Quantitative description device capable of being used for researching karst collapse and use method of quantitative description device

Abstract

The invention relates to the technical field of physical simulation, monitoring and early warning of karst geological disasters, in particular to a quantitative description device capable of being used for researching karst collapse and a use method thereof, and the quantitative description device comprises a main body model, a karst pipeline simulation system, a hydrological process control system and a multi-parameter data monitoring and acquisition system. Through cooperative operation of the systems, the physical process of'differential pressure induced collapse 'induced by rapid rising and falling of the underground water level can be simulated, and quantitative data acquisition and fusion analysis of the whole process of intra-cavity differential pressure, soil internal stress and strain and earth surface deformation are realized by means of an integrated multi-dimensional synchronous monitoring network; the dynamic mechanism and the key threshold value of differential pressure collapse are disclosed, and a reliable experimental platform and a quantitative basis are provided for mechanism research, risk assessment and early warning prevention and control of karst collapse.

Description

Technical Field

[0001] This invention relates to the field of physical simulation and monitoring and early warning technology for karst geological disasters, and in particular to a quantitative characterization device for studying karst collapse and its usage method. Background Technology

[0002] Karst collapse is a common geological hazard in overburdened karst areas, with a complex formation mechanism. "Pressure differential collapse" is one of the important triggering mechanisms. Currently, quantitative and visual research methods for pressure differential collapse processes are inadequate, lacking experimental devices and methods capable of systematically simulating the positive and negative pressure differential effects caused by water level fluctuations and achieving simultaneous monitoring and quantitative characterization of multiple parameters. Therefore, there is an urgent need for a device and method capable of reproducing the entire collapse process, collecting multi-dimensional data, and establishing early warning indicators based on this data.

[0003] Therefore, we propose a quantitative characterization device and its usage method for studying karst collapse, in order to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a quantitative characterization device and its usage method for studying karst collapse, which solves the problem in the prior art of lacking an integrated physical simulation method that can highly reproduce complex karst conduit structures, accurately control hydrological processes, and simultaneously realize quantitative monitoring and fusion analysis of multi-dimensional parameters for pressure differential collapse mechanisms.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A quantitative characterization device for studying karst collapse includes: The main model box has a transparent observation section at the top and a connection port at the bottom. The simulated karst conduit system has its top sealed to the bottom of the model box. The hydrological process control system includes a water injection device connected to the pipeline system, a main drainage device for simulating water level drop, and a dredging drainage device for clearing sediment; the water injection device and the main drainage device are equipped with flow sensors. The multi-parameter data monitoring and acquisition system includes a sensor group deployed inside the soil, pressure sensors deployed in the pipeline system, image acquisition equipment deployed above the model box, and a data acquisition unit.

[0006] Preferably, the simulated karst pipeline system is a resin structure integrally formed based on a three-dimensional geological model using 3D printing technology, with multiple channels reserved inside for simulating the main pipeline, dissolution fissures, and sensor interfaces.

[0007] Preferably, the sensor group deployed inside the soil includes pore pressure sensors, displacement sensors, and soil pressure sensors arranged at different depths along the vertical direction; the image acquisition equipment includes a three-dimensional laser scanner and a high-speed camera.

[0008] Preferably, the transparent observation section of the main model box is equipped with a scale, and the water injection device and drainage device of the hydrological process control system are both equipped with a high-precision first flow sensor, a second flow sensor and a controllable valve to accurately simulate water level rise and fall at different rates. The dredging and drainage device is connected to the lowest point of the simulated karst pipeline system.

[0009] A method for using a quantitative characterization device for studying karst collapse, based on the quantitative characterization device for studying karst collapse as described in claim 1, is characterized by comprising the following steps: S1. Equipment preparation and soil laying: Fill the transparent model box with simulated overburden soil; S2. Sensor deployment and system debugging: Deploy various types of sensors inside the soil, on the surface, and at key locations in the simulated karst pipeline, and connect them to the data acquisition system. S3. Simulate the collapse process caused by water level changes: By controlling the rate of water inlet and outlet of the connected pipeline system, simulate the rapid drop and rapid rise of the groundwater level respectively. S4. Multi-parameter synchronous monitoring: During the water level change process, the air pressure or water pressure data in the karst pipe, the pore water pressure inside the overburden soil, displacement and earth pressure data, and deformation image data of the soil surface are collected simultaneously. S5. Data Fusion and Relationship Analysis: Align and fuse the collected multi-source time series data to quantitatively analyze the dynamic relationship between water level change rate, pressure difference change in karst pipeline and overburden soil response. S6. Establishing the early warning threshold: Based on the quantitative relationship in step S5, determine the critical differential pressure threshold that induces the destruction of the overburden and the corresponding water level change conditions.

