Air pressure auxiliary type depressurization well backfill plugging device and method

Abstract

The device comprises a water level control module and a grouting backfilling module, the water level control module comprises a flange pipe, a sealing end, a drainage valve, an air compression valve, an air pressure servo pump and a laser range finder, and the sealing end is in sealed connection with a depressurization well pipe through the flange pipe; the sealing end is respectively connected with the drainage valve and the compressed air valve, and a laser range finder is arranged at the top of the sealing end; the grouting and backfilling module comprises a grouting pipe, a grouting pump, a grouting valve, a grouting material, backfilling granules and concrete; the grouting pipe penetrates through the top of the sealing end and is connected with the grouting valve and the grouting pump; the backfill aggregates are laid at the bottom of the depressurization well pipe, the grouting material is injected into the depressurization well pipe through the grouting pipe, the liquid level is higher than the top surface of the backfill aggregates, and the concrete is poured above the grouting material. The underground water level is controlled by pressing air into the pressure reduction well pipe, the influence of underground water flowing on the grouting effect is avoided, and the grouting construction quality and the sealing effect are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering construction, and in particular to a gas pressure-assisted pressure-reducing well backfilling and plugging device and method. Background Art

[0002] During the excavation of deep foundation pits, pressurized water is one of the main threats to the safety of the foundation pit. The excavation depth of deep foundation pits is usually much lower than the natural water level of pressurized water. In order to prevent hazards such as sudden surges at the bottom of the foundation pit, it is necessary to reduce the water level of pressurized water within the foundation pit to a certain depth below the excavation during the excavation process. Reducing the water level of pressurized water is mainly achieved by pressure reduction wells. Please refer to Figure 1 The pressure reduction well is a well tunnel dug from the foundation pit excavation space 01 to the bottom of the foundation pit bottom plate 02. The impermeable layer 03 within the corresponding foundation pit excavation depth range is a solid pipe section 05, and the pressurized water layer 04 below the pit bottom is a permeable filter pipe section 06. By placing a submersible pump 08 in the filter pipe section 06, the pressurized water is pumped to the ground to achieve the purpose of lowering the pressurized water level.

[0003] After the internal structure of the deep foundation pit is constructed to meet the anti-floating requirements, the pressure-reducing well needs to be backfilled and plugged, and the well pipe within the scope of the foundation pit needs to be cut off. The conventional backfilling and plugging process is: first restore the water level in the pressure-reducing well to the natural water level, so that the water in the pressure-reducing well is in a stable state, and then pour filler into the well pipe to solidify the filler under static water conditions to form a stable and well-sealed plugging body. However, during the construction of underground structures, the position of the pressure-reducing well often conflicts with the main structure due to problems such as changes in drawings. It is necessary to first cut off the well pipe within the excavation depth of the foundation pit, then construct the internal structure, and finally backfill and plug. Because the natural water level of the pressurized water is higher than the bottom of the foundation pit, the water level in the well cannot be restored to the natural state under this condition. When the direct backfilling method is used for plugging, the dynamic water pressure in the well is relatively large during the solidification of the backfill material, and the water body has a tendency to flow upward. After the backfill material is solidified, it is very easy to have a seepage channel, resulting in a loose plugging and substandard sealing effect.

[0004] In order to solve the above-mentioned problem of plugging under pressure, it is necessary to improve the plugging process of pressure-reducing wells. The main improvements are: the water level in the well can be maintained after the well pipe is cut off and the water pump is removed, and the dense injection of the filling material can be achieved under a relatively stable water body state. In the prior art, the invention patent "A structure and method for plugging water in a pressure-reducing well" with application publication number CN111926841A and the invention patent "A device and method for plugging a pressure-reducing well combined with a solidifying capsule" with application publication number CN116950105A both use an inflated (liquid) pressure bag to seal the well pipe, and then inject the filling material into the upper part of the bag or inside the bag to plug the well pipe. However, the above process has two defects. First, the dynamic water pressure of the pressure-relief well in the ultra-deep foundation pit is large, and the temporary sealing effect of the inflatable (hydraulic) bag is poor, resulting in upward water flow during backfilling, affecting the sealing quality of the backfill material; second, the bag structure itself is a flexible material with poor strength and durability. It is a weak point in the backfill material, which is not conducive to the long-term sealing of the backfill seal, resulting in the risk of water seepage in the backfill seal in the later stage.

