Experimental device and method for simulating ground collapse induced by water seepage in complex karst

Abstract

The present invention discloses a test device for simulating ground collapse induced by water seepage in complex karst. The device comprises a model box, a seepage water control module disposed in the model box, and the model box is divided into a collapse simulation chamber located in the middle and a seepage chamber located outside the collapse simulation chamber by the seepage water control module. The aqueous solution in the seepage chamber seeps into the collapse simulation chamber through the seepage water control module. The karst simulation module is disposed below the bottom of the model box, a cavity opening is formed at the bottom of the collapse simulation chamber, and a plurality of stress sensors and displacement meters are disposed outside the cavity opening in the collapse simulation chamber. The complex karst simulation module comprises a karst box disposed corresponding to the bottom of the model box and a karst simulation body disposed in the karst box. The karst simulation body has the same cavity distribution as the actual karst condition to be tested. By constructing a karst simulation body with the same cavity distribution as the actual karst condition to be tested, karst collapse under the action of seepage is simulated.

Description

Technical Field

[0001] The invention belongs to the field of karst collapse testing, and in particular relates to a testing device and a testing method for simulating ground collapse induced by complex karst caused by water seepage. Background Art

[0002] my country has the most extensive distribution of carbonate rocks in the world, and also boasts the greatest variety of karst types. Numerous cities are located in areas prone to karst formations, causing significant disruption to urban construction and major projects, significantly impacting progress and the safety of people and property.

[0003] Model tests of karst collapse have been extensively studied in the past. Conventional model tests often focus on material similarity, configuring similar materials, ignoring existing size and boundary effects, and oversimplifying the simulation of various structures. While these factors can be ignored in qualitative studies, quantitative studies of complex karst collapses under complex conditions often oversimplify the karst structure and fail to accurately simulate the various influencing factors within the karst system. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a test device and test method for simulating ground collapse induced by complex karst due to water seepage. By constructing a karst simulation body with the same cavity distribution as the actual karst condition to be tested, the karst collapse under the action of seepage is simulated.

[0005] Technical solution: To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] An experimental device for simulating ground collapse induced by water seepage in complex karst includes a model box, a complex karst simulation module, a seepage water control module, a stress sensor, and a displacement meter. The seepage water control module is provided in the model box, and the model box is divided into a collapse simulation chamber located in the middle and a seepage chamber located outside the collapse simulation chamber by the seepage water control module. The aqueous solution in the seepage chamber seeps into the collapse simulation chamber through the seepage water control module.

[0007] The karst simulation module is arranged below the bottom of the model box, and a cavity opening connected to the complex karst simulation module is opened at the bottom of the collapse simulation cavity. Several stress sensors and displacement meters are arranged on the outside of the cavity opening in the collapse simulation cavity. The complex karst simulation module includes a karst box arranged corresponding to the bottom of the model box and a karst simulation body arranged in the karst box. The karst simulation body has the same cavity distribution state as the actual karst condition to be measured.

[0008] Furthermore, the karst simulation body is arranged at a distance from the bottom wall of the karst box, and a hydrodynamic cavity is formed between the karst simulation body and the bottom wall of the karst box. The hydrodynamic cavity is connected to the hydrodynamic control device, and the aqueous solution in the hydrodynamic cavity forms a dynamic water flow through the hydrodynamic control device.

[0009] Furthermore, the hydrodynamic control equipment includes a water supply tank, a water inlet pipe and a water pump, one end of the water inlet pipe is connected to the water supply tank and the other end is connected to the hydrodynamic chamber, a water pump is provided on the water inlet pipe, a water inlet corresponding to the size of the water inlet pipe is provided on the wall of the karst box, a drain is provided on the wall of the hydrodynamic chamber on a side located in the direction of water flow and away from the water inlet; a dynamic water flow is formed between the outlet end of the water inlet pipe and the drain.

[0010] Furthermore, the karst box is located above the hydrodynamic chamber and is provided with a simulation body accommodating frame which can be pulled out in the transverse direction, and different types of karst simulation bodies can be replaced through the simulation body accommodating frame.

