CN110374125A - Metro Deep Excavation side wall interlayer method for treating water - Google Patents

Abstract

The invention relates to a method for treating interlayer water on the side wall of a deep foundation pit of a subway. The steps are as follows: 1) Construction of a dewatering well outside the foundation pit: burying a casing; drilling a rig to form a hole; hanging the well pipe and filter tube; filling filter material; washing the well ;Water pump installation; laying drainage pipe network; water level pumping down; water level observation; precipitation; pumping operation; 2), construction of dewatering wells in foundation pits; 5) Drainage system is installed in the pit foundation; 6) Well closure inside the foundation pit; 7) Well closure outside the foundation pit. The coordination of precipitation inside and outside the foundation pit ensures the smooth implementation of the project and solves the problem that the aquifer and interlayer water are difficult to drain.

Description

Water Treatment Method for Side Wall Interlayer of Subway Deep Foundation Pit

technical field

The invention relates to a water treatment method, in particular to a method for treating interlayer water on the side wall of a subway deep foundation pit, and belongs to the field of subway building construction.

Background technique

With the development of society, the foundation pits of modern subway stations are gradually becoming larger and deeper, and groundwater poses a huge safety hazard to the construction of deep foundation pits. Indispensable measures in the construction process, especially in strata with rich groundwater and poor geological conditions, the scheme of groundwater treatment and construction quality can directly affect the safety performance of the foundation pit.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for treating the interlayer water on the side wall of the deep foundation pit of the subway. The inside and outside of the foundation pit cooperate with each other to dewater, which ensures the smooth implementation of the project and solves the problem that the aquifer and interlayer water are difficult to drain.

In order to solve the above problems, the specific technical scheme of the present invention is as follows: a method for treating interlayer water on the side wall of a deep foundation pit of a subway, the steps are as follows: 1), the construction of the dewatering well outside the foundation pit: 1.1) burying the casing: bury the bottom of the casing into the original soil layer; 1.2) Drilling rig to form a hole: After step 1.1), the drilling rig is in place to form a dewatering well; 1.3) Hanging the well pipe and filter tube: the well pipe is made of sand-free cement pipe and lowered into the well; 1.4) Filling Filter material: after step 1.3), fill the filter tube with filter material; 1.5) Well washing: Use a piston air compressor to wash the well, and after the well is completed, use a sewage pump and an air compressor to clean it repeatedly until the water is clean and the sand is clean; 1.6) The water pump Installation: Put the submersible pump into the well with nylon rope, lay cables and electric switch box; 1.7) Lay drainage pipe network: Lay drainage pipes on the ground, reserve taps for each well position and connect high-pressure screw valves; 1.8) Water level pumping and lowering: 1.9) Water level observation: static water level observation, once in the morning and evening at the initial stage, once a day after the water level stabilizes; 1.10) Precipitation; 1.11) Pumping operation; The surroundings of the water collection wells are supported by steel casings, holes are reserved on the side walls of the steel casings, and double-layer filter screens are used for winding; 3) Dewatering at transfer station nodes: use tube well dewatering system for pumping and dewatering; 4), base Set open ditch or blind ditch drainage system in the pit: Blind ditch is set horizontally and vertically, and a 3‰ flow slope is set on the blind ditch; 5) Drainage system is set in the pit foundation; 6) Well is sealed inside the foundation pit; 7) Outside the foundation pit Seal the well.

In the above step 1.10), the precipitation well pumping was started 15 days before the excavation, and the precipitation dropped to 1m below the basement.

In the above step 1.11), the pre-sealed precipitation time before excavation shall not be less than 15 days; pumping sand content: the content of coarse sand is less than 1/50000, the content of medium sand is less than 1/20000, and the content of fine sand is less than 1/10000 .

In the step 3) the well wall pipe of the middle dewatering well adopts flower pipes, the outer diameter of the well wall pipe is 380mm, and the flower pipes adopt concrete prefabricated filter pipes, and each section of the filter pipes is 0.9m. When the well pipes are lowered, the joints of the two filter pipes are The woven bag is wrapped tightly, and the upper and lower sections are fixed firmly with three bamboo pieces combined with iron wire. The well spacing is 8.0-12.0m. Each dewatering well is equipped with a submersible pump with a flow rate of 10m ³ /h. The submersible pump and the drainage pipe are connected by Plastic hose, the diameter of the plastic hose is determined by the connection joint of the submersible pump, and a steel pipe with a diameter of 273mm is installed next to each dewatering well to drain water into the rainwater well according to the slope.

