Physical model experiment system and method for deep complex karst surface collapse

Abstract

The invention provides a physical model experiment system and method for deep complex karst surface collapse, and the system comprises a covering layer rock-soil simulation module which simulates the geological environment of a karst covering layer; the karst fissure pipeline simulation module is used for simulating geological environments such as deep karst fissures and pipelines; the karst cave stratum simulation module is used for simulating a karst cave and a cave stratum environment; the hydrodynamic condition simulation module is used for simulating the influence of underground water and rainfall on the karst system; the underground engineering excavation and load disturbance simulation module is used for simulating underground engineering excavation, vibration loading and ground surface load influence; and the monitoring and measuring module is used for monitoring the change of various key physical quantities in the experiment process. The deep complex karst collapse formation process under stress of various factors can be truly represented, and an experimental research platform is provided for karst geological disaster prevention and control.

Description

Technical Field

[0001] The present invention relates to the technical field of physical simulation of deep karst ground collapse, and in particular to a physical model experimental system and method for deep complex karst ground collapse. Background Art

[0002] Karst collapse is the most common geological hazard in areas with karst development. Karst collapse has numerous causes and complex mechanisms. The mechanisms and prevention and control technologies of karst collapse induced by hydrodynamic conditions have long received widespread attention. However, with the frequent occurrence of extreme climates, the rapid advancement of urban infrastructure construction, and the increasing depth of underground space development and utilization, the problem of deep karst collapse has become increasingly prominent. The exposure of deep karst by underground engineering excavation not only induces the collapse of the overlying ground layer, but also damages the ecological environment and water resources. There is currently no clear definition of deep karst collapse in the field of karst collapse. Engineering geology believes that deep karst develops below the erosion base level, with relatively weak karst groundwater movement. There are karst forms dominated by pores, cracks, and pipes, and caves and underground river-type karst may also appear. Karst development is complex and usually in a water-rich state, storing abundant groundwater resources. This patent focuses on the presence of large underground spaces containing karst caves, karst cavities, and karst conduits in deeply buried rock formations, which develop upward along karst conduits and dissolution fissures to the loose Quaternary overburden. This type of karst has complex karst structures with caves, karst conduits, dissolution gaps, and dissolution pores. The karst cave rock formations may be exposed to high ground stress and high water pressure for a long time. The paths of water and soil migration during the development and collapse of soil caves in the overburden layer are long and complex. These characteristics have led to the unclear catastrophic mechanism and evolution mechanism of deep karst ground collapse. Physical model experiments are an important technical means to study the causes and development processes of karst collapse disasters, providing a certain scientific basis for disaster prevention, control, and management.

[0003] Patent publication number CN118275650A discloses a physical simulation test device for studying the causes of karst collapse. The device comprises a main model, an injection and drainage system, and a multi-data monitoring and acquisition system. A dedicated test chamber for karst fracture simulation is located at the bottom of the open-top model chamber, overlain by Quaternary cover. The holes and cracks in the chamber's bottom correspond to the karst cave and fracture openings at the bottom of the chamber. A 3D-printed, translucent karst pipe, whose shape matches actual exploration results, is connected to the bottom of the chamber. The injection and drainage system controls groundwater level fluctuations, enabling simulation of karst collapse under various conditions: water level drop-seepage erosion, sudden water level drop-negative pressure erosion, sudden water level rise-positive pressure bursting, and water level fluctuations. This system can measure changes in karst gas and water vapor pressures, overburden soil pressure, and deformation parameters. However, this device fails to simulate the effects of underground excavation disturbances and fails to consider the complex engineering geological environment of deep karst collapse.

[0004] Patent publication number CN117760862A discloses a test method and apparatus for simulating deep karst collapse induced by overloading of densely populated buildings. The method includes a model test chamber, a karst channel mechanism, a loading mechanism, an intelligent display and image acquisition mechanism, a data analysis mechanism, a karst collapse soil collection mechanism, and a support mechanism. The karst channel mechanism is located at the bottom of the model test chamber, the loading mechanism is located at the top of the model test chamber, and the support mechanism connects and fixes the model test chamber and the support mechanism reaction frame assembly. The model test chamber is filled with a cover soil sample. This method can simulate deep karst collapse induced by overloading of densely populated buildings. The cover soil structure type and the size, shape, and number of karst channels are adjustable. However, the device only considers the karst cover layer and karst opening structure, and cannot fully characterize the complex geological structure of concealed karst, nor does it consider the conditions of groundwater seepage. Summary of the Invention

