Recharge system for confined aquifer outside deep foundation pit adjacent to existing building and operation method

Abstract

The invention discloses a deep foundation pit outer confined aquifer recharge system adjacent to an existing building and an operation method, the system comprises the existing building, a foundation pit and a waterproof curtain, a recharge well hole is arranged between the existing building and the waterproof curtain, a pressurization recharge system is installed in the recharge well hole, and the pressurization recharge system is connected with the existing building. The pressurization recharge system comprises an adjustable recharge device, a pressure detection unit, a control unit and a data acquisition unit. The data acquisition unit comprises a plurality of soil permeability sensors and a plurality of water level sensors; the control unit carries out processing according to information measured by the pressure detection unit and the data acquisition unit and controls the pressurization recharge assembly to inject corresponding water into the recharge well hole. The operation method comprises the steps of recharge well hole construction, adjustable recharge device installation and pressurization recharge operation. The system can avoid the problem that the water level of the confined aquifer outside the foundation pit is reduced so as to influence the safety of the existing building under the condition of ensuring the safety of the foundation pit without sudden gushing, is simple and reliable in construction method and low in cost, and has relatively strong popularization significance.

Description

Technical Field

[0001] The invention relates to the technical field of a pressurized water layer recharging system outside a deep foundation pit, and in particular to a pressurized water layer recharging system outside a deep foundation pit adjacent to an existing building. Background Art

[0002] With the construction of more and more new projects in the old city, deep foundation pit projects adjacent to existing buildings have become a challenge that engineers have to face; in order to prevent precipitation in the foundation pit from causing settlement of buildings outside the pit, the project designs a water-stop curtain along the perimeter of the foundation pit and goes deep into the impermeable layer at the bottom of the foundation pit. The precipitation in the pit only pumps out the groundwater or pressurized water above the impermeable layer in the foundation pit. However, due to the complex underground soil environment, there may be uneven pressure seepage paths in the pressurized water layer. The precipitation of the pressurized water layer in the foundation pit causes the water level of the pressurized water layer outside the pit to drop, thereby causing the existing buildings beside the foundation pit to settle. The utility model patent with the authorization announcement number CN207525767 U discloses a recharge system, including a recharge well, a precipitation well, a water pump, a pumping pipe, an airtight steel pipe, a sealing cover, a pressure gauge and a frequency conversion control cabinet. The recharge well is located between the precipitation well and the building, the water pump is located in the precipitation well, one end of the pumping pipe is connected to the water pump, and the other end leads to the recharge well; the airtight steel pipe is located in the recharge well, and the sealing cover is fixed to the top surface of the airtight steel pipe, so that the recharge well becomes a closed structure; the pressure gauge is set on the top surface of the sealing cover to monitor the internal pressure of the recharge well, and the pressure gauge is connected to the frequency conversion control cabinet; the frequency conversion control cabinet is connected to the water pump, and when the frequency conversion control cabinet detects the pressure change of the pressure gauge, it adjusts the pumping speed of the water pump to keep the water in the well at a fixed pressure. The utility model pressurizes the recharge well, increases the recharge speed, and automatically adjusts the switch state and speed of the water pump, which is easy to operate. However, the construction of the airtight steel pipe in the recharge system is difficult, and it is easy to cause leakage and pressure relief accidents, which affects the recharge effect. Summary of the invention

[0003] The purpose of the present invention is to provide a recharging system and operation method for the pressurized water layer outside a deep foundation pit adjacent to an existing building. The system can avoid the problem of lowering the water level of the pressurized water layer outside the foundation pit and thus affecting the safety of the existing buildings while ensuring the safety of the foundation pit and preventing sudden surges. The construction method is simple and reliable, low in cost, and has a strong promotion significance.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A recharging system for a pressurized water layer outside a deep foundation pit adjacent to an existing building, comprising an existing building, a foundation pit and a water-stop curtain arranged between the existing building and the foundation pit, a recharging well hole is arranged between the existing building and the water-stop curtain, a pressurized recharging system is installed in the recharging well hole, the pressurized recharging system comprises an adjustable recharging device, a pressure detection unit, a control unit and a data acquisition unit; the adjustable recharging device comprises a pressurized recharging component, a water-proof filling layer and a filter layer, the pressurized recharging component is arranged in the recharging well hole, the filter layer is arranged between the pressurized recharging component and the recharging well hole, the water-proof filling layer is located between the pressurized recharging component and the recharging well hole, and the water-proof filling layer is located between the pressurized recharging component and the recharging well hole. The layer is located on the top of the filter layer; the pressure detection unit is installed on the top of the pressurized recharge component to detect the water pressure of the pressurized recharge component, and electrically transmits the detected water pressure value to the control unit; the data acquisition unit includes a plurality of soil permeability sensors arranged around the recharge wellbore and a plurality of water level sensors arranged in the pressurized recharge component, the soil permeability sensor electrically transmits the measured moisture content or conductivity of the soil to the control unit, and the water level sensor electrically transmits the detected water level height information to the control unit; the control unit processes the information measured by the pressure detection unit and the data acquisition unit, and controls the pressurized recharge component to inject corresponding water into the recharge wellbore.

