Device and method for reducing foundation pit dewatering sand content

Abstract

According to the device and method for reducing the foundation pit dewatering sand content, a well wall (101) is placed in a municipal drainage well body, and the outer side of the well wall (101) is wrapped with a nylon net water filtering pipe (102); a coarse grain filter material (103) is backfilled between the outer side of the well wall (101) and the inner side of the municipal drainage well body; cohesive soil (104) is adopted to seal the top between the top of the well wall (101) and the top of the municipal drainage well body; a water pump is placed in the well wall (101), and water in the dewatering well (1) is pumped into the third-stage sedimentation tank (2) by the water pump; the third-stage sedimentation tank (2) adopts a bricking form, the inner layer and the outer layer are subjected to surface finishing and troweling by adopting waterproof mortar, water is directly discharged into the first-stage tank (201) at an inlet by adopting a drainage ditch, and the water is directly discharged into a municipal rainwater drainage pipe network from an opening of the third-stage tank (203) after being settled by the first-stage tank (201) and the second-stage tank (202).

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, in particular to a device and method for reducing the sand content of a foundation pit during dewatering. Background Art

[0002] As the construction project is close to a protected area, the foundation pit excavation dewatering adopts the form of open drainage plus precipitation wells. Due to the silt sand structure of the geology, a certain amount of silt sand is mixed in the foundation pit drainage process, and the drainage is directly discharged from the rainwater well to a protected area, which has a certain impact on the ecology of the protected area. Therefore, how to reasonably discharge the foundation pit dewatering is a difficulty in this project.

[0003] In order to reduce the sand content of foundation pit precipitation and reduce the impact on the ecology of a certain protected area, the present invention provides a device and method for reducing the sand content of foundation pit precipitation. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present invention provides a device and method for reducing the sand content of foundation pit dewatering.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A device for reducing the sand content of foundation pit dewatering, comprising a dewatering well 1 and a three-stage sedimentation tank 2; wherein: the dewatering well 1 comprises a well wall 101, a nylon mesh water filter pipe 102, coarse-grained filter material 103 and clay 104; the well wall 101 is placed in a municipal drainage well body, and the outside of the well wall 101 is wrapped with a nylon mesh water filter pipe 102; the space between the outside of the well wall 101 and the inside of the municipal drainage well body is backfilled with coarse-grained filter material 103; the top and The top of the municipal drainage well body is capped with clay 104; a water pump is placed in the well wall 101, and the water pump draws water from the precipitation well 1 into the tertiary sedimentation tank 2; the tertiary sedimentation tank 2 is brick-built, and the inner and outer layers are smoothed with waterproof mortar, and the inlet is directly discharged into the first pool (201) through a drainage ditch, and after sedimentation in the first pool (201) and the second pool (202), it is directly discharged into the municipal rainwater drainage network at the opening of the tertiary pool (203).

[0007] A method for reducing the sand content of foundation pit dewatering adopts a three-stage method to reduce the sand content of foundation pit dewatering, and the extracted groundwater is filtered, precipitated, and neutralized before being discharged into a designated location.

[0008] The first stage: adopt precipitation 1, install different mesh filter screens at the end of the drainage pipe according to the geological conditions to achieve the purpose of separating sand and mud. The method is:

[0009] First, when lowering the water pump, the position of the water pump should be controlled to be 50 cm from the bottom and suspended in the water. Use steel bars or steel pipes to place at the wellhead to fix the water pump. Do not place the water inlet of the water pump close to the pipe wall and bottom, as this will easily carry away nearby mud and sand when pumping water.

[0010] Secondly, leveraging the pump's pumping function and properly controlling the pumping flow rate are crucial. Excessive pumping flow rates accelerate water flow, potentially carrying large amounts of sediment, and thus increasing the sand content of the water. Conversely, too low a pumping flow rate can lead to inefficient dewatering and fail to meet the actual needs of foundation pit dewatering. In addition to selecting an appropriate pumping flow rate, it's also important to consider the pump's operational stability. Regularly inspect and maintain the pump to ensure it's in good working condition. This can prevent pumping flow fluctuations caused by pump failure, which can affect the effectiveness of controlling the sand content of the water.