[0005] In response to the above-mentioned technical deficiencies, the purpose of the present invention is to provide a physical model experimental system and method for deep complex karst ground collapse, which can simulate the complex karst structure and karst environment of deep karst collapse, and reveal the disaster mechanism and disaster mode of deep complex karst collapse induced by engineering activities such as underground engineering excavation.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A physical model experimental system for deep complex karst ground collapse, comprising: an overburden rock and soil simulation module, a karst fracture pipeline simulation module, a karst cave formation simulation module, a hydrodynamic condition simulation module, an underground engineering excavation and load disturbance simulation module, and a monitoring and measurement module; the karst cave formation simulation module is arranged below the overburden rock and soil simulation module, and the karst fracture pipeline simulation module is arranged between the karst cave formation simulation module and the overburden rock and soil simulation module; the top of the karst fracture pipeline simulation module is connected to the bottom of the overburden rock and soil simulation module, and the bottom is connected to the karst cave formation simulation module , forming the covering layer-karst fracture pipeline-karst cave formation structure of deep karst collapse; the hydrodynamic condition simulation module is used to control the groundwater level in the covering layer geotechnical simulation module, the karst fracture pipeline simulation module and the karst cave formation simulation module, as well as rainfall recharge; the underground engineering excavation and load disturbance simulation module includes the underground engineering excavation mechanism and the underground space vibration loading mechanism set in the karst cave formation simulation module, as well as the ground static and dynamic load and construction impact load loading mechanism set above the covering layer geotechnical simulation module; the monitoring and measurement module is used to obtain multivariate information data during the experiment.

[0008] Preferably, the covering layer geotechnical simulation module includes a covering layer geotechnical simulation box and a water tank; the interior of the covering layer geotechnical simulation box is filled with covering layer geotechnical body; the water tank is installed inside the covering layer geotechnical simulation box and is located outside the covering layer geotechnical body; a porous groundwater supply and drainage outlet is provided at the bottom of the water tank; one side of the water tank that is in contact with the covering layer geotechnical body is configured as a porous permeable board and geotextile; the water tank is filled with porous groundwater; at least one first karst opening is provided at the bottom of the covering layer geotechnical simulation box, the size and shape of which can be adjusted according to actual conditions, and the first karst opening is located below the covering layer geotechnical body; a first karst control valve is installed on the first karst opening; the first karst control valve is connected to the karst fracture pipeline simulation module.

[0009] Preferably, the karst fissure pipeline simulation module is used to simulate deep karst geological environment; it includes a karst fissure pipeline mechanism and an upper flexible end and a lower flexible end; the upper end of the upper flexible end is connected to the first karst control valve, and the lower end is connected to the upper end of the karst fissure pipeline mechanism; the upper end of the lower flexible end is connected to the lower end of the karst fissure pipeline mechanism, and the lower end is connected to the karst cave formation simulation module.

[0010] Preferably, the karst cave formation simulation module is used to simulate the deep karst formation environment; it includes a karst formation simulation box, a ground stress loading mechanism, and a first movable lifting mechanism; the karst formation simulation box is arranged on the first movable lifting mechanism; the interior of the karst formation simulation box is filled with karst rock formations; a karst cave underground space is arranged inside the karst rock formation; the karst cave underground space extends upward, and a second karst opening is arranged on the top, and the second karst opening is connected to the lower flexible end head; the ground stress loading mechanism is arranged on the outer surface of the karst formation simulation box, including a reaction frame, a power device and a loading pressure plate; the reaction frame is fixed on the first movable lifting mechanism; the loading pressure plate is fitted on the inner side of the karst formation simulation box; the power device is placed between the reaction frame and the loading pressure plate, one end of the power device is fixedly connected to the reaction frame, and the other end is fixedly connected to the loading pressure plate; the loading pressure plate is provided with a first reserved hole adapted to the second karst opening and a second reserved hole adapted to the cross-section of the underground space.

[0011] Preferably, the first movable lifting mechanism includes a first movable trolley and a first elevator; the first elevator is installed on the first movable trolley; the karst formation simulation box is hingedly installed on the first elevator; the horizontal position of the karst formation simulation box is controlled by the first movable trolley, and the height and inclination angle of the karst formation simulation box are controlled by the first elevator.