[0005] Preferably, the pressurized recharge component includes a water injection steel pipe, an end cover, a pressurized water pipe, a variable frequency water pump, a bridge filter and a sand settling pipe. The water injection steel pipe is installed in the recharge wellbore with the top exposed above the recharge wellbore; the end cover is sealed and fixedly installed on the top of the water injection steel pipe, one end of the pressurized water pipe is fixedly installed on the end cover and located in the water injection steel pipe, and the other end of the pressurized water pipe is connected to the variable frequency water pump; the bridge filter is arranged at the bottom of the water injection steel pipe; the sand settling pipe is arranged at the bottom of the bridge filter.

[0006] Preferably, the filter layer is located outside the bridge filter, the top of the filter layer is higher than the top of the bridge filter by not less than 1000 mm, and the bottom of the filter layer is lower than the bottom of the bridge filter by not less than 1000 mm.

[0007] Preferably, the filter layer is formed by stacking crushed stones with a size of 1 to 3 mm.

[0008] Preferably, the waterproof filling layer is composed of cement soil at the bottom and plugging slurry at the top, and the cement content in the cement soil is 20%; the plugging slurry is composed of cement slurry and water glass in a mass ratio of 1:1.

[0009] Preferably, the pressure detection unit is a water pressure sensor, and a pressure gauge is provided on the water pressure sensor, and the pressure gauge displays the detected water pressure value in real time.

[0010] Preferably, the soil permeability sensor is a soil moisture sensor or a conductivity sensor.

[0011] Preferably, a water inlet filter is provided on the pressurized water pipe.

[0012] An operating method for a confined water layer recharging system outside a deep foundation pit adjacent to an existing building, the operating method comprising the following steps: Step 1: Recharge wellbore construction: drilling a hole at a preset location using a submersible drilling rig to form a mud-walled recharge wellbore; Step 2: Install the adjustable recharge device. After the pressurized recharge component is assembled on the ground, it is hoisted in the recharge well as a whole, and the pressurized recharge component is temporarily fixed with a temporary bracket; the crushed stone is evenly poured into the circumferential gap between the water injection steel pipe and the recharge well to form a filter layer; the cement soil is evenly poured into the circumferential gap between the water injection steel pipe and the recharge well, and compacted during pouring. After the cement soil is filled, cement slurry and water glass with a mass ratio of 1:1 are grouted and plugged; the soil permeability sensor is installed according to the preset position; Step three, pressurized reinjection operation, the control unit injects water into the water injection steel pipe through the variable frequency water pump and the pressurized water pipe according to the built-in program and the control of the operator. The injected water is reinjected into the underground through the bridge filter and the permeation layer.

[0013] In the present invention, a recharge well is set between the existing building and the water-stop curtain, and groundwater is pressurized and recharged through the recharge well, thereby solving the problem of settlement of the existing building structure caused by dewatering of the foundation pit when constructing a foundation pit within the radiation range of the existing building structure, thereby ensuring the stability and safety of the existing structure.

[0014] The adjustable recharging device uses the pressurized recharging component to inject water of matching pressure into the ground to supplement the water lost due to foundation pit construction. The injected water penetrates the surrounding area through the filter layer to ensure the water pressure of the groundwater. The gap between the water injection steel pipe and the recharging well hole is grout-sealed through the waterproof filling layer to prevent the pressurized injected water from overflowing from the gap between the water injection steel pipe and the recharging well hole, thus ensuring the stability of the pressurized operation. The cement slurry and water glass with a mass ratio of 1:1 are used for sealing, which effectively ensures the sealing effect.

[0015] The pressure detection unit and data acquisition unit can monitor the water level, pressure and water content status of the surrounding area in the water injection steel pipe to ensure the accuracy of groundwater recharge and avoid the danger of recharged water to existing structures. The control unit uses the detected information for real-time analysis and processing according to the built-in program, automatically adjusts the water injection volume and pressure, ensures the accuracy of recharge operation, and improves the safety of construction operations.