[0005] Therefore, how to provide a gas pressure-assisted pressure-reducing well backfilling and plugging device and method that can maintain the water level in the well after the well pipe is cut off and the water pump is removed, and achieve dense injection and dense solidification of the backfill material under the conditions of high water pressure in the well and a flow tendency, is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0006] The present invention provides a gas pressure-assisted depressurization well backfilling and plugging device and method to solve the above technical problems.

[0007] In order to solve the above technical problems, the present invention provides a gas pressure-assisted depressurization well backfilling and plugging device, including a water level control module and a grouting backfilling module.

[0008] The water level control module includes a flange pipe, a sealing end, a drainage valve, a compressed air valve, a pneumatic servo pump and a laser rangefinder. The flange pipe is fixedly installed on the top of the cut pressure-reducing well pipe, and the sealing end is sealed and connected to the pressure-reducing well pipe through the flange pipe; the side of the sealing end is connected to the drainage valve through a first sealing joint, and is connected to the compressed air valve and the pneumatic servo pump through a second sealing joint, and a third sealing joint is provided on the top of the sealing end; the laser rangefinder is installed on the top of the sealing end to detect the liquid level in the pressure-reducing well pipe;

[0009] The grouting backfill module includes a grouting pipe, a grouting pump, a grouting valve, grouting materials, backfill aggregates and concrete. The grouting pipe is connected to the grouting valve and the grouting pump through the third sealing joint, and the free end is inserted into the bottom of the pressure-reducing well pipe; the backfill aggregates are laid on the bottom of the pressure-reducing well pipe, the grouting material is injected into the pressure-reducing well pipe through the grouting pipe, and the liquid level is higher than the top surface of the backfill aggregates, and the concrete is poured above the grouting material to the top surface of the foundation pit bottom plate.

[0010] Preferably, the flange pipe is a cylindrical structure, the upper end of which is an open flange structure with bolt holes, and the lower end is a circular opening, and the circular opening is welded and fixed to the top of the pressure-reducing well pipe.

[0011] Preferably, the sealing end is a cylindrical structure with a closed upper end and an open flange structure with bolt holes at the lower end matching the upper end of the flange pipe, and the sealing end is connected to the flange pipe by bolts.

[0012] Preferably, a sealing ring is provided on the contact surface between the flange pipe and the sealing end.

[0013] Preferably, the output end of the laser rangefinder is connected to the pneumatic servo pump signal.

[0014] Preferably, the grouting pipe is coaxially arranged with the pressure-reducing well pipe.

[0015] Preferably, the backfill granular material is fine gravel or coarse sand.

[0016] Preferably, the grouting material is a high-strength fast-setting slurry.

[0017] The present invention also provides a gas pressure-assisted depressurization well backfilling and plugging method, which uses the gas pressure-assisted depressurization well backfilling and plugging device as described above, and includes the following steps:

[0018] The first stage: the continued dewatering stage after the pressure-reducing well pipe is cut off, including:

[0019] Step 11: cutting the pressure-reducing well pipe to the upper end surface of the foundation pit bottom plate, and fixedly connecting the flange pipe to the cut pressure-reducing well pipe; placing a submersible pump into the pressure-reducing well pipe, and controlling the groundwater level by pumping water through the submersible pump;

[0020] The second stage: the pressure reduction well plugging stage, including:

[0021] Step 21: taking out the submersible pump, installing the grouting pipe in the pressure-reducing well pipe and injecting the backfill granular material, wherein the height of the backfill granular material is higher than the top of the filter pipe section of the pressure-reducing well pipe;

[0022] Step 22: Connect the sealing end with the grouting pipe and the flange, and based on the rising speed of the groundwater level, open the drainage valve to lead out the groundwater; then close the drainage valve and the grouting valve, open the air pressure valve and start the air pressure servo pump to pressurize the inside of the pressure-reducing well pipe to reduce the groundwater level to below the top surface of the backfill granular material;

