Tunnel piping prevention and control structure and drainage prevention and control method

Abstract

The tunnel piping prevention and control structure comprises an anti-floating unit, a drainage unit and a water collecting well, the anti-floating unit comprises an anti-floating pile with a built-in water guide pipe, a spiral water guide groove is formed in the surface of the water guide pipe, an expansion grouting layer is arranged on the surface of the anti-floating pile, and the water collecting well is arranged in the anti-floating pile. A permeable layer is arranged between the outer side of the expansion grouting layer and the pile hole for placing the anti-floating pile; the drainage unit comprises drainage pipes vertically arranged in soil on the two sides of the tunnel, water collecting holes are formed in the surfaces of the drainage pipes, and floating ball valves are arranged at the bottoms of the drainage pipes. The water collecting pipe is connected with the water guide pipe and the floating ball valve, the water collecting pipe is communicated with the water collecting well through an electric valve, and a pressure sensor is arranged in the water collecting pipe. According to the anti-floating pile, the anti-pulling force of the anti-floating pile can be guaranteed, and meanwhile the reinforcement cage in the anti-floating pile is protected; in addition, intelligent drainage can be achieved, and the problems of anti-floating and water seepage control of tunnel underground engineering are effectively solved.

Description

Technical Field:

[0001] The present invention relates to the technical field of waterproof and anti - floating for underground engineering, and particularly to a tunnel piping prevention structure and a drainage prevention method. Background Art:

[0002] With the acceleration of the urbanization process, the depth of underground space development is increasing continuously. For example, when constructing tunnels, especially in high - water - level areas along the coast and rivers (such as the Ningxia region), the groundwater level is often 3 - 5 m above the structure base. When building tunnels in high - water - content areas, anti - floating piles are generally driven to make the road surface in close contact with the rammed soil layer through frictional force. However, traditional anti - floating piles rely on pile - soil frictional resistance. However, the fluctuation of the groundwater level (the daily amplitude can reach 1 - 2 m) causes a sharp increase in pore water pressure, reduces the effective stress, and the uplift force decays by 30% - 50%. At the same time, the seepage water forms a hydraulic channel along the pile - soil interface, causing the corrosion rate of steel bars to increase by 5 - 8 times and resulting in subsidence of the surrounding strata due to subsurface erosion.

[0003] At the same time, during the process of excavating urban under - crossing tunnels, the soil layers on both sides of the tunnel will continuously seep water into the excavated tunnel, thus affecting the construction. The solution is to drive some plum - blossom piles on the ground on both sides of the tunnel to allow groundwater to seep into the plum - blossom piles, thereby avoiding seepage into the tunnel. However, traditional plum - blossom piles cannot respond to water - level changes, and excessive drainage during the dry period will cause subsidence of the strata due to water loss. Summary of the Invention:

[0004] In view of this, it is necessary to design a tunnel piping prevention structure and a drainage prevention method that can overcome the above problems, ensure the uplift force of the anti - floating piles, prevent the steel bars of the anti - floating piles from corroding too fast, and at the same time avoid subsidence of the strata due to water loss caused by excessive drainage during the dry period.

[0005] In a first aspect, the present application provides a tunnel piping prevention structure, including an anti - floating unit located below the tunnel road surface for enhancing the frictional force between the tunnel road surface and the foundation. At the same time, drainage units are arranged in the soil on both sides of the tunnel, and a sump is arranged in the tunnel foundation and is connected to the anti - floating unit and the drainage unit. The anti - floating unit includes anti - floating piles with built - in water conduits. The surface of the water conduit is provided with spiral water - guiding grooves. The surface of the anti - floating pile is provided with an expansion grouting layer, and a permeable layer is arranged between the outer side of the expansion grouting layer and the pile hole for placing the anti - floating pile.

[0006] The drainage unit includes drain pipes vertically arranged in the soil on both sides of the tunnel. The surface of the drain pipe is provided with water - collecting holes, and a float valve is arranged at the bottom of the drain pipe. The floating ball of the float valve is located above the water - collecting hole in the drain pipe.

