Freezing method foundation pit anti-permeation isolation system

Abstract

The invention relates to a freezing method foundation pit anti-permeation isolation system which comprises a plurality of freezing pipes inserted into a soil body near a foundation pit and distributed in an arch shape, a saline water main pipe sequentially connected with the freezing pipes and freezing stations connected to the two ends of the saline water main pipe. A lead screw, a nut lifting plate matched with the lead screw and a partition plate for guiding the nut lifting plate are arranged in a pipe body of the freezing pipe, the nut lifting plate divides the pipe body of the freezing pipe into an upper cavity and a lower cavity which are not communicated with each other, and a liquid inlet and a liquid outlet which are communicated with the brine main pipe are formed in the top of the pipe body of the freezing pipe; a heating plate is arranged in the partition plate; low-temperature saline water in the freezing station enters an upper cavity of the freezing pipe through the saline water main pipe to freeze a soil body, and anti-permeation isolation is carried out; the driving motor drives the lead screw to rotate, the lead screw drives the nut lifting plate to move up and down in the pipe body of the freezing pipe, the height of the upper cavity is adjusted, and freezing of stratums of different depths is achieved. And the heating plate is used for heating the low-temperature saline water in the freezing pipe and unfreezing the soil body.

Description

Technical Field

[0001] The invention relates to a freezing method foundation pit anti-seepage isolation system, belonging to the technical field of freezing method and foundation pit anti-seepage isolation and support. Background Art

[0002] When constructing foundation pits in the strata, it is inevitable to drain water from the pits. Outside the pits within the influence range of the funnel formed by precipitation, the groundwater level will drop significantly. The surrounding sensitive pile-supported buildings will experience ground settlement due to the increase in effective stress of the soil below, which will lead to increased differential settlement of surrounding buildings, which will cause cracks in the buildings and cause local component fractures, posing a safety hazard.

[0003] In engineering construction, we often encounter some situations with short construction periods and requirements for anti-seepage isolation. In the existing technology, concrete underground anti-seepage walls and freezing methods are generally used to construct isolation walls. Concrete underground anti-seepage walls cause great environmental pollution; and the freezing method construction technology uses artificial refrigeration to turn the pore water in the stratum into ice, and the ice cements the soil particles to form frozen soil, thereby improving the overall strength of the soil and making it impermeable. The frozen soil body reinforced by the freezing method has good integrity and a large elastic modulus. Not only does it have significantly improved mechanical properties such as compressive, shear and tensile strength, but it can also prevent water isolation. It has incomparable advantages in construction in water-rich layers or some unstable strata. The excavation construction of the foundation pit can be carried out under the protection of this high-strength and waterproof frozen soil wall; the existing freezing method construction isolation wall can only freeze the entire section, which is easy to cause waste of cold and materials. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a foundation pit anti-seepage isolation system that can be frozen in layers. In order to achieve the above-mentioned purpose, the technical solution proposed by the present invention is: a freezing method foundation pit anti-seepage isolation system, including a refrigeration support system and a transmission system; the refrigeration support system includes a plurality of freezing pipes inserted into the soil near the foundation pit and distributed in an arch shape, a brine dry pipe connecting the plurality of freezing pipes in sequence, and a freezing station connected to both ends of the brine dry pipe; a lead screw, a nut lifting plate cooperating with the lead screw, and a partition guiding the nut lifting plate are provided in the pipe body of the freezing pipe, the nut lifting plate divides the pipe body of the freezing pipe into an upper cavity and a lower cavity that are not connected, and a liquid inlet and a liquid outlet connected to the brine dry pipe are provided at the top of the pipe body of the freezing pipe; a heating plate is provided in the partition; the transmission system includes a driving motor that drives the lead screw to rotate; the top end of the lead screw extends out of the freezing pipe and is transmission-connected to the driving motor, and a vent is provided inside the lead screw along the central axis, and the vent is connected to the lower cavity of the freezing pipe;

[0005] The low-temperature brine in the freezing station enters the upper cavity of the freezing pipe through the brine dry pipe, freezes the soil, and performs anti-seepage isolation; the drive motor drives the lead screw to rotate, and the lead screw drives the nut lifting plate to move up and down in the pipe body of the freezing pipe, adjusts the height of the upper cavity, and controls the depth of the frozen soil; the heating plate is used to heat the low-temperature brine in the freezing pipe to thaw the soil.

