Precipitation well air bag plugging construction method for high-water-level gravel bed foundation pit

Abstract

The invention discloses a dewatering well air bag plugging construction method for a high-water-level gravel layer foundation pit, and belongs to the technical field of foundation pit construction. The method comprises the steps that waterproof construction is conducted, double-layer SBS waterproof coiled materials are laid on the surface of a foundation pit cushion layer for bottom sealing, a steel pipe sleeve with a water stop ring is pre-buried in the cushion layer, a wide water stop ring is welded to the middle of the exterior of the steel pipe sleeve, and a flange is welded to the top of the steel pipe sleeve; selecting water pumping equipment according to the water level condition of the foundation pit, starting water pumping, regularly detecting the water level, and stopping the pump after the water level is reduced to the design requirement; a multi-layer structure air bag is installed in the steel pipe sleeve, a thick steel plate with the diameter smaller than that of the pipe well is welded to the bottom of the steel pipe sleeve, a rubber gasket is arranged between a flange at the top of the steel pipe sleeve and the blind plate, the blind plate is fixed through embedded bolts, and high-strength grouting materials are backfilled through embedded steel bars; by means of the dewatering well air bag plugging construction method for the high-water-level gravel bed foundation pit, underground water seepage can be effectively prevented, the risk of the foundation pit is reduced, meanwhile, the equipment investment is reduced, the plugging period is shortened, and the engineering efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation pit construction, and particularly to a construction method for plugging a dewatering well airbag in a foundation pit with a high water table and gravel layer. Background Art

[0002] During the construction of a foundation pit, especially in areas with a high water table and gravel layer, the control of groundwater is a key factor to ensure the safety and smooth progress of construction. The seepage and influx of groundwater often cause difficulties in foundation pit construction, increasing construction costs and safety risks. Traditional dewatering plugging methods such as conventional slightly expanding concrete, due to its slightly expanding characteristics, can effectively fill cracks and voids, and have better impermeability and durability. However, it usually requires a large amount of equipment and manpower investment, as well as complex equipment layout and operation, resulting in an increase in construction costs, construction difficulties and risks. Especially in complex geological conditions, operators often need a high level of technical skills. In addition, its plugging effect is unstable, especially in a high water table and gravel layer, and it is easily affected by the external environment. Therefore, there is an urgent need for a new dewatering plugging technology to solve the dewatering well plugging technology problem in the construction of a foundation pit with a high water table and gravel layer.

[0003] The airbag plugging technology for steel pipe dewatering wells in a foundation pit with a high water table and gravel layer simplifies the equipment and operation process, reduces the input of manpower and material resources, thereby reducing the overall construction cost. And a more durable and sealed airbag is designed to adapt to the complex environment of a high water table and gravel layer, ensuring a long-term effective plugging effect, so as to provide a more efficient, economical and environmentally friendly solution for foundation pit construction. Summary of the Invention

[0004] The purpose of the present invention is to provide a construction method for plugging a dewatering well airbag in a foundation pit with a high water table and gravel layer, so as to solve many problems existing in the traditional foundation pit dewatering plugging method in a high water table and gravel layer, such as high cost, complex construction, low efficiency, large environmental impact, and difficult maintenance, and provide a more efficient, economical and environmentally friendly solution for the dewatering of a foundation pit with a high water table and gravel layer.

[0005] To achieve the above purpose, the present invention provides a construction method for plugging a dewatering well airbag in a foundation pit with a high water table and gravel layer, including the following steps:

[0006] S1. Carry out waterproof construction, lay a double-layer SBS waterproof coiled material on the surface of the foundation pit cushion for bottom sealing, clean the sundries, oil stains and moisture on the surface of the cushion, compact the overlapping part of the coiled material and seal it with waterproof glue or sealant, and process the connection between the flexible waterproof layer and the steel pipe sleeve into an arc shape and turn it up.