[0007] It further includes a water collecting pipe connected to the water guide pipe and the float valve. The water collecting pipe is communicated with the sump through an electric valve. A pressure sensor for detecting the water flow pressure in the water collecting pipe and signal-connected to the electric valve is arranged at a position upstream of the electric valve in the water collecting pipe along the water flow direction.

[0008] Preferably, water inlet through holes staggered with the spiral water guide grooves are formed on the surface of the water guide pipe, and the bottom end of the water guide pipe is connected to the water collecting pipe through a Venturi tube.

[0009] Preferably, the pitch of the spiral water guide groove is 1.2 - 1.5 times the diameter of the water guide pipe, and the groove depth of the spiral water guide groove is 1 / 3 of the wall thickness of the water guide pipe.

[0010] Preferably, the expansion grouting layer is formed by grouting a cement-based material containing water-absorbing resin. The expansion rate of the expansion grouting layer when solidified upon contact with water is 15% - 20%, and the water permeability coefficient of the expansion grouting layer after solidification ≤ 1×10 -7 cm / s.

[0011] Preferably, diatomite nanoparticles are incorporated into the concrete of the anti-floating pile, thereby forming a dendritic pore water seepage network with a pore tortuosity < 1.5 in the anti-floating pile.

[0012] Preferably, an anti-blocking layer is sleeved on the surface of the drain pipe corresponding to the position of the water collecting hole.

[0013] In this application, by providing an anti-floating unit, the friction between the tunnel road surface and the foundation can be enhanced; at the same time, a water guide pipe is provided in the anti-floating unit, which can discharge the groundwater in the foundation to the water collecting pipe and the sump, preventing the groundwater in the foundation from entering between the foundation and the road surface, so as to achieve the purpose of stable contact between the road surface and the foundation; at the same time, through the provided spiral water guide grooves, the drainage path can be increased and the drainage can be accelerated; through the provided expansion grouting layer, it can absorb water and expand when groundwater enters the pile-soil interface, eliminate the water film effect, and increase the uplift resistance of the anti-floating pile by 30% - 50%; the permeable layer in this application can prevent mud from entering the water guide pipe along with the groundwater and blocking the water guide pipe or the spiral water guide grooves; the drainage unit provided in this application can prevent the soil layers on both sides of the tunnel from seeping water into the excavated tunnel; at the same time, through the mutual cooperation of the provided float valve and the electric valve, intelligent drainage can be realized, that is, when the groundwater level in the soil layers on both sides of the tunnel is relatively high, drainage is carried out to prevent the soil layers on both sides of the tunnel from seeping water into the excavated tunnel, and when the groundwater level in the soil layers on both sides of the tunnel is relatively low, drainage is stopped, thereby preventing the stratum from losing water and subsiding.

[0014] In the second aspect, a method for preventing and controlling tunnel piping drainage adopts the above prevention and control structure and includes the following steps:

[0015] S1. Rotary dig placement holes at the positions where the anti-floating units and the drainage units need to be placed, and rotary dig installation holes at the positions where the collecting water pipes and the collecting wells need to be placed by the method of blind tunneling;

[0016] S2. Place the anti-floating units in the placement holes corresponding to the anti-floating units, place the drainage units in the placement holes corresponding to the drainage units, and at the same time install the collecting water pipes and the collecting wells in the installation holes;

[0017] S3. Connect the anti-floating units with the collecting water pipes, the drainage units with the collecting water pipes, and the collecting water pipes with the collecting wells;

[0018] S4. In the initial state, the groundwater level is in a normal state, the float valve is closed, the electric valve is at the first opening degree of the electric valve, and the expansion grouting layer is in a semi-saturated state;

[0019] During rainfall, as the water level around the tunnel rises, the float valve is at the first opening degree of the float valve. At the same time, the pressure sensor detects the water flow pressure in the collecting water pipe in real time. When the water flow pressure exceeds the set value, both the float valve and the electric valve are fully opened;

[0020] After the rainfall stops, the opening degrees of the float valve and the electric valve gradually decrease to the initial state, and at the same time, the expansion grouting layer releases water and returns to its original state.