[0011] The second stage: Use the three-stage sedimentation tank 2 to send the water discharged from the precipitation well to the sedimentation tank, and the fine sand in the water will be completely settled through the three-stage sedimentation tank.

[0012] The tertiary sedimentation tank 2 is brick-built, with the inner and outer layers smoothed with waterproof mortar. The inlet is directly discharged into the primary tank (201) through a drainage ditch. After sedimentation in the primary tank (201) and the secondary tank (202), the water is directly discharged into the municipal rainwater drainage network at the opening of the tertiary tank (203).

[0013] The different depths of the primary and secondary tanks gradually slow the water flow, allowing large particles of impurities to settle and further reducing the sand content in the water. The tertiary tank serves as the final sedimentation tank, and the sediment deposited at the bottom can be regularly cleaned to maintain the sedimentation effect.

[0014] To achieve optimal sedimentation results, regular silt removal is required in primary and secondary sedimentation tanks. When the silt in the tank exceeds two-thirds of its depth, manual cleaning is necessary. Failure to do so will significantly reduce the sedimentation effect. Sedimentation measurements should also be regularly taken in municipal drainage wells. If an increase in sediment is detected, immediate action should be taken, including cleaning of the municipal drainage wells if necessary.

[0015] The third section: Neutralize the pH value. A neutralization treatment device is installed at the outlet of the tertiary sedimentation tank to adjust the pH value and disinfect the water after sedimentation to ensure that the water quality meets the discharge standards before discharging it into the municipal rainwater drainage network.

[0016] The present invention also has the following additional technical features:

[0017] As a further specific optimization of the technical solution of the present invention: a steel pipe with a diameter of φ350 mm is used as the well wall 101, the opening rate of the side of the well wall 101 is 29%, and the opening diameter is 1.6 cm.

[0018] As a further optimization of the present invention's technical solution, the nylon mesh filter pipe 102 is wrapped with two layers of 40-mesh nylon mesh to effectively reduce the sand content in the water. The two-layer wrapping method involves evenly wrapping the nylon mesh filter pipe 102 around the well wall 101, first diagonally wrapping it around one end and then around the other end. After this, the pipe is securely fastened with wire at 1-meter intervals.

[0019] As a further specific optimization of the technical solution of the present invention, the coarse-grained filter material 103 adopts filter stones with a diameter of 1-2 cm.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This device can effectively reduce the sand content in foundation pit precipitation through the installation of precipitation wells and three-stage sedimentation tanks. In the precipitation well, the nylon mesh filter pipe wrapped around the outside of the well wall and the coarse-grained filter material backfill can initially filter out larger particles of impurities in the water. The clay soil capping further prevents external sediment from entering the precipitation well. The water pump draws the water that has undergone preliminary filtration into the three-stage sedimentation tank. Through step-by-step sedimentation, the relatively clear water is eventually discharged into the municipal rainwater drainage network, thereby achieving the purpose of reducing the sand content in foundation pit precipitation. In addition, this device has a simple structure, is easy to install and maintain, and has a low cost, and has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a precipitation well 1 according to the present invention;

[0023] Figure 2 This is a schematic diagram of the top view of the three-stage sedimentation tank 2 of the present invention;

[0024] Figure 3 It is a schematic diagram of the main structure of the three-stage sedimentation tank 2 of the present invention.

[0025] Explanation of the reference numerals: precipitation well 1 and tertiary sedimentation tank 2. DETAILED DESCRIPTION

[0026] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0027] Example 1

[0028] A device for reducing the sand content of foundation pit dewatering includes a dewatering well 1 and a three-stage sedimentation tank 2. The dewatering well 1 includes a well wall 101, a nylon mesh water filter pipe 102, coarse-grained filter material 103, and clay 104. A steel pipe with a diameter of φ350 mm is used as the well wall 101. The opening rate of the side of the well wall 101 is 29%, and the opening diameter is 1.6 cm.