[0006] A further design of the above technical solution is as follows: the partitions are arranged opposite to each other and are in a "C" shape, a gap is provided between the two partitions, and a plurality of drainage holes are provided on the partitions. The two partitions separate the tube body of the freezing tube into an inner cavity and an outer cavity. The inner cavity and the outer cavity are connected through the gap and the drainage holes provided between the two partitions. The liquid inlet and the liquid outlet are respectively arranged at the top of the freezing tube corresponding to the inner cavity and the outer cavity.

[0007] The heating plates in the partition are provided with multiple layers along the height direction.

[0008] At least part of the freezing pipe is covered with steel pipe piles, and the length of the steel pipe piles is greater than the length of the freezing pipe; the arched part of the freezing pipe is provided with an inclined bracing structure on the side close to the foundation pit, and the inclined bracing structure is formed by the inclined setting of another freezing pipe. The freezing pipe forming the inclined bracing structure is also connected to the brine main pipe.

[0009] A spiral pile tip structure is provided at the bottom of the freezing pipe, and the spiral pile tip structure includes a conical pile tip, a pile tip thread and a pressure relief port. The pile tip thread is spirally evenly distributed on the conical pile tip, and the pressure relief port is a circular hole arranged on the conical pile tip, and multiple pressure relief ports are evenly distributed between the pile tip threads.

[0010] The nut lifting plate includes a metal outer layer and an elastic cushion layer, an anti-seepage layer, a thermal insulation layer and an elastic cushion layer stacked in sequence from top to bottom in the metal outer layer; an internal thread hole matching the external thread of the screw rod is provided on the inner side of the nut lifting plate.

[0011] A pump station is provided at the freezing station, and the low-temperature brine of the freezing station is pumped into the brine main pipe through the pump station.

[0012] The transmission system also includes a turbine and a worm gear that cooperate with each other. The turbine is fixed to one end of the lead screw extending out of the freezing pipe, and the worm gear is connected to the output end of the driving motor.

[0013] The exterior of the brine main pipe is wrapped with an anti-collision insulation layer.

[0014] The anti-seepage isolation system also includes a monitoring system, which includes an electronic temperature measuring device, a flow monitor, a pressure sensor, an inclinometer sensor, a distance sensor and a groundwater level monitoring device; the electronic temperature measuring device is arranged in the temperature measuring holes around the freezing pipe, the flow monitor is arranged at the inlet and outlet at both ends of the brine main pipe, the pressure sensor is arranged in the pressure relief holes around the freezing pipe, the inclinometer sensor is fixed on the diagonal support structure, the distance sensor is arranged on the nut lifting plate, and the groundwater level monitoring device is arranged around the freezing pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The frozen soil structure formed by multiple freezing pipes in the present invention is connected to each other to form a frozen soil wall protection, which can effectively isolate groundwater near the foundation pit; and the position of the nut lifting plate can be adjusted through the transmission system to control the circulation depth of the brine in the freezing pipe, thereby realizing the freezing of strata at different depths. The flow rate and temperature of the low-temperature brine can also be controlled by the freezing station to adjust the freezing thickness and then adjust the thickness of the frozen soil curtain, so that the whole system has extremely high freezing efficiency and accuracy, avoiding the traditional full-depth freezing pipe that can only freeze the entire section and the resulting waste of cold and materials.

[0017] The present invention heats the salt water by a heating plate installed inside the freezing pipe to force thawing. Compared with the traditional method of circulating hot water in the freezing pipe, it can save water and avoid heat loss due to transmission. At the same time, the integrated design of the freezing pipe and the heating function makes the construction process simple and convenient, reduces the on-site construction time, and realizes efficient freezing and thawing.