[0021] Preferably, placing the anti-floating units in the placement holes corresponding to the anti-floating units in step S2 includes the following steps:

[0022] S2.1. Implant a steel reinforcement cage with the water guide pipe into the placement hole corresponding to the anti-floating unit, and the water guide pipe is located outside the steel reinforcement cage;

[0023] S2.2. First, pour the anti-floating pile body, and after the pile body is cured, high-pressure jet expansion grout on its surface to form the expansion grouting layer. Finally, backfill the permeable layer between the placement hole wall and the expansion grouting layer.

[0024] Preferably, the water guide pipe is fixed to the steel reinforcement cage through a fixing clip. Before the steel reinforcement cage is implanted into the placement hole, soluble foaming rubber plugs are arranged at the end of the water guide pipe and the water inlet through hole, and water-swellable rubber bands are pasted in the spiral water guide grooves.

[0025] Preferably, when pouring the anti-floating pile body, a layered pouring method of bottom layer pouring, middle layer pouring and top layer pouring is adopted.

[0026] Through the above method, it is ensured that the anti-floating units, drainage units, collecting water pipes and collecting wells are installed in place, effectively solving the problems of anti-floating and seepage control in tunnel underground engineering. Description of the Drawings:

[0027] Figure Figure 1 is a schematic structural diagram of the tunnel piping prevention and control structure provided by the present invention;

[0028] Figure Figure 2 is a schematic structural diagram of the drainage unit provided by the present invention;

[0029] Figure Figure 3 is a schematic connection structural diagram of the steel reinforcement cage and the water guide pipe of the anti - floating unit provided by the present invention;

[0030] Figure Figure 4 is a schematic structural diagram of the water guide pipe provided by the present invention.

[0031] In the figures:

[0032] 1, Road surface;

[0033] 2, Anti - floating unit; 21, Water guide pipe; 22, Spiral water guide groove; 23, Water inlet through - hole; 24, Steel reinforcement cage; 25, Collection pipe;

[0034] 3, Drainage unit; 31, Drain pipe; 32, Water collection hole; 33, Float valve;

[0035] 4, Catch basin; 5, Collection pipe; 6, Electric valve. Detailed Embodiments:

[0036] In order to make the objectives, technical solutions, and advantages of the present disclosure clearer and more understandable, the following further elaborates on the present disclosure in detail with reference to specific embodiments and the accompanying drawings.

[0037] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by those with ordinary skills in the field to which the present disclosure pertains. The "first", "second", and similar terms used in one or more embodiments of this specification do not denote any order, quantity, or importance, but are only used to distinguish different components.

[0038] The terms "including" or "comprising" and the like mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms "connected" or "coupled" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0039] To facilitate the understanding of the tunnel piping prevention structure and drainage prevention method provided by the embodiments of the present application, the application scenario will be described first. With the acceleration of the urbanization process, the depth of underground space development continues to increase, such as the construction of tunnels. Especially in high water table areas along the coast and rivers (such as Shanghai, Guangzhou, etc.), the groundwater level is often 3-5 m above the structure base. When constructing a tunnel in a high water content area, anti-floating piles are generally driven to make the road surface in close contact with the rammed soil layer through frictional force. However, traditional anti-floating piles rely on pile-soil frictional resistance. However, the fluctuation of the groundwater level (the daily amplitude can reach 1-2 m) leads to a sharp increase in pore water pressure, reducing the effective stress, and the uplift force decays by 30%-50%. At the same time, the seepage water forms a hydraulic channel along the pile-soil interface, causing the corrosion rate of the steel bars to accelerate by 5-8 times and resulting in subsidence of the surrounding strata due to piping. At the same time, during the process of excavating an urban underpass tunnel, the soil layers on both sides of the tunnel will continuously seep water into the excavated tunnel, thus affecting the construction. The solution is to drive some plum blossom piles on the ground on both sides of the tunnel to allow the groundwater to seep into the plum blossom piles, thereby preventing seepage into the tunnel. However, traditional plum blossom piles cannot respond to the change of the water level, and excessive drainage during the dry period will cause the formation to lose water and subside. In view of this, the tunnel piping prevention structure and drainage prevention method of the present application can ensure the uplift force of the anti-floating piles, prevent the steel bars of the anti-floating piles from corroding too fast, and at the same time avoid excessive drainage during the dry period causing the formation to lose water and subside.