[0029] Well wall 101 is placed within the municipal drainage well. Nylon mesh filter pipe 102 is wrapped around the outside of well wall 101. Nylon mesh filter pipe 102 is made of 40-mesh nylon mesh and is wrapped in two layers. The 40-mesh nylon mesh filter pipe 102 has good sand-removal properties, effectively reducing the sand content in the water and meeting the required water seepage rate. 100-mesh and 60-mesh nylon mesh filter pipes, due to their dense mesh count, cannot meet the required water seepage rate, resulting in unsatisfactory foundation pit dewatering.

[0030] The two-layer wrapping method is: the nylon mesh water filter pipe 102 is evenly wrapped around the well wall 101, first wrapped around it obliquely from one end and then wrapped around it obliquely from the other end. After completion, it is firmly fixed with iron wire at intervals of 1m.

[0031] Coarse-grained filter material 103 is used to backfill between the outer side of the well wall 101 and the inner side of the municipal drainage well body; the coarse-grained filter material 103 uses filter stone with a diameter of 1-2 cm, but if the diameter of the coarse-grained filter material 103 is too small, it will directly affect the water permeability of the precipitation well 1. After comprehensive consideration, it is more appropriate to choose between 1-2 cm.

[0032] The top of the well wall 101 and the top of the municipal drainage well body are sealed with clay 104; a water pump is placed in the well wall 101, and the water pump draws water from the precipitation well 1 into the tertiary sedimentation tank 2.

[0033] The tertiary sedimentation tank 2 is brick-built, with the inner and outer layers smoothed with waterproof mortar. The inlet is directly discharged into the primary tank (201) through a drainage ditch. After sedimentation in the primary tank (201) and the secondary tank (202), the water is directly discharged into the municipal rainwater drainage network at the opening of the tertiary tank (203).

[0034] Example 2

[0035] A method for reducing the sand content of foundation pit dewatering adopts a three-stage method to reduce the sand content of foundation pit dewatering, and the extracted groundwater is filtered, precipitated, and neutralized before being discharged into a designated location.

[0036] The first stage: adopt precipitation 1, install different mesh filter screens at the end of the drainage pipe according to the geological conditions to achieve the purpose of separating sand and mud. The method is:

[0037] First, when lowering the water pump, the position of the water pump should be controlled to be 50 cm from the bottom and suspended in the water. Use steel bars or steel pipes to place at the wellhead to fix the water pump. Do not place the water inlet of the water pump close to the pipe wall and bottom, as this will easily carry away nearby mud and sand when pumping water.

[0038] Secondly, leveraging the pump's pumping function and properly controlling the pumping flow rate are crucial. Excessive pumping flow rates accelerate water flow, potentially carrying large amounts of sediment, and thus increasing the sand content of the water. Conversely, too low a pumping flow rate can lead to inefficient dewatering and fail to meet the actual needs of foundation pit dewatering. In addition to selecting an appropriate pumping flow rate, it's also important to consider the pump's operational stability. Regularly inspect and maintain the pump to ensure it's in good working condition. This can prevent pumping flow fluctuations caused by pump failure, which can affect the effectiveness of controlling the sand content of the water.

[0039] The second stage: Use the three-stage sedimentation tank 2 to send the water discharged from the precipitation well to the sedimentation tank, and the fine sand in the water will be completely settled through the three-stage sedimentation tank.

[0040] The tertiary sedimentation tank 2 is brick-built, and the inner and outer layers are smoothed with waterproof mortar. The inlet is directly discharged into the first-level tank 201 through a drainage ditch. After sedimentation in the first-level tank 201 and the second-level tank 202, it is directly discharged into the municipal rainwater drainage network through the opening of the tertiary tank 203.

