Karst tunnel safe and environment-friendly drainage control method and system

Abstract

The application discloses a karst tunnel safe and environment-friendly drainage control method and system, and belongs to the technical field of intersection of tunnel engineering and geotechnical engineering. The method comprises the following steps: obtaining hydrogeological parameters of a tunnel site, tunnel structure parameters, rainfall recharge parameters, underground water flow monitoring data and lining pressure monitoring data; calculating total water inflow during the tunnel construction period; determining an ecological safe drainage amount range based on a vegetation ecological water demand theory; determining a structure safe drainage amount range based on surrounding rock-lining seepage stress coupling analysis; obtaining an allowable drainage amount range by taking the intersection of the two; constructing an automatic drainage system comprising a sensor, a local collection terminal, a transmission link, a local controller, a remote control center, a control logic engine, an emergency guarantee component, an alarm component, a primary electric main valve and a secondary buffer electric valve; and dynamically controlling in the underground water compensation stage during the construction period and the rainfall-drainage balance stage during the operation period. The application can ensure the safety of the tunnel lining structure while reducing the underground water level drop amplitude of the tunnel site, and realizes the automatic and fine control of the tunnel drainage.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly drainage technology, which is an intersection of tunnel engineering and geotechnical engineering. Specifically, it relates to a safe and environmentally friendly drainage control method and system for karst tunnels. Background Technology

[0002] When tunnel excavation and operation are carried out in water-rich karst areas, the tunnel lining structure is susceptible to high groundwater pressure, which can cause structural deformation, lining cracking, and even water leakage. Therefore, groundwater drainage is a core and critical process in water-rich karst tunnel engineering.

[0003] Traditional manual drainage systems are commonly used in existing tunnel engineering projects. Drainage is achieved by manually controlling the start and stop of water pumps. However, these systems can only perform simple on / off control and suffer from problems such as low automation, long delays in drainage regulation, and excessive reliance on the experience of operators, making it difficult to achieve precise control of drainage volume.

[0004] Currently, there is an urgent need for a precise and automated drainage system in water-rich karst tunnel projects. To solve the technical problems of "low degree of automation and poor emergency response capability" of traditional drainage systems, this invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a safe and environmentally friendly drainage control method and system for karst tunnels. By combining real-time monitoring, theoretical calculation, numerical simulation, and automatic control, an active drainage control system suitable for water-rich karst tunnels is constructed to achieve the following objectives: First, to rationally control the drainage volume and reduce the risk of structural water load while ensuring the safety of the tunnel lining structure; second, to slow down the decline of the groundwater level and reduce the adverse impact on the groundwater environment and vegetation ecosystem of the tunnel site while meeting ecological environmental protection requirements; and third, to improve the automation level, control accuracy, operational reliability, and ability to handle abnormal operating conditions of the drainage system. To achieve the above objectives, this invention provides the following technical solution.

[0006] A safe and environmentally friendly drainage control method and system for karst tunnels includes the following steps:

[0007] (1) Calculate the water inflow during tunnel construction based on railway engineering standard formulas and environmental precipitation theory;

[0008] (2) Based on the theory of vegetation ecological water demand and the stress simulation analysis of tunnel structure, the range of ecological safety drainage volume and the range of structural safety drainage volume are determined respectively. The intersection of the two is taken, and combined with the rainfall replenishment, the allowable drainage volume range that meets both ecological protection requirements and structural safety requirements is obtained.

[0009] (3) Construct an automated control drainage system, which includes a remote transmission component and an automated control component;

[0010] (4) Drainage regulation is performed based on real-time monitoring data. The drainage regulation process is divided into two stages: the first stage is the groundwater loss compensation stage during the construction period, and the second stage is the environmental rainfall and tunnel drainage balance stage during the operation period.

[0011] Furthermore, in step (1), the calculation process for the water inflow during the construction period includes:

[0012] ① Obtain hydrogeological data and tunnel engineering data from geological exploration departments and water conservancy management departments, and input the relevant data into the remote control center;

[0013] ② Calculate the initial water inflow of the tunnel :

[0014] (1)

[0015] In the formula: —Permeability coefficient of the aquifer, m / d; —Distance from the groundwater level to the tunnel centerline, in meters; — The radius of the tunnel, in meters; —The conversion factor is generally taken as 0.86.