In the step 4), the vertical blind ditch has a water slope of 3‰ from west to east, and the horizontal blind ditch has a water slope of 3‰ from the north and south sides to the middle, and flows into the temporary water collection well. A horizontal drainage blind ditch is set at the end of the section 4m to the maximum mileage. First, a layer of 0.8mm thick plastic cloth is laid on the bottom of the blind ditch, and 10cm thick pebbles are backfilled on it, and then backfilled with graded gravel to the top of the blind ditch.

In step 5), use a Ф100 PVC pipe with a horizontal eye, each section is 100cm long, insert 100cm into the soil, expose a 90° elbow to the inside of the steel mesh, and then connect a vertical Ф100mm PVC pipe to the top of the blind ditch; blind ditch structure Dimensions: 30cm wide and 50cm deep. After the blind ditch is built, backfill well-graded gravel to the top of the blind ditch; wrap the PVC pipe with gauze and insert it into the soil; 5°~15°, for holes with severe sand loss between piles, use a grouting machine to backfill the holes with grouting, the grouting pressure is 0.3Mpa~0.5Mpa, and the grout water-cement ratio=1:1.

Step 6) Before sealing the well, spread the waterproof layer to 5cm above the well pipe, spread the reinforcement layer to 10cm above the well pipe, and spread the reinforcement layer to a size of 20cm, and use sealant for the well pipe, waterproof layer, and reinforcement layer Adhesively, the top of the reinforcement layer is fixed with a metal hoop; before sealing the well, install a water-stop flange with a thickness of 8mm and a length of 10cm, and install a water-swellable water-stop strip with a cross-section of 20mm*10mm on the water-stop flange along the water-stop One circle around the flange; when installing the waterproof layer at the intersection of the bottom plate and the well body, use sealing glue to seal the inside of an equilateral triangle along the knuckle angle of 5cm; when sealing the well, use two 10mm thick round steel plates with a rubber sealing ring plate in the middle, The sides are fixed with bolts, and the sealing place is filled with waterproof mortar.

In the above step 7), the use time of the dewatering well outside the foundation pit is from the excavation of the foundation pit to the completion of the construction of the anti-floating beam on the roof, and plain concrete is used for backfilling and sealing.

The beneficial effects brought by the invention are: the inside and outside of the foundation pit cooperate with each other for dewatering, which ensures the smooth implementation of the project and solves the problem that the water in the submerged layer and the interlayer is difficult to drain.

Description of drawings

Figure 1 is a schematic diagram of the construction principle of the interlayer water treatment method for the side wall of the subway deep foundation pit.

Detailed ways

As shown in Figure 1, a method for treating interlayer water on the side wall of a subway deep foundation pit, the steps are as follows: 1) Construction of the dewatering well outside the foundation pit: 1.1) Embedding the casing: bury the bottom of the casing into the original soil layer; 1.2) Drilling rig to form a hole: After step 1.1), the drilling rig is in place to form a dewatering well; 1.3) Hanging the well pipe and filter tube: the well pipe is made of sand-free cement pipe and lowered into the well; 1.4) Filling the filter material: after step 1.3) Fill the filter tube with filter material; 1.5) Well cleaning: use a piston air compressor to clean the well, and after the well is completed, use a sewage pump and an air compressor to clean it repeatedly until the water and sand are clean; 1.6) Water pump installation: use nylon rope for submersible pumps Put it into the well, lay cables and electric switch boxes; 1.7) Lay the drainage pipe network: lay drainage pipes on the ground, and the drainage pipes reserve taps at each well position and connect with high-pressure screw valves; when pumping water, first pump the water to the water tank During the construction period in winter, the drainage pipe adopts the method of rubber and plastic sponge insulation board + self-temperature control heating belt + heat preservation aluminum pipe, along the waterfront The bottom of the pipeline is first wrapped with a rubber-plastic sponge insulation board, and then a self-temperature-controlling heating belt is laid out, which is outsourced with a 70mm thick thermal insulation aluminum tube. 1.8) Water level pumping down: 1.9) Water level observation: static water level observation, once in the morning and evening at the beginning, once a day after the water level stabilizes; 1.10) Precipitation; 1.11) Pumping operation; In the form of manual excavation, the surrounding of the water collection well is supported by steel casings, holes are reserved on the side walls of the steel casings, and double-layer filters are used for winding; 3) Dewatering at transfer station nodes: use tube well dewatering system for pumping and dewatering ;4) Set up open ditch or blind ditch drainage system in the foundation pit: Blind ditch is set horizontally and vertically, and a 3‰ flow slope is set on the blind ditch; 5) Drainage system is set in the pit foundation; 6) The well is closed in the foundation pit; 7) Well sealing outside the foundation pit.