[0018] The present invention can realize real-time monitoring of the water level of the foundation pit and the temperature, inclination, soil pressure, flow rate and freezing depth of the freezing support system by various sensors arranged inside and outside the freezing pipe, so as to timely control the depth and thickness of the frozen soil through the computer according to the construction progress and engineering needs, and to check for safety hazards and causes of accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is an overall top view of the anti-seepage isolation system for foundation pit using the freezing method of the present invention;

[0020] Figure 2 for Figure 1 AA section view;

[0021] Figure 3 It is a cross-sectional view of the freezing pipe;

[0022] Figure 4 is a top view of the nut lifting plate;

[0023] Figure 5 It is the BB section view of the nut lifting plate;

[0024] Figure 6 is a schematic diagram of the partition;

[0025] Figure 7 is a schematic diagram of the lead screw;

[0026] Figure 8 It is a top view of the transmission system;

[0027] Fig. 9 It is the front view of the transmission system;

[0028] Fig.10 This is the front view of the spiral pile tip structure;

[0029] Fig.11 A cross-sectional view of the anti-collision thermal insulation device;

[0030] In the figure: 1- steel pipe pile; 2- freezing pipe; 3- diagonal bracing structure; 4- pumping well; 5- foundation pit; 6- groundwater level monitoring device; 7- temperature measuring hole; 8- pressure relief hole; 9- inclinometer sensor; 10- frozen soil curtain boundary; 11- brine main pipe; 12- pump station; 13- power supply, 14- computer control terminal, 15- flow monitor, 16- sensitive building, 17- sensitive building foundation, 18- turbine, 19- worm shaft, 20- fixed seat, 21- driving motor , 22-screw, 23-liquid inlet, 24-liquid outlet, 25-drainage hole, 26-partition, 27-heating plate, 28-tube wall, 29-nut lifting plate, 30-thread, 31-vent, 32-distance measuring sensor, 33-metal outer layer, 34-elastic cushion layer, 35-anti-seepage layer, 36-thermal insulation layer; 37-freezing station, 38-conical pile tip, 39-pile tip thread, 40-spiral pile tip structure, 41-foam insulation material, 42-pressure relief port. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] like Figure 1 As shown, the freezing method foundation pit anti-seepage isolation system of this embodiment is arranged near one side of the foundation pit 5 that needs to be anti-seepage isolated. Pumping wells are arranged around the foundation pit 5 to avoid sensitive buildings 16 and sensitive building foundations 17 during construction.

[0034] The anti-seepage isolation system includes a refrigeration support system and a transmission system; the refrigeration support system includes a plurality of freezing pipes 2 inserted into the soil near the foundation pit 5 and distributed in an arch shape, the plurality of freezing pipes 2 are connected by a brine main pipe 11, both ends of the brine main pipe 11 are connected to a pump station 12 and a freezing station 37, the pump station 12 is used to pump the low-temperature brine in the freezing station 37 into the brine main pipe 11, the low-temperature brine enters the freezing pipe 2 through the brine main pipe 11 to freeze the soil, each freezing pipe 2 forms a cylindrical freezing area, the freezing areas formed by the plurality of freezing pipes 2 are connected to each other to form a frozen soil curtain, which has the effect of anti-seepage isolation.

[0035] Combination Figure 3 As shown, a lead screw 22 , a nut lifting plate 29 cooperating with the lead screw 22 , and a partition plate 26 guiding the nut lifting plate 29 are provided in the tube body of the freezing tube 2 .