[0016] ③ Calculate the radius of influence of the ground :

[0017] (Confined water)(2)

[0018] (Diving)(3)

[0019] In the formula: —Thickness of the aquifer, in meters; -for Arbitrary decrease time between; μ—specific yield of the aquifer.

[0020] ④ Calculate rainfall replenishment :

[0021] (4)

[0022] In the formula: —Rainfall infiltration coefficient; —Average annual rainfall, in meters; B—is the width of the tunnel; —Tunnel length, in meters (m).

[0023] ⑤ Calculate the total water inflow during the construction period :

[0024] (5)

[0025] ⑥ Calculate the total inflow. Set as the target value for the subsequent first phase of regulation.

[0026] Furthermore, in step (2), the specific calculation and simulation process is as follows:

[0027] ① Calculate the flow rate from the point where the maximum flow rate begins to decrease until a certain point in time. :

[0028] (6)

[0029] In the formula: ε—empirical factor, generally taken as 12.8;

[0030] ② Calculate the maximum drawdown depth that satisfies ecological security.

[0031] (7)

[0032] ③ Calculate the volume of the drainage funnel :

[0033] (8)

[0034] In the formula: —Water storage coefficient; —Depth of the cave wall, m.

[0035] ④ Calculate the maximum drainage volume when the maximum drawdown depth meets ecological security requirements. :

[0036] (9)

[0037] ⑤ Investigate water-rich areas of the tunnel, select the tunnel section with the most severe defects to establish a model, and calculate the tunnel diameter on the left and right sides of the model by 3 to 5 times.

[0038] ⑥ The model employs a coupled seepage and stress analysis. A total load is applied at the top to simulate the superposition of the self-weight load of the upper rock mass and the equivalent water pressure. Fixed constraints are applied at the bottom, while horizontal constraints on both sides serve as stress boundary conditions. Simultaneously, the pore pressure on both sides and the bottom of the model is fixed to allow for fluid exchange with the external environment.

[0039] ⑦ The surrounding rock is simulated using solid elements and follows the Mohr-Coulomb yield criterion. The tunnel support is considered as an elastic material, and the parameters are determined based on the geological survey report, indoor tests, and engineering experience.

[0040] ⑧ Set the drainage outlet of the secondary lining to a predetermined water pressure to simulate the drainage valve in the actual project. When the water pressure in the drainage pipe exceeds the pressure of the drainage valve, the water will be discharged.

[0041] ⑨ Set the predetermined water pressure at the outlet of the drainage pipe, simulate the coupling effect of the seepage field and stress field under different valve pressures, and obtain the water pressure distribution outside the lining and the stress state of the structure.

[0042] ⑩ Based on the safety factor calculation formula:

[0043] (10)

[0044] In the formula: —The critical stress of the material, ; —Maximum working stress, .

[0045] ⑪ Extract the maximum stress value of key components of the lining. Quantify structural safety by calculating the safety factor of these key components, and determine the range of tunnel drainage at this point. As the range of drainage capacity for structural safety.

[0046] ⑫ Calculate rainfall replenishment :

[0047] (11)

[0048] In the formula: —Average rainfall during the dry season, in meters.

[0049] ⑬ Take the allowable drainage volume :

[0050] (12)

[0051] Furthermore, in step (3), the automated control drainage system includes a remote transmission component and an automated control component;

[0052] The remote transmission component includes sensors, a local acquisition terminal, and a transmission link; the automation control component includes a local controller, a remote control center, a control logic engine, an emergency support component, an alarm component, and a secondary electric valve.

[0053] Furthermore, the sensors include a tunnel lining pressure sensor and a groundwater flow sensor. The lining pressure sensor is installed in the circumferential stress concentration area of ​​the lining in the water-rich karst section, preferably within a range of 45° to 60° on both sides of the arch; the groundwater flow sensor is installed in the main drainage pipe to monitor the drainage volume.