[0010] Preferably, in step S3, the simulated rapid rise in groundwater level specifically involves: by controlling the water injection rate of the water injection device, a positive pressure environment is created within the simulated karst pipeline system, inducing a "burst" type collapse.

[0011] Preferably, in step S3, the simulated rapid rise in groundwater level specifically involves: by controlling the water injection rate of the water injection device, a positive pressure environment is created within the simulated karst pipeline system, inducing a "burst" type collapse.

[0012] Preferably, in step S4, the synchronous monitoring includes at least monitoring the air pressure at the top of the pipeline using a pressure sensor, monitoring the response at different depths inside the soil using a pore pressure sensor, a displacement sensor, and a soil pressure sensor, and monitoring the full-field deformation and fracture development process of the soil surface using a 3D scanner and a high-speed camera.

[0013] Preferably, in step S5, the quantitative analysis specifically includes establishing the time history curve of pressure difference in the pipeline, the time history curve of displacement of key points in the soil, and the surface settlement rate curve, and analyzing the phase and amplitude coupling relationship between them.

[0014] Preferably, in step S6, model verification and parameter expansion, i.e., by adjusting the thickness, density or mechanical parameters of the overburden soil, repeating steps S3 to S6, the universality of the warning threshold is verified and a warning parameter system for different geological conditions is established.

[0015] The present invention has at least the following beneficial effects: This invention enables a refined quantitative study of the pressure differential-induced collapse process: By integrating a high-precision flow control system with a multi-parameter synchronous monitoring system, it can precisely control the rate of water level rise and fall and capture millisecond-level dynamic changes in intracavitary pressure differential, soil internal response, and surface morphology in real time. This allows researchers to establish a precise quantitative relationship between the rate of water level change, the critical pressure differential threshold, and the failure mode of the overburden layer, breaking through the limitations of previous qualitative or semi-quantitative studies and providing high-precision experimental data support for the study of the mechanism of karst collapse.

[0016] The present invention also has the following beneficial effects: This method enhances the realism and flexibility of geological prototype simulation: 3D printing technology based on a three-dimensional geological model is used to integrate the fabrication of karst conduit systems. This allows for highly accurate reproduction of the complex conduit networks, dissolution cavities, and fracture structures found in actual geological sites, overcoming the limitations of traditional hand-fabricated conduits, which suffer from limited form and difficulty in replicating realistic structures. Furthermore, this method allows for the rapid replacement of conduit models with different geological structures, significantly improving the device's adaptability to various karst hydrogeological conditions and enhancing research efficiency.

[0017] The present invention also has the following beneficial effects: This invention bridges the gap between experimental and early warning applications: The device and method not only reproduce the collapse phenomenon but also focus on collecting multi-dimensional data through systematic parametric experiments (such as changing overburden thickness, soil properties, and water level fluctuations) to construct a database of the correspondence between "collapse conditions, monitoring parameters, and early warning thresholds." This provides a direct and reliable technical approach to transforming laboratory research results into quantitative early warning indicators (such as critical pressure difference and safe water level change rate) applicable to practical engineering, strongly supporting risk assessment and proactive prevention of karst collapse. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a top view of the structure of the present invention; Figure 3 This is a schematic diagram of the main pipeline structure of the present invention.

[0020] In the diagram: 1. Main model; 2. Water inlet; 3. Dredging and drainage outlet; 4. Main drainage outlet; 5. Air pressure sensor; 6. First flow sensor; 7. Second flow sensor; 8. Pore pressure sensor; 9. Displacement sensor; 10. Soil pressure sensor; 11. 3D scanner; 12. High-speed camera. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Reference Figure 1-3 A quantitative characterization device for studying karst collapse and its usage method, comprising: a main model 1, a simulated karst conduit system, a hydrological process control system, and a multi-parameter data monitoring and acquisition system.

[0023] The main model 1 is a box-shaped structure with an open top, measuring 0.6m (length) × 0.6m (width) × 1.0m (height). The upper part (approximately 0.6m high) is made of high-strength transparent acrylic glass for easy observation throughout the process, and precise vertical and horizontal scales are etched on the outer wall for quantitative monitoring of soil deformation. The lower part (approximately 0.4m high) is a stable steel frame structure supported by four 0.05m × 0.05m cross-section columns. The tops of the columns have grooves that fit tightly into the upper glass box, ensuring overall stability. A circular connection port is located at the center of the bottom of the box.