[0040] Reference Figure 1 , Figure 1 shows a schematic structural diagram of the tunnel piping prevention structure; the present application provides a tunnel piping prevention structure, including an anti-floating unit 2, which is installed under the tunnel road surface 1 and can drain the groundwater between the road surface 1 and the foundation while enhancing the frictional force between the road surface 1 and the foundation, so that the tunnel road surface 1 and the foundation are in stable contact; the tunnel piping prevention structure of the present application further includes a drainage unit 3, which is vertically arranged in the soil on both sides of the tunnel and can intelligently drain the groundwater in the soil on both sides of the tunnel, that is, drain water when the groundwater level in the soil layers on both sides of the tunnel is high to prevent the soil layers on both sides of the tunnel from seeping water into the excavated tunnel, and stop draining when the groundwater level in the soil layers on both sides of the tunnel is low, thereby preventing the formation from losing water and subsiding; at the same time, the present application also includes a collecting pipe 5 located below the anti-floating unit 2 and the drainage unit 3, which is connected to the anti-floating unit 2 and the drainage unit 3, and a collecting well 4 communicating with the collecting pipe 5 is arranged below the collecting pipe 5.

[0041] Specifically, the anti-floating unit 2 in the present application includes anti-floating piles vertically arranged in the foundation under the tunnel road surface 1, and a water guide pipe 21 is provided in the anti-floating piles. As Figure 3 and Figure 4As shown in the figure, specifically, a plurality of water guide pipes 21 are vertically arranged on the outer side of the steel reinforcement cage 24 of the anti-floating pile. Each water guide pipe 21 is fixed to the steel reinforcement cage 24 by a fixing clip (such as a stainless steel clamp). The distance between every two adjacent water guide pipes 21 is 1.5 times the diameter of the steel bars of the steel reinforcement cage 24. At the same time, in order to increase the drainage path, spiral drainage grooves 22 are spirally opened downward on the surface of each water guide pipe 21, and the pitch of the spiral drainage grooves 22 is 1.2 - 1.5 times the diameter of the corresponding water guide pipe 21, preferably 1.3 times. At the same time, the depth of the spiral drainage grooves 22 is 1 / 3 of the wall thickness of the water guide pipe 21. In order to enhance the drainage effect, water inlet through holes 23 are also opened on the surface of the water guide pipe 21 and are arranged in a staggered manner with the spiral drainage grooves 22. At the same time, a collecting pipe 25 communicating with the collecting pipe 5 is arranged at the bottom of the anti-floating pile. The collecting pipe 25 can collect all the groundwater discharged from the water guide pipes 21 in the corresponding anti-floating pile and transport it into the collecting pipe 25. Specifically, each water guide pipe 21 is connected to the collecting pipe 25 through a tapered nozzle (such as a Venturi tube). The thick end of the tapered nozzle is connected to the water guide pipe 21, and the thin end is connected to the collecting pipe 25.

[0042] Since the water guide pipes 21 are located on the outer side of the steel reinforcement cage 24 and the groundwater is drained away through the water guide pipes 21, the groundwater will not come into contact with the steel reinforcement cage 24, thereby preventing or slowing down the corrosion rate of the steel reinforcement cage 24.

[0043] In the present application, diatomite nanoparticles (with a particle size of 100 - 200 nm) are incorporated into the concrete of the anti-floating pile. After the concrete incorporated with diatomite nanoparticles is cured, a dendritic pore seepage network with a pore tortuosity < 1.5 will be formed inside the anti-floating pile, thus facilitating the groundwater to enter the water guide pipes 21 through the dendritic pore seepage network.

[0044] In the present application, an expansion grouting layer with a thickness of 2 - 3 cm is also sprayed on the surface of the anti-floating pile. The expansion grouting layer is formed by grouting a cement-based material containing a water-absorbing resin. The content of the water-absorbing resin in the cement-based material is 5% - 8%. In the present application, the expansion rate of the expansion grouting layer formed by grouting a cement-based material containing a water-absorbing resin after curing when encountering water is 15% - 20%. At the same time, the water permeability coefficient of the expansion grouting layer after curing is ≤ 1×10-7 cm / s.