In the above step 1.10), the precipitation well pumping was started 15 days before the excavation, and the precipitation dropped to 1m below the basement.

In the above step 1.11), the pre-sealed precipitation time before excavation shall not be less than 15 days; pumping sand content: the content of coarse sand is less than 1/50000, the content of medium sand is less than 1/20000, and the content of fine sand is less than 1/10000 .

In the step 3) the well wall pipe of the middle dewatering well adopts flower pipes, the outer diameter of the well wall pipe is 380mm, and the flower pipes adopt concrete prefabricated filter pipes, and each section of the filter pipes is 0.9m. When the well pipes are lowered, the joints of the two filter pipes are The woven bag is wrapped tightly, and the upper and lower sections are fixed firmly with three bamboo pieces combined with iron wire. The well spacing is 8.0-12.0m. Each dewatering well is equipped with a submersible pump with a flow rate of 10m ³ /h. The submersible pump and the drainage pipe are connected by Plastic hose, the diameter of the plastic hose is determined by the connection joint of the submersible pump, and a steel pipe with a diameter of 273mm is installed next to each dewatering well to drain water into the rainwater well according to the slope.

In the step 4), the vertical blind ditch has a water slope of 3‰ from west to east, and the horizontal blind ditch has a water slope of 3‰ from the north and south sides to the middle, and flows into the temporary water collection well. A horizontal drainage blind ditch is set at the end of the section 4m to the maximum mileage. First, a layer of 0.8mm thick plastic cloth is laid on the bottom of the blind ditch, and 10cm thick pebbles are backfilled on it, and then backfilled with graded gravel to the top of the blind ditch.

In step 5), use a Ф100 PVC pipe with a horizontal eye, each section is 100cm long, insert 100cm into the soil, expose a 90° elbow to the inside of the steel mesh, and then connect a vertical Ф100mm PVC pipe to the top of the blind ditch; blind ditch structure Dimensions: 30cm wide and 50cm deep. After the blind ditch is built, backfill well-graded gravel to the top of the blind ditch; wrap the PVC pipe with gauze and insert it into the soil; 5°~15°, for holes with severe sand loss between piles, use a grouting machine to backfill the holes with grouting, the grouting pressure is 0.3Mpa~0.5Mpa, and the grout water-cement ratio=1:1.

Step 6) Before sealing the well, spread the waterproof layer to 5cm above the well pipe, spread the reinforcement layer to 10cm above the well pipe, and spread the reinforcement layer to a size of 20cm, and use sealant for the well pipe, waterproof layer, and reinforcement layer Adhesively, the top of the reinforcement layer is fixed with a metal hoop; before sealing the well, install a water-stop flange with a thickness of 8mm and a length of 10cm, and install a water-swellable water-stop strip with a cross-section of 20mm*10mm on the water-stop flange along the water-stop One circle around the flange; when installing the waterproof layer at the intersection of the bottom plate and the well body, use sealing glue to seal the inside of an equilateral triangle along the knuckle angle of 5cm; when sealing the well, use two 10mm thick round steel plates with a rubber sealing ring plate in the middle, The sides are fixed with bolts, and the sealing place is filled with waterproof mortar.

In the above step 7), the use time of the dewatering well outside the foundation pit is from the excavation of the foundation pit to the completion of the construction of the anti-floating beam on the roof, and plain concrete is used for backfilling and sealing.