[0007] S2. Embedded waterproof steel pipe sleeve. Embed a steel pipe sleeve with a water stop ring in the cushion layer. Weld a water stop ring with a width of 80 mm in the middle outside the steel pipe sleeve, and weld a flange with a thickness of 12 mm at the top. The flange is connected to a blind plate with a thickness of 10 mm prefabricated through M28 bolts;

[0008] S3. Drain accumulated water and stop the pump. Select pumping equipment according to the foundation pit water level and start pumping. Regularly detect the water level until it drops to the design requirement and then stop the pump;

[0009] S4. Install the airbag. Install a multi-layer structure airbag in the steel pipe sleeve. Inflate the airbag to 2.5 MPa and fix it. After draining the accumulated water at the top, observe for 1 hour to confirm no leakage;

[0010] S5. Weld the lower blind plate. Weld a 10 mm thick steel plate with a diameter 5 mm smaller than the inner diameter of the pipe well to the bottom of the steel pipe sleeve to ensure no welding defects;

[0011] S6. Install the top blind plate. Set a rubber gasket between the flange at the top of the steel pipe sleeve and the blind plate, and fix the blind plate through the embedded bolts;

[0012] S7. Rebar planting and backfilling with high-strength grouting material. Arrange single-layer bidirectional steel bars above the blind plate, pour C60 high-strength grouting material to 5 cm above the flange top, and sprinkle water for covering and curing for seven days after solidification.

[0013] Preferably, in S2, the steel pipe sleeve is made of carbon steel or stainless steel, and the surface is treated by sandblasting or polishing to remove oxides and impurities, and coated with an epoxy anti-corrosion coating to ensure the corrosion resistance and strength of the steel pipe sleeve.

[0014] Preferably, the specific steps of stopping the pump in S3 are as follows:

[0015] S31. Before stopping the pump, remove the formwork and square timbers at the wellhead and clean them. If it is difficult to remove, it can be removed after installing the airbag;

[0016] S32. Do relevant preparatory work, prepare the personnel, materials and tools for stopping the pump;

[0017] S33. Gradually shut down the dewatering wells in the order from low to high, from large to small, from the periphery to the middle, and give priority to shutting down the dewatering wells with large water inflow;

[0018] S34. According to the determined order, shut down the dewatering wells one by one. Immediately seal the well after shutting down one dewatering well. It is strictly prohibited to simultaneously close multiple dewatering wells in the pit. The dewatering wells outside the pit should operate normally during the sealing period. The process of stopping the pump should be fast to reduce the water inflow in the pit.

[0019] Preferably, the specific steps of S4 are as follows:

[0020] S41. Select high-strength polyurethane or fluororubber as the main material of the airbag, and the airbag adopts a multi-layer structure design;

[0021] S42. Check the appearance integrity of the airbag. For larger precipitation wells, install a support structure to ensure the airbag maintains a stable structure after inflation;

[0022] S43. Install the airbag at a position 20 cm from the top flange, pressurize the airbag to 2.5 MPa using an air pump, stop pressurizing and tighten the airbag;

[0023] S44. Observe for 1 hour to confirm that there is no water gushing at the top of the airbag. If water gushes from the airbag, use a self-priming pump to drain the accumulated water at the top. If there is a deviation in the installation height of the airbag, backfill C60 high-strength grouting material to 5 cm from the top of the flange.

[0024] Preferably, the airbag in S4 is composed of an outer wear-resistant layer, an intermediate airtight layer, and an inner waterproof layer. The inner wall of the airbag is coated with a polyurethane waterproof coating, and a pressure sensor is integrated inside to detect the air pressure in real time.

[0025] Preferably, during the inflation process of S43, manual stepping is used to prevent the airbag from floating.

[0026] Preferably, before welding the lower blind plate in S5, use a wire brush or sandpaper to remove rust and impurities on the welding surface. After welding, check the appearance of the weld, and use a wire brush or sandpaper to clean the surface of the weld to remove welding slag and oxides.