[0045] At the same time, in the present application, a permeable layer is backfilled between the expansion grouting layer and the hole wall for placing the anti-floating pile. The material of the permeable layer can adopt the commonly used sand and gravel backfill material in the prior art (with a particle size of 5 - 20 mm and a porosity of 35% - 40%). The above permeable layer can also play a filtering role, that is, preventing the soil around the anti-floating pile from following the groundwater into the water guide pipes 21, thereby preventing the water guide pipes 21, the spiral drainage grooves 22 and the water inlet through holes 23 from being blocked by soil.

[0046] After the anti-floating unit 2 in this application is arranged, the groundwater around the anti-floating unit 2 sequentially passes through the permeable layer, the expansion grouting layer, and the concrete outside the water guide pipe 21. Part of the groundwater enters the water guide pipe 21 through the water inlet at the top of the water guide pipe 21 and the water inlet through holes 23 on the surface, and then passes downward through the tapered nozzle into the collection pipe 25. The remaining groundwater flows downward along the spiral water guide groove 22 on the surface of the water guide pipe 21 and enters the collection pipe 25 through the tapered nozzle. When the groundwater flows through the tapered nozzle, the Bernoulli effect is formed, so that the groundwater in the water guide pipe 21 is accelerated and discharged into the collection pipe 25; when the groundwater in the water guide pipe 21 accelerates, a negative pressure is formed, and under the action of the negative pressure, the groundwater entering the anti-floating pile concrete can actively enter the water guide pipe 21, thus avoiding the contact between the groundwater and the steel reinforcement cage 24.

[0047] When the anti-floating unit 2 in this application is initially arranged, the expansion grouting layer is in a semi-expanded state (7%-10%). When the groundwater flows through the expansion grouting layer, the expansion grouting layer absorbs water and expands by 15%-20%. On the one hand, it fills the pile-soil gap and eliminates the water film effect. On the other hand, the radial pressure generated by the expansion increases the friction force at the pile-soil contact surface by 30%-50%, and at the same time forms a self-healing layer to dynamically compensate for the micro-cracks generated by construction vibration; at the same time, after the expansion grouting layer absorbs water, its volume expands, squeezing the permeable layer to form a non-uniform pore structure, optimizing the drainage path, and avoiding soil loss caused by concentrated seepage.

[0048] In this application, the drainage unit 3 includes drain pipes 31 vertically arranged in the soil on both sides of the tunnel. The drain pipes 31 can be the plum blossom pipes or other pipe bodies commonly used in the prior art, such as Figure 2 As shown, a plurality of water collection holes 32 are opened on the surface of the drain pipe 31. Specifically, the water collection holes 32 can be opened at a position 1 / 3-1 / 2 away from the drain pipe 31. The specific opening height should be determined according to the depth of the drain pipe 31 in the soil and the current water content in the soil. At the same time, in order to prevent soil from entering the drain pipe 31 through the water collection holes 32 and blocking the drain pipe 31, an anti-blocking layer is provided on the surface of the drain pipe 31 corresponding to the position of the water collection holes 32. The anti-blocking layer can specifically be a geotextile wrapped outside the water collection holes 32.

[0049] At the same time, the bottom of the drain pipe 31 is connected to the above-mentioned collection pipe 5 through a float valve 33. Specifically, the float of the float valve 33 is located in the drain pipe 31, and the specific height of the float is flush with or slightly higher than the water collection holes 32.

[0050] In this application, in order to prevent backflow, the collecting pipe 5 is inclined downward and connected to the collecting well 4. At the same time, the top end of the collecting pipe 5 is connected to the water outlet of the float valve 33, and the bottom end of the collecting pipe 5 is connected to the collecting well 4 through an electric valve. The collecting pipe 25 at the lower part of the water guiding pipe 21 is connected to the position of the collecting pipe 5 upstream of the electric valve. At the same time, a pressure sensor for detecting the water flow pressure inside the collecting pipe 5 is fixedly connected inside the collecting pipe 5, and this pressure sensor is located between the position where the collecting pipe 25 is connected to the collecting pipe 5 and the electric valve. In this application, the pressure sensor is signal-connected to the electric valve through a signal line, and the above-mentioned electric valve can adopt an electric valve with a PLC controller commonly used in the prior art.