[0036] Combination Figure 4 and Figure 6 As shown, in this embodiment, the partition 26 is fixedly connected to the inside of the freezing pipe 2, and the cross-section of the partition 26 is "C"-shaped. The two partitions 26 are arranged opposite to each other to form a cylindrical shape with gaps on both sides. The corresponding nut lifting plate 29 is provided with a "C"-shaped hole matching the partition 26. The partition 26 is slidably connected in the "C"-shaped hole. The partition 26 also prevents the nut lifting plate 29 from rotating horizontally. The middle part of the nut lifting plate 29 is provided with an internal threaded hole matching the external thread 30 of the screw rod 22. The outer diameter of the nut lifting plate 29 matches the inner diameter of the pipe wall 28 of the freezing pipe 2, so that the inside of the pipe body of the freezing pipe 2 is The nut lifting plate 29 is divided into an upper cavity and a lower cavity which are not connected, and is also divided into an inner cavity and an outer cavity which are connected by two partitions 26. The partition 26 is provided with a plurality of drainage holes 25. The inner cavity and the outer cavity are connected through the gap between the partitions 25 and the two partitions. The top of the freezing tube 2 is provided with a liquid inlet 23 and a liquid outlet 24 which are connected to the brine main pipe 11, corresponding to the inner cavity and the outer cavity. Low-temperature brine enters the upper cavity of the freezing tube 2 through the liquid inlet 23. The brine first enters the inner cavity from the liquid inlet 23, then flows to the outer cavity from the drainage holes 25 and the gap between the partitions 26, and then returns to the brine main pipe 11 through the liquid outlet 24. Due to the brine isolation effect of the nut lifting plate 29, low-temperature brine will not flow into the lower cavity.

[0037] Combination Figure 7 As shown, the top end of the screw rod 22 extends out of the freezing tube 2, and a vent hole 31 is provided inside the screw rod 22 along the central axis. The vent hole 31 is connected to the lower cavity of the freezing tube 2 to prevent the nut lifting plate 29 from being difficult to lift and lower due to too low or too high pressure in the lower cavity, thereby damaging the components.

[0038] Combination Figure 8 and Fig. 9As shown, the transmission system includes a driving motor 21 for driving the lead screw to rotate. The driving motor 21 drives the lead screw 22 through the turbine 18 and the worm 19 that cooperate with each other. The turbine 18 is fixed to one end of the lead screw 22 extending out of the freezing tube 2. The worm 19 is connected to the output end of the driving motor 21. The driving motor 21 is set on the fixed seat 20 at the top of the freezing tube 2. When the power supply 13 is turned on, the driving motor 21 drives the lead screw 22 to rotate, and then drives the nut lifting plate 29 to rise and fall along the lead screw 22 in the tube body of the freezing tube, thereby changing the depth of the low-temperature brine in the freezing tube 2, thereby controlling the freezing position of the low-temperature brine. According to different freezing requirements, the depth of the frozen soil body is controlled to achieve the purpose of layered and segmented freezing.

[0039] Combination Figure 5 As shown, the nut lifting plate 29 is provided with a metal outer layer 3 on the outside, which plays the role of integrating and wrapping the inside into a unified whole, and a distance sensor 32 is also embedded on the surface of the metal outer layer 3. From top to bottom, the inside of the nut lifting plate 29 is an elastic cushion layer 34, an anti-seepage layer 35, a thermal insulation layer 36 and another elastic cushion layer 34. Among them, the anti-seepage layer 35 adopts a polyethylene geomembrane, and the thermal insulation layer 36 adopts a polyurethane board.

[0040] The partition 25 is provided with arc-shaped heating plates 27 arranged in multiple layers up and down. By controlling and starting the heating plates 27 of the corresponding number of layers, the low-temperature brine in the freezing pipe 2 is heated, and the soil can be thawed. At the same time, the multi-layered heating plates 27 can control the heating plates at different depths to heat, and layered and segmented thawing can be achieved to a certain extent.

[0041] Embodiment 2

[0042] like Figure 1 and 2 As shown, the outer part of the freezing pipes 2 at the top of the arch formed by multiple freezing pipes 2 is covered with a steel pipe pile 1, which is hollow and has an inner diameter larger than the outer diameter of the freezing pipe 2 and a length slightly longer than the freezing pipe 2. The freezing pipes 2 on the inner side of the arch facing the foundation pit 5 are provided with another diagonal brace structure 3 formed by the freezing pipes 2 being tilted toward the foundation pit. The frozen area formed by the freezing pipes 2 forming the diagonal brace structure 3 can play a supporting role.

[0043] The frozen soil curtain of the steel pipe pile 1 and the freezing pipe 2 forms a composite frozen soil wall protection with high rigidity, making the isolation wall as the enclosure structure not easy to be destroyed, effectively isolating the groundwater and bearing part of the soil pressure. Compared with the traditional vertical underground continuous wall, this technology is also provided with a diagonal bracing structure, which is conducive to the formation of the frozen soil wall to resist the soil pressure, and increases the horizontal rigidity and anti-tilt stability of the frozen soil wall. In addition, the length of the steel pipe pile is set longer than the freezing pipe, which is convenient for transmitting the force on the frozen soil wall to the deeper part of the stratum.