[0016] Through the pressurized recharge operation, when constructing a deep foundation pit next to an existing building, the groundwater in the pit can be extracted instead of affecting the stability of the existing building. This avoids the problem of foundation settlement of the existing building caused by extracting groundwater from the pit, and provides a solid operating premise for the construction of new projects in the old city. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention; In the figure: 1. existing building; 2. foundation pit; 3. water-stop curtain; 4. adjustable recharge device; 5. pressure detection unit; 6. control unit; 7. data acquisition unit; 40. pressurized recharge component; 41. waterproof filling layer; 42. filter layer; 70. soil permeability sensor; 71. water level sensor; 400. water injection steel pipe; 401. end cover; 402. pressurized water pipe; 403. variable frequency water pump; 404. bridge filter; 405. sand settling pipe; 410. cement soil; 411. plugging slurry. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1 The shown system is a recharge system for the pressurized water layer outside a deep foundation pit adjacent to an existing building, comprising an existing building 1, a foundation pit 2 and a water-stop curtain 3 arranged between the existing building 1 and the foundation pit 2. The water-stop curtain 3 is arranged along the periphery of the foundation pit, and the water-stop curtain 3 penetrates into the impermeable layer at the bottom of the foundation pit 2. The precipitation in the pit only pumps out the groundwater or pressurized water above the impermeable layer in the foundation pit 2. However, due to the complex underground soil environment, there may be uneven pressure seepage paths in the pressurized water layer. The precipitation of the pressurized water layer in the foundation pit 2 causes the water level of the pressurized water layer outside the pit to drop, thereby causing the existing building 1 next to the foundation pit to sink. Therefore, in order to avoid this phenomenon, a recharge well is arranged between the existing building 1 and the water-stop curtain 3, and pressurized recharge is carried out through the recharge well to ensure the water pressure at the bottom of the existing building 1, thereby avoiding the occurrence of settlement.

[0019] A pressurized recharge system is installed in the recharge well, and the pressurized recharge system includes an adjustable recharge device 4, a pressure detection unit 5, a control unit 6 and a data acquisition unit 7. During operation, the control unit 6 controls the pressurized recharge component 40 to inject corresponding water into the recharge well according to the corresponding information detected by the pressure detection unit 5 and the data acquisition unit 7 using a built-in program. The depth of the recharge well is located below the impermeable layer. In this embodiment, the depth of the recharge well is not less than 25m.

[0020] The adjustable recharging device 4 includes a pressurized recharging component 40, a water-proof filling layer 41 and a filter layer 42. The pressurized recharging component 40 is arranged in the recharging well hole. The pressurized recharging component 40 includes a water injection steel pipe 400, an end cover 401, a pressurized water pipe 402, a variable frequency water pump 403, a bridge filter 404 and a sand settling pipe 405. The water injection steel pipe 400 is installed in the recharging well hole, and the top is exposed above the recharging well hole, and the exposed height is 500 mm. The end cover 401 is fixedly installed on the top of the water injection steel pipe 400 by welding and sealing, so that the top of the water injection steel pipe 400 is sealed. One end of the pressurized water pipe 402 is fixedly mounted on the end cap 401 and is located in the water injection steel pipe 400. The other end of the pressurized water pipe 402 is sealed and fixedly connected to the variable frequency water pump 403. The variable frequency water pump 403 starts and stops according to the control instruction and absorbs water at different flow rates, and injects water into the water injection steel pipe 400 through the pressurized water pipe 402. The bridge filter 404 is fixedly arranged at the bottom of the water injection steel pipe 400, and the water in the water injection steel pipe 400 passes through the bridge filter 404 and evenly penetrates to the surroundings. The sand settling pipe 405 is fixedly arranged at the bottom of the bridge filter 404, and the sand settling pipe 405 can avoid the problem of clogging of the bridge filter 404 due to sedimentation of silt. In a preferred embodiment, an inlet filter is arranged on the pressurized water pipe 402, and the inlet filter filters the pressurized recharged water to ensure the quality of the recharged groundwater and avoid groundwater pollution.

[0021] The filter layer 42 is disposed between the pressurized reinjection assembly 40 and the reinjection wellbore. Specifically, the filter layer 42 is located outside the bridge filter 404. The top of the filter layer 42 is higher than the top of the bridge filter 404 by at least 1000 mm, and the bottom of the filter layer 42 is lower than the bottom of the bridge filter 404 by at least 1000 mm. The filter layer 42 is formed by stacking crushed stones of 1 to 3 mm.