[0051] In addition, this application also provides a method for preventing and controlling tunnel pipe gushing drainage. Using the above prevention and control structure, it includes the following steps:

[0052] S1. Rotary dig placement holes at the positions where the anti-floating unit 2 and the drainage unit 3 need to be placed, and rotary dig installation holes at the positions where the collecting pipe 5 and the collecting well 4 need to be placed by the method of adit excavation; both the above-mentioned rotary dig placement holes and rotary dig installation holes adopt the existing rotary digging technology.

[0053] S2. Place the anti-floating unit 2 in the placement hole corresponding to the anti-floating unit 2, place the drainage unit 3 in the placement hole corresponding to the drainage unit 3, and at the same time install the collecting pipe 5 and the collecting well 4 in the installation hole. Since the collecting pipe 5 and the collecting well 4 are installed in the installation hole, it is convenient to supply power to and repair the collecting pipe 5 and the collecting well 4.

[0054] The specific steps of placing the anti-floating unit 2 in the placement hole corresponding to the anti-floating unit 2 in the above step S2 include the following steps:

[0055] S2.1. First, weld the steel reinforcement cage 24, then fix the prefabricated water guiding pipe 21 in the factory outside the steel reinforcement cage 24, and then implant the steel reinforcement cage 24 with the water guiding pipe 21 in the placement hole corresponding to the anti-floating unit 2.

[0056] S2.2. First, pour the anti-floating pile body. After the pile body is cured, high-pressure jet expanding slurry is formed on its surface to form an expanding grouting layer. Finally, a permeable layer is backfilled between the placement hole wall and the expanding grouting layer. When pouring the anti-floating pile body, a layered pouring strategy of bottom layer pouring, middle layer pouring and top layer pouring is adopted. At the same time, when pouring the pile body, an attached vibrator (frequency 8000 - 12000 times / min) should be installed outside the anti-floating pile formwork. The attached vibrator transmits the vibration force to the outside of the formwork, and the outside of the formwork transmits the vibration force to the concrete inside the formwork, so as to avoid the vibrator directly contacting the water guiding pipe 21.

[0057] Meanwhile, during the above-mentioned pouring process, in order to prevent concrete from entering the water guide pipe 21 and the water inlet through-hole 23 and blocking the water guide pipe 21, soluble foam rubber plugs should be pre-installed at the top and bottom ends of the water guide pipe 21 and at the position of the water inlet through-hole 23 before the water guide pipe 21 leaves the factory. The soluble foam rubber plugs are made of traditional water-soluble PVA material, and the compressive strength of the soluble foam rubber plugs should be ≥ 0.5 MPa.

[0058] Furthermore, in order to prevent the spiral water guide groove 22 from being blocked by concrete, a water-swelling rubber strip should be pasted on the surface of the water guide pipe 21 before the water guide pipe 21 leaves the factory. The swelling rate of the water-swelling rubber strip is 300%. At the same time, the above-mentioned water-swelling rubber strip can also be replaced by a soluble strip made of traditional water-soluble PVA material.

[0059] When the concrete of the anti-floating pile solidifies, the soluble foam rubber plug dissolves in water, thus facilitating the entry of groundwater into the water guide pipe 21. At the same time, the water-swelling rubber strip swells in water and automatically peels off from the spiral water guide groove 22 or the soluble strip in the spiral water guide groove 22 dissolves in water, thus opening up the spiral water guide groove 22.

[0060] Meanwhile, in this application, the water guide pipe 21 should adopt a water guide pipe 21 with an internal support structure (such as a spring steel skeleton) to support the outer wall of the water guide pipe 21 and prevent the water guide pipe 21 from being extruded and deformed by concrete during the pouring of the anti-floating pile.

[0061] S3. Connect the anti-floating unit 2 with the water collecting pipe 5, the drainage unit 3 with the water collecting pipe 5, and the water collecting pipe 5 with the water collecting well 4.