[0024] The simulated karst pipeline system is based on a three-dimensional digital model of the karst geological structure of the target site. It is manufactured using stereolithography (SLA) 3D printing technology and integrally molded with translucent photosensitive resin. The system simulates the main pipeline, branch fissures, and dissolution cavities, and includes a total of five standard interface channels. The main pipeline outlet at the top is sealed to the connection port at the bottom of the main model 1 via a flange and sealing ring.

[0025] Hydrological process control systems include: 1. Water injection device: Composed of an external water storage tank, a miniature water pump, a precision regulating valve, and PVC pipes, with its water injection port 2 connected to the front end of the pipeline system. A first high-precision flow sensor 6 (range 0-20 L / min, accuracy ±0.5%) is installed on the water injection pipeline to monitor and control the water injection rate; 2. Main drainage device: used to actively control the drop in water level. Its main drainage outlet 4 is connected to the middle of the pipeline system. A second high-precision flow sensor 7 and a solenoid valve are installed on the pipeline to accurately control the drainage rate. 3. Dredging and Drainage Device: This is an independent drainage pipeline. Its dredging and drainage outlet 3 is directly connected to the lowest point at the end of the simulated karst pipeline system and is equipped with a manual ball valve. This device does not participate in the water level control process and is specifically used to quickly remove silt and sediment deposits caused by the collapse after the test, ensuring the pipeline remains unobstructed for repeated tests.

[0026] The multi-parameter data monitoring and acquisition system includes: 1. Internal sensor array: Within the filled overburden soil, miniature pore pressure sensors 8, miniature displacement sensors 9, and miniature earth pressure sensors 10 are deployed vertically in three layers (e.g., 0.1m, 0.25m, and 0.4m from the bedrock surface). All sensor signal lines exit through pre-drilled holes in the side wall of the model box. 2. Pipeline monitoring sensor: A high-precision air pressure sensor 5 is installed at the top of the simulated pipeline system, at the same height as the bottom of the main model 1, to monitor changes in air pressure (or water pressure) within the karst cavity; 3. Surface Image Acquisition Equipment: A 3D laser scanner 11 (such as a ground-based lidar) and a high-speed camera 12 (frame rate no less than 500fps) are fixedly installed approximately 1.5m directly above the main model 1. The 3D laser scanner is used to acquire high-precision surface topography data before, during, and after the collapse, while the high-speed camera is used to capture the dynamic fracturing process at the moment of collapse. 4. Data Acquisition Unit: A multi-channel synchronous data acquisition unit is used, with all sensor signal lines connected to it. The acquisition unit connects to the monitoring computer, and dedicated software enables synchronous triggering, real-time display, high-speed recording, and storage of all data.

[0027] Example 1: Quantitative characterization of the collapse process caused by differential pressure under a standard red clay overburden layer This embodiment aims to simulate the entire process of collapse induced by rapid water level changes under typical red clay overburden conditions, and to determine the critical threshold.

[0028] S1: Equipment Preparation and Soil Laying: Inside the main model 1, an undulating simulated bedrock surface is constructed using bricks and cement mortar, with interfaces reserved at predetermined locations for connection to the piping system. Natural red clay taken from a karst area is air-dried, crushed, and sieved through a 2mm sieve. A soil sample with a moisture content of 18% is prepared and layered into the model box, each layer 5cm thick. A custom-made compaction hammer is used to control the compaction effort, achieving a soil density of 1.65 g / cm³. 3 This ultimately forms a uniform covering layer with a total thickness of 40cm.

[0029] S2: Sensor Deployment and System Debugging: During the backfilling process, bury the pore pressure sensor 8, displacement sensor 9, and earth pressure sensor 10 at the preset locations, and install and connect all monitoring equipment. Close the dredging drainage outlet 3 and the main drainage outlet 4, and slowly inject water into the pipeline system through the water inlet 2 until it is full, then let it stand for 5 minutes. Observe the reading of the air pressure sensor 5; if its fluctuation is less than ±0.2 kPa, it indicates that the system has good airtightness.

[0030] S3: Simulated Water Level Drop Induced by Negative Pressure Collapse: Initial State: Open all valves to allow the water in the system to remain still and the air pressure to balance with atmospheric pressure; Experimental Process: Close water inlet 2, quickly open the solenoid valve of main drain outlet 4, and stabilize the drainage rate at 12 L / min by monitoring the second flow sensor 7. The rapid drop in water level creates negative pressure in the cavity at the top of the karst pipe; Data Acquisition: Simultaneously start the data acquisition instrument, 3D laser scanner 11, and high-speed camera 12. Continuously monitor until the overburden layer shows obvious collapse or drainage ends.