[0011] Furthermore, it also includes a vacuum control system, which is connected to the inner cavity of the karst box and adjusts the vacuum degree of the karst box.

[0012] Furthermore, it comprises two groups of seepage water control modules spaced apart in the model box, wherein the inner cavity of the model box is divided into a collapse simulation cavity in the middle and seepage cavities on both sides of the collapse simulation cavity by the two groups of seepage water control modules.

[0013] Furthermore, the seepage direction and height of the aqueous solution in the seepage cavity toward the collapse simulation cavity are adjusted by a seepage water control module.

[0014] Furthermore, the seepage water control module includes a support frame and a number of baffles vertically distributed on the support frame, the two ends of the baffles are rotatably set on the support frame, and the baffles are adjusted at an angle relative to the vertical plane; the angle adjustment of the baffles relative to the vertical plane is used to adjust the size, seepage angle and seepage height of the seepage channel.

[0015] The test method of the test device for simulating water seepage complex karst induced ground collapse includes the following steps:

[0016] a. Obtain the spatial structure diagram of the underground karst system using detection instruments and analysis software, calculate the similarity ratio based on similarity theory, and determine the geometric similarity ratio of the complex karst simulation system;

[0017] b. Based on the calculated geometric similarity ratio of the complex karst simulation system, use an industrial-grade 3D printer to print the cavity of each karst cavity;

[0018] c. Prepare the silicone material, place the cavity positions in the prepared rectangular container and fix them, pour the prepared silicone material to half the height of the container, and after half of the silicone solidifies, apply the interface release agent and set the separation sign, and continue pouring the remaining half of the silicone;

[0019] d. After the silicone gel has completely solidified, separate the silicone gel from the separation mark and remove the 3D-printed cavity. Then, apply adhesive to the separation surface of the two silicone gels after removing the cavity model and adhere the two silicone gels to obtain a karst simulation body;

[0020] e. Place the karst simulation body into the karst box where the complex karst simulation system is located;

[0021] f. Fill the simulation cavity of the model box with soil materials designed according to similarity theory;

[0022] g. Adjust the seepage water control module to simulate different groundwater seepage paths;

[0023] or simulating groundwater level fluctuations through hydrodynamic control systems;

[0024] Or the vacuum control system can be used to simulate the effect of vacuum changes in the karst system on karst;

[0025] h. Through pre-buried stress sensors and displacement meters, the stress field and displacement field of the overlying soil of the karst system are recorded in all directions and at all times.

[0026] Beneficial effects: The present invention simulates the karst collapse under the action of seepage by constructing a karst simulation body with the same cavitation distribution state as the actual karst condition to be measured. The karst simulation body of the component is similar to the actual karst layer and can simulate the complex karst layer structure. The karst system is simulated with high similarity in the model. By proportionally casting the real karst system, high structural similarity is achieved. Compared with the traditional simplified method, the simulation structure can be made more accurate and the loss of influencing factors caused by over-simplification of the karst system can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Attachment Figure 1 Schematic diagram of the overall structure of the test device of the present invention;

[0028] Attachment Figure 2 is a cross-sectional schematic diagram of the test device of the present invention;

[0029] Attachment Figure 3 It is a three-dimensional schematic diagram of the internal structure of the karst box of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] As attached Figure 1and attached Figure 2 As shown, a test device for simulating ground collapse induced by complex karst due to water seepage includes a model box 1, a complex karst simulation module, a seepage water control module 3, a stress sensor 5 and a displacement meter 6. The seepage water control module 3 is provided in the model box 1, and the model box is divided into a collapse simulation chamber 1a in the middle and a seepage chamber 1b located outside the collapse simulation chamber 1a by the seepage water control module 3. The seepage chamber 1b is used to be filled with aqueous solution to simulate water seepage, and the collapse simulation chamber 1a is used to be filled with soil material 100 similar to the soil layer to be tested to simulate bottom surface collapse. The aqueous solution in the seepage chamber seeps into the collapse simulation chamber 1a through the seepage water control module to form a seepage model.

[0032] The karst simulation module is arranged below the bottom of the model box 1. The bottom of the collapse simulation chamber 1a is provided with a cavity opening 4 connected to the complex karst simulation module. The seepage solution enters the karst simulation module through the cavity opening. Several stress sensors 5 and displacement meters 6 are arranged outside the cavity opening 4 in the collapse simulation chamber 1a. The pre-buried stress sensors 5 and displacement meters 6 record the stress field and displacement field of the overlying soil of the karst system in all directions and at all times. The complex karst simulation module includes a karst box 20 arranged corresponding to the bottom of the model box and a karst simulation body 2 arranged in the karst box. The karst box 20 is a box structure with an open top, and the top opening of the karst box 20 is sealed to the bottom of the model box 1. The karst simulation body has the same cavity distribution as the actual karst condition to be measured.

[0033] By constructing a karst simulation body with the same karst cavity distribution as the actual karst condition to be tested, the karst collapse under the action of seepage is simulated. The karst simulation body of the component is similar to the actual karst layer and can simulate the complex karst layer structure. The karst system is simulated with high similarity in the model. By proportionally casting the real karst system, high structural similarity is achieved. Compared with the traditional simplified method, the simulated structure can be made more accurate and the loss of influencing factors caused by over-simplification of the karst system can be avoided.

[0034] The karst simulation body is arranged at a distance from the bottom wall of the karst box 20, and a hydrodynamic chamber 22 is formed between the karst simulation body 2 and the bottom wall of the karst box 20. The hydrodynamic chamber 22 is connected to a hydrodynamic control device. The aqueous solution in the hydrodynamic chamber 22 forms a dynamic water flow through the hydrodynamic control device. Through the hydrodynamic control system at the bottom, the influence of water level fluctuations on karst collapse can be simulated.

[0035] The hydrodynamic control equipment includes a water supply tank 7, a water inlet pipe 8 and a water pump 9. One end of the water inlet pipe 8 is connected to the water supply tank and the other end is connected to the hydrodynamic chamber 22. A water pump is provided on the water inlet pipe. A water inlet 10 corresponding to the size of the water inlet pipe is provided on the wall of the karst box 20. A drain outlet 11 is provided on the wall of the hydrodynamic chamber 22 on a side located in the direction of water flow and away from the water inlet 10. A switch valve is provided in the drain outlet 11 for opening or closing the drain outlet. A dynamic water flow is formed between the water outlet end of the water inlet pipe and the drain outlet.

[0036] A flow meter and a flow velocity meter are also provided on the water inlet pipe 8, and the law of karst collapse under different flow rates and flow velocities is analyzed by the flow meter and the flow velocity meter.

[0037] The karst box 1 is located above the hydrodynamic chamber and is provided with a simulated body accommodating frame 21 that can be pulled out laterally. The simulated body accommodating frame allows for easy and quick replacement of different types of karst simulated bodies 2. Each time, a karst simulated body 2 similar to the detection result is produced according to different karst conditions and placed in the simulated body accommodating frame.

[0038] The model also includes a vacuum control system, which is connected to the inner cavity of the karst box 20 and regulates the vacuum level of the karst box. The vacuum control system, located at the bottom of the model, uses a vacuum pump to adjust the vacuum level within the karst system, taking into account the instability of the soil cavity caused by negative pressure, which can cause karst collapse.

[0039] The system comprises two sets of seepage water control modules 3 spaced apart within the model box 1. These modules are plate-shaped and serve to separate chambers. Their lateral walls adhere to the inner wall of the model box 1. The two sets of seepage water control modules divide the inner chamber of the model box into a central collapse simulation chamber and two seepage chambers on either side of the collapse simulation chamber, forming three parallel chambers. The seepage chambers are also supplied with water via a water supply tank 7.

[0040] The seepage direction and height of the aqueous solution in the seepage cavity toward the collapse simulation cavity are adjusted by the seepage water control module 3 to simulate different seepage conditions.

[0041] The seepage water control module 3 includes a support frame 31 and a plurality of baffles 32 vertically distributed on the support frame 31. The two ends of the baffles 32 are rotatably mounted on the support frame, and the baffles 32 are angularly adjustable relative to the vertical plane. The angle adjustment of the baffles 31 relative to the vertical plane is used to adjust the size of the seepage channel and the seepage angle. Each baffle 31 is independently rotated and adjusted relative to the support frame, so that the seepage height of the seepage cavity 1b relative to the soil material in the simulation cavity 1a can be adjusted. The adopted seepage control system can easily control different head heights and seepage velocities, and can also simulate different infiltration directions to achieve the simulation of karst collapse processes under different seepage paths.

[0042] The support frame 31 is provided with a driving mechanism for adjusting the angle deflection of the baffles 32 independently or synchronously.

[0043] This model can simulate karst collapse, where the walls of earth caves gradually erode and expand under water-level fluctuations until they collapse. It can also simulate karst collapse caused by a sudden drop in groundwater, resulting in a local vacuum and leading to instability in earth caves. It can also simulate karst collapse under the influence of different seepage paths. This model can comprehensively simulate multiple factors influencing karst collapse and structurally simulate complex karst systems with high precision. It is a versatile, high-similarity experimental device that facilitates quantitative research on the impact of multiple factors on complex karst systems.

[0044] This multifunctional karst collapse model test device can comprehensively analyze the impact of various factors on karst collapse, especially the effects of groundwater seepage and water vapor pressure. Because it considers a comprehensive and integrated approach and accurately simulates complex karst systems, it can be used to more comprehensively study karst collapse mechanisms.

[0045] As attached Figure 2 and 3 As shown, a water level fluctuation driving mechanism is provided in the hydrodynamic chamber 22, and the water level fluctuation driving mechanism forms the aqueous solution in the hydrodynamic chamber 22 into a fluctuating water flow. During the flow of the fluctuating water flow, the water surface fluctuates up and down, forming an impact fluctuation on the karst simulation body 2. As the water level fluctuates, the air pressure in the water level dynamic chamber 22 and the caves of the karst simulation body also changes, thereby observing its influence on the soil material.

[0046] Among them, the water level fluctuation driving mechanism is at least arranged at the water inlet end close to the hydrodynamic chamber 22, and is used to cause the water level to fluctuate at the water inlet end. In order to increase the cavity and maintain the intensity of the water level fluctuation, at least one group of water level fluctuation driving mechanisms can be further arranged in the direction of the water flow.

[0047] The water level fluctuation driving mechanism 23 includes a driving motor 23.3, a rotating shaft 23.2 and a deflection blade 23.1. The bottom end of the deflection blade 23.1 is provided with a rotating shaft 23.2, and the deflection blade 23.1 is rotated by the rotating shaft 23.2 and is arranged in the inner cavity of the karst box 20. The deflection blade and the rotating shaft are perpendicular to the water flow direction in the hydrodynamic chamber 22. The driving motor is arranged on the outside of the karst box 20, and drives the rotating shaft and the deflection blade to deflect around the axis. The deflection action of the deflection blade causes the aqueous solution in the hydrodynamic chamber 22 to produce lateral oscillations and fluctuations, thereby forming a wave-like water flow, causing the water level to fluctuate.

[0048] The test method of the test device for simulating water seepage complex karst induced ground collapse includes the following steps:

[0049] a. Obtain the spatial structure diagram of the underground karst system using detection instruments and analysis software, calculate the similarity ratio based on similarity theory, and determine the geometric similarity ratio of the complex karst simulation system;

[0050] b. Based on the calculated geometric similarity ratio of the complex karst simulation system, use an industrial-grade 3D printer to print the cavity of each karst cavity;

[0051] c. Prepare the silicone material, place the cavity positions in the prepared rectangular container and fix them, pour the prepared silicone material to half the height of the container, and after half of the silicone solidifies, apply the interface release agent and set the separation sign, and continue pouring the remaining half of the silicone;

[0052] d. After the silicone gel is completely solidified, separate the silicone gel from the separation mark and remove the 3D-printed cavity. Then, after removing the cavity model, apply adhesive to the separation surface of the two silicone gels and adhere the two silicone gels to obtain karst simulation body 2;