[0044] The frozen pipes are arranged continuously in an arch shape. On the one hand, the soil arch effect can effectively concentrate the stress and pressure of the entire freezing support system on the top of the arch ring. Steel pipe piles and diagonal bracing structures are arranged on the top of the arch ring to concentrate the stress for support. The steel pipe piles 1, diagonal bracing 3 structures and frozen soil work together to effectively improve the stress efficiency and material utilization rate, and less building materials can be used to achieve the same engineering purpose. On the other hand, the arch arrangement effectively improves the lateral overload capacity of the overall frozen soil wall structure, and the support safety is high. Compared with the traditional straight line arrangement, the engineering safety is better.

[0045] The brine main pipe 11 in this embodiment is used to transport low-temperature brine. In order to prevent the loss of cold, a polyethylene plastic hose or PC pipe with good thermal insulation effect and high flexibility at low temperatures is used. The outside of the pipe is wrapped with a layer of foam insulation material to form an anti-collision insulation layer, such as Fig.11 As shown, the anti-collision insulation layer is round or square. By setting the insulation material, the temperature of the refrigeration medium in the pipeline can be better guaranteed, the temperature transmission loss can be reduced, the best working effect can be achieved, and people can be prevented from touching the pipeline and getting injured.

[0046] In this embodiment, the material of the freezing pipe wall 28 is a low-carbon steel seamless steel pipe. Fig.10 As shown, a spiral pile tip structure 40 is provided at the bottom end of the freezing pipe 2. The spiral pile tip structure 40 includes a conical pile tip 38, a pile tip thread 39 and a pressure relief port 42. The pile tip thread 39 is spirally evenly distributed on the conical pile tip. The pressure relief port 42 is a circular hole reserved on the conical pile tip, and each pressure relief port 42 is evenly distributed between the pile tip threads 39. The pressure relief port 42 is used to unload the water and soil pressure generated by the soil squeezing effect during the construction and placement of the freezing pipe.

[0047] In this embodiment, the steel pipe pile 1 and the freezing pipe 2 can be removed and completely recycled after the construction is completed, without affecting the secondary use. At the same time, compared with the pollution to the environment caused by the traditional underground continuous concrete wall and bored pile, the freezing method of this technology has almost no effect on the groundwater level and the environment, whether during the freezing process or after thawing, and will not produce construction mud, and will not cause pollution to the soil and groundwater. It is green and environmentally friendly, and has good ecological and economic benefits.

[0048] In this embodiment, an independent freezing station and a pumping station are set at the boundaries of both sides of the frozen soil curtain. Compared with setting a single freezing station and a single pumping station in the middle of the frozen soil wall, the amount of frozen soil and frost heave and thaw settlement are significantly reduced. Compared with setting a freezing station on one side for cooling, the cooling effect is better and the freezing rate is faster.

[0049] like Figure 1As shown, temperature measuring holes 7 are arranged around the freezing pipe 2, and pressure relief holes 8 are provided in the unfrozen soil in the frozen soil curtain. The pressure relief holes 8 are seamless steel pipes. The pressure relief holes 8 are used to reduce the impact of frost heave on the soil. When frost heave causes ground compression, part of the soil is removed from the pressure relief holes 8.

