Emergency Treatment Methods for Sudden Inrush in Large Deep Foundation Pit

Abstract

This invention provides an emergency response method for sudden water inrush in large deep foundation pits, comprising the following steps: S1, assessing the inrush situation; S2, if the inrush water volume or flow rate is less than a preset value, employing back pressure and grouting to seal the leak at the inrush location; S3, if the inrush water volume or flow rate is greater than the preset value, then employing dewatering measures such as pumping water from external dewatering wells, followed by back pressure at the inrush location, and then grouting to seal the leak around the perimeter or outside the foundation pit; through these steps, emergency response to the inrush is achieved. Based on geological surveys and the layout of road structures, multiple dewatering wells are installed outside the foundation pit, including shallow dewatering wells and confined dewatering wells; the inflow of water during the inrush is assessed to determine whether it originates from shallow or confined layers, and different drainage plans are initiated for the shallow and confined dewatering wells around the foundation pit respectively. The method offers rapid response, significantly reduces water volume, and minimizes new uncontrollable risks associated with dewatering.

Description

Technical Field

[0001] This invention relates to the field of large-scale underground engineering construction technology, and in particular to an emergency treatment method for sudden inrush in large deep foundation pits. Background Technology

[0002] A large-scale underground project involves the excavation of a single independent foundation pit, exceeding 200,000 cubic meters of earthwork. Each pit is 420 meters long, approximately 14.9-17.3 meters wide, and 30-43 meters deep. The large volume and long distance of the retaining structure construction, coupled with various uncontrollable factors during construction, may lead to defects below the excavation surface. Water seepage at the pit bottom due to the water level difference between the inside and outside of the pit can cause sudden water inrushes, posing a significant challenge to handling. CN108018859A describes an emergency treatment method and structure for foundation pit inrushes, employing a pipeline depressurization scheme. However, this scheme only serves as an emergency depressurization measure and lacks further follow-up treatment measures, meaning it cannot fundamentally solve the inrush problem. Existing inrush control methods also include reinforcing the retaining structure with cast-in-place concrete piles or mixing piles, but these methods involve substantial investment and waste. Summary of the Invention The technical problem to be solved by the present invention is to provide an emergency treatment method for sudden surge in large deep foundation pits, which can quickly and economically solve the problem of sudden surge in large deep foundation pits, and in particular, can fundamentally solve the technical problem of sudden surge control in an economical way.

[0003] To solve the above-mentioned technical problems, the technical solution of the present invention is: an emergency treatment method for sudden inrush in large deep foundation pits, comprising the following steps: S1. Assess the sudden surge situation; S2. If the sudden inflow volume or flow rate is less than the preset value, back pressure and grouting should be used to plug the leak at the location of the sudden inflow. S3. If the sudden inflow or flow rate exceeds the preset value, the following measures shall be taken: after dewatering in the dewatering well outside the pit, back pressure shall be applied at the sudden inflow location, and then grouting shall be used to seal the leak around the perimeter or outside the pit. By following the steps above, emergency response to sudden surges can be achieved.

[0004] In the preferred embodiment, based on geological surveys and the layout of road structures, multiple dewatering wells are installed outside the foundation pit. These dewatering wells include shallow dewatering wells and confined dewatering wells. In step S1, the situation of the sudden inrush water is assessed to determine whether the sudden inrush water is shallow water or confined layer water, and different drainage plans are initiated for the shallow dewatering wells and confined layer dewatering wells around the foundation pit respectively. If the sudden surge of water mainly originates from shallow layers, the pumping capacity of shallow dewatering wells is greater than that of confined dewatering wells. If the sudden surge of water mainly originates from confined layers, the water level in confined dewatering wells is controlled by dewatering the confined layers to reduce the water pressure at the location of the surge.

[0005] In the preferred embodiment, settlement monitoring pipes are installed between the foundation pit and the surrounding existing structures to monitor the settlement of the surrounding water level in real time during the dewatering process of the foundation pit. Multiple shallow recharge wells are installed around the foundation pit and between it and the existing structures. Recharge operations are carried out as needed based on the observation data from the settlement monitoring pipes.

[0006] In the preferred embodiment, in steps S2 and S3, the grouting and sealing measure is to drill grouting holes around the sudden surge location and perform pressure grouting until grout flows out of the hole at the sudden surge location.

[0007] In a preferred embodiment, heavy objects are applied to the location of the sudden surge, followed by compaction grouting to seal the perimeter of the pit.