[0031] S4: Simulated Water Level Rise Inducing Positive Pressure Collapse: Recovery and Preparation: Slowly inject water through injection port 2 to restore the system to its initial static state, and allow it to stand for 24 hours to allow the pore water pressure in the soil to rebalance. Use dredging and drainage port 3 to remove the small amount of silt generated in the previous test; Test Procedure: Close all drainage valves. Start the water injection pump, and use the first flow sensor 6 to stabilize the water injection rate at 15 L / min to simulate a sudden rise in groundwater level, generating positive pressure in the pipe cavity; Data Acquisition: Same as above, simultaneously start all monitoring equipment to record the entire process of positive pressure burst collapse.

[0032] S5: Data Fusion and Relationship Analysis: All sensor data (time series) were synchronized and aligned with high-speed video frames and 3D scanning time points at the millisecond level; Key parameters were extracted: Using data from barometric pressure sensor 5 as a benchmark, a "pressure difference within the cavity (relative to atmospheric pressure) - time" curve was plotted; Data from displacement sensor 9 at a specific depth was extracted, and a "soil displacement - time" curve was plotted; The "surface settlement - time" curve was calculated using 3D scanning point cloud data; Quantitative analysis revealed that when the negative pressure within the cavity reached the range of -4.8 kPa to -5.2 kPa, the overburden layer began to undergo accelerated displacement, and overall collapse occurred approximately 1.2 seconds later. The critical threshold range for positive pressure-induced collapse was +7.5 kPa to +8.0 kPa.

[0033] S6: Early warning threshold establishment: Based on the statistical data of 5 repeated experiments, the early warning threshold was determined under the following experimental conditions (red clay, density 1.65 g / cm³). 3 Under conditions of 40cm thickness: the warning threshold for negative pressure-induced collapse is -4.5 kPa. When the monitored negative pressure inside the cavity approaches this value, the risk of collapse increases significantly; the warning threshold for positive pressure (burst)-induced collapse is +7.0 kPa; a preliminary dataset of the correspondence between "critical differential pressure threshold - overburden thickness" has been established.

[0034] Example 2: Verification and Expansion of Pressure Difference-Induced Collapse Threshold under Different Cover Layer Thicknesses This embodiment is based on Embodiment 1. By changing key parameters, it verifies the universality of the device and method and expands the early warning model.

[0035] S1: Parameter Adjustment: Maintain soil type (red clay), moisture content (18%), and compaction density (1.65 g / cm³). 3 The thickness of the covering layer remains unchanged, but is adjusted to two working conditions: 30cm and 50cm.

[0036] S2-S4: Repeated tests: For the cover layer with a thickness of 30cm and 50cm respectively, strictly follow the steps S2 to S4 of Example 1 to repeat the two sets of simulation tests of "water level drop - negative pressure collapse" and "water level rise - positive pressure collapse", and repeat each thickness condition 3 times.

[0037] S5: Comparative Analysis: Compile critical pressure difference data for different thicknesses: When the overburden thickness is 30cm: the critical threshold for collapse under negative pressure is -3.2 kPa ± 0.3 kPa; the critical threshold for collapse under positive pressure is +5.5 kPa ± 0.4 kPa; When the overburden thickness is 50cm: the critical threshold for collapse under negative pressure is -6.5 kPa ± 0.4 kPa; the critical threshold for collapse under positive pressure is +9.8 kPa ± 0.5 kPa; The analysis shows that under the same soil conditions, the greater the thickness of the overburden, the stronger the ability to resist collapse under pressure difference, and the greater the critical pressure difference (absolute value) required to trigger collapse.

[0038] S6: Establishment of Early Warning Parameter System: Based on the data from Example 1 and this example, a pressure differential collapse early warning threshold matrix can be established for this red clay at different thicknesses. For example, by interpolation, it can be estimated that for a similar overburden layer with a thickness of 35cm, the negative pressure early warning threshold is approximately -3.8 kPa, and the positive pressure early warning threshold is approximately +6.2 kPa. This result verifies that the device and method of this invention can be used to systematically study the influence of different geological condition parameters on pressure differential collapse sensitivity, providing a reliable experimental data basis and quantitative research method for constructing a more universal karst collapse early warning model.

