Karst tunnel lining bearing capacity and external water pressure balancing system and method

Abstract

This invention relates to a system and method for balancing the bearing capacity and external water pressure of karst tunnel lining, belonging to the field of tunnel lining disaster prevention. It includes two drainage lines located below and on both sides of a karst cavity. Each drainage line comprises multiple water pressure regulating chambers connected sequentially from top to bottom. The uppermost water pressure regulating chamber is connected to the bottom of the karst cavity via a pipe, adjacent water pressure regulating chambers are connected via pipes, and the lowermost water pressure regulating chamber is connected to a drainage ditch via a pipe. All pipes are equipped with electromagnetic valves. The water pressure regulating chambers are located at key points in the lining, including between the tunnel arch lining and the surrounding rock, the tunnel sidewall lining and the surrounding rock, and the tunnel arch foot lining and the surrounding rock. The electromagnetic valves control the water flow dispersion in each water pressure regulating chamber. This solution can evenly distribute local water pressure behind the tunnel lining throughout the entire lining ring, reducing stress concentration, protecting the lining structure, and ensuring the safe operation of the tunnel.

Description

Technical Field

[0001] This invention belongs to the field of tunnel lining disaster prevention and control, and relates to drainage control of karst cavities, and an adaptive balance method for bearing capacity and external water pressure of karst tunnel lining. Background Technology

[0002] One of the common quality problems in karst tunnels is the presence of cavities behind the lining, which can pose a serious threat to the operational safety of the tunnel. If cavities appear behind the tunnel lining, groundwater will flow into the cavities along the fissures. The water accumulated in the cavities will be converted into pressure on the tunnel lining structure, leading to cracking of the lining structure. Measures must be taken to deal with the water present in the karst cavities behind the tunnel.

[0003] Existing technologies often adopt a drainage design principle that prioritizes drainage, using pre-buried blind drainage pipes. However, during tunnel construction, factors such as face excavation and lining construction can cause disturbance and damage to karst conduits. By the operational phase, the damage to these karst conduits behind the tunnel can gradually expand, leading to blockages. During the rainy season when karst groundwater is abundant, the water pressure behind the lining can rise sharply, causing localized stress concentrations. This can result in serious structural defects such as lining cracking, water seepage, and even collapse and water inrush, affecting the safe operation of the tunnel. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a system and method for balancing the bearing capacity and external water pressure of karst tunnel lining, which can effectively distribute the local water pressure behind the tunnel lining evenly to the entire lining ring, reduce stress concentration, protect the lining structure, and ensure the safe operation of the tunnel.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A karst tunnel lining bearing capacity and external water pressure balance system includes two drainage lines located at the same cross-section below both sides of a karst cavity. Each drainage line comprises multiple water pressure regulating chambers connected sequentially from top to bottom. The uppermost water pressure regulating chamber is connected to the bottom of the karst cavity via a water flow dispersion pipe. Adjacent water pressure regulating chambers are connected via water flow dispersion pipes. The lowermost water pressure regulating chamber is connected to a drainage ditch via a drainage control pipe. Each water flow dispersion pipe is equipped with a dispersion control solenoid valve, and each drainage control pipe is equipped with a drainage control solenoid valve. The water pressure regulating chambers are respectively located at key lining points, including the area between the tunnel arch waist lining and the surrounding rock, the area between the tunnel sidewall lining and the surrounding rock, and the area between the tunnel arch foot lining and the surrounding rock.

[0007] Both the karst cavity and the water pressure regulating chamber are equipped with water level sensors and water pressure gauges. The water level sensors monitor the water volume inside the karst cavity and the water pressure regulating chamber in real time, and the water pressure gauges monitor the external water pressure behind the corresponding tunnel lining.

[0008] It also includes an industrial control computer and a monitoring center. The industrial control computer is electrically connected to the solenoid valve, the water level sensor, and the water pressure gauge, respectively. The industrial control computer reads the monitoring data from the water level sensor and the water pressure gauge and uploads it to the monitoring center. The monitoring center controls the industrial control computer to switch the distributed control solenoid valve and the drainage control solenoid valve according to the monitoring data.