[0054] Furthermore, the local acquisition terminal is deployed in the segmented maintenance wells or segmented pumping stations in the water-rich karst section to preprocess, locally cache, and convert the data collected by the sensors; the transmission link adopts a wired transmission as the main method and a wireless transmission as a supplement to improve the stability of data transmission under complex tunnel conditions.

[0055] Furthermore, the remote control center is used to process monitoring data, visualize and display it, issue remote commands, monitor pump group status, issue alarms for abnormalities, and store historical data; the control logic engine is used to generate valve control commands according to preset control logic; the local controller is used to receive control commands output by the control logic engine and control the primary electric main valve and the secondary buffer electric valve to perform corresponding actions.

[0056] Furthermore, the emergency support component is used to switch the automatic control mode to the manual control mode when a drainage pipe ruptures, control abnormalities occur, or other emergency conditions occur; the alarm component is used to issue graded alarms for situations such as abnormal water accumulation, pump set failure, and failure to obtain the allowable drainage volume within a predetermined number of cycles.

[0057] Furthermore, in step (4), the first stage is the groundwater loss compensation stage during the construction period, and its control process includes:

[0058] The total inflow calculated in step (1) is used as the first-stage control target;

[0059] The maximum value in the allowable drainage range determined in step (2) is taken as the initial preset value of the first-stage electric main valve;

[0060] Real-time monitoring of underground flow changes, and combined with the calculation results of step (2) to determine whether the current drainage volume is within the range of ecologically safe drainage volume;

[0061] When the current drainage volume is within the ecological safety drainage volume range, continue to monitor the lining pressure change, and combine the numerical simulation results of step (2) to determine whether the current drainage volume is within the structural safety drainage volume range;

[0062] If the current drainage volume does not meet the structural safety drainage volume range, the secondary buffer electric valve is activated for compensation and adjustment; if the structural safety requirements are still not met after adjustment, the flow rate of the primary electric main valve is reset by the remote control center, and the above process is repeated until the current drainage volume meets both the ecological safety drainage volume range and the structural safety drainage volume range.

[0063] If the required number of adjustments exceeds the predetermined number and the required drainage volume that simultaneously satisfies both constraints is still not obtained, then the drainage volume that meets the ecological security requirements and is closest to the structural safety range from the historical adjustment results will be selected as the new preset value, and adjustments will continue until the predetermined error threshold is reached.

[0064] Furthermore, the second stage is the operational phase, which involves balancing environmental rainfall and tunnel drainage. Its control process includes:

[0065] The middle value in the allowable drainage range determined in step (2) is used as the initial preset value of the first-stage electric main valve;

[0066] The subsequent monitoring, assessment, and control processes are the same as in the first stage;

[0067] During this stage, as long as the actual drainage volume of the tunnel remains within the allowable drainage volume range, the control is considered successful.

[0068] The present invention also provides an apparatus, device, and computer-readable storage medium. The apparatus includes a processor and a memory, the memory storing a computer program. When the processor executes the computer program, it implements the steps of the above-described construction method. The storage medium stores a computer program, which, when executed by the processor, implements the steps of the above-described construction method. Specifically, the apparatus may correspond to a remote control center, a local controller, or a control unit composed of both.

[0069] Beneficial effects

[0070] Compared with the prior art, the present invention has at least the following beneficial effects:

[0071] This invention achieves a balance between ecological environmental protection and tunnel structural safety during drainage control by separately determining the ecological safety drainage range and the structural safety drainage range, and using the intersection of the two as the allowable drainage range.

[0072] This invention combines theoretical calculations, numerical simulations, real-time monitoring, and automatic control, enabling dynamic adjustment of the primary electric main valve and the secondary buffer electric valve based on changes in groundwater level and lining pressure, thereby improving the accuracy and responsiveness of drainage control.

[0073] This invention adopts a two-stage control strategy that combines the groundwater loss compensation stage during construction and the environmental rainfall-drainage balance stage during operation. This strategy can both compensate for groundwater loss during construction and maintain a relatively stable groundwater level during operation.

[0074] This invention improves the system's automation level, operational reliability, and ability to respond to abnormal conditions by setting up a remote control center, control logic engine, alarm components, and emergency support components. Attached Figure Description

[0075] Figure 1 This is a schematic diagram of the automated control drainage logic of a safe and environmentally friendly drainage system for karst tunnels, provided as an embodiment of the present invention.