[0039] Post-test cleanup: After each series of tests, open the ball valve of dredging and drainage port 3, and use water flow to thoroughly flush out the collapsed soil and silt accumulated in the pipeline system and at the bottom of the model box, ensuring the device is clean and ready for the next test.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A device for quantitative characterization of karst collapse, which can be used for research, characterized in that, The utility model relates to a karst collapse simulation device and method, comprising: a main body model (1) with a transparent observation part in the upper part and a connecting port in the bottom part; a simulated karst conduit system with the top part being in sealed connection with the connecting port in the bottom part of the main body model (1); a hydrological process control system comprising a water injection device, a main drainage device for simulating water level drop and a dredging drainage device (3) for cleaning sediments, which are in communication with the conduit system; the water injection device and the main drainage device are provided with flow sensors; a multi-parameter data monitoring and acquisition system comprising a sensor group arranged in the soil body, pressure sensors arranged in the conduit system, an image acquisition device arranged above the model box and a data collector.

2. A device for quantitative characterization of karst collapse, according to claim 1, characterized in that, The simulated karst conduit system is a resin structure integrally formed based on a three-dimensional geological model by using 3D printing technology, and a plurality of channels for simulating main conduits, corrosion fissures and sensor interfaces are reserved in the resin structure.

3. A device for quantitative characterization of karst collapse, according to claim 1, characterized in that, The sensor group arranged in the soil body comprises pore pressure sensors (8), displacement sensors (9) and soil pressure sensors (10) arranged at different vertical depths; the image acquisition device comprises a three-dimensional laser scanner and a high-speed camera (12).

4. The device for quantitative characterization of karst collapse according to claim 1, characterized in that, The transparent observation part of the main body model (1) is provided with a scale, and the water injection port (2) of the water injection device and the main drainage port (4) of the drainage device of the hydrological process control system are each provided with a high-precision first flow sensor (6), a second flow sensor (7) and a controllable valve for accurately realizing water level drop simulation at different rates; the dredging drainage device (3) is connected to the lowest point of the simulated karst conduit system.

5. The method for using the device for quantitative characterization of karst collapse, according to claim 1, characterized in that, The method comprises the following steps: S1, device preparation and soil laying: filling simulated overburden soil in the transparent model box; S2, sensor arrangement and system debugging: arranging multiple types of sensors in the soil body, on the surface of the soil body and at key positions of the simulated karst conduit, and connecting a data acquisition system; S3, simulation of collapse process caused by water level change: respectively simulating the process of rapid drop and rapid rise of underground water level by controlling the rate of the water injection and drainage device connected to the conduit system; S4, multi-parameter synchronous monitoring: synchronously collecting air pressure or water pressure data in the karst conduit, pore water pressure, displacement and soil pressure data in the overburden soil body and deformation image data on the surface of the soil body during the water level change process; S5, data fusion and relationship analysis: aligning and fusing the collected multi-source time series data, and quantitatively analyzing the dynamic relationship between the water level change rate, the pressure difference change in the karst conduit and the response of the overburden soil body; S6, establishment of early warning threshold: determining the critical pressure difference threshold and the corresponding water level change condition for inducing overburden damage based on the quantitative relationship in step S5.

6. A device for quantitative characterization of karst collapse and method of use thereof according to claim 5, characterized in that, In step S3, the simulated process of rapid drop of underground water level specifically comprises: forming a negative pressure environment in the simulated karst conduit system by controlling the drainage rate of the drainage device, and inducing "suction erosion" type collapse.

7. A device useful for quantitative characterization of karst collapse and method of use thereof according to claim 5, wherein, In step S3, the simulated process of rapid rise of underground water level specifically comprises: forming a positive pressure environment in the simulated karst conduit system by controlling the water injection rate of the water injection device, and inducing "blasting" type collapse.

8. A device for quantitative characterization of karst collapse and method of use thereof according to claim 5, characterized in that, In step S4, the synchronous monitoring includes at least monitoring the air pressure at the top of the pipe through the air pressure sensor (5), monitoring the response at different depths inside the soil through the pore pressure sensor (8), displacement sensor (9) and soil pressure sensor (10), and monitoring the full-field deformation and fracture development process of the soil surface through the three-dimensional scanner (11) and high-speed camera (12).

9. A device useful for quantitative characterization of karst collapse and method of use thereof according to claim 5, wherein, In step S5, the quantitative analysis specifically includes establishing the time history curve of pressure difference in the pipeline, the time history curve of displacement of key points in the soil, and the surface settlement rate curve, and analyzing the phase and amplitude coupling relationship between them.

10. A device for quantitative characterization of karst collapse and method of use thereof according to claim 5, characterized in that, In step S6, model verification and parameter expansion are performed by adjusting the thickness, density, or mechanical parameters of the overburden soil and repeating steps S3 to S6 to verify the universality of the warning threshold and establish a warning parameter system for different geological conditions.

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