[0008] In a preferred embodiment, step S1 further includes monitoring the direction of incoming water: S11. Around the location of the sudden surge, multiple seepage monitoring pipes are installed inside the retaining structure. Indicators are installed inside the seepage monitoring pipes, with different indicators for each direction. The direction of incoming water is determined based on the indicators monitored at the location of the sudden surge.

[0009] In a preferred embodiment, the indicator includes a dye indicator, i.e., dyes of different colors or mineral powders that can develop color, which helps to determine the direction of incoming water after color development by visual observation or auxiliary measures.

[0010] In a preferred embodiment, the seepage monitoring pipe has the following structure: it includes at least one sleeve, a monitoring pipe is provided at the front end of the sleeve, and a tapered head is provided at the front end of the monitoring pipe; Both the casing and the monitoring tube are hollow structures. An indicator is placed inside the monitoring tube, and multiple through holes are provided on the outer wall of the monitoring tube. A plug is placed in each through hole, and a connector is provided at the tail end of the casing for connecting to a pump. When the pump injects pressurized water, the plug falls out of the through hole, and the indicator enters the ground.

[0011] The preferred embodiment also includes the step of arranging temporary water-retaining piles in the direction of incoming water: S21. Temporary water-retaining piles are arranged inside the retaining structure in the direction of water inflow, and a guide frame is set up. Multiple limiting blocks are provided on the guide frame, and wing plate guide grooves are provided on the side of the limiting blocks. Multiple first pile units are driven into the ground at intervals along the guide frame. S22. Remove the guide frame, and after multiple second pile units are interlocked with the first pile unit, drive them into the ground; Observe the water outflow at the location of the sudden surge. If the situation improves, stop construction. If the situation does not improve, continue to extend the temporary water-retaining piles. The above steps can quickly reduce the water volume at the sudden surge location.

[0012] In the preferred embodiment, the structure of the temporary water-retaining pile is as follows: it includes a pile body made of aluminum alloy, multiple steel cores arranged vertically inside the pile body, an upper pad plate at the top of the pile body, and a pile head at the bottom of the pile body; Extended wing plates are provided on both wings of the pile body. The extended wing plates are arc-shaped structures arranged in the vertical direction so that the extension range of the extended wing plates can be adjusted within the range of -2~2cm. The free end of one side of the extended wing plate is provided with a connecting column arranged in the vertical direction, and the free end of the other side of the extended wing plate is provided with an interlocking groove arranged in the vertical direction so that adjacent temporary water-retaining piles are sealed to each other.

[0013] This invention provides an emergency response method for sudden water inrush in large deep foundation pits, which has the following advantages compared with existing technologies: 1. The response is fast, significantly reducing rainfall and minimizing new uncontrollable risks caused by precipitation.

[0014] 2. The scheme of using shallow dewatering wells and confined dewatering wells for dewatering can avoid the impact of excessive dewatering on surrounding existing structures and reduce the risk of settlement.

[0015] 3. The installed seepage monitoring pipes can be used for targeted treatment based on the direction of incoming water, which can significantly reduce treatment costs, improve treatment efficiency, and reduce risks.

[0016] 4. The method of using indicators can easily, quickly and intuitively monitor the direction of incoming water, providing guidance for subsequent treatment measures.

[0017] 5. Compared with cast-in-place concrete piles or mixing piles, temporary water-retaining piles have a faster construction speed and very low cost. Moreover, temporary water-retaining piles can be reused after the treatment is completed or the foundation pit is excavated. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: (To be modified) Figure 1 This is a schematic diagram of the elevation structure of the present invention.

[0019] Figure 2 This is a partial top view of the present invention.

[0020] Figure 3 This is a top view of the present invention.

[0021] Figure 4 This is a top view schematic diagram of another preferred embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the seepage monitoring pipe in this invention.

[0023] Figure 6 This is a top view of the temporary water-retaining pile in this invention.

[0024] Figure 7 This is a schematic diagram of the elevation structure of the temporary water-retaining pile in this invention.

[0025] Figure 8 This is a flowchart of the construction process of temporary water-retaining piles in this invention.

[0026] Figure 9 This is a flowchart of the surge handling process of the present invention.

[0027] Figure 10 This is another preferred flow chart for handling sudden surges according to the present invention.

[0028] Figure 11 This is another preferred flow chart for handling sudden surges according to the present invention.

[0029] Figure 12 This is a flowchart of the temporary surge interception process of the present invention.