Example: The expanded section on the west side of Line 1 and the standard section are designated as clear rows, that is, an open (blind) ditch drainage system is installed in the foundation pit, and a drainage blind ditch is installed along the entire length of the pile. The size of the blind ditch is: 0.5m deep and 0.3m wide , the longitudinal blind ditches used have a water slope of 3‰ from west to east, and all horizontal blind ditches have a water slope of 3‰ from the north and south sides to the middle, and flow into the temporary water collection well. A horizontal drainage blind ditch is set at the end of each construction section 4m away from the maximum mileage. First lay a layer of 0.8mm thick plastic sheeting on the bottom of the blind ditch (to prevent the soil at the bottom of the blind ditch from being soaked), backfill 10cm thick pebbles on it, and then backfill graded gravel to the top of the blind ditch, and drain the middle of the blind ditch horizontally Set up a temporary sump, pump it to the nearest rainwater well on the ground through a 10m³/d submersible pump.

Before constructing the floor cushion of this section, the drainage blind ditch and temporary sump of the next construction section shall be completed, and the water shall be drained into the temporary sump of the next construction section through the submersible pump and blind ditch, and the floor of this section shall be constructed Cushion, water collection wells are filled with C20 concrete. For example, when the overturning beam is dug, the water will be drained into the temporary sump well through the blind ditch. For example, when digging the downturned beam, after the downturned beam is dug, immediately dig the blind ditch at the bottom of the downturned beam, and then spray C20 fine stone concrete on the blind ditch and the soil beside the beam, and the mix ratio of C20 fine stone concrete: cement : fine stone: sand: water: accelerator = 1:2.027:2.37:0.49:0.04, a 3‰ blind ditch is set in the middle of the bottom of the two downturn beams, the slope of the blind ditch is manually repaired, and a layer is first laid at the bottom of the blind ditch Plastic cloth with a thickness of 0.8mm is backfilled with 10cm thick pebbles, and then backfilled with graded gravel to the top of the blind ditch. A temporary water collection well is installed at each end of the two downturning beams to ensure that the water flows to the sump and the water flows smoothly. , the water in the sump is pumped to the nearest rainwater well on the ground through a 10m³/d submersible pump. Adjustment.

During the excavation of the foundation pit, there is water seepage in some parts of the net sprayed surface, so if necessary, use PVC pipe cutouts before the anchor sprayed concrete, and wrap two layers of 80-mesh gauze on the outside for drainage. The drainage position is from the seepage to the bottom of the pit. Make the water flow directly into the open (blind) ditch drainage system at the bottom of the pit.

In describing the present invention, it is to be understood that the terms "vertical", "upper", "lower", "side end", "one end", "upper end", "horizontal", "above", "below" , "vertical", "middle", "lower end", "other end", "longitudinal" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for describing the present invention and simplifying the description , rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore, should not be construed as limiting the invention.

In the present invention, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense unless otherwise clearly specified and limited, for example, it may be a fixed connection or a detachable connection, or Integrate; it can be mechanical connection or electrical connection; it can be direct connection, it can be indirect connection through an intermediary, it can be the internal communication of two components or the interaction relationship between two components, for ordinary skills in the art Personnel can understand the specific meanings of the above terms in the present invention according to specific situations.

What has been described above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some modifications and improvements can be made, which should also be considered as belonging to the protection scope of the present invention.

Claims (8)