[0009] Furthermore, the interior of the water pressure regulating tunnel is constructed with waterproof concrete. This design effectively prevents water from the surrounding rock from seeping into the water pressure regulating tunnel.

[0010] Furthermore, waterproof walls are installed at the connection points between the water pressure regulating chamber and the tunnel, and these waterproof walls are composed of M10 mortar-grouted rubble masonry. This design effectively prevents water from leaking from the water pressure regulating chamber into the tunnel.

[0011] Furthermore, all drainage control pipes are HDPE non-porous corrugated pipes. HDPE stands for high-density polyethylene.

[0012] Furthermore, the HDPE non-porous corrugated pipe is of specification A100mm.

[0013] Furthermore, the water pressure regulating chamber is a column.

[0014] Furthermore, the size of the water pressure regulating chamber is calculated based on the pressure formula, and the size of the water pressure regulating chamber satisfies the condition that, when filled with water, the water pressure on the bottom lining structure is less than the ultimate water pressure value of the lining structure.

[0015] A method for balancing the bearing capacity of karst tunnel lining with external water pressure includes the following steps:

[0016] S1. The monitoring center sets the regulating water pressure value, the safe water pressure value, and the maximum water level of each water pressure regulating chamber according to the ultimate water pressure value that the lining structure can withstand, so as to satisfy the ultimate water pressure value > regulating water pressure value > safe water pressure value.

[0017] S2. Collect the water level of the karst cavity and the corresponding water pressure regulating chamber through water level sensors at various locations, and collect the external water pressure of the karst cavity and the corresponding water pressure regulating chamber through water pressure gauges at various locations.

[0018] S3. When the monitoring center detects that the external water pressure at the karst cavity location is less than the safe water pressure value, all the decentralized control solenoid valves are in the closed state.

[0019] S4. When the external water pressure at the karst cavity location is greater than the regulating pressure value, open the decentralized control solenoid valves corresponding to each water pressure regulating chamber on any side of the drainage pipeline, so that the water in the karst cavity is dispersed along the drainage pipeline to the water pressure regulating chamber below, thereby reducing the pressure value at the karst cavity location.

[0020] S5. Determine whether the pressure value at the location of the karst cavity has decreased to the safe water pressure value. If yes, and the water level value of the lowest water pressure regulating chamber has not reached the maximum water level value, then close all the decentralized control solenoid valves above the lowest water pressure regulating chamber. If no, and the water level value of the lowest water pressure regulating chamber has reached the maximum water level value, then close the corresponding decentralized control solenoid valve, so that the water stays in the water pressure regulating chamber adjacent to the lowest water pressure regulating chamber and no longer flows into the lowest water pressure regulating chamber.

[0021] S6. Perform the judgment and operation of S5 on other water pressure regulating chambers on the drainage pipeline on this side from bottom to top, until the water level of the uppermost water pressure regulating chamber reaches the maximum water level. Then close the decentralized control solenoid valve between the karst cavity and the uppermost water pressure regulating chamber, and open each decentralized control solenoid valve on the drainage pipeline on the other side.

[0022] S7. Perform the judgments and operations of S5 and S6 on each water pressure regulating chamber on the other side of the drainage pipeline.

[0023] S8. When the water level in the uppermost water pressure regulating chamber of both drainage pipelines reaches the maximum water level, open all the decentralized control solenoid valves and drainage control solenoid valves below the uppermost water pressure regulating chamber to allow all water in the water pressure regulating chambers to be discharged from the tunnel through the drainage ditch. When the monitoring center detects that the water level sensor values ​​in each water pressure regulating chamber are all zero, close all the decentralized control solenoid valves and drainage control solenoid valves.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention is automatically analyzed and controlled by a monitoring system. Based on the water level and water pressure values ​​at each monitoring point, it automatically controls the opening and closing of pipeline valves. The computer control system can adjust the pressure on the lining more quickly and accurately.

[0026] This invention can avoid the impact of blind drainage on the ecological environment, and can also effectively reduce the impact of external water pressure on the lining structure, thus effectively ensuring the safe operation of the tunnel.