[0022] The waterproof filling layer 41 is located between the pressurized reinjection assembly 40 and the reinjection wellbore, and the waterproof filling layer 41 is located on the top of the filter layer 42. The waterproof filling layer 41 is composed of cement soil 410 located at the bottom and plugging slurry 411 located at the top. The cement content in the cement soil 410 is 20%, and the plugging slurry 411 is composed of cement slurry and water glass with a mass ratio of 1:1.

[0023] The pressure detection unit 5 is installed on the top 40 of the pressurized recharging component, and is used to detect the water pressure of the pressurized recharging component 40, and electrically transmit the detected water pressure value to the control unit 6. In this embodiment, the pressure detection unit 5 is a water pressure sensor, and a pressure gauge is set on the water pressure sensor. The pressure gauge displays the detected water pressure value in real time. The water pressure sensor is installed on the pressurized water pipe 402. When the water pressure in the pressurized water pipe 402 exceeds the preset value, the water pressure sensor transmits this information to the control unit 6, and the control unit 6 controls the variable frequency water pump 403 to stop supplying water to avoid danger caused by excessive water pressure. The variable frequency water pump 403 can supply water at different flow rates according to the control of the control unit 6 to adapt to different recharging operation conditions. The variable frequency water pump 403 is located in the pool, and a water quality detection sensor is set in the pool. When the water quality detected by the water quality detection sensor is qualified, the variable frequency water pump 403 can perform recharging operation to ensure the water quality of the recharging water.

[0024] The data acquisition unit 7 includes a plurality of soil permeability sensors 70 arranged around the recharge well and a plurality of water level sensors 71 arranged in the pressurized recharge assembly 40. The soil permeability sensor 70 electrically transmits the measured soil moisture content or conductivity to the control unit 6, and the water level sensor 71 electrically transmits the detected water level height information to the control unit 6. The soil permeability sensor 70 is a soil moisture sensor or a conductivity sensor. The soil moisture sensor or the conductivity sensor is used to indirectly monitor the change of soil permeability, so as to understand the moisture content of the soil near the existing building 1 in real time, and avoid the recharge water affecting the stability and safety of the existing building 1. Water level sensors 71 are also arranged at different depths of the recharge well to detect water level information at different depths, so as to further improve the accuracy of monitoring.

[0025] The control unit 6 is used to receive data transmitted by each sensor, and analyze and process it according to the preset algorithm and model, and can respond to changes in groundwater level and soil permeability in real time. The preset algorithm is based on machine learning or deep learning technology, and continuously optimizes and adjusts the recharge strategy through the analysis of historical data and real-time data to ensure the accuracy of recharge. The preset algorithm and program are adjusted in real time by personnel in this field according to the operation requirements. The program is not described in detail in this manual. Of course, existing mature algorithms and programs can also be used.

[0026] like Figure 1 The operating method of the outer confined water layer recharging system of a deep foundation pit adjacent to an existing building is shown, and the operating method comprises the following steps: Step 1: Recharge wellbore construction: a submersible drilling rig is used to drill a hole at a preset position to form a mud-walled recharge wellbore; after the diameter and depth of the recharge wellbore reach the preset values, a water level sensor 71 is installed at different depths of the recharge wellbore, and the signal line of the water level sensor 71 is hidden to avoid damage caused by subsequent construction.

[0027] Step 2, installation of adjustable recharging device. After the pressurized recharging assembly 40 is assembled on the ground, it is hoisted as a whole into the recharging wellbore, and the pressurized recharging assembly 40 is temporarily fixed with a temporary bracket; the crushed stone is evenly poured into the circumferential gap between the water injection steel pipe 400 and the recharging wellbore to form a filter layer 42, and tools are used to tamp it during pouring to ensure the filtering effect of the filter layer 42. The cement soil is evenly poured into the circumferential gap between the water injection steel pipe 400 and the recharging wellbore, and it is tamped during pouring. After the cement soil is filled, cement slurry and water glass with a mass ratio of 1:1 are grouted and blocked to form a water-proof filling layer 41 to prevent groundwater from overflowing from the gap between the water injection steel pipe 400 and the recharging wellbore. The soil permeability sensor 70 is installed according to the preset position, and after installation, it is electrically connected to the control unit 6 for testing. The control unit 6 uses a prefabricated program to process the detection signal.

[0028] Step three, pressurized recharge operation, the control unit 6 injects water into the water injection steel pipe 400 through the variable frequency water pump 403 and the pressurized water pipe 402 according to the built-in program and the control of the operator, and the injected water is recharged into the underground through the bridge filter 404 and the permeable layer 42.