[0076] Figure 2 This diagram illustrates the control effect of a safe and environmentally friendly drainage system for karst tunnels, as provided in an embodiment of the present invention. Detailed Implementation

[0077] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, improvements, and variations made within the spirit and principles of the present invention should fall within the scope of protection of the present invention.

[0078] Implementation Cases

[0079] Taking a railway tunnel project in a water-rich karst area as an example, the specific implementation of the present invention will be described. The tunnel is 6.8 km long, with a water-rich karst section of 2.9 km. The aquifer permeability coefficient is 0.65 m / d, the tunnel radius is 4.8 m, and the burial depth ranges from 65 m to 130 m. The surface vegetation in the tunnel site area is mainly subtropical evergreen broad-leaved forest, which requires high stability of the groundwater environment.

[0080] Step 1 Data acquisition and calculation of water inflow during the construction period

[0081] First, geological and hydrological data of the tunnel's surrounding area and tunnel engineering data were obtained from local geological survey and water conservancy departments. The acquired data was standardized and then input into the remote control center. Next, the initial water inflow of the tunnel was calculated using the railway engineering specification formulas in the original document, and the rainfall replenishment was calculated based on environmental precipitation theory. The initial water inflow was calculated to be 2350 m³ / d, and the average annual rainfall replenishment was 486 m³ / d. The final total water inflow during the tunnel construction period was determined to be 1864 m³ / d, which was then used as the control target for the groundwater loss compensation stage.

[0082] Step Two Determination of permissible discharge range

[0083] Based on the theory of vegetation ecological water demand, the maximum drawdown of the groundwater level in the tunnel site area to meet the ecological safety requirements was calculated to be 3.2 m, and the corresponding ecological safety drainage volume ranged from 700 m³ / d to 1100 m³ / d.

[0084] Meanwhile, a numerical model of tunnel seepage-stress coupling was established using FLAC3D to simulate the stress state of the lining structure under different valve pressure conditions, and the safe drainage capacity of the structure was determined to be between 800 m³ / d and 1200 m³ / d based on the safety factor calculation results.

[0085] The intersection of the above-mentioned ecological safety drainage range and structural safety drainage range is calculated, and then corrected by incorporating the dry season rainfall replenishment of 168 m³ / d. The final permissible drainage range is 800 m³ / d to 1100 m³ / d, with a maximum value of 1100 m³ / d and a median value of 950 m³ / d.

[0086] Step 3 Construction of Automated Control Drainage System

[0087] Complete the selection, installation, and deployment of each component of the system in accordance with the requirements of this invention specification.

[0088] The sensor section includes 58 lining pressure sensors and groundwater flow monitoring devices, used to collect lining pressure data and groundwater flow data, respectively; five local acquisition terminals are deployed in the water-rich karst section, one every 600 m, used for preprocessing, local caching and protocol conversion of monitoring data; the transmission link adopts wired transmission as the main method and wireless transmission as a supplement to ensure the reliability of data transmission in complex tunnel environments.

[0089] The control components include a local controller, a control logic engine, a remote control center, emergency backup components, alarm components, and two-stage electric valves, used to perform functions such as command generation, valve execution, abnormal alarms, and emergency switching. After the installation of each component is completed, the platform setup, transmission links, control logic, and valve regulation functions are integrated and tested to form a closed-loop control system.

[0090] Step Four Phased drainage regulation

[0091] (I) Groundwater Loss Compensation Phase during Construction

[0092] A total inflow of 1864 m³ / d was input into the system, and the maximum value of 1100 m³ / d within the allowable drainage range was selected as the initial preset flow rate for the primary electric main valve. Subsequently, dynamic control was performed according to the preset control logic of this invention: first, the groundwater flow rate was monitored to determine whether the current drainage volume met the ecological safety drainage range; then, the lining pressure was monitored to determine whether the current drainage volume met the structural safety drainage range. When the structural safety requirements were not met, the secondary buffer electric valve was activated for compensation and adjustment, and the flow rate of the primary electric main valve was reset if necessary. During the control process, the groundwater level gradually rose, and groundwater loss compensation was completed in the ninth month, with the groundwater level recovering to above the ecological threshold, marking the end of the first stage.