[0062] S4. In the initial state, the groundwater level is in a normal state. At this time, the water levels in the soils on both sides of the tunnel are below the water collecting holes 32, the float valve 33 is closed, the electric valve is at the first opening degree of the electric valve (such as 30% opening degree), and the expansion grouting layer is in a semi-saturated state (7% - 10%);

[0063] During rainfall, as the groundwater level around the tunnel rises, when the water level reaches or is higher than the water collecting holes 32, groundwater enters the drain pipe 31 through the water collecting holes 32 until the water level in the drain pipe 31 pushes the float of the float valve 33 upwards. At this time, the float valve 33 is at the first opening degree of the float valve 33 (such as 10%). According to the principle of the communicating vessel, the water level in the drain pipe 31 is the same as the water level around the tunnel. The higher the water level in the drain pipe 31, the larger the opening degree of the float valve 33; when there is a heavy rain or a torrential rain, the groundwater around the tunnel cannot be drained in time. At this time, the water level in the drain pipe 31 is at the highest state, and at the same time, the float valve 33 is in a fully open state;

[0064] Meanwhile, the pressure sensor detects the water flow pressure in the collecting pipe 5 in real time. When the water flow pressure exceeds the set value (such as 180 - 200 KPa), it indicates that heavy rain or torrential rain is occurring at this time. The PLC controls the fully opening of the electric valve to drain water with all efforts and prevent piping;

[0065] After the rainfall stops and with the continuous drainage, the water level around the tunnel gradually drops, and the opening degree of the float valve 33 gradually returns from the fully open state to the closed state, thus preventing excessive drainage from causing the loss of water and settlement of the formation; meanwhile, as the water flow pressure in the collecting pipe 5 gradually decreases, the opening degree of the electric valve gradually decreases to the initial state, and the water released from the expansion grouting layer returns to its original state.

[0066] Through the above method, while ensuring the uplift resistance of the anti - floating piles, the steel reinforcement cage in the anti - floating piles can be protected to prevent the steel bars of the anti - floating piles from rusting too fast; at the same time, intelligent drainage can be realized, that is, when the groundwater level in the soil layers on both sides of the tunnel is relatively high, drainage is carried out to prevent the soil layers on both sides of the tunnel from seeping water into the excavated tunnel, and when the groundwater level in the soil layers on both sides of the tunnel is relatively low, drainage stops, thus preventing the loss of water and settlement of the formation.

[0067] Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples; under the concept of the present disclosure, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of one or more embodiments of the present specification as described above, and for the sake of brevity, they are not provided in detail.

[0068] In addition, for the sake of simplicity of description and discussion, and in order not to make one or more embodiments of the present specification difficult to understand, the well - known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. In addition, the device can be shown in the form of a block diagram to avoid making one or more embodiments of the present specification difficult to understand, and this also takes into account the fact that the details of the implementation of these block - diagram devices are highly dependent on the platform on which one or more embodiments of the present specification will be implemented (that is, these details should be fully within the understanding of those skilled in the art). In the case where specific details (such as circuits) are set forth to describe the exemplary embodiments of the present disclosure, it is obvious to those skilled in the art that one or more embodiments of the present specification can be implemented without these specific details or with variations of these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0069] Although the present disclosure has been described in connection with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description.

[0070] One or more embodiments of this specification are intended to cover all such alternatives, modifications, and variations that fall within the broad scope of the appended claims. Accordingly, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included within the scope of protection of the present disclosure.

Claims

1. A tunnel piping prevention and control structure includes an anti-floating unit located below the tunnel road surface for enhancing the friction between the tunnel road surface and the foundation. At the same time, drainage units are arranged in the soil on both sides of the tunnel, and a sump well connected to the anti-floating unit and the drainage unit is arranged in the tunnel foundation. It is characterized in that, The anti-floating unit includes anti-floating piles with built-in water conduits. The surface of the water conduit is provided with spiral water guide grooves. The surface of the anti-floating pile is provided with an expansion grouting layer, and a water-permeable layer is arranged between the outer side of the expansion grouting layer and the pile hole for placing the anti-floating pile. The drainage unit includes drain pipes vertically arranged in the soil on both sides of the tunnel. The surface of the drain pipe is provided with water collection holes, and a float valve is arranged at the bottom of the drain pipe. The float ball of the float valve is located above the water collection hole in the drain pipe. It further includes a water collection pipe connected to the water conduit and the float valve. The water collection pipe is communicated with the water collection well through an electric valve. A pressure sensor for detecting the water flow pressure in the water collection pipe and signal-connected to the electric valve is arranged at a position upstream of the electric valve along the water flow direction in the water collection pipe.