[0023] Step 23: Open the grouting valve and start the grouting pump to press the grouting material into the pressure-reducing well pipe through the grouting pipe. After the liquid level of the grouting material rises to a level higher than the top surface of the backfill granular material, stop grouting;

[0024] Step 24: After the grouting material is solidified, the sealing end and the connected pipes and equipment are removed, and the plugging effect in the pressure-reducing well pipe is observed. If there is still water seepage, the sealing end is reinstalled and the compressed air grouting operation is repeated; if there is no water seepage, concrete is poured into the pressure-reducing well pipe to the top surface of the foundation pit bottom plate;

[0025] Step 25: After the concrete is solidified, the flange pipe and the pressure-reducing well pipe and grouting pipe above the foundation pit bottom plate are cut off, and the pressure-reducing well is sealed.

[0026] Preferably, in step 23, the liquid level change of the grouting material is observed by the laser rangefinder, and if the liquid level drops, compensation grouting is performed to the set liquid level.

[0027] Compared with the prior art, the gas pressure-assisted pressure-reducing well backfilling and plugging device and method provided by the present invention has the following advantages:

[0028] 1. Compared with the traditional pressure-reducing well sealing process, the present invention can control the groundwater level by compressing gas into the pressure-reducing well pipe, thereby avoiding the influence of groundwater flow on the grouting effect and ensuring the quality of grouting construction;

[0029] 2. Compared with the existing process of sealing the well after cutting off the well pipe, the method proposed by the present invention is more reliable and effective, and can significantly improve the sealing effect of the grouting material after solidification. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figures 1 to 6 The following are schematic diagrams of the construction steps of a gas pressure-assisted depressurization well backfilling and plugging method in a specific embodiment of the present invention.

[0031] In the figure: 01- foundation pit excavation space, 02- foundation pit bottom plate, 03- impermeable layer, 04- pressure water layer, 05- solid pipe section, 06- filter pipe section, 07- water level line, 08- submersible pump; 10- flange pipe, 11- sealing ring, 20- sealing end, 21- first sealing joint, 22- second sealing joint, 23- third sealing joint, 30- drainage valve, 40- compressed air valve, 41- air pressure servo pump, 50- laser rangefinder, 60- grouting pipe, 61- grouting pump, 62- grouting valve, 70- grouting material, 80- backfill aggregate, 90- concrete. DETAILED DESCRIPTION

[0032] In order to describe the technical solution of the above invention in more detail, specific embodiments are listed below to demonstrate the technical effects; it should be emphasized that these embodiments are used to illustrate the present invention but not to limit the scope of the present invention.

[0033] The gas pressure assisted pressure reduction well backfill plugging device provided by the present invention is as follows: Figures 1 to 6 As shown, it includes two parts: water level control module and grouting backfill module, where:

[0034] The water level control module includes a flange pipe 10, a sealing end 20, a drainage valve 30, an air pressure valve 40, an air pressure servo pump 41 and a laser rangefinder 50. The flange pipe 10 is fixedly installed on the top of the cut pressure-reducing well pipe. The sealing end 20 is sealed and connected to the pressure-reducing well pipe through the flange pipe 10 to form a sealed space. The side of the sealing end 20 is connected to the drainage valve 30 through a first sealing joint 21, and is connected to the air pressure valve 40 and the air pressure servo pump 41 through a second sealing joint 22. A third sealing joint 23 is provided on the top of the sealing end 20. The laser rangefinder 30 is installed on the top of the sealing end 20 to detect the liquid level in the pressure-reducing well pipe.

[0035] The grouting backfill module includes a grouting pipe 60, a grouting pump 61, a grouting valve 62, grouting material 70, backfill aggregate 80 and concrete 90. The grouting pipe 60 is connected to the grouting valve 62 and the grouting pump 64 through the third sealing joint 23, and the free end is inserted into the bottom of the pressure-reducing well pipe; the backfill aggregate 80 is laid on the bottom of the pressure-reducing well pipe, and the grouting material 70 is injected into the pressure-reducing well pipe through the grouting pipe 60, and the liquid level is higher than the top surface of the backfill aggregate 80, and the concrete 90 is poured above the grouting material 70 to the top surface of the foundation pit bottom plate 02.