[0027] Therefore, the present invention adopts the above-mentioned construction method for plugging a precipitation well airbag in a foundation pit with high water level in gravel layer, and has the following beneficial effects:

[0028] (1) Simple construction: The installation and operation of the airbag are relatively simple, easy for construction personnel to master, and the maintenance and inspection are relatively simple, enabling problems to be discovered and handled in a timely manner;

[0029] (2) Improve construction safety: The airbag has good sealing performance, can effectively prevent the infiltration of groundwater, reduce the risk of water accumulation in the foundation pit, and the well plugging does not change the stress and use function of the original structure, reducing the risk of instability of the original structure and collapse of the foundation pit.

[0030] (3) Reduce equipment investment and reduce the plugging cycle: Compared with traditional plugging technologies, the airbag plugging technology requires lower equipment and material costs, and can quickly complete the well plugging construction under feasible auxiliary measures, ensuring that the water stop work is completed before the water level rises to the wellhead, which can greatly improve the engineering efficiency.

[0031] The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings

[0032] Figure 1Flow chart of a construction method for plugging a dewatering well airbag in a foundation pit with high water level and gravel layer according to the present invention;

[0033] Figure 2 Structural schematic diagram of a waterproof steel pipe sleeve for a construction method for plugging a dewatering well airbag in a foundation pit with high water level and gravel layer according to the present invention;

[0034] Figure 3 Structural schematic diagram of the top flange of a waterproof steel pipe sleeve for a construction method for plugging a dewatering well airbag in a foundation pit with high water level and gravel layer according to the present invention;

[0035] Reference numerals: 1, blind plate; 2, rubber gasket; 3, steel pipe sleeve; 4, flange; 5, water stop ring; 6, bolt. Detailed implementation manners

[0036] The following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention claimed, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0037] Embodiment

[0038] The project of this example is a natural foundation, the cushion is 150 mm thick C15 concrete, the foundation is 950 mm thick C30 concrete, and the waterproofing is double-layer SBS waterproof coiled material.

[0039] As Figure 1 shown, the present invention provides a construction method for plugging a dewatering well airbag in a foundation pit with high water level and gravel layer, including the following steps:

[0040] S1. Conduct waterproof construction. Since the underground water level is high and the formation has high permeability, the surface of the cushion is relatively humid. Lay double-layer SBS waterproof coiled material on the surface of the foundation pit cushion for bottom sealing. When using the coiled material for bottom sealing, clean the sundries, oil stains and moisture on the surface of the cushion, compact the overlapping part of the coiled material to ensure that there are no bubbles and voids, further seal the edge of the overlapping part with waterproof glue or sealant, and conduct waterproof testing in a timely manner to ensure that there are no leakage points. The connection between the flexible waterproof layer and the steel pipe sleeve is processed into an arc shape and turned up.

[0041] S2. Embed as Figure 2The waterproof steel pipe sleeve shown below has a steel pipe sleeve 3 with a water stop ring 5 embedded in the cushion layer. The steel pipe sleeve 3 is made of carbon steel or stainless steel, and its surface is treated by sandblasting or polishing to remove oxides and impurities, and an epoxy anti-corrosion coating is applied to ensure the corrosion resistance and strength of the steel pipe sleeve. A 80-mm-wide water stop ring 5 is welded in the middle outside the steel pipe sleeve 3, and a flange 4 with a thickness of 12 mm is welded at the top. Increasing the thickness of the flange 4 to 12 mm can improve the connection strength and sealing performance. The flange 4 is connected to a blind plate 1 with a prefabricated thickness of 10 mm through M28 bolts 6. The structure of the flange 4 is as Figure 3 shown.

[0042] S3. Drain accumulated water and stop the pump. Select pumping equipment (such as a water pump) according to the foundation pit water level situation and start pumping. Regularly detect the water level to ensure that the accumulated water in the foundation pit is drained in time. Stop the pump after the foundation pit water level drops to the design requirement.