1. A method for treating interlayer water on the side wall of a subway deep foundation pit, characterized by the following steps: 1), construction of a dewatering well outside the foundation pit: 1.1) Embedding the casing: bury the bottom of the casing into the original soil layer; 1.2) Drilling rig Hole forming: After step 1.1), the drilling rig is in place, and the dewatering well is formed; 1.3) Hanging the well pipe and filter pipe: the well pipe is made of sand-free cement pipe and lowered into the well; 1.4) Filling filter material: after step 1.3) Fill the filter tube with filter material; 1.5) Well cleaning: Use a piston air compressor to clean the well, and after the well is completed, use a sewage pump and an air compressor to clean it repeatedly until the water and sand are clean; Enter the well, lay cables and electric switch boxes; 1.7) Lay the drainage pipe network: lay drainage pipes on the ground, and the drainage pipes reserve taps at each well position and connect with high-pressure screw valves; 1.8) Water level pumping down: 1.9) Water level observation : Static water level observation, once in the morning and evening at the beginning, once a day after the water level stabilizes; 1.10) precipitation; For support, holes are reserved on the side wall of the steel casing, and double-layer filter screens are used for winding; 3) Dewatering at transfer station nodes: tube well dewatering system is used for pumping and dewatering; 4) Open ditch or blind ditch drainage system is set in the foundation pit : Blind ditches are installed both horizontally and vertically, and a 3‰ flowing water slope is provided on the blind ditches; 5) Drainage systems are installed in the pit foundation; 6) Wells are sealed inside the pit; 7) Wells are closed outside the pit. 2. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: in the step 1.10), the dewatering well pumping is started 15 days before the excavation, and the dewatering drops to 1m below the base . 3. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: in the step 1.11), the pre-sealed precipitation time before excavation is not less than 15 days; : The coarse sand content is less than 1/50000, the medium sand content is less than 1/20000, and the fine sand content is less than 1/10000. 4. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: in the step 3), the well wall pipe of the dewatering well adopts flower pipes, the outer diameter of the well wall pipes is 380mm, and the flower pipes adopt Concrete prefabricated filter pipe, each section of the filter pipe is 0.9m. When the well pipe is lowered, the joints of the two filter pipes are tightly wrapped with woven bags, and the upper and lower sections are fixed firmly with three bamboo pieces combined with iron wire. The well spacing is 8.0-12.0m. Each dewatering well is equipped with a submersible pump with a flow rate of 10m ³ /h. The connection between the submersible pump and the drainage pipe is made of a plastic hose. Drainage is carried out according to the slope to the inside of the rainwater well. 5. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: in the step 4), the vertical blind ditch is provided with a running water slope of 3‰ from west to east, and the horizontal blind ditch The ditch has a slope of 3‰ in the middle of the north and south sides, and flows into the temporary water collection well. A horizontal drainage blind ditch is set at the end of each construction section 4m away from the maximum mileage. The bottom of the blind ditch is first paved with a layer of 0.8mm thick Plastic sheet, backfill with 10cm thick pebbles, and then backfill with graded gravel to the top of the blind ditch. 6. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: in the step 5), a Ф100 PVC pipe with a horizontal eye is used, each section is 100 cm long, inserted into the soil body for 100 cm, and exposed 90° elbow to the inner side of the steel mesh, and then connect the vertical Ф100mm PVC pipe to the top of the blind ditch; the structural size of the blind ditch is: width 30cm, depth 50cm, after the blind ditch is completed, backfill with well-graded gravel to the top of the blind ditch Surface; the gauze-wrapped PVC pipe is inserted into the soil part; the Ф100mm permeable PVC pipe penetrates into the soil part and the downward slope should be 5°~15°. For holes with serious sand loss between piles, use a grouting machine to backfill the holes. The grouting pressure is 0.3Mpa~0.5Mpa, and the grout water-cement ratio=1:1. 7. The method for treating interlayer water on the side wall of subway deep foundation pit as claimed in claim 1, characterized in that: before the well is sealed in step 6), the waterproof layer is tiled to 5 cm above the well pipe, and the reinforcement layer is tiled to The top of the well pipe is 10cm, and the size of the reinforcement layer is 20cm. The well pipe, the waterproof layer, and the reinforcement layer are glued tightly with sealant, and the top of the reinforcement layer is fixed with a metal hoop. Before sealing the well, install a water stop with a thickness of 8mm and a length of 10cm. For the flange, install a water-swelling water-stop strip with a cross-section of 20mm*10mm on the water-stop flange and make a circle around the water-stop flange; when installing a waterproof layer at the intersection of the bottom plate and the well body, use a seal along an equilateral triangle with a knuckle angle of 5cm Glue to death; when sealing the well, use two 10mm thick round steel plates with a rubber sealing ring plate sandwiched between them, and fix them with bolts on the sides, and fill the well sealing place with waterproof mortar. 8. The method for treating interlayer water on the side wall of subway deep foundation pit according to claim 1, characterized in that in step 7), the use time of the dewatering well outside the foundation pit is from excavation of the foundation pit to the construction of the anti-floating beam on the roof Completed, backfill and seal with plain concrete.