[0050] This embodiment also includes a monitoring system, which includes an electronic temperature measuring device, a flow monitor 15, a pressure sensor, an inclinometer sensor 9, a distance sensor 32, and a groundwater level monitoring device 6. The monitoring data of each measuring instrument are shared with the computer master control terminal 14. Among them, the electronic temperature measuring device is arranged in the temperature measuring hole 7 around the freezing pipe 2 to measure the thickness of the frozen soil and the degree of thawing; the flow monitor 15 is arranged at the inlet and outlet of the return brine main pipe 11 to measure the transmission rate of the brine; the pressure sensor is arranged in the pressure relief hole 8 around the freezing pipe 2 to monitor the frost heave pressure of the soil; the inclinometer sensor 9 is fixed on the diagonal bracing structure 3 to measure the deflection angle of the diagonal bracing structure 3 relative to the vertical direction, thereby reflecting the stability and anti-overturning condition of the refrigeration support system; the distance sensor 32 is arranged inside the freezing pipe 2 to monitor the position of the nut lifting plate 29 in the freezing pipe 2, thereby measuring the circulation depth of the brine in the freezing pipe 2, thereby reflecting the depth of the frozen soil; the groundwater level monitoring device 6 is arranged around the freezing pipe 2 to monitor the water level around the foundation pit and the refrigeration support system.

[0051] The construction steps of the freezing method foundation pit anti-seepage isolation system of this embodiment are as follows:

[0052] 1. Use a pile driver to drive the steel pipe piles into the predetermined position according to the design.

[0053] 2. Construction of frozen pipes and diagonal bracing structures.

[0054] 3. Use freezing pipes and diagonal bracing structures to cool the surrounding soil.

[0055] 4. Actively freeze to form a freezing method foundation pit anti-seepage isolation system. During the freezing period of the ground, the circulating brine flow, the temperature of the frozen soil area, the ground frost heave and the deformation of the foundation pit support structure should be regularly detected and monitored.

[0056] 5. Excavate the foundation pit within the frozen soil wall of the freezing method foundation pit anti-seepage isolation system.

[0057] 6. After the foundation pit is excavated, the brine circulation is stopped and the arc heating plate starts heating

[0058] 7. After heating and thawing until the frozen soil disappears, stop heating and recover the frozen pipes, diagonal bracing structures, steel pipe piles and monitoring systems.

[0059] The steps for using the freezing pipe to achieve layered controllable freezing and thawing are as follows:

[0060] 1. To achieve layered freezing: ① The motor is turned on, driving the worm, worm wheel, and screw to rotate in sequence, thereby driving the nut lifting plate to move up and down. ② The nut lifting plate blocks the low-temperature brine above itself. Therefore, the freezing depth can be adjusted by the height position of the nut lifting plate. ③ At the same time, a distance sensor is installed on the pad, which can be sent to the computer master control terminal to realize real-time monitoring of the position and realize automatic intelligent control.

[0061] 2. Realize layered thawing: The heating plates are installed inside the C-shaped partition and arranged in multiple layers in the vertical direction. Control the opening of the corresponding number of layers of heating plates to achieve layered heating.

[0062] The intelligent control process of the computer master control terminal is as follows:

[0063] When the groundwater level monitoring device detects an increase in the foundation pit water level, resulting in a higher water head in the foundation pit and an increase in the soil pressure on the freezing pipe near the foundation pit, the freezing pipe and the diagonal bracing structure increase the freezing thickness and depth, thereby increasing the thickness of the frozen soil curtain, the pile end soil stiffness of the diagonal bracing structure, and the anti-seepage width of the bottom of the frozen soil wall. The computer terminal of the refrigeration intelligent control can preset and monitor the thickness and depth of soil freezing. The computer master control terminal 14 can intelligently control the freezing station 37 and the freezing pipe 2 based on the monitoring data, thereby adjusting the freezing thickness and depth of the frozen soil wall and the thawing heating power.

[0064] The technical solutions of the present invention are not limited to the above-mentioned embodiments, and any technical solutions obtained by equivalent replacement methods fall within the scope of protection required by the present invention.