[0030] In the diagram: 1. Ground surface; 2. Shallow dewatering well; 3. Pressurized dewatering well; 4. Seepage monitoring pipe; 41. Casing; 42. Monitoring pipe; 43. Indicator; 44. Plug; 45. Conical head; 46. Connector; 47. Pipeline; 48. Pump; 5. Excavation pit; 6. Retaining structure; 7. Soil layer to be excavated; 8. Pump house; 9. Temporary water-retaining pile; 91. Pile body; 92. Steel core; 93. Extended wing plate; 94. Connecting column; 95. Upper pad plate; 96. Pile head; 97. Interlocking groove; 10. Sudden surge location; 11. Guide frame; 12. Limiting block; 121. Wing plate guide groove; 13. Existing structure; 14. Settlement observation pipe; 15. Recharge well; 100. First pile unit; 200. Second pile unit. Detailed Implementation

[0031] Example 1: like Figure 9 A method for emergency response to sudden water inrush in a large deep foundation pit includes the following steps: S1. Assess the sudden inrush situation; assessment data includes the inrush inflow volume and flow rate.

[0032] S2. If the sudden inflow volume or flow rate is less than the preset value, heavy object back pressure and grouting are used to plug the leak at the sudden inflow location 10; preferably, grouting is used around the sudden inflow location 10 of the foundation pit 5 to plug the leak.

[0033] S3. If the sudden inflow or flow rate is greater than the preset value, the following measures shall be taken: after dewatering in the dewatering well outside the pit, back pressure shall be applied at the sudden inflow location, and grouting shall be applied around the sudden inflow location or around the retaining structure 6 of the pit 5 to seal the leak. The above steps enable emergency response and follow-up treatment of sudden surges.

[0034] Preferred solutions include Figures 1-3 In the process, based on geological surveys and the layout of road structures, multiple dewatering wells are set outside the foundation pit 5, including shallow dewatering well 2 and pressurized dewatering well 3; Figure 3 This is a schematic diagram used to illustrate the positional relationship between shallow dewatering well 2 and confined dewatering well 3.

[0035] In this example, the pumping capacity of a single well is 2400 m³. 3 / d. Considering actual drainage, well pumping attenuation, and backup pumps, a total of 35 100m³ pumps were configured. 3 Pumps with a capacity of 1 h or more can meet the emergency dewatering needs of foundation pits.

[0036] In step S1, the situation of the sudden water inflow is assessed. Based on the height of the water inflow and the cross section of the sudden water inflow location 10, it is assessed whether the sudden water inflow is shallow water or confined layer water. Different drainage plans are initiated for the shallow dewatering well 2 and the confined dewatering well 3 around the foundation pit 5 respectively. If the sudden surge of water mainly comes from the shallow layer, the pumping capacity of the shallow dewatering well 2 is greater than that of the confined dewatering well 3; if the sudden surge of water mainly comes from the confined layer, the water level in the confined dewatering well 3 is controlled by the dewatering of the confined dewatering well 3, thereby reducing the water pressure at the sudden surge location 10.

[0037] Preferred solutions include Figure 4 In this process, a settlement observation pipe 14 is installed between the foundation pit 5 and the surrounding existing structures 13 to observe the settlement of the surrounding water level in real time during the dewatering process of the foundation pit 5; preferably, the settlement observation pipe 14 is a PVC pipe and a water level gauge is installed inside the settlement observation pipe 14.

[0038] Further preferred options include Figure 4 In this method, multiple shallow recharge wells 15 are installed around the foundation pit 5 and between it and the existing structures. Recharge operations are carried out as needed based on the observation data from the settlement monitoring pipes 14. This scheme avoids the impact of large-volume precipitation on the surrounding existing structures 13.

[0039] In the preferred embodiment, in steps S2 and S3, the grouting and sealing measure is to drill grouting holes around the surge location 10 and perform pressure grouting until grout flows out of the hole at the surge location 10.

[0040] In the preferred embodiment, if the concrete grout is difficult to fix, the solution also includes applying a heavy object to the surge location 10 for counter-pressure, and then performing compaction grouting to seal the perimeter of the foundation pit 5.

[0041] In a preferred embodiment, step S1 further includes monitoring the direction of incoming water: S11. Around the sudden surge location 10, multiple seepage monitoring pipes 4 are installed inside the retaining structure 6. Indicators 43 are installed inside the seepage monitoring pipes 4, with each indicator 43 being different for each direction. The direction of incoming water is determined based on the indicator 43 detected at the sudden surge location 10. Preferably, the indicator 43 for each direction is a different color, and the direction of incoming water is determined based on the color of the indicator 43 detected at the sudden surge location 10.