[0043] The specific steps for stopping the pump are as follows:

[0044] S31. Before stopping the pump, remove the formwork and square timbers at the wellhead and clean them. If it is difficult to remove, it can be removed after installing the airbag;

[0045] S32. Do relevant preparatory work, and prepare the personnel, materials and tools for stopping the pump;

[0046] S33. Gradually shut down the dewatering wells in the order from low to high, from large to small, and from the periphery to the middle, and give priority to shutting down the dewatering wells with large water inflow;

[0047] S34. According to the determined order, shut down the dewatering wells one by one. Immediately seal the well after shutting down one dewatering well. It is strictly prohibited to simultaneously close multiple dewatering wells inside the pit. During the sealing period, the dewatering wells outside the pit should operate normally. The process of stopping the pump should be fast to reduce the water inflow inside the pit.

[0048] S4. Install the airbag. Install a multi-layer airbag inside the steel pipe sleeve 3. Inflate the airbag to 2.5 MPa and fix it. Observe for 1 hour after draining the accumulated water at the top to confirm no leakage.

[0049] S41. Select high-strength polyurethane (PU) or fluororubber (FKM) as the main material of the airbag. The airbag adopts a multi-layer structure design. The airbag consists of an outer wear-resistant layer, a middle airtight layer and an inner waterproof layer. The inner wall of the airbag is coated with a polyurethane waterproof coating to enhance the sealing performance of the airbag and prevent gas and moisture from permeating. A pressure sensor is integrated inside to detect the air pressure in real time and timely discover potential leakage problems.

[0050] The multi-layer design can effectively improve the durability and sealing performance of the airbag and can withstand a large water pressure.

[0051] S42. Before installation, check the integrity of the airbag appearance to ensure there are no damages, cracks or other defects. For precipitation wells that need to block larger areas, install a support structure to ensure the airbag maintains a stable structure after inflation.

[0052] S43. Install the airbag at a position 20 cm away from the flange 4. Use an air pump to pressurize the airbag to 2.5 MPa. During the inflation process, manually step on the airbag to prevent it from floating. Stop pressurizing and tighten the airbag.

[0053] S44. Observe for 1 hour. If there is no water gushing from the top of the airbag, the next process can be entered. If water gushes from the airbag, use a self-priming pump to drain the accumulated water at the top. If there is a deviation in the installation height of the airbag, backfill C60 high-strength grouting material to 5 cm above the top of the flange 4.

[0054] S5. Weld the lower blind plate 1. Weld a 10-mm-thick steel plate with a diameter 5 mm smaller than the inner diameter of the pipe well to the bottom of the steel pipe sleeve 3 to ensure there are no welding defects.

[0055] Before welding the lower blind plate 1, use a wire brush or sandpaper to remove rust and impurities on the welding surface to ensure close welding quality. After welding, check the appearance of the weld to ensure there are no cracks, pores and other defects, and use a wire brush or sandpaper to clean the weld surface to remove welding slag and oxides.

[0056] S6. Install the top blind plate 1. Set a rubber gasket 2 between the flange 4 of the steel pipe sleeve 3 and the blind plate 1, and fix the blind plate 1 through the embedded bolts 6.

[0057] The bolts 6 are welded and fixed before being embedded in the steel casing 3 to ensure that the position, elevation and verticality meet the requirements. After passing the trial assembly, weld and fix them. If the bolts 6 are damaged, the blind plate 1 is lost or the model does not match during the construction process, welding can be used.

[0058] S7. Plant steel bars and backfill high-strength grouting material. Arrange single-layer bidirectional steel bars above the blind plate 1, pour C60 high-strength grouting material to 5 cm above the top of the flange 4, and sprinkle water for covering and curing for seven days after solidification.