[0036] Compared with the traditional pressure-reducing well sealing process, the present invention can control the groundwater level by compressing air into the pressure-reducing well pipe, thereby avoiding the influence of groundwater flow on the grouting effect and ensuring the quality of grouting construction; compared with the existing process of sealing the well after cutting off the well pipe, the method proposed by the present invention is more reliable and effective, and can significantly improve the sealing effect of the grouting material 70 after solidification.

[0037] In some embodiments, please refer to Figures 1 to 5 The flange pipe 10 is a cylindrical structure, the upper end of which is an open flange structure with bolt holes, and the lower end is a circular opening, and the circular opening is welded and fixed to the top of the step-down well pipe; the sealing end 20 is also a cylindrical structure, the upper end is closed, and the lower end is an open flange structure with bolt holes matching the upper end of the flange pipe 10. The sealing end 20 is connected to the flange pipe 10 by bolts, thereby forming a sealed space with the inside of the step-down well pipe after cutting, and facilitating later removal.

[0038] In some embodiments, a sealing ring 11 is provided on the contact surface between the flange pipe 10 and the sealing end 20 to ensure a sealing effect.

[0039] In some embodiments, the output end of the laser rangefinder 50 is connected to the signal of the pneumatic servo pump 41. The pneumatic servo pump 41 pressurizes air into the step-down well pipe to force the groundwater level to drop. At this time, the pneumatic servo pump 41 is controlled by feedback of the observation data of the laser rangefinder 50 to achieve precise control of the groundwater level.

[0040] In some embodiments, the grouting pipe 60 is coaxially arranged with the pressure-reducing well pipe to ensure uniform grouting.

[0041] In some embodiments, the backfill aggregate 80 may be made of fine gravel or coarse sand; the grouting material 70 may be made of high-strength fast-setting slurry, such as cement-water-glass double-liquid slurry, to ensure the plugging effect of the pressure-reducing well.

[0042] The present invention also provides a gas pressure-assisted depressurization well backfilling and plugging method, which uses the gas pressure-assisted depressurization well backfilling and plugging device as described above, and includes the following steps:

[0043] The first stage: the continued dewatering stage after the pressure-reducing well pipe is cut off, including:

[0044] Step 11: Cut the pressure-reducing well pipe to the upper end surface of the foundation pit bottom plate 02, and fix the flange pipe 10 to the cut pressure-reducing well pipe, for example, by welding; put a submersible pump 08 into the pressure-reducing well pipe, and control the groundwater level by pumping water through the submersible pump 08, such as Figure 1 shown.

[0045] The second stage: the pressure reduction well plugging stage, including:

[0046] Step 21: Take out the submersible pump 08, install the grouting pipe 60 in the pressure-reducing well pipe and put in the backfill granular material 80. The height of the backfill granular material 80 is higher than the top of the pressure-reducing well pipe filter pipe section 06. Figure 2 shown.

[0047] Step 22: Connect the sealing end 20 to the grouting pipe 60 and the flange 10. This embodiment adopts bolt connection. Based on the rising speed of the groundwater level, for example, if the groundwater level rises quickly and reaches the position of the foundation pit bottom plate 02, the drainage valve 30 can be opened to lead out the groundwater; then the drainage valve 30 and the grouting valve 62 are closed, the compressed air valve 40 is opened and the air pressure servo pump 41 is started to pressurize the inside of the pressure-reducing well pipe to lower the groundwater level. At this time, the air pressure servo pump 41 can be controlled by the data feedback of the laser rangefinder 50 until the water level line 07 drops below the top surface of the backfill granular material 80, as shown in FIG. Figure 3 shown.

[0048] Step 23: Open the grouting valve 62 and start the grouting pump 61 to press the grouting material 70 into the pressure-reducing well pipe through the grouting pipe 60. After the liquid level of the grouting material 70 rises to a level higher than the top surface of the backfill granular material 80, stop grouting. Figure 4 shown.