[0093] (II) Environmental Rainfall-Drainage Balance Phase During Operation

[0094] After the first phase was completed, the system automatically switched to the second phase. The median value of 950 m³ / d within the permissible drainage range was selected as the initial preset flow rate for the primary electric main valve. Subsequent monitoring, judgment, and control processes were the same as in the first phase. After 12 months of continuous monitoring, the groundwater level in the tunnel site remained stable between 155 m and 160 m, consistently above the ecological threshold. The safety factor of the tunnel lining structure remained between 1.9 and 2.3, meeting structural safety requirements, thus achieving the dual goals of tunnel structural safety and ecological environmental protection.

[0095] Other implementation details

[0096] The above embodiments are merely preferred embodiments of the present invention. For those skilled in the art, without departing from the concept of the present invention, the model parameters, the number of sensors, valve specifications, and control parameters can be adaptively adjusted according to different tunnel depths, surrounding rock conditions, aquifer types, rainfall recharge conditions, and monitoring deployment schemes; these adjustments should not be considered as departing from the protection scope of the present invention.

Claims

1. A safe and environmentally friendly drainage control method for karst tunnels, characterized in that, Includes the following steps: (1) Obtain hydrogeological parameters, tunnel engineering parameters, rainfall recharge parameters, groundwater flow monitoring data and tunnel lining pressure monitoring data of the tunnel site area; (2) Calculate the total water inflow during the tunnel construction period based on the hydrogeological parameters of the tunnel site area, tunnel engineering parameters, and rainfall recharge parameters; (3) Determine the range of ecological safety drainage volume based on the theory of vegetation ecological water demand and the allowable drawdown of groundwater level; (4) Based on the seepage stress coupling analysis of surrounding rock and lining, determine the range of safe drainage volume of the structure; (5) Find the intersection of the ecological safety drainage range and the structural safety drainage range to obtain the allowable drainage range; (6) Construct an automated control drainage system, wherein the automated control drainage system includes at least sensors, local acquisition terminals, transmission links, local controllers, remote control centers, control logic engines, emergency support components, alarm components, and secondary electric valves, wherein the secondary electric valves include primary electric main valves and secondary buffer electric valves; (7) During the groundwater compensation phase of the construction period, the total inflow during the construction period is used as the control target and the allowable drainage range is used as the constraint. Based on the groundwater level drawdown calculation data and lining pressure monitoring data, the opening degree of the primary electric main valve and the secondary buffer electric valve are dynamically adjusted. (8) During the rainfall-drainage balance phase of the operation period, the allowable drainage volume range is used as the control interval. Based on real-time monitoring data, the opening degree of the first-stage electric main valve and the second-stage buffer electric valve are dynamically adjusted so that the actual drainage volume is maintained within the allowable drainage volume range.

2. The safe and environmentally friendly drainage control method for karst tunnels according to claim 1, characterized in that, Step (2) includes: Calculate the initial water inflow of the tunnel according to the formula in the railway engineering specifications. : (1) In the formula: —Permeability coefficient of the aquifer, m / d; —Distance from the groundwater level to the tunnel centerline, in meters; — The radius of the tunnel, in meters; —Conversion factor, generally taken as 0.86; Calculate the ground influence radius based on aquifer type. : (Confined water)(2) (Diving)(3) In the formula: —Thickness of the aquifer, in meters; -for Arbitrary decreasing time between intervals; μ—specific yield of the aquifer; Rainfall replenishment is calculated based on rainfall infiltration coefficient, annual average rainfall, tunnel width, and tunnel length. : (4) In the formula: —Rainfall infiltration coefficient; —Average annual rainfall, in meters; B—is the width of the tunnel; —Tunnel length, in meters; The total water inflow during the tunnel construction period is determined based on the initial water inflow and the rainfall replenishment. : (5) by This serves as the theoretical basis for the first-stage control target.