2. The tunnel piping prevention and control structure according to claim 1, characterized in that, The surface of the water conduit is provided with water inlet through holes arranged in a staggered manner with the spiral water guide grooves, and the bottom end of the water conduit is connected to the water collection pipe through a Venturi tube.

3. The tunnel piping prevention and control structure according to claim 1, characterized in that, The pitch of the spiral water guide groove is 1.2 - 1.5 times the diameter of the water conduit, and the groove depth of the spiral water guide groove is 1 / 3 of the wall thickness of the water conduit.

4. The tunnel piping prevention and control structure according to claim 1, characterized in that, The swelling grouting layer is formed by grouting a cement-based material containing a water-absorbing resin. The swelling ratio of the swelling grouting layer after curing is 15%-20% when it meets water, and the water permeability coefficient of the swelling grouting layer after curing is ≤1×10 -7 cm / s.

5. The tunnel piping prevention and control structure according to claim 1, characterized in that, Diatomite nanoparticles are incorporated into the concrete of the anti-floating pile, thereby forming a dendritic pore seepage network with a pore tortuosity < 1.5 in the anti-floating pile.

6. The tunnel piping prevention and control structure according to claim 1, characterized in that, A clogging prevention layer is sleeved on the surface of the drain pipe corresponding to the position of the water collection hole.

7. A method for preventing and controlling tunnel piping drainage, characterized in that, Adopting the prevention and control structure described in any one of claims 1 - 6, including the following steps: S1. Rotary dig placement holes at positions where the anti-floating unit and the drainage unit need to be placed, and rotary dig installation holes at positions where the water collection pipe and the water collection well need to be placed by the cut-and-cover method. S2. Place the anti-floating unit in the placement hole corresponding to the anti-floating unit, place the drainage unit in the placement hole corresponding to the drainage unit, and install the water collection pipe and the water collection well in the installation hole at the same time. S3. Connect the anti-floating unit with the water collection pipe, the drainage unit with the water collection pipe, and the water collection pipe with the water collection well. S4. In the initial state, the groundwater level is in a normal state, the float valve is closed, the electric valve is at the first opening degree of the electric valve, and the expansion grouting layer is in a semi-saturated state. During rainfall, as the water level around the tunnel rises, the float valve is at the first opening degree of the float valve. At the same time, the pressure sensor continuously detects the water flow pressure in the water collection pipe. When the water flow pressure exceeds the set value, both the float valve and the electric valve are fully opened. After the rainfall stops, the opening degrees of the float valve and the electric valve gradually decrease to the initial state, and at the same time, the expansion grouting layer releases water and returns to its original state.

8. The tunnel piping prevention and control structure according to claim 7, characterized in that, Placing the anti-floating unit in the placement hole corresponding to the anti-floating unit in step S2 includes the following steps: S2.

1. Insert a steel reinforcement cage with the water conduit into the placement hole corresponding to the anti-floating unit, and the water conduit is located outside the steel reinforcement cage. S2.

2. First, pour the anti-floating pile body. After the pile body is cured, high-pressure jet the expansion grout on its surface to form the expansion grouting layer. Finally, backfill the permeable layer between the placement hole wall and the expansion grouting layer.

9. The tunnel piping prevention and control structure according to claim 8, wherein, The water guide pipe is fixed to the steel reinforcement cage through a fixing clip. Before the steel reinforcement cage is implanted into the placement hole, soluble foam rubber plugs are arranged at the end of the water guide pipe and the water inlet through hole, and water-swellable rubber bands are pasted in the spiral water guide grooves.

10. The tunnel piping prevention and control structure according to claim 8, wherein, When pouring the anti-floating pile body, a layered pouring method of bottom layer pouring, middle layer pouring and top layer pouring is adopted.

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