[0012] Preferably, the power device is any one of a servo hydraulic loading cylinder or a high-power servo motor.

[0013] Preferably, the hydrodynamic condition simulation module includes a porous groundwater control mechanism, a karst groundwater control mechanism, and an atmospheric rainfall control mechanism; the porous groundwater control mechanism includes a first box, a first controller, and a first water pipe; one end of the first water pipe is connected to the porous groundwater supply and drainage port, and the other end is connected to the first box; the first controller is installed between the first water pipe and the first box, and is used to control the water supply from the first box to the water tank; the karst groundwater control mechanism is used to control the groundwater conditions of the karst cave underground space and the karst fissure pipeline simulation module, and includes a second box, a second water pipe, and a funnel-shaped karst pipeline; the first water pipe is connected to the first water pipe and the first box, and is used to control the water supply from the first box to the water tank; the first water pipe is connected to the first water pipe and the first box, and is used to control the water supply from the first box to the water tank; the first water pipe is connected to the first water pipe and the first box, and is used to control the water supply from the first box to the water tank; the first water pipe is connected to the first water pipe and the first box, and is used to control the water supply from the first box to the water tank; the first water pipe is connected to the first water pipe and the first water pipe ... A second controller is provided on the second box body; one end of the second water pipe is connected to the second controller, and the other end is connected to the second karst opening; the funnel-shaped karst pipeline is vertically arranged above the second water pipe; a second karst control valve is installed at the lower end of the funnel-shaped karst pipeline; the second karst control valve is connected to the second water pipe; the atmospheric rainfall control mechanism is used to simulate the atmospheric rainfall environment, including a third controller, a third water pipe and an artificial rainfall sprinkler head; the third controller is installed on the first box body; the third water pipe is arranged above the covering layer rock and soil simulation box, and one end is connected to the third controller; the artificial rainfall sprinkler head is installed on the third water pipe.

[0014] Preferably, the underground engineering excavation and load disturbance simulation module includes an underground engineering excavation mechanism, an underground space vibration loading mechanism, a ground static and dynamic load and construction impact load loading mechanism; the underground engineering excavation mechanism includes an excavation drill, an excavation controller, and a second movable lifting platform; the second movable lifting platform includes a second movable trolley and a second elevator; the second elevator is arranged on the second movable trolley; the excavation drill is installed on the second elevator, and the front end extends toward the karst formation simulation box; the excavation controller is electrically connected to the excavation drill; the underground space vibration loading mechanism includes an underground space structure model, a signal generator, and a ground vibration loading mechanism. generator, a power amplifier, and an exciter; the underground space structure model is arranged in the karst rock layer; the exciter is arranged in the underground space structure model or the karst rock layer; one end of the power amplifier is electrically connected to the signal generator, and the other end is electrically connected to the exciter; the ground static and dynamic load and construction impact load loading mechanism is arranged above the covering rock and soil body, including an actuator, a ground static and dynamic load and construction impact load controller, a drilling simulation model drill rod / pile foundation simulation model pile; the drilling simulation model drill rod / pile foundation simulation model pile is installed on the actuator; the actuator is electrically connected to the ground static and dynamic load and construction impact load controller.

[0015] A physical model experimental method for deep complex karst ground collapse, including:

[0016] 1) Based on the engineering site investigation data and the experimental design similarity ratio, prepare similar materials for fluid-solid coupling of the overburden rock mass, fluid-solid coupling of the karst rock layer, underground space structure model, and pile foundation simulation model piles; cast the prefabricated underground space structure model and drilling simulation model drill rod / pile foundation simulation model piles; select the dominant karst fissures, pipelines, and sinkholes with good connectivity and a significant impact on karst collapse, perform 3D modeling, and use 3D printing technology to produce transparent karst fissure pipeline structures based on real forms, funnel-shaped karst pipelines, upper flexible ends, and lower flexible ends;