3. The safe and environmentally friendly drainage control method for karst tunnels according to claim 1, characterized in that, Steps (3) and (4) include: The maximum drawdown of groundwater level to meet ecological security requirements is calculated based on the theory of vegetation ecological water demand, and the range of ecological security drainage volume is determined accordingly. A seepage stress coupling model of tunnel surrounding rock-lining was established. By setting a predetermined water pressure at the outlet of the drainage pipe, the coupling effect of seepage field and stress field under different valve pressure conditions was simulated to obtain the external water pressure distribution and structural stress state of the lining. The safety factor is calculated based on the maximum working stress and critical stress of the material in the key parts of the lining, and the drainage range corresponding to the preset safety factor requirement is determined as the structural safe drainage range. The allowable drainage range is obtained by intersecting the ecological safety drainage range and the structural safety drainage range, and then adjusting it based on the amount of rainfall replenishment during the dry season.

4. The safe and environmentally friendly drainage control method for karst tunnels according to claim 1, characterized in that, The sensors include a groundwater flow sensor and a lining pressure sensor; the lining pressure sensor is deployed in the circumferential stress concentration area of ​​the lining in the water-rich karst section; the groundwater flow sensor is deployed in the drainage pipe; the local acquisition terminal is used to preprocess, locally cache, and convert the data collected by the sensors; the transmission link adopts wired transmission as the main method and wireless transmission as the auxiliary method to realize data transmission; the remote control center is used for monitoring data processing, visualization display, control command issuance, alarm management, and historical data storage; the local controller is used to receive control commands output by the control logic engine and execute valve adjustment.

5. The safe and environmentally friendly drainage control method for karst tunnels according to claim 1, characterized in that, The control process of the groundwater compensation stage during the construction period in step (7) includes: taking the total inflow during the construction period as the first-stage control target; taking the upper limit of the allowable drainage range as the initial preset value of the primary electric main valve; acquiring groundwater flow monitoring data in real time to determine whether the current drainage volume is within the ecological safety drainage range; when the current drainage volume is within the ecological safety drainage range, further acquiring lining pressure monitoring data to determine whether the current drainage volume is within the structural safety drainage range; when the current drainage volume is not within the structural safety drainage range, activating the secondary buffer electric valve for compensation adjustment; when the structural safety drainage range is still not met after adjustment by the secondary buffer electric valve, resetting the preset value of the primary electric main valve and repeating the adjustment until the current drainage volume enters the allowable drainage range.

6. The safe and environmentally friendly drainage control method for karst tunnels according to claim 5, characterized in that, If the current drainage volume fails to enter the allowable drainage volume range within the preset number of times, the corresponding drainage volume value that meets the ecological safety requirements and is closest to the structural safety drainage volume range is selected from the previous control results and used as the reset preset value of the first-stage electric main valve. After resetting, groundwater flow monitoring data and lining pressure monitoring data are collected to check the deviation between the current drainage volume and the preset drainage volume until the deviation does not exceed the preset error threshold.

7. The safe and environmentally friendly drainage control method for karst tunnels according to claim 1, characterized in that, The operation period rainfall-drainage balance stage in step (8) includes: using the middle value of the allowable drainage volume range as the initial preset value of the primary electric main valve; controlling according to the same monitoring, judgment and adjustment logic as the groundwater compensation stage during the construction period; and determining that the control is successful when the actual drainage volume is maintained within the allowable drainage volume range.

8. A safe and environmentally friendly drainage control system for karst tunnels, characterized in that, include: Sensors are used to collect data on groundwater drainage and lining pressure. A local data acquisition terminal is used to receive and preprocess the data acquired by the sensor. A transmission link is used to realize data transmission between the local acquisition terminal, the local controller, and the remote control center; the remote control center is used to process the monitoring data according to the preset control logic and generate valve control commands; the control logic engine is used to output control strategies based on lining pressure data, drainage pipe flow data, and allowable drainage range; the local controller is used to drive the secondary electric valves to operate according to the control strategy; the secondary electric valves include a primary electric main valve and a secondary buffer electric valve; an emergency backup component is used to switch the automatic control mode to the manual control mode under abnormal operating conditions; an alarm component is used to provide graded alarms for abnormal water accumulation, pump set failure, and control failure; wherein, the system is configured to execute the method described in any one of claims 1 to 7.

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