[0041] The different depths of the primary and secondary tanks gradually slow the water flow, allowing large particles of impurities to settle and further reducing the sand content in the water. The tertiary tank serves as the final sedimentation tank, and the sediment deposited at the bottom can be regularly cleaned to maintain the sedimentation effect.

[0042] To achieve optimal sedimentation results, regular silt removal is required in primary and secondary sedimentation tanks. When the silt in the tank exceeds two-thirds of its depth, manual cleaning is necessary. Failure to do so will significantly reduce the sedimentation effect. Sedimentation measurements should also be regularly taken in municipal drainage wells. If an increase in sediment is detected, immediate action should be taken, including cleaning of the municipal drainage wells if necessary.

[0043] The third section: Neutralize the pH value. A neutralization treatment device is installed at the outlet of the tertiary sedimentation tank to adjust the pH value and disinfect the water after sedimentation to ensure that the water quality meets the discharge standards before discharging it into the municipal rainwater drainage network.

[0044] Example 3

[0045] 1. Construction instructions for the device to reduce the sand content of foundation pit dewatering:

[0046] A corrugated pipe with a diameter of φ800 is used as the municipal drainage well body. The use of double-wall corrugated pipe can effectively prevent the municipal drainage well body from being squeezed and deformed, and at the same time it is convenient for construction and opening holes, and the cost is also relatively economical; coarse-grained filter material 103 is used for backfilling between the municipal drainage well body and the well wall 101, which can achieve a water-permeable effect and prevent the backflow of quicksand and the squeezing of the pipe wall to cause deformation.

[0047] When lowering the water pump, the pump should be positioned 50 cm above the bottom and suspended in the water. Use steel bars or steel pipes placed at the wellhead to secure the pump. Do not place the water inlet of the pump close to the pipe wall or bottom, as this will easily carry away nearby mud and sand when pumping water.

[0048] 2. Controlling sediment content during foundation pit drainage

[0049] The main measure to reduce the sediment content during the pumping process is to set up a sedimentation tank to filter out the sediment in the drainage. Generally, the sedimentation effect of the secondary sedimentation tank cannot meet the actual drainage requirements on site. After communicating with other projects in the region, the project department finally adopted the tertiary sedimentation tank 2.

[0050] The tertiary sedimentation tank 2 is brick-built, with the inner and outer layers smoothed with waterproof mortar. The inlet is directly discharged into the primary tank (201) through a drainage ditch. After sedimentation in the primary tank (201) and the secondary tank (202), the water is directly discharged into the municipal rainwater drainage network at the opening of the tertiary tank (203).

[0051] After sedimentation in the sedimentation tank, the sand content of the water body has been significantly improved. Most of the sand in the water body is controlled in the first-level tank (201) through sedimentation. After the second-level sedimentation, the water volume discharged into the third-level tank (203) has fully met the design requirements of the drawings.

[0052] In order to achieve better sedimentation effect, regular silt cleaning work should be carried out in the first and second sedimentation tanks. When the silt in the tank exceeds 2 / 3 of the depth, manual cleaning should be arranged. If it is not cleaned in time, the sedimentation effect will be greatly reduced.

[0053] At the same time, regular sedimentation measurements should be carried out on municipal drainage wells. If an increase in sedimentation is found, measures should be taken immediately and the municipal pipe wells should be cleaned if necessary.

[0054] 3. Control the pumping flow to reduce the sand content in the water

[0055] Flow rate control mainly controls the model of the water pump used. Choosing a suitable water pump can reduce the amount of sediment in the drainage. Too high a flow rate will cause sediment loss around the precipitation well 1, and too low a flow rate cannot meet the on-site precipitation needs.

[0056] At the same time, the power and lift of the water pump must be considered. Since the wellhead size is φ350mm, the selection of a water pump with a suitable diameter must also be considered. After the actual test in the early stage, the power is finally determined to be 7.5KW, the maximum lift is 110m, and the flow rate is 20m 3 / h submersible pump is more suitable, but considering the choice of wellhead diameter, most water pumps with the same parameters are not suitable. Only deep well submersible pump can meet the needs.