[0042] In a preferred embodiment, indicator 43 includes a dye indicator, i.e., dyes of different colors or mineral powders capable of color development, which help determine the direction of incoming water after color development through visual observation or auxiliary measures. In this example, the mineral powder includes manganese ore powder, and the direction of incoming water is determined by the degree of reddening of the water after chlorine gas is injected into it.

[0043] Preferred solutions include Figure 5 In the middle, the structure of the seepage monitoring pipe 4 is as follows: it includes at least one sleeve 41, a monitoring pipe 42 is provided at the front end of the sleeve 41, and a conical head 45 is provided at the front end of the monitoring pipe 42; Both the casing 41 and the monitoring tube 42 are hollow structures. An indicator 43 is provided inside the monitoring tube 42. Multiple through holes are provided on the outer wall of the monitoring tube 42. A plug 44 is provided in each through hole. A connector 46 is provided at the tail end of the casing 41 for connecting to the pump 48. When the pump injects pressurized water, the plug 44 falls out of the through hole and the indicator 43 enters the ground.

[0044] During construction, multiple seepage monitoring pipes 4 are driven into the soil layer 7 to be excavated. The seepage monitoring pipes 4 in each direction are connected to pumps 48 in sequence. Clean water is injected into the seepage monitoring pipes 4 through pipes 47. The water pressure will open the plug 44. Observation is carried out at the sudden surge location 10. When the corresponding indicator 43 appears, such as the indicator 43 of the corresponding color, the specific direction of the leaking water can be revealed.

[0045] In the preferred embodiment, the method further includes the step of arranging temporary water-retaining piles 9 in the direction of incoming water: Preferred solutions include Figure 6 , 7As described above, the structure of the temporary water-retaining pile 9 is as follows: it includes a pile body 91, which is made of aluminum alloy. The pile body 91 contains multiple steel cores 92 arranged in the vertical direction. An upper pad 95 is provided at the top of the pile body 91, and a pile head 96 is provided at the bottom of the pile body 91. The combination structure of aluminum alloy and steel core can significantly reduce the weight of a single unit of the temporary water-retaining pile 9. During on-site construction, only 1 to 2 construction workers can move a temporary water-retaining pile unit, reducing labor intensity. The steel cores 92 can ensure bending strength and can transfer the force from the upper pad 95 to the pile head 96 during driving.

[0046] Extended wing plates 93 are provided on both wings of the pile body 91. The extended wing plates 93 are arc-shaped structures arranged in the vertical direction so that the extension range of the extended wing plates 93 can be adjusted within the range of -2~2cm. One side of the extended wing plate 93 has a connecting column 94 arranged in the vertical direction at its free end, and the other side of the extended wing plate 93 has an interlocking groove 97 arranged in the vertical direction at its free end. One side of the interlocking groove 97 has an opening structure so that adjacent temporary water-retaining piles 9 are sealed to each other.

[0047] S21. Temporary water-retaining piles 9 are arranged inside the retaining structure 6 in the direction of incoming water. The length of the temporary water-retaining piles 9 is 6-12 meters. A guide frame 11 is set on the surface of the soil layer 7 to be excavated. Multiple limiting blocks 12 are provided on the guide frame 11. The side of the limiting block 12 is provided with a wing plate guide groove 121. Each limiting block 12 separates the first pile unit 100 exactly by the distance of a second pile unit 200. The wing plate guide groove 121 is provided to prevent deformation of the extended wing plate 93.

[0048] Multiple first pile units 100 are driven into the ground at intervals along the guide frame 11; S22. Remove the guide frame 11, and after multiple second pile units 200 and first pile unit 100 are interlocked, drive them into the ground; Observe the water outflow at the sudden surge location 10. If the situation improves, stop construction. If the situation does not improve, continue to extend the temporary water-retaining pile 9. The above steps can quickly reduce the water volume at the sudden surge location 10.