[0049] Step 24: After the grouting material 70 is cured, the sealing end 20 and the connected pipes and equipment are removed, and the plugging effect in the pressure-reducing well pipe is observed. If there is still obvious water seepage, the sealing end 20 is reinstalled and the compressed air grouting operation is repeated; if there is no obvious water seepage, concrete 90 is poured into the pressure-reducing well pipe to the top surface of the foundation pit bottom plate 02. Figure 5 shown.

[0050] Step 25: After the concrete 90 is solidified, the flange pipe 10 and the pressure-reducing well pipe and the grouting pipe 60 above the bottom plate of the foundation pit are cut off, and the pressure-reducing well is sealed. Figure 6 shown.

[0051] The above method is used to backfill and seal the pressure reduction well, thereby avoiding the influence of groundwater flow on the grouting effect and ensuring the sealing effect of the grouting.

[0052] In some embodiments, in step 23, the liquid level change of the grouting material 70 is observed by the laser rangefinder 50. If the liquid level drops, compensation grouting is performed to the set liquid level to avoid insufficient grouting, which affects the plugging effect.

[0053] In summary, the air pressure-assisted pressure-reducing well backfilling and plugging device and method provided by the present invention include a water level control module and a grouting backfilling module. The water level control module includes a flange pipe 10, a sealing end 20, a drainage valve 30, an air pressure valve 40, an air pressure servo pump 41 and a laser rangefinder 50. The flange pipe 10 is fixedly installed on the top of the cut pressure-reducing well pipe, and the sealing end 20 is sealed and connected to the pressure-reducing well pipe through the flange pipe 10; the side of the sealing end 20 is connected to the drainage valve 30 through a first sealing joint 21, and is connected to the air pressure valve 40 and the air pressure servo pump 41 through a second sealing joint 22. The top of the sealing end 20 is provided with a third sealing joint 23; The laser rangefinder 30 is installed on the top of the sealing end 20 to detect the liquid level in the pressure-reducing well pipe; the grouting backfill module includes a grouting pipe 60, a grouting pump 61, a grouting valve 62, grouting material 70, backfill aggregate 80 and concrete 90. The grouting pipe 60 is connected to the grouting valve 62 and the grouting pump 64 through the third sealing joint 23, and the free end is inserted into the bottom of the pressure-reducing well pipe; the backfill aggregate 80 is laid on the bottom of the pressure-reducing well pipe, the grouting material 70 is injected into the pressure-reducing well pipe through the grouting pipe 60, and the liquid level is higher than the top surface of the backfill aggregate 80, and the concrete 90 is poured above the grouting material 70 to the top surface of the foundation pit bottom plate 02. The present invention utilizes the sealed connection between the sealing end 20, the flange pipe 10 and the pressure-reducing well pipe to form a sealed space in the pressure-reducing well pipe, pressurizes air into the pressure-reducing well pipe through the air pressure servo pump 41, forces the groundwater level to drop, and controls the air pressure servo pump 41 through feedback of the observation data of the laser rangefinder 50, thereby achieving precise control of the groundwater level. Under the premise that the groundwater level is controllable, grouting and sealing are implemented in the pressure-reducing well pipe, thereby avoiding the influence of groundwater flow on the grouting effect and ensuring the sealing effect of the grouting.

[0054] Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A gas pressure assisted depressurization well backfill plugging device, characterized in that: Including water level control module and grouting backfill module, The water level control module includes a flange pipe, a sealing end, a drainage valve, a compressed air valve, a pneumatic servo pump and a laser rangefinder. The flange pipe is fixedly installed on the top of the cut pressure-reducing well pipe, and the sealing end is sealed and connected to the pressure-reducing well pipe through the flange pipe; the side of the sealing end is connected to the drainage valve through a first sealing joint, and is connected to the compressed air valve and the pneumatic servo pump through a second sealing joint, and a third sealing joint is provided on the top of the sealing end; the laser rangefinder is installed on the top of the sealing end to detect the liquid level in the pressure-reducing well pipe; The grouting backfill module includes a grouting pipe, a grouting pump, a grouting valve, grouting materials, backfill aggregates and concrete. The grouting pipe is connected to the grouting valve and the grouting pump through the third sealing joint, and the free end is inserted into the bottom of the pressure-reducing well pipe; the backfill aggregates are laid on the bottom of the pressure-reducing well pipe, the grouting material is injected into the pressure-reducing well pipe through the grouting pipe, and the liquid level is higher than the top surface of the backfill aggregates, and the concrete is poured above the grouting material to the top surface of the foundation pit bottom plate.