[0017] 2) Assemble the overburden geotechnical simulation module, determine the plane position and height of the karst cave formation simulation module according to the actual karst morphology, fix it through the first movable lifting mechanism, close the first karst control valve, and respectively fill the overburden soil fluid-solid coupling similar materials and karst rock layer fluid-solid coupling similar materials into the overburden geotechnical simulation box and the karst formation simulation box in layers, and simultaneously bury the monitoring elements in the corresponding positions according to the experimental plan until the designed thickness is reached, and the laying of the overburden soil and karst rock layer is completed. When the rock layer is laid to the cave position, the melting dissolution method or the air bag and splicing method are used to simultaneously prepare the cave underground space in the karst formation that meets the experimental morphology during the rock layer laying process. During the laying process, the underground space structure model, drilling simulation model drill rod / pile foundation simulation model pile are pre-buried according to the experimental plan;

[0018] 3) Install a geostress loading mechanism and a transparent karst fissure pipe mechanism, so that its upper flexible end is correspondingly connected to the first karst control valve below the overburden rock and soil simulation box, and its lower flexible end is correspondingly connected to the second karst opening at the top of the karst cave formation simulation module. The water tanks on both sides of the overburden rock and soil simulation module are connected to the porous groundwater control mechanism, and the bottom of the cave space of the karst cave formation simulation module is connected to the karst groundwater control mechanism. Apply geostress to the karst rock formation in the karst formation simulation box according to the experimental design requirements, check the sealing of the experimental system, first slowly supply water to the cave underground space and the karst fissure pipe mechanism to a predetermined water level through the karst groundwater control mechanism, and then slowly supply water to the overburden rock and soil body to a predetermined water level through the porous groundwater control mechanism, maintain the two water levels and let it stand;

[0019] 4) Select and install a dynamic coercion device according to the experimental requirements, connect and start the monitoring and measurement module, open the first karst control valve, conduct ambient acoustic emission, initial geological radar, and high-density electrical geophysical measurements, perform disturbances according to the experimental design parameters, record the parameters of the applied disturbance factors, and regularly conduct geological radar and high-density electrical geophysical measurements until the overburden rock and soil mass completely collapses;

[0020] 5) After the collapse develops stably and the monitoring data is stable, geological radar and high-density electrical geophysical prospecting measurements are carried out, the monitoring and measurement module is turned off, the dynamic coercion device is removed, and the groundwater in the overburden rock and soil simulation box, water tank, underground space of karst cave, funnel-shaped karst pipeline and karst fissure pipeline structure is slowly drained, the soil in the overburden rock and soil simulation box is excavated layer by layer and the shape of the collapse pit is recorded.

[0021] Preferably, the dynamic coercion device is at least one of an underground engineering excavation mechanism, an underground space vibration loading mechanism, a ground static and dynamic load and construction impact load loading mechanism, a porous groundwater control mechanism, a karst groundwater control mechanism, and an atmospheric rainfall control mechanism.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The physical model experimental system provided by the present invention can simulate the complex karst geological structure of deep karst collapse and the high ground stress and high water pressure environment in which it is located.

[0024] (2) The present invention can apply the disturbing effects of various deep karst collapse disaster-causing factors such as underground engineering excavation and underground space vibration, atmospheric rainfall infiltration recharge to the covering rock and soil and vertical recharge to karst groundwater, pumping karst groundwater, karst vacuum negative pressure erosion, ground static and dynamic loads, drilling / pile foundation dynamic loads and construction impact loads, which is more in line with actual engineering scenarios.

[0025] (3) The present invention has the advantages of simple structure, good visual effect, strong scalability, easy assembly and disassembly, and simple experimental operation. It can conveniently change the key parameters of the covering rock and soil (soil properties, thickness, etc.), karst development (shape, number, size and inclination of cracks, karst pipes, caves, etc.), engineering geological conditions, groundwater conditions (porous groundwater, karst groundwater), and dynamic factors (engineering construction and static and dynamic loads, atmospheric rainfall, vacuum negative pressure, groundwater level changes, etc.), and can carry out a variety of physical simulations of deep complex karst ground collapse conditions.