[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0029] Figure 1 A cross-sectional view of the lining for adaptive equilibrium of external water pressure;

[0030] Attached reference numerals: 1-Water pressure regulating chamber No. 1, 2-Water pressure regulating chamber No. 2, 3-Water pressure regulating chamber No. 3, 4-Water pressure regulating chamber No. 4, 5-Water pressure regulating chamber No. 5, 6-Water pressure regulating chamber No. 6; 11-First solenoid valve, 12-Second solenoid valve, 13-Third solenoid valve, 14-Fourth solenoid valve, 15-Fifth solenoid valve, 16-Sixth solenoid valve, 17-Seventh solenoid valve, 18-Eighth solenoid valve, 31-Water level sensor, 41-Water pressure gauge, 51-HDPE non-porous corrugated pipe, 61-Waterproof wall, 101-Tunnel, 102-Karst cavity, 103-Drainage ditch;

[0031] Figure 2 Schematic diagram of the adaptive balance control principle for external water pressure of the lining;

[0032] Figure 3 Flowchart for adaptive balance control of external water pressure in lining;

[0033] Figure 4 Diagram illustrating the working principle of adaptive water pressure balancing for lining. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0037] Please see Figures 1-4 This relates to a system and method for balancing the bearing capacity of karst tunnel lining with external water pressure, wherein... Figure 1 This is one implementation method of the system in this solution. Figure 2 , Figure 3 and Figure 4 This section describes the control principles and methods corresponding to this implementation method.

[0038] like Figure 1As shown, in this embodiment, two drainage lines are provided below both sides of the karst cavity 102. Each drainage line includes three water pressure regulating chambers connected sequentially from top to bottom. On the left side, from top to bottom, they are water pressure regulating chamber 1, water pressure regulating chamber 2, and water pressure regulating chamber 3. On the right side, from top to bottom, they are water pressure regulating chamber 4, water pressure regulating chamber 5, and water pressure regulating chamber 6. The uppermost water pressure regulating chamber (i.e., water pressure regulating chamber 1 and water pressure regulating chamber 4) is connected to the bottom of the karst cavity 102 through a water flow dispersion pipe. Adjacent water pressure regulating chambers (e.g., water pressure regulating chamber 1 and water pressure regulating chamber 2, water pressure regulating chamber 2 and water pressure regulating chamber 3) are connected to each other. Water pressure regulating chambers 4 and 5 (and 6) are connected by a water flow dispersion pipe. The lowest water pressure regulating chambers (i.e., water pressure regulating chambers 3 and 6) are connected to drainage ditch 103 by a drainage control pipe. The water pressure regulating chambers are respectively set at key lining points, including the area between the tunnel 101 arch waist lining and the surrounding rock, the area between the tunnel 101 sidewall lining and the surrounding rock, and the area between the tunnel 101 arch foot lining and the surrounding rock. Depending on the actual situation, the location and number of water pressure regulating chambers can be determined based on factors such as the location of the cavities, geological conditions, and construction quality. The operation method and principle are the same.

[0039] Specifically, in this embodiment, the karst cavity 102 is located at the upper left shoulder of the tunnel 101. Therefore, the system described in this scheme can be obtained by constructing it according to the following steps.

[0040] (1) A water outlet is provided on each of the left and right sides of the lower part of the karst cavity 102.

[0041] (2) At the same cross section of the karst cavity 102, a No. 1 water pressure regulating chamber 1 is arranged between the left arch waist lining of the tunnel 101 and the surrounding rock. A water inlet is arranged at the top of the No. 1 water pressure regulating chamber 1 and a water outlet is arranged at the bottom. The water inlet of the No. 1 water pressure regulating chamber 1 is connected to the water outlet on the lower left side of the karst cavity 102 through a pipe.

[0042] (3) At the same cross section of the karst cavity 102, a second water pressure regulating chamber 2 is set up between the left wall lining of the tunnel 101 and the surrounding rock. A water inlet is set up at the top of the second water pressure regulating chamber 2 and a water outlet is set up at the bottom. The water inlet of the second water pressure regulating chamber 2 is connected to the water outlet at the bottom of the first water pressure regulating chamber 1 through a pipe.