2. The gas pressure-assisted depressurization well backfill plugging device according to claim 1, characterized in that: The flange pipe is a cylindrical structure, the upper end of which is an open flange structure with bolt holes, and the lower end is a circular opening, and the circular opening is welded and fixed to the top of the pressure-reducing well pipe.

3. The gas pressure-assisted depressurization well backfill plugging device according to claim 2, characterized in that: The sealing end is a cylindrical structure with a closed upper end and an open flange structure with bolt holes matching the upper end of the flange pipe at the lower end. The sealing end is connected to the flange pipe by bolts.

4. The gas pressure-assisted depressurization well backfill plugging device according to claim 3, characterized in that: A sealing ring is provided on the contact surface between the flange pipe and the sealing end.

5. The gas pressure-assisted depressurization well backfill plugging device according to claim 1, characterized in that: The output end of the laser rangefinder is connected to the air pressure servo pump signal.

6. The gas pressure-assisted depressurization well backfill plugging device according to claim 1, characterized in that: The grouting pipe is coaxially arranged with the pressure-reducing well pipe.

7. The gas pressure-assisted depressurization well backfill plugging device according to claim 1, characterized in that: The backfill granular material is fine gravel or coarse sand.

8. The gas pressure-assisted depressurization well backfill plugging device according to claim 1, characterized in that: The grouting material adopts high-strength fast-setting slurry.

9. A gas pressure assisted depressurization well backfilling and plugging method, using the gas pressure assisted depressurization well backfilling and plugging device as claimed in any one of claims 1 to 8, characterized in that: The steps include: The first stage: the continued dewatering stage after the pressure-reducing well pipe is cut off, including: Step 11: cutting the pressure-reducing well pipe to the upper end surface of the foundation pit bottom plate, and fixedly connecting the flange pipe to the cut pressure-reducing well pipe; placing a submersible pump into the pressure-reducing well pipe, and controlling the groundwater level by pumping water through the submersible pump; The second stage: the pressure reduction well plugging stage, including: Step 21: taking out the submersible pump, installing the grouting pipe in the pressure-reducing well pipe and injecting the backfill granular material, wherein the height of the backfill granular material is higher than the top of the filter pipe section of the pressure-reducing well pipe; Step 22: Connect the sealing end with the grouting pipe and the flange, and based on the rising speed of the groundwater level, open the drainage valve to lead out the groundwater; then close the drainage valve and the grouting valve, open the air pressure valve and start the air pressure servo pump to pressurize the inside of the pressure-reducing well pipe to reduce the groundwater level to below the top surface of the backfill granular material; Step 23: Open the grouting valve and start the grouting pump to press the grouting material into the pressure-reducing well pipe through the grouting pipe. After the liquid level of the grouting material rises to a level higher than the top surface of the backfill granular material, stop grouting; Step 24: After the grouting material is solidified, the sealing end and the connected pipes and equipment are removed, and the plugging effect in the pressure-reducing well pipe is observed. If there is still water seepage, the sealing end is reinstalled and the compressed air grouting operation is repeated; if there is no water seepage, concrete is poured into the pressure-reducing well pipe to the top surface of the foundation pit bottom plate; Step 25: After the concrete is solidified, the flange pipe and the pressure-reducing well pipe and grouting pipe above the foundation pit bottom plate are cut off, and the pressure-reducing well is sealed.

10. The gas pressure-assisted depressurization well backfilling and plugging method according to claim 9, characterized in that: In step 23, the liquid level change of the grouting material is observed by the laser rangefinder. If the liquid level drops, compensation grouting is performed to the set liquid level.

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