[0029] The above embodiments are only some illustrations of the concept and implementation of the present invention, and are not intended to limit the same. Under the concept of the present invention, technical solutions that have not been substantially changed are still within the scope of protection.

Claims

1. A recharging system for a confined water layer outside a deep foundation pit adjacent to an existing building, comprising an existing building, a foundation pit and a water-stop curtain arranged between the existing building and the foundation pit, a recharging well hole is drilled between the existing building and the water-stop curtain, and a pressurized recharging system is installed in the recharging well hole, characterized in that: The pressurized recharge system includes an adjustable recharge device, a pressure detection unit, a control unit and a data acquisition unit; the adjustable recharge device includes a pressurized recharge component, a water-proof filling layer and a filter layer, the pressurized recharge component is arranged in the recharge well, the filter layer is arranged between the pressurized recharge component and the recharge well, the water-proof filling layer is located between the pressurized recharge component and the recharge well, and the water-proof filling layer is located on the top of the filter layer; the pressure detection unit is installed on the top of the pressurized recharge component to detect the water supply pressure of the pressurized recharge component, and electrically transmits the detected water pressure value to the control unit; the data acquisition unit includes a plurality of soil permeability sensors arranged around the recharge well and a plurality of water level sensors arranged in the pressurized recharge component, the soil permeability sensor electrically transmits the measured soil moisture content or conductivity to the control unit, and the water level sensor electrically transmits the detected water level height information to the control unit; the control unit processes the information measured by the pressure detection unit and the data acquisition unit, and controls the pressurized recharge component to inject corresponding water into the recharge well.

2. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 1 is characterized in that: The pressurized recharge component includes a water injection steel pipe, an end cover, a pressurized water pipe, a variable frequency water pump, a bridge filter and a sand settling pipe. The water injection steel pipe is installed in the recharge wellbore with the top exposed above the recharge wellbore; the end cover is sealed and fixedly installed on the top of the water injection steel pipe, one end of the pressurized water pipe is fixedly installed on the end cover and located in the water injection steel pipe, and the other end of the pressurized water pipe is connected to the variable frequency water pump; the bridge filter is arranged at the bottom of the water injection steel pipe; the sand settling pipe is arranged at the bottom of the bridge filter.

3. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 2 is characterized in that: The filter layer is located outside the bridge filter, the top of the filter layer is higher than the top of the bridge filter by not less than 1000 mm, and the bottom of the filter layer is lower than the bottom of the bridge filter by not less than 1000 mm.

4. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 3 is characterized in that: The filter layer is formed by piling up crushed stones with a size of 1 to 3 mm.

5. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 1 or 4, characterized in that: The waterproof filling layer is composed of cement soil at the bottom and plugging slurry at the top, wherein the cement content of the cement soil is 20%; the plugging slurry is composed of cement slurry and water glass in a mass ratio of 1:

1.

6. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 1 is characterized in that: The pressure detection unit is a water pressure sensor, on which a pressure gauge is arranged, and the pressure gauge displays the detected water pressure value in real time.

7. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 1 is characterized by: The soil permeability sensor is a soil moisture sensor or a conductivity sensor.

8. The recharging system for the outer confined water layer of a deep foundation pit adjacent to an existing building according to claim 2 is characterized by: A water inlet filter is arranged on the pressurized water pipe.

9. An operating method for the confined water layer recharging system outside a deep foundation pit adjacent to an existing building as claimed in claims 1 to 8, characterized in that: The operation method comprises the following steps: Step 1: Construction of reinjection wellbore: drilling a reinjection wellbore at a preset location; Step 2: Install the adjustable recharge device. After the pressurized recharge component is assembled on the ground, it is hoisted in the recharge well as a whole, and the pressurized recharge component is temporarily fixed with a temporary bracket; the crushed stone is evenly poured into the circumferential gap between the water injection steel pipe and the recharge well to form a filter layer; the cement soil is evenly poured into the circumferential gap between the water injection steel pipe and the recharge well, and compacted during pouring. After the cement soil is filled, cement slurry and water glass with a mass ratio of 1:1 are grouted and plugged; the soil permeability sensor is installed according to the preset position; Step three, pressurized reinjection operation, the control unit injects water into the water injection steel pipe through the variable frequency water pump and the pressurized water pipe according to the built-in program and the control of the operator. The injected water is reinjected into the underground through the bridge filter and the permeation layer.

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