[0049] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. An emergency treatment method for sudden inrush in large deep foundation pits, characterized by: Includes the following steps: S1. Assess the sudden surge situation; Based on geological surveys and the layout of road structures, multiple dewatering wells are set outside the foundation pit (5), including shallow dewatering wells (2) and pressurized dewatering wells (3). Assess the situation of the sudden inrush water, and determine whether the sudden inrush water is shallow water or confined water. Initiate different drainage plans for the shallow dewatering wells (2) and confined dewatering wells (3) around the foundation pit (5). If the sudden surge of water mainly comes from the shallow layer, the pumping capacity of the shallow dewatering well (2) is greater than that of the confined dewatering well (3); if the sudden surge of water mainly comes from the confined layer, the water level in the confined dewatering well (3) is controlled by the dewatering of the confined dewatering well (3), thereby reducing the water pressure at the sudden surge location (10). It also includes the step of monitoring the direction of incoming water: S11. Around the sudden surge location (10), multiple seepage monitoring pipes (4) are installed inside the retaining structure (6). Indicators (43) are installed inside the seepage monitoring pipes (4). The indicators (43) in each direction are different. The direction of incoming water is determined based on the indicators (43) monitored at the sudden surge location (10). Indicators (43) include dye indicators, namely dyes of different colors or mineral powders that can develop color, which can help determine the direction of incoming water after color development by visual observation or auxiliary measures; The structure of the seepage monitoring pipe (4) is as follows: it includes at least one sleeve (41), a monitoring pipe (42) is provided at the front end of the sleeve (41), and a conical head (45) is provided at the front end of the monitoring pipe (42). Both the casing (41) and the monitoring tube (42) are hollow structures. An indicator (43) is provided inside the monitoring tube (42). Multiple through holes are provided on the outer wall of the monitoring tube (42). A plug (44) is provided in the through hole. A connector (46) is provided at the tail end of the casing (41) for connecting to the pump (48). When the pump injects pressurized water, the plug (44) falls out of the through hole and the indicator (43) enters the ground. S2. If the sudden inflow or flow rate is less than the preset value, back pressure and grouting are used to plug the leak at the sudden inflow location (10). The grouting and plugging measure is to drill grouting holes around the gushing location (10) and perform pressure grouting until the grouting location (10) hole is filled with grout. It also includes the step of arranging temporary water-retaining piles (9) in the direction of incoming water: S21. Temporary water-retaining piles (9) are arranged inside the retaining structure (6) in the direction of incoming water, and a guide frame (11) is set up. Multiple limiting blocks (12) are provided on the guide frame (11), and wing plate guide grooves (121) are provided on the side of the limiting block (12). Multiple first pile units (100) are driven into the ground at intervals along the guide frame (11). S22. Remove the guide frame (11), and after interlocking multiple second pile units (200) with the first pile unit (100), drive them into the ground; Observe the water outflow at the sudden surge location (10). If the situation improves, stop construction. If the situation does not improve, continue to extend the temporary water-retaining piles (9). The above steps can be used to quickly reduce the water volume at the sudden surge location (10); The structure of the temporary water-retaining pile (9) is as follows: it includes a pile body (91), which is made of aluminum alloy. The pile body (91) has multiple steel cores (92) in the vertical direction. An upper pad (95) is provided at the top of the pile body (91), and a pile head (96) is provided at the bottom of the pile body (91). Extended wing plates (93) are provided on both wings of the pile body (91). The extended wing plates (93) are arc-shaped structures arranged in the vertical direction so that the extension range of the extended wing plates (93) can be adjusted within the range of -2~2cm. The free end of one side of the extended wing plate (93) is provided with a connecting column (94) arranged in the vertical direction, and the free end of the other side of the extended wing plate (93) is provided with an interlocking groove (97) arranged in the vertical direction so that the adjacent temporary water-retaining piles (9) are sealed and connected to each other. S3. If the sudden inflow or flow rate is greater than the preset value, the following measures shall be taken: after pumping water from the dewatering well outside the pit, back pressure shall be applied at the sudden inflow location, and grouting shall be applied around the perimeter or outside the pit (5) to seal the leak. By following the steps above, emergency response to sudden surges can be achieved.

2. The emergency response method for sudden inrush in a large deep foundation pit according to claim 1, characterized in that: Settlement observation pipes (14) are installed between the foundation pit (5) and the surrounding existing structures (13) to observe the settlement of the surrounding water level in real time during the dewatering process of the foundation pit (5). Multiple shallow recharge wells (15) are set up around the foundation pit (5) and between it and the existing structures. Recharge operations are carried out as needed based on the observation data from the settlement observation pipe (14).

3. The emergency response method for sudden inrush in a large deep foundation pit according to claim 1, characterized in that: It also includes applying heavy objects to the sudden surge location (10) and then compacting and sealing the perimeter of the pit (5) with grout.

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