[0043] (4) At the same cross section of the karst cavity 102, a No. 3 water pressure regulating chamber 3 is arranged between the lining of the left arch foot of tunnel 101 and the surrounding rock. A water inlet is arranged at the top of the No. 3 water pressure regulating chamber 3 and a water outlet is arranged at the bottom. The water inlet of the No. 3 water pressure regulating chamber 3 is connected to the water outlet at the bottom of the No. 2 water pressure regulating chamber 2 through a pipe, and the water outlet of the No. 3 water pressure regulating chamber 3 is connected to the drainage ditch 103 at the bottom of the tunnel invert arch through a pipe.

[0044] (5) At the same cross section of the karst cavity 102, a No. 4 water pressure regulating chamber 4 is arranged between the right arch waist lining of tunnel 101 and the surrounding rock. A water inlet is arranged at the top of the No. 4 water pressure regulating chamber 4 and a water outlet is arranged at the bottom; the water inlet of the No. 4 water pressure regulating chamber 4 is connected to the water outlet on the right side of the bottom of the karst cavity 102 through a pipe.

[0045] (6) At the same cross section of the karst cavity 102, a No. 5 water pressure regulating chamber 5 is arranged between the right wall lining of tunnel 101 and the surrounding rock. A water inlet is arranged at the top of the No. 5 water pressure regulating chamber 5 and a water outlet is arranged at the bottom; the water inlet of the No. 5 water pressure regulating chamber 5 is connected to the water outlet at the bottom of the No. 4 water pressure regulating chamber 4 through a pipe.

[0046] (7) At the same cross-section of the karst cavity 102, a No. 6 water pressure regulating chamber 6 is arranged between the right arch foot lining of tunnel 101 and the surrounding rock. A water inlet is arranged at the top of the No. 6 water pressure regulating chamber 6 and a water outlet is arranged at the bottom. The water inlet of the No. 6 water pressure regulating chamber 6 is connected to the water outlet at the bottom of the No. 5 water pressure regulating chamber 5 through a pipe, and the water outlet of the No. 6 water pressure regulating chamber 6 is connected to the drainage ditch 103 at the bottom of the tunnel invert arch through a pipe.

[0047] All water pressure regulating chambers will be filled with a layer of waterproof concrete to prevent water from the surrounding rock from seeping into them. At the connection points between all water pressure regulating chambers and tunnel 101, a waterproof wall 61 composed of M10 mortar-grouted rubble masonry will be installed to prevent water from seeping into tunnel 101.

[0048] All connected pipes are A100mm HDPE non-porous corrugated pipes 51, with pipe lengths determined according to specific circumstances. The inlet height of all HDPE non-porous corrugated pipes 51 is higher than the outlet height, allowing water to flow within the pipes by gravity when the solenoid valves are opened. The aforementioned distributed control solenoid valves and drainage control solenoid valves are all remotely controllable, used to control the flow of water in the pipes. In this embodiment, they are distinguished by different markings, including the first solenoid valve 11, the second solenoid valve 12, the third solenoid valve 13, the fourth solenoid valve 14, the fifth solenoid valve 15, the sixth solenoid valve 16, the seventh solenoid valve 17, and the eighth solenoid valve 18.

[0049] A water level sensor 31 is installed inside each water pressure regulating chamber and karst cavity 102 to monitor the water volume inside these chambers in real time. A water pressure gauge 41 is installed behind the lining of each water pressure regulating chamber and karst cavity 102 corresponding to the location behind the lining of tunnel 101, to monitor the external water pressure behind the corresponding lining. All water level sensors 31, solenoid valves, and water pressure gauges 41 are connected to an industrial control computer. The computer can read and record the values ​​of the water level sensors 31 and water pressure gauges 41, and then upload the data to the monitoring center. The monitoring center determines whether the water pressure at the location of the karst cavity 102 has reached the limit water pressure value and whether the water level in each water distribution tunnel has reached its maximum value. It then issues instructions to the industrial control computer to control the opening and closing of the solenoid valves, allowing the water in the karst cavity 102 to be dispersed into each water pressure regulating chamber or discharged into tunnel 101 through the drainage ditch 103. The preferred structure for the water pressure regulating chamber is a column. The dimensions of the chamber are calculated using the liquid pressure formula. These dimensions ensure that the water pressure exerted on the lining structure at the bottom of the chamber, when filled with water, is less than the lining structure's ultimate water pressure. Specifically, the dimensions are calculated using the liquid pressure formula P = ρgh and the volume formula v = s·h. Here, P is the water pressure exerted on the lining structure at the bottom of the chamber by the water in the chamber; a value less than the lining structure's ultimate water pressure is sufficient for safety. ρ is the density of the liquid; g is the gravitational constant; v is the volume of the chamber; h is the height of the chamber, h = P / ρg; and s is the area of ​​the bottom of the chamber, typically 0.5-2m to meet the requirements for normal operation by construction workers. 2 Based on the above formulas and taking into account the actual terrain, the dimensions s, h, and v of the water pressure regulating chamber can be reasonably determined.

[0050] like Figure 2 The diagram shows the hardware schematic of the system. All water level sensors, solenoid valves, and water pressure gauges are connected to the industrial control computer. The industrial control computer can read and record the values ​​of the water level sensors and water pressure gauges, and then upload the data to the monitoring center. The monitoring center determines whether the water pressure value at the karst cavity location has reached the limit water pressure value and whether the water level in each water distribution tunnel has reached the maximum value. Then, it issues instructions to the industrial control computer to control the opening and closing of the solenoid valves, so that the water in the karst cavity is dispersed into each water pressure regulating tunnel or discharged into the tunnel through the drainage ditch.

[0051] like Figure 3 and Figure 4 As shown, a method for balancing the bearing capacity of karst tunnel lining with external water pressure based on the above system includes the following steps:

[0052] S1. The monitoring center sets the regulating water pressure value, the safe water pressure value, and the maximum water level of each water pressure regulating chamber according to the ultimate water pressure value that the lining structure can withstand, so as to satisfy the ultimate water pressure value > regulating water pressure value > safe water pressure value.

[0053] S2. The water level of the karst cavity 102 and the corresponding water pressure regulating chamber is collected by the water level sensor 31 at various locations, and the external water pressure of the karst cavity 102 and the corresponding water pressure regulating chamber is collected by the water pressure gauge 41 at various locations.

[0054] S3. When the monitoring center detects that the external water pressure at the karst cavity 102 is less than the safe water pressure value, all the distributed control electromagnetic valves are closed. Initially, the amount of water inside the karst cavity 102 is small, and the external water pressure on the lining structure is within the safe water pressure value range of the structural bearing capacity. All electromagnetic valves are closed, and the water in the karst cavity 102 cannot be distributed to each water pressure regulating chamber.

[0055] S4. When the external water pressure at the karst cavity 102 is greater than the regulating pressure value, open the distributed control solenoid valves corresponding to each water pressure regulating chamber on either side of the drainage pipeline. This allows the water in the karst cavity 102 to be dispersed along the drainage pipeline to the water pressure regulating chamber below, reducing the pressure value at the karst cavity 102. There are two flow paths for the water in the pipeline: First: Karst cavity 102 → No. 1 water pressure regulating chamber 1 → No. 2 water pressure regulating chamber 2 → No. 3 water pressure regulating chamber 3 → Drainage ditch 103; Second: Karst cavity 102 → No. 4 water pressure regulating chamber 4 → No. 5 water pressure regulating chamber 5 → No. 6 water pressure regulating chamber 6 → Drainage ditch 103. In this implementation, it is assumed that the drainage pipeline on the left side is opened first, i.e., the first flow path.

[0056] S5. Determine if the pressure value at the karst cavity 102 has decreased to a safe water pressure value. If yes, and the water level in the lowest water pressure regulating chamber 3 (No. 3) has not reached the maximum water level, it means that there is no need to disperse the water flow into the lower water pressure regulating chambers. In this case, close all the dispersion control solenoid valves (i.e., the first solenoid valve 11, the second solenoid valve 12, and the third solenoid valve 13) above the lowest water pressure regulating chamber 3 to stop dispersing the water flow and prevent the water remaining in the first and second water pressure regulating chambers 1 and 2 from continuing to enter the third water pressure regulating chamber 3. If no, it means that water dispersion is still needed. If the third water pressure regulating chamber 3 is full, close its corresponding dispersion control solenoid valve (i.e., the third solenoid valve 13) so that the water stays in the water pressure regulating chamber adjacent to the lowest water pressure regulating chamber (i.e., the second water pressure regulating chamber 2) and no longer flows into the lowest water pressure regulating chamber 3.

[0057] S6. From bottom to top, perform the judgment and operation of S5 on other water pressure regulating chambers on the drainage pipeline on this side until the water level of the uppermost water pressure regulating chamber reaches the maximum water level. Then, close the distributed control solenoid valve between the karst cavity 102 and the uppermost water pressure regulating chamber, and open each water pressure regulating chamber on the other side of the drainage pipeline. When the third water pressure regulating chamber 3 is closed, if the pressure value at the location of the karst cavity 102 is still greater than the safe water pressure value, and the water volume of the second water pressure regulating chamber 2 is full, close the second solenoid valve 12 to prevent water from flowing into the second water pressure regulating chamber 2. When the second water pressure regulating chamber 2 is closed, if the pressure value at the location of the karst cavity 102 is still greater than the safe water pressure value, and the water volume of the first water pressure regulating chamber 1 is full, close the first solenoid valve 11 to prevent water from flowing into the first water pressure regulating chamber 1, and open the fourth solenoid valve 14, the fifth solenoid valve 15, and the sixth solenoid valve 16 to use the second flow path.

[0058] S7. Perform judgments and operations S5 and S6 on each water pressure regulating chamber on the other side of the drainage pipeline; so that the water in the karst cavity 102 is distributed sequentially into the right side water pressure regulating chamber 6, water pressure regulating chamber 5, and water pressure regulating chamber 4. If, in any judgment, the pressure value at the location of the karst cavity 102 is less than the safe water pressure value, then close all the solenoid valves above the water pressure regulating chamber.

[0059] S8. When the water level values ​​of the uppermost water pressure regulating chambers (i.e., water pressure regulating chamber 1 and water pressure regulating chamber 4) in both drainage pipelines reach the maximum water level value, open all the decentralized control solenoid valves and drainage control solenoid valves below the uppermost water pressure regulating chamber (i.e., open the second solenoid valve 12, the third solenoid valve 13, the fifth solenoid valve 15, the sixth solenoid valve 16, the seventh solenoid valve 17, and the eighth solenoid valve 18) so that the water in all water pressure regulating chambers is discharged from the drainage ditch 103 into the tunnel 101; when the monitoring center detects that the water level sensor 31 values ​​in each water pressure regulating chamber are all zero, close all the decentralized control solenoid valves and drainage control solenoid valves.

[0060] Figure 4 The control principle of this scheme is as follows: when the water pressure in the karst cavity reaches the regulated water pressure value, the valve is opened to adjust the water pressure in the karst cavity, thereby reducing the water pressure and preventing the water pressure in the karst cavity from continuously increasing to the limit water pressure value, which would damage the lining structure. When the regulated water pressure in the karst cavity gradually decreases to the safe water pressure value, the valve is closed to control the water flow, thereby preventing continuous drainage from causing rapid expansion of damage to the karst pipes caused by the previous construction, extending the service life, reducing maintenance costs, and preventing the damage from expanding too quickly and making it impossible to maintain in time.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A system for balancing the bearing capacity of karst tunnel lining with external water pressure, characterized in that: The system includes two drainage lines located at the same cross-section below both sides of the karst cavity. Each drainage line comprises multiple water pressure regulating chambers connected sequentially from top to bottom. The uppermost water pressure regulating chamber is connected to the bottom of the karst cavity via a water flow dispersion pipe. Adjacent water pressure regulating chambers are connected via water flow dispersion pipes. The lowermost water pressure regulating chamber is connected to a drainage ditch via a drainage control pipe. Each water flow dispersion pipe is equipped with a dispersion control solenoid valve, and each drainage control pipe is equipped with a drainage control solenoid valve. The water pressure regulating chambers are located at key lining points, including the area between the tunnel arch lining and the surrounding rock, the area between the tunnel sidewall lining and the surrounding rock, and the area between the tunnel arch foot lining and the surrounding rock. Both the karst cavity and the water pressure regulating chamber are equipped with water level sensors and water pressure gauges. The water level sensors monitor the water volume inside the karst cavity and the water pressure regulating chamber in real time, and the water pressure gauges monitor the external water pressure behind the corresponding tunnel lining. It also includes an industrial control computer and a monitoring center. The industrial control computer is electrically connected to the solenoid valve, the water level sensor, and the water pressure gauge, respectively. The industrial control computer reads the monitoring data from the water level sensor and the water pressure gauge and uploads it to the monitoring center. The monitoring center controls the industrial control computer to switch the distributed control solenoid valve and the drainage control solenoid valve according to the monitoring data. The monitoring center determines whether the water pressure in the karst cavity has reached the limit water pressure value and whether the water level in each water distribution tunnel has reached the maximum value. Then, it issues instructions to the industrial control computer to control the opening and closing of the electromagnetic valves, so that the water in the karst cavity is dispersed into each water pressure regulating tunnel or discharged into the tunnel through the drainage ditch.

2. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 1, characterized in that: The interior of the water pressure regulating tunnel is all constructed with waterproof concrete.

3. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 2, characterized in that: The water pressure regulating chamber and the tunnel are connected by a waterproof wall, which is composed of M10 mortar-grouted rubble masonry.

4. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 1, characterized in that: All drainage control pipes are HDPE non-porous corrugated pipes.

5. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 4, characterized in that: The HDPE non-porous corrugated pipe is of specification A100mm.

6. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 1, characterized in that: The water pressure regulating chamber is a column.

7. The karst tunnel lining bearing capacity and external water pressure balance system according to claim 6, characterized in that: The size of the water pressure regulating chamber is calculated based on the pressure formula. The size of the water pressure regulating chamber satisfies the condition that, when the chamber is filled with water, the water pressure on the bottom lining structure is less than the ultimate water pressure value of the lining structure.

8. A method for balancing the bearing capacity and external water pressure of karst tunnel lining in a karst tunnel lining bearing capacity and external water pressure balancing system as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. The monitoring center sets the regulating water pressure value, the safe water pressure value, and the maximum water level of each water pressure regulating chamber according to the ultimate water pressure value that the lining structure can withstand, so as to satisfy the ultimate water pressure value > regulating water pressure value > safe water pressure value. S2. Collect the water level of the karst cavity and the corresponding water pressure regulating chamber through water level sensors at various locations, and collect the external water pressure of the karst cavity and the corresponding water pressure regulating chamber through water pressure gauges at various locations. S3. When the monitoring center detects that the external water pressure at the karst cavity location is less than the safe water pressure value, all the decentralized control solenoid valves are in the closed state. S4. When the external water pressure at the karst cavity location is greater than the regulating pressure value, open the decentralized control solenoid valves corresponding to each water pressure regulating chamber on any side of the drainage pipeline, so that the water in the karst cavity is dispersed along the drainage pipeline to the water pressure regulating chamber below, thereby reducing the pressure value at the karst cavity location. S5. Determine whether the pressure value at the location of the karst cavity has decreased to the safe water pressure value. If yes, and the water level value of the lowest water pressure regulating chamber has not reached the maximum water level value, then close all the decentralized control solenoid valves above the lowest water pressure regulating chamber. If no, and the water level value of the lowest water pressure regulating chamber has reached the maximum water level value, then close the corresponding decentralized control solenoid valve, so that the water stays in the water pressure regulating chamber adjacent to the lowest water pressure regulating chamber and no longer flows into the lowest water pressure regulating chamber. S6. Perform the judgment and operation of S5 on other water pressure regulating chambers on the drainage pipeline on this side from bottom to top, until the water level of the uppermost water pressure regulating chamber reaches the maximum water level. Then close the decentralized control solenoid valve between the karst cavity and the uppermost water pressure regulating chamber, and open each decentralized control solenoid valve on the drainage pipeline on the other side. S7. Perform the judgments and operations of S5 and S6 on each water pressure regulating chamber on the other side of the drainage pipeline. S8. When the water level in the uppermost water pressure regulating chamber of both drainage pipelines reaches the maximum water level, open all the decentralized control solenoid valves and drainage control solenoid valves below the uppermost water pressure regulating chamber to allow all water in the water pressure regulating chambers to be discharged from the tunnel through the drainage ditch. When the monitoring center detects that the water level sensor values ​​in each water pressure regulating chamber are all zero, close all the decentralized control solenoid valves and drainage control solenoid valves.

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