[0026] (4) The present invention deploys a variety of monitoring elements during the experiment, which can obtain the stress of the covering rock and soil, pore water pressure, pore groundwater level, water content, strain, acceleration, ground displacement, ground collapse development, water and soil movement process in the karst fissure pipeline, stress and strain of the cave surrounding rock, karst groundwater level, cave water and gas pressure, as well as the underground space structure and surrounding rock fissure development and destruction mode and other multi-information changes. At the same time, with the help of geophysical exploration methods such as acoustic emission monitoring, high-density electrical method and geological radar, the development and destruction process of the underground space structure surrounding rock fissure, as well as the development state and collapse process of soil caves are clarified, which helps to reveal the deep complex karst ground collapse mechanism under the coercion of single or multiple factors, and helps to accurately assess the risk of deep karst ground collapse. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the overall structure of the experimental system in the present invention;

[0028] Figure 2 Schematic diagram of the structure of the overburden geotechnical simulation module in the present invention;

[0029] Figure 3 Schematic diagram of the structure of the karst fissure pipeline simulation module in the present invention;

[0030] Figure 4 Schematic diagram of the structure of the karst formation simulation box and the ground stress loading mechanism in the present invention;

[0031] Figure 5 Schematic diagram of the loading mechanism for ground static and dynamic loads and construction impact loads in the present invention;

[0032] Figure 6 It is a schematic diagram of the underground engineering excavation mechanism in the present invention;

[0033] Figure 7 It is a schematic diagram of the underground space vibration loading mechanism in the present invention.

[0034] in:

[0035] 1. Overburden geotechnical simulation module; 101. Porous permeable board and geotextile; 102. Overburden geotechnical simulation box; 103. Water tank; 104. Overburden geotechnical body; 105. Porous groundwater; 106. Porous groundwater supply and drainage outlet; 107. First karst opening; 108. First karst control valve; 2. First box; 3. First controller; 4. First water pipe; 5. Karst fissure pipeline simulation module; 501. Karst fissure pipeline Mechanism; 502, upper flexible end; 503, lower flexible end; 6, karst stratum simulation box; 601, karst rock layer; 602, karst cave underground space; 603, second karst opening; 7, ground stress loading mechanism; 701, reaction frame; 702, power device, which is a servo hydraulic loading cylinder or a high-power servo motor; 703, loading pressure plate; 704, first reserved hole; 705, second reserved hole; 8, first movable lifting mechanism ;801. First movable trolley;802. First elevator;9. Second box;10. Second controller;11. Second water pipe;12. Third controller;13. Third water pipe;14. Artificial rainfall sprinkler head;15. Funnel-shaped karst pipe;16. Second karst control valve;17. Underground engineering excavation mechanism;1701. Excavation drilling rig;1702. Excavation controller;18. Second movable lifting platform;1801. Second movable trolley;1802. Second elevator;19. Underground space vibration loading mechanism;1901. Signal generator;1902. Power amplifier;1903. Vibrator;1904. Underground space structure model;20. Ground static and dynamic load and construction impact load loading mechanism;2001. Ground static and dynamic load and construction impact load controller;2002. Actuator;2003. Drilling simulation model drill rod / pile foundation simulation model pile. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings.

[0037] like Figures 1 to 7As shown, a physical model experimental system for deep complex karst ground collapse includes: an overburden rock and soil simulation module 1, a karst fracture pipeline simulation module 5, a karst cave formation simulation module, a hydrodynamic condition simulation module, an underground engineering excavation and load disturbance simulation module, and a monitoring and measurement module; the karst cave formation simulation module is arranged below the overburden rock and soil simulation module 1, and the karst fracture pipeline simulation module 5 is arranged between the karst cave formation simulation module and the overburden rock and soil simulation module 1; the top end of the karst fracture pipeline simulation module 5 is connected to the bottom end of the overburden rock and soil simulation module 1, and the bottom end is connected to the karst cave formation simulation module The overburden-karst fracture pipeline-karst cave formation structure of deep karst collapse is formed; the hydrodynamic condition simulation module is used to control the groundwater level in the overburden geotechnical simulation module 1, the karst fracture pipeline simulation module 5 and the karst cave formation simulation module, as well as rainfall recharge; the underground engineering excavation and load disturbance simulation module includes an underground engineering excavation mechanism 17 and an underground space vibration loading mechanism 19 arranged in the karst cave formation simulation module, as well as a ground static and dynamic load and construction impact load loading mechanism arranged above the overburden geotechnical simulation module 1; the monitoring and measurement module is used to obtain multivariate information data during the experiment.

[0038] Furthermore, the overburden geotechnical simulation module 1 is used to simulate the geological environment of the karst overburden, and includes an overburden geotechnical simