatering construction method includes the following steps:
1) whole precipitation design prepares well point pipe and self priming pump 4: observing and analyzing the sand water emission phenomenon of the deep foundation pit, carrying out integral precipitation design around an elevation area of the basement by combining engineering geological survey data, and preparing a well point pipe and a self-sucking pump 4 for precipitation;
2) positioning and paying off: after the foundation pit is excavated greatly, the position of the core barrel is accurately positioned and marked according to the planar arrangement of the design drawing, and a drainage ditch is arranged on the outer side of the top of the foundation pit;
3) excavating a core barrel part of the foundation pit: firstly, enlarging each side of a water collecting well and/or an elevator well 10 positioned at the deepest part of excavation by not less than 2500mm to excavate to 1-2 m below the underground water level;
4) arranging dewatering well points: according to the number of the calculated precipitation wells, pumping wells for draining and reducing the level of the diving and confined water are uniformly distributed in the foundation pit, precipitation well points are distributed around the water collecting well and/or the foundation pit 10 in a closed mode, PVC vertical pipes 2 are inserted into the foundation pit at the precipitation well points, the PVC vertical pipes 2 are connected into a whole at intervals of 0.8-1 m and every 6-8 PVC vertical pipes 2, and the PVC vertical pipes are arranged in a staggered mode from front to back according to the pumping influence radius to form a continuous precipitation closed ring;
5) communicating the PVC vertical pipe 2 with a water collecting main pipe: the lower end of a PVC vertical pipe 2 is connected with a filter pipe 3, the upper end of the PVC vertical pipe is connected with a transverse pipe 1, the transverse pipe 1 is communicated with a water collecting main pipe, and water in the water collecting main pipe is pumped out by a self-priming pump 4;
6) draining the foundation pit: adopt a bore to be 100mm in the foundation ditch, power is 5.5 KW's immersible pump 11 takes out the open water to the escape canal at foundation ditch top, and a set of self priming pump 4 arranges, plans every sump pit and/or elevartor shaft 10 peripheral 10 ~ 12 1.1KW self priming pumps 4 of arranging altogether, unitedly takes out the escape canal to the roadside, discharges outside the ground again.
In this embodiment, the diameter of PVC standpipe in step 4) is 30 ~ 40mm, and the depth of insertion of PVC standpipe 2 is 4 ~ 6m, and the spacing distance of PVC standpipe 2 is 0.8 ~ 1 m.
In this embodiment, when PVC standpipe 2 inserted foundation ditch silt layer in step 4), should rotate the insertion repeatedly, when soil texture was harder, can push into the back with the excavator earlier with the conical head steel pipe and then extract the conical head steel pipe, make it form the precipitation well the same with conical head steel pipe diameter, carry out the PVC standpipe 2 of shutoff with the filter screen for the tip and insert again.
In this embodiment, the PVC standpipe 2 bottommost of inserting the foundation ditch in step 4) is the chimney filter 3, chimney filter 3 is diameter 50 mm's stereoplasm plastic tubing promptly, 3 side of chimney filter slots with the paper cutter drilling, form the filtration pore 6 that the strip form was arranged, be connected with PVC standpipe 2, the filter screen shutoff is applied to 3 tip of chimney filter, the inlayer is wrapped up with net cloth, the skin is wrapped up with geotechnological cloth 7, place the chimney filter 3 in the soil layer that the water permeability is good, sink to below the minimum water level when absorbing water, and install floater liquid level switch on chimney filter 3.
In the embodiment, the length of the filter tube 3 is more than or equal to 500mm, the mesh cloth is 30-40 holes/cm, the length of the filter holes 6 of the filter tube 3 is 40-50 mm, the width of the filter holes is 5-10 mm, one end of the filter tube 3 is buried underground, the other end of the filter tube is connected with the PVC vertical tube 2 through the reducing direct connector 5, and the filter tube is placed in a proper range of a water-bearing stratum according to the geological survey data and the situation of the original site underground water level line 8.
In the embodiment, the arrangement of the dewatering well in the step 4) needs to divide the area according to the excavation elevation condition, avoid the sand overflowing point and cover soil on the original sand overflowing part.
In this embodiment, every 6 to 8 PVC vertical pipes 2 in the step 5) are connected into a whole.
In the embodiment, the PVC standpipe 2 in the step 4) is arranged according to the size, the plane size and the precipitation depth of the foundation pit, the permeability of the aquifer and the groundwater flow direction, and the well point arrangement is comprehensively carried out, and during winter construction, the heat preservation treatment is carried out on the water collecting main pipe.
In the embodiment, the water leakage caused by the breakage of various factors is fully considered in the water drainage design in the step 5), the tee joint and the valve are arranged at the wellhead section of the water outlet pipe of each pipe well, the hose is equipped, so that the drainage pipeline can be repaired without stopping the pump, and the drainage pipeline is arranged to avoid a construction access as much as possible.