[0057] According to the above three methods of controlling the sand content in water bodies, the sand content in the sedimentation tank was finally tested and the sand content in the drainage was well controlled.

[0058] Field verification has shown that it can not only meet precipitation requirements, but also reduce the sand content in the water.

[0059] The above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention but is merely representative of selected embodiments of the present invention.

Claims

1. A device for reducing the sand content of foundation pit precipitation, characterized by: The invention comprises a precipitation well (1) and a three-stage sedimentation tank (2); wherein: the precipitation well (1) comprises a well wall (101), a nylon mesh water filter pipe (102), coarse-grained filter material (103) and clay (104); the well wall (101) is placed in a municipal drainage well body, and the outside of the well wall (101) is wrapped with a nylon mesh water filter pipe (102); the coarse-grained filter material (103) is backfilled between the outside of the well wall (101) and the inside of the municipal drainage well body; the top and The top of the municipal drainage well body is sealed with clay (104); a water pump is placed in the well wall (101), and the water pump draws water from the precipitation well (1) into the tertiary sedimentation tank (2); the tertiary sedimentation tank (2) is brick-built, and the inner and outer layers are smoothed with waterproof mortar. The inlet is directly discharged into the first pool (201) through a drainage ditch. After sedimentation in the first pool (201) and the second pool (202), the water is directly discharged into the municipal rainwater drainage network at the opening of the tertiary pool (203).

2. The device for reducing the sand content of foundation pit according to claim 1, characterized in that: A steel pipe with a diameter of φ350 mm is used as the well wall (101), the opening rate of the side of the well wall (101) is 29%, and the opening diameter is 1.6 cm.

3. The device for reducing the sand content of foundation pit according to claim 1, characterized in that: The nylon mesh water filter pipe (102) is made of a 40-mesh nylon mesh and wrapped in two layers.

4. The device for reducing the sand content of foundation pit according to claim 1, characterized in that: The coarse filter material (103) is a filter stone with a diameter of 1-2 cm.

5. A method for reducing the sand content of foundation pit precipitation, characterized by: A three-stage method is used to reduce the sand content of foundation pit dewatering, and the extracted groundwater is filtered, precipitated, and neutralized before being discharged to a designated location; among them: The first paragraph: Use precipitation (1) by: First, when lowering the water pump, make sure it is suspended in the water 50cm from the bottom. Use steel bars or steel pipes to secure the pump at the wellhead. Do not place the water inlet of the pump close to the pipe wall or bottom. Secondly, use the pumping function of the water pump to reasonably control the pumping flow rate; on the basis of selecting the appropriate pumping flow rate, you also need to pay attention to the operating stability of the water pump; regularly inspect and maintain the water pump to ensure that it is in good working condition; The second stage: using a three-stage sedimentation tank (2), the water discharged from the precipitation well is sent to the sedimentation tank, and the fine sand in the water is completely settled through the three-stage sedimentation tank; The tertiary sedimentation tank (2) is brick-built, with the inner and outer layers smoothed with waterproof mortar. The inlet is directly discharged into the primary tank (201) through a drainage ditch. After sedimentation in the primary tank (201) and the secondary tank (202), the water is directly discharged into the municipal rainwater drainage network at the opening of the tertiary tank (203). Regularly clean the primary and secondary sedimentation tanks. When the sediment in the tank exceeds 2 / 3 of the depth, manual cleaning must be arranged. At the same time, regular sediment measurement work should be carried out on municipal drainage wells. The third section: Neutralize the pH value. A neutralization treatment device is installed at the outlet of the tertiary sedimentation tank to adjust the pH value and disinfect the water after sedimentation to ensure that the water quality meets the discharge standards before discharging it into the municipal rainwater drainage network.

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