[0053] e. The karst simulation body 2 is placed in the karst box where the complex karst simulation system is located;

[0054] f. Filling the simulation cavity 1a of the model box with soil material 100 designed according to similarity theory;

[0055] g. Adjust the seepage water control module to simulate different groundwater seepage paths;

[0056] or simulating groundwater level fluctuations through hydrodynamic control systems;

[0057] Or the vacuum control system can be used to simulate the effect of vacuum changes in the karst system on karst;

[0058] Or the water level fluctuation driving mechanism is used to make the water flow in the hydrodynamic cavity generate water level fluctuation, thereby simulating the influence of groundwater level fluctuation on karst;

[0059] h. Through the pre-buried stress sensors 5 and displacement meters 6, the stress field and displacement field of the overlying soil of the karst system are recorded in all directions and at all times.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A test device for simulating ground collapse induced by water seepage in complex karst, characterized by: The invention comprises a model box (1), a complex karst simulation module, a seepage water control module (3), a stress sensor (5) and a displacement meter (6); the seepage water control module (3) is provided in the model box (1), and the model box (1) is divided into a collapse simulation chamber (1a) located in the middle and a seepage chamber (1b) located outside the collapse simulation chamber (1a) by the seepage water control module (3); the aqueous solution in the seepage chamber (1b) seeps into the collapse simulation chamber (1a) from different seepage heights, seepage velocities, different infiltration directions and different seepage paths through the seepage water control module (3); The karst simulation module is arranged below the bottom of the model box (1); a cavity opening (4) connected to the complex karst simulation module is provided at the bottom of the collapse simulation chamber (1a); a plurality of stress sensors (5) and displacement meters (6) are arranged outside the cavity opening (4) in the collapse simulation chamber (1a); the complex karst simulation module comprises a karst box (20) arranged corresponding to the bottom of the model box (1) and a karst simulation body (2) arranged in the karst box (20); the karst simulation body (2) has the same cavity distribution state as the actual karst condition to be measured; It also includes a hydrodynamic control device, which includes a water supply box (7), a water inlet pipe (8) and a water pump (9), one end of the water inlet pipe (8) is connected to the water supply box (7) and the other end is connected to the hydrodynamic chamber (22), a water pump (9) is provided on the pipeline of the water inlet pipe (8), a water inlet (10) corresponding to the size of the water inlet pipe (8) is provided on the wall of the karst box (20), and a drain (11) is provided on the wall of the hydrodynamic chamber (22) on a side located in the direction of water flow and away from the water inlet (10); a dynamic water flow is formed between the water outlet end of the water inlet pipe (8) and the drain (11); The karst simulation body (2) is arranged at a distance from the bottom wall of the karst box (20), and a hydrodynamic chamber (22) is formed between the karst simulation body (2) and the bottom wall of the karst box (20). The hydrodynamic chamber (22) is connected to a hydrodynamic control device. The aqueous solution in the hydrodynamic chamber (22) forms a dynamic water flow through the hydrodynamic control device. The flow rate and flow rate of the aqueous solution in the hydrodynamic chamber (22) and the height of the water level can be adjusted by the hydrodynamic control device. It also includes a vacuum control system, which is connected to the inner cavity of the karst box (20) and adjusts the vacuum of the karst box (20); the vacuum in the karst system is adjusted by a vacuum pump; It also includes a water level fluctuation driving mechanism (23), wherein the water level fluctuation driving mechanism (23) is at least arranged near the water inlet end of the hydrodynamic chamber (22); or at least one more set of water level fluctuation driving mechanisms (23) can be arranged in the water flow direction of the hydrodynamic chamber (22); The water level fluctuation driving mechanism (23) can cause the water level to fluctuate at the water inlet end, and enhance and maintain the intensity of the water level fluctuation; The water level fluctuation driving mechanism (23) comprises a driving motor (23.3), a rotating shaft (23.2) and a deflection blade (23.1); the bottom end of the deflection blade (23.1) is provided with a rotating shaft (23.2), and the deflection blade (23.1) is rotatably arranged in the inner cavity of the karst box (20) via the rotating shaft (23.2); the deflection blade (23.1) and the rotating shaft (23.2) are perpendicular to the direction of water flow in the hydrodynamic chamber (22); the driving motor (23.3) is arranged outside the karst chamber (20), and drives the rotating shaft (23.2) and the deflection blade (23.1) to perform a deflection action around the axis; the deflection action of the deflection blade (23.1) causes the aqueous solution in the hydrodynamic chamber (22) to generate lateral oscillations and fluctuations, thereby forming a wave-like water flow, causing the water level to fluctuate; The water level fluctuation driving mechanism (23) can cause the aqueous solution in the hydrodynamic chamber (22) to produce lateral oscillations and fluctuations, so that a wave-like water flow is formed in the hydrodynamic chamber (22). The up and down fluctuating water surface of the wave-like water flow impacts the karst simulation body (2); and the water level fluctuation of the wave-like water flow causes the air pressure in the hydrodynamic chamber (22) and the various caves of the karst simulation body (2) to fluctuate.

2. The test device for simulating water seepage and complex karst-induced ground collapse according to claim 1, characterized in that: The karst box (20) is located above the hydrodynamic chamber (22) and is provided with a simulation body accommodating frame (21) that can be pulled out in the transverse direction. Different types of karst simulation bodies (2) can be replaced through the simulation body accommodating frame (21).

3. The test device for simulating water seepage and complex karst-induced ground collapse according to claim 1, characterized in that: The invention comprises two groups of seepage water control modules (3) arranged at intervals in a model box (1); the inner cavity of the model box (1) is divided into a collapse simulation cavity (1a) located in the middle and seepage cavities (1b) located on both sides of the collapse simulation cavity (1a) by the two groups of seepage water control modules (3).

4. The test device for simulating water seepage and complex karst-induced ground collapse according to claim 1, characterized in that: The aqueous solution in the seepage cavity (1b) is adjusted in the seepage direction and height toward the collapse simulation cavity (1a) by the seepage water control module (3).

5. The test device for simulating water seepage and complex karst-induced ground collapse according to claim 4, characterized in that: The seepage water control module (3) comprises a support frame (31) and a plurality of baffles (32) vertically distributed on the support frame (31), the two ends of the baffles (32) being rotatably arranged on the support frame (31), and the baffles (32) being arranged to be angle-adjustable relative to the vertical surface; the angle adjustment of the baffles (32) relative to the vertical surface is used to adjust the size, seepage angle, and seepage height of the seepage channel.

6. The test method of the test device for simulating water seepage complex karst induced ground collapse according to any one of claims 1 to 5, characterized in that: The following steps are involved: a. Obtain the spatial structure diagram of the underground karst system using detection instruments and analysis software, calculate the similarity ratio based on similarity theory, and determine the geometric similarity ratio of the complex karst simulation system; b. Based on the calculated geometric similarity ratio of the complex karst simulation system, use an industrial-grade 3D printer to print the cavity of each karst cavity; c. Prepare the silicone material, place the cavity positions in the prepared rectangular container and fix them, pour the prepared silicone material to half the height of the container, and after half of the silicone solidifies, apply the interface release agent and set the separation sign, and continue pouring the remaining half of the silicone; d. After the silicone gel is completely solidified, separate the silicone gel from the separation mark and take out the 3D printed cavity. Then, apply adhesive to the separation surface of the two silicone gels after removing the cavity model and adhere the two silicone gels to obtain a karst simulation body (2); e. Place the karst simulation body (2) into the karst box (20) where the complex karst simulation system is located; f. Filling the collapse simulation cavity (1a) of the model box (1) with soil material (100) designed according to similarity theory; g. Adjust the seepage water control module (3) to simulate different groundwater seepage paths; or simulating groundwater level fluctuations through hydrodynamic control equipment; Or the vacuum control system can be used to simulate the effect of vacuum changes in the karst system on karst; h. The stress field and displacement field of the overlying soil of the karst system are recorded in all directions and at all times through the pre-buried stress sensors (5) and displacement meters (6).

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