In the embodiment, when local open water exists in the precipitation foundation pit in the step 6), a small excavator is used for digging a water collecting pit at the middle position in the pit, an empty oil drum is placed, the side surface of the oil drum is drilled with a hole, the part which is sunk below the digging surface is blocked by a filter screen, a submersible pump 11 is placed in the oil drum during water pumping, and the automatic water pumping controller realizes the discharge of the open water; when a large amount of stagnant water is formed in the foundation trench, the trench digging speed is slowed down, blind pipes are arranged at the wall of the trench for diversion in time, blind ditches are dug at the sides of the trench for water collection, the collected water is drained away, the underground water level line 9 needs to be below 0.5m of the bottom of the cushion layer of the bearing platform after the trench is lowered, the soil surface at the bottom of the trench is kept in a water-free state, the pumping drainage and precipitation time is determined according to the basic construction requirements, and the precipitation system can be detached after the basic construction is completed.
Specific application example 1:
the Shenzhou peninsula C05 plot project of Hainanwanning city, which is acquired by Wu-Ming-Twen-Si-Wu-san-Yuan construction group Limited company, is built in 1 month in 2017 and completed in 4 months in 2018. The project is 6 residential buildings with the length of 96 meters, the frame shear wall structure is close to the sea, and the underground water level is high. The soil is fine sand, and the buried depth of the stable underground water level is 1.20-4.60 m according to a geological survey report. In the basement excavation process, the phenomenon of sand gushing water of the whole foundation pit is continuous, the deeper part of the engineering foundation pit is mainly a main building basement fire-fighting elevator shaft and a water collecting well, aiming at the actual situation on site, the elevation of the pile top of the elevator shaft foundation pit is-8.15 m, the elevation of the pile top of the water collecting well foundation pit is-8.8 m (the elevation of the bottom of a cushion layer is-9.05 m), the elevation of the bottom plate of the basement is-5.55 m, the height difference of the deepest part reaches 3.5m, the underground water level is effectively reduced after the construction by adopting the construction method, so that one underground water level is lower than the bottom of the cushion layer of the bearing platform, and the safe construction of the basement is ensured. The construction is simple and quick, and the requirements of design and national standard are met. Greatly reducing the construction cost and shortening the construction period of the foundation.
Specific application example 2:
the project of the thumb commercial plaza is positioned at the intersection of the continent avenue and the cottage way of the Tianyuan region of the continent city, and the project is started in 2015 in 6 months and completed in 2017 in 4 months. The project is apartment building with frame shear wall structure and commercial support, two floors underground and 22 floors above ground. During foundation construction, water gushes from the bottom of the pit continuously, the construction method is adopted for construction, the construction operation condition is effectively improved, the bottom of the pit is prevented from bulging and damaging, and the construction speed is high. Practice proves that the construction method is simple, feasible, economical and efficient, and is worthy of popularization and application.
Specific application example 3:
the Canxi gold harbor international project born by Wu-Ore Twenty-Sanyu construction group Limited is located in Canxi county of Sichuan province, occupies 12.15 mu of land, has a construction area of 16.5 ten thousand square meters, consists of 6 commercial buildings of 99.9 meters, has four underground layers, 33 above ground layers and has a frame shear wall structure. The project is built in 2016 in 1 month and completed in 2017 in 12 months. The geological conditions mainly comprise silty clay, a fine sand layer is locally clamped, the underground water level is-4.8 m, the actual precipitation level is-6.0 m, the construction method is adopted for construction, the well point depth is 12.5m, the interval is 10m, and the inner diameter of a pipe well is 500mm, so that the rapid precipitation is realized, the foundation pit is dry after precipitation, the side slope is stable, and the effect is good.
In the above application example, the deep foundation pit dewatering process is successfully implemented. The three projects applied by the construction method meet the requirements of design and construction units in the aspects of safety, quality, progress, benefit, environmental protection and the like, obtain high recognition of the construction units and obtain good economic benefit and social benefit. The construction method has the advantages of mature technology, simple process, convenient operation, safety and reliability. Is worthy of popularization and application.