Claims

1. A freezing method foundation pit anti-seepage isolation system, characterized by: It includes a refrigeration support system and a transmission system; the refrigeration support system includes a plurality of freezing pipes inserted into the soil near the foundation pit and distributed in an arch shape, a brine main pipe connected to the plurality of freezing pipes in sequence, and a refrigeration station connected to both ends of the brine main pipe; The freezing tube body is provided with a lead screw, a nut lifting plate matched with the lead screw, and a partition for guiding the nut lifting plate. The nut lifting plate separates the freezing tube body into an upper cavity and a lower cavity which are not connected. The top of the freezing tube body is provided with a liquid inlet and a liquid outlet connected with the brine dry pipe. A heating plate is provided in the partition. The transmission system includes a driving motor for driving the lead screw to rotate; The top end of the screw rod extends out of the freezing pipe and is transmission-connected to the driving motor; a vent hole is provided inside the screw rod along the central axis, and the vent hole is connected to the lower cavity of the freezing pipe; The low-temperature brine in the freezing station enters the upper cavity of the freezing pipe through the brine main pipe, freezes the soil, and performs anti-seepage isolation; The driving motor drives the lead screw to rotate, and the lead screw drives the nut lifting plate to move up and down in the pipe body of the freezing pipe, so as to adjust the height of the upper cavity and control the depth of the frozen soil body; The heating plate is used to heat the low-temperature brine in the freezing pipe to thaw the soil.

2. According to the freezing method foundation pit anti-seepage isolation system of claim 1, it is characterized by: The partitions are arranged opposite to each other and are in a "C" shape, with a gap between the two partitions and a plurality of drainage holes on the partitions. The two partitions separate the tube body of the freezing tube into an inner cavity and an outer cavity, and the inner cavity and the outer cavity are connected through the gap and the drainage holes between the two partitions. The liquid inlet and the liquid outlet are respectively arranged at the top of the freezing tube corresponding to the inner cavity and the outer cavity.

3. The freezing method foundation pit anti-seepage isolation system according to claim 2 is characterized by: The heating plates in the partition are provided with multiple layers along the height direction.

4. The freezing method foundation pit anti-seepage isolation system according to claim 1 is characterized by: At least part of the freezing pipe is covered with steel pipe piles, and the length of the steel pipe piles is greater than the length of the freezing pipe; the arched part of the freezing pipe is provided with an inclined bracing structure on the side close to the foundation pit, and the inclined bracing structure is formed by the inclined setting of another freezing pipe. The freezing pipe forming the inclined bracing structure is also connected to the brine main pipe.

5. The freezing method foundation pit anti-seepage isolation system according to claim 4 is characterized by: A spiral pile tip structure is provided at the bottom of the freezing pipe, and the spiral pile tip structure includes a conical pile tip, a pile tip thread and a pressure relief port. The pile tip thread is spirally evenly distributed on the conical pile tip, and the pressure relief port is a circular hole arranged on the conical pile tip, and multiple pressure relief ports are evenly distributed between the pile tip threads.

6. The freezing method foundation pit anti-seepage isolation system according to claim 5 is characterized by: The nut lifting plate includes a metal outer layer and an elastic cushion layer, an anti-seepage layer, a thermal insulation layer and an elastic cushion layer stacked in sequence from top to bottom in the metal outer layer; an internal thread hole matching the external thread of the screw rod is provided on the inner side of the nut lifting plate.

7. The freezing method foundation pit anti-seepage isolation system according to claim 1 is characterized by: A pump station is provided at the freezing station, and the low-temperature brine of the freezing station is pumped into the brine main pipe through the pump station.

8. The freezing method foundation pit anti-seepage isolation system according to claim 1 is characterized by: The transmission system also includes a turbine and a worm gear that cooperate with each other. The turbine is fixed to one end of the lead screw extending out of the freezing pipe, and the worm gear is connected to the output end of the driving motor.

9. The freezing method foundation pit anti-seepage isolation system according to claim 1 is characterized by: The exterior of the brine main pipe is wrapped with an anti-collision insulation layer.

10. The freezing method foundation pit anti-seepage isolation system according to claim 1 is characterized by: It also includes a monitoring system, which includes an electronic temperature measuring device, a flow monitor, a pressure sensor, an inclinometer sensor, a distance sensor and a groundwater level monitoring device; the electronic temperature measuring device is arranged in the temperature measuring holes around the freezing pipe, the flow monitor is arranged at the inlet and outlet at both ends of the brine main pipe, the pressure sensor is arranged in the pressure relief holes around the freezing pipe, the inclinometer sensor is fixed on the diagonal support structure, the distance sensor is arranged on the nut lifting plate, and the groundwater level monitoring device is arranged around the freezing pipe.

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