[0059] Therefore, the present invention adopts the above-mentioned construction method for airbag plugging of precipitation wells in high-water-level gravel layer foundation pits, which is simple in construction, high in safety, can effectively prevent groundwater from seeping in, reduce the foundation pit risk, and at the same time reduce equipment investment and plugging cycle, and significantly improve the engineering efficiency.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and such modifications or equivalent replacements do not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A construction method for airbag plugging of a drainage well in a high-water gravel layer foundation pit, characterized in that: The following steps are involved: S1. Carry out waterproofing construction. Lay a double layer of SBS waterproofing membrane on the surface of the foundation pit cushion layer to seal the bottom. Clean the debris, oil and water on the cushion layer surface. Compact the overlapping parts of the membrane and seal them with waterproof glue or sealant. The connection between the flexible waterproof layer and the steel pipe sleeve is processed into an arc shape and folded upwards. S2. Pre-buried waterproof steel pipe sleeve: a steel pipe sleeve with a water stop ring is pre-buried in the cushion layer. An 80mm wide water stop ring is welded in the middle of the steel pipe sleeve, and a 12mm thick flange is welded on the top. The flange is connected to a prefabricated blind plate with a thickness of 10mm through M28 bolts; S3, pump out the accumulated water and stop the pump. Select the pumping equipment according to the water level of the foundation pit and start pumping. Check the water level regularly until it drops to the design requirement and then stop the pump. S4. Install the airbag. Install the multi-layer airbag in the steel pipe sleeve. Inflate the airbag to 2.5MPa and fix it. Drain the water on the top and observe for 1 hour to confirm that there is no leakage. S5. Weld the lower blind plate and weld a 10mm thick steel plate with a diameter 5mm smaller than the inner diameter of the pipe well to the bottom of the steel pipe sleeve to ensure that there are no defects in the welding; S6. Install the top blind plate, set a rubber gasket between the top flange of the steel pipe sleeve and the blind plate, and fix the blind plate with embedded bolts; S7. Plant reinforcement and backfill with high-strength grouting material. Arrange φ16 single-layer bidirectional steel bars above the blind plate. Pour C60 high-strength grouting material to 5 cm from the top of the flange. After solidification, sprinkle water and cover for seven days of maintenance.

2. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 1 is characterized in that: The S2 steel pipe sleeve is made of carbon steel or stainless steel, and the surface is sandblasted or polished and coated with epoxy anti-corrosion coating.

3. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 1 is characterized in that: The specific steps for stopping the pump in S3 are as follows: S31. Before stopping the pump, remove the template and square wood at the wellhead and clean them; S32. Make relevant preparations and prepare personnel, materials and equipment for stopping the pump; S33. Close down the drainage wells gradually in the order from low to high, from large to small, and from the periphery to the middle, giving priority to closing down the drainage wells with large water inflow; S34. Shut down the drainage wells one by one in a determined order, and immediately seal them after shutting down a drainage well. It is strictly forbidden to shut down multiple drainage wells in the pit at the same time. During the sealing period, the drainage wells outside the pit should operate normally, and the pump stopping process should be quick to reduce the amount of water gushing into the pit.

4. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 1 is characterized in that: The specific steps of S4 are as follows: S41. Use high-strength polyurethane or fluororubber as the main material of the airbag, and the airbag adopts a multi-layer structure design; S42. Check the appearance integrity of the airbag and install a support structure for larger precipitation wells to ensure that the airbag maintains a stable structure after inflation; S43. Install the airbag at a position 20 cm away from the top flange, use an air pump to pressurize the airbag to 2.5 MPa, stop pressurizing and tighten the airbag; S44. Observe for 1 hour to confirm that there is no water gushing from the top of the airbag. If water gushes from the airbag, use a self-priming pump to drain the water on the top. If the airbag is installed with a height deviation, backfill C60 high-strength grouting material to 5 cm from the top of the flange.

5. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 4 is characterized in that: The airbag in S4 is composed of an outer wear-resistant layer, a middle airtight layer and an inner waterproof layer. The inner wall of the airbag is coated with a polyurethane waterproof coating, and an integrated pressure sensor is used to detect the air pressure in real time.

6. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 4 is characterized in that: During the inflation process of S43, manual pressure is required to prevent the airbag from floating up.

7. The method for airbag plugging of a drainage well in a high-water gravel layer foundation pit according to claim 1 is characterized in that: Before welding the lower blind plate in S5, use a wire brush or sandpaper to remove rust and impurities on the welding surface. After welding, check the appearance of the weld and use a wire brush or sandpaper to clean the weld surface to remove welding slag and oxides.

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