Claims (4)

1. A deep foundation pit dewatering construction method is characterized by comprising the following steps:
1) the integral precipitation design comprises a preparation well point pipe and a self-priming pump (4): the method comprises the following steps of (1) carrying out overall precipitation design around a basement elevation area by combining engineering geological survey data, and preparing a well point pipe and a self-sucking pump (4) for precipitation;
2) positioning and paying off, namely accurately positioning the position of the core barrel and the elevation of the substrate according to the plane arrangement of the design drawing, and marking; arranging a drainage ditch at the outer side of the top of the foundation pit;
3) excavating a core barrel part of the foundation pit: enlarging the water collecting well and/or the elevator well (10) at the deepest part of the excavation along each side line by not less than 2500mm and excavating to 1-2 m below the underground water level;
4) arranging dewatering well points: uniformly distributing pumping wells for draining and reducing the water level of diving and confined water in the foundation pit according to the calculated number of the dewatering wells, arranging dewatering well points around the foundation pit of the water collecting well and/or the elevator shaft (10) in a closed manner, inserting the dewatering well points into the foundation pit by adopting PVC vertical pipes (2), repeatedly inserting the PVC vertical pipes in a rotating manner when the PVC vertical pipes (2) are inserted into a sand layer of the foundation pit, pressing the conical head steel pipe into the foundation pit by using an excavator when the soil is hard, then pulling out the conical head steel pipe to form the dewatering well with the diameter being the same as that of the conical head steel pipe, and then inserting the PVC vertical pipes (2); the PVC vertical pipes (2) are connected into a whole at intervals of 0.8-1 m and every 6-8 PVC vertical pipes (2), and are staggered front and back according to the radius influenced by pumping water to form a continuous precipitation sealing ring; the PVC vertical pipe (2) is characterized in that a filter pipe (3) is arranged at the bottommost part, the filter pipe (3) is a hard plastic pipe with the diameter of 50mm, the side surface of the filter pipe (3) is drilled and grooved by a paper cutter to form filter holes (6) which are arranged in a strip shape, the strip-shaped filter holes (6) are obliquely arranged on the side surface of the filter pipe (3) and are connected with the PVC vertical pipe (2), the end part of the filter pipe (3) is plugged by a filter screen, the inner layer is wrapped by gridding cloth, the outer layer is wrapped by geotextile (7), the filter pipe (3) is placed in a soil layer with good water permeability and sinks below the lowest water level when absorbing water, and a floating ball liquid level switch is installed on the filter pipe (3); the length of the filter tube (3) is more than or equal to 500mm, and the mesh cloth is 30-40 holes/cm2The length of a filter hole (6) of the filter pipe (3) is 40-50 mm, the width of the filter hole is 5-10 mm, one end of the filter pipe (3) is buried underground, and the other end of the filter pipe is connected with the PVC vertical pipe (2) through a reducing direct joint (5);
5) the PVC vertical pipe (2) is communicated with the water collecting main pipe: the upper end of a PVC vertical pipe (2) is connected with a transverse pipe (1), the transverse pipe (1) is communicated with a water collecting main pipe, and water in the water collecting main pipe is pumped out by a self-priming pump (4); the water leakage caused by various factors is fully considered during the drainage design, a tee joint and a valve are arranged at the wellhead section of the water outlet pipe of each pipe well, a hose is arranged, so that the drainage pipeline can be repaired without stopping a pump, and the drainage pipeline is arranged to avoid a construction access as much as possible;
6) draining the foundation pit: the open water is pumped to a drainage ditch at the top of the foundation pit by a submersible pump (11) in the foundation pit; when local open water exists in the precipitation foundation pit, a small excavator is used for digging a water collecting pit at the middle position in the pit, an empty oil drum is placed, the side surface of the oil drum is drilled with a hole, the part sinking below the digging surface is blocked by a filter screen, a submersible pump (11) is placed in the oil drum when water is pumped, and the open water is discharged by an automatic water pumping controller.
2. The deep foundation pit dewatering construction method according to claim 1, wherein the diameter of the PVC vertical pipe (2) in the step 4) is 30-40 mm, and the insertion depth of the PVC vertical pipe (2) is 4-6 m.
3. The deep foundation pit dewatering construction method according to claim 1 or 2, wherein in the step 4), the arrangement of the dewatering well needs to divide areas according to the excavation elevation condition, avoid sand blasting points and cover soil on the original sand blasting positions.
4. A deep foundation pit dewatering construction method according to claim 1 or 2, wherein the PVC standpipe (2) in the step 4) is arranged according to the size of the foundation pit, the dewatering depth requirement, the permeability of a water-bearing layer and the groundwater flow direction, well point arrangement is comprehensively carried out, and during winter construction, heat preservation treatment needs to be carried out on a water collecting main pipe.
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CN110552362A (en) * 2019-09-16 2019-12-10 中铁十二局集团有限公司 Foundation pit dewatering construction method of mixed well and light well in confined water stratum
CN110761308A (en) * 2019-10-29 2020-02-07 北京崇建工程有限公司 Local foundation pit construction method
CN111945758A (en) * 2020-08-27 2020-11-17 河南科技大学 Reusable dewatering tank, foundation pit operation surface dewatering system and method

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CN203530996U (en) * 2013-09-25 2014-04-09 杭州萧山路桥工程处 Multi-well-point combined type precipitation facility
CN205954648U (en) * 2016-08-22 2017-02-15 中国二十冶集团有限公司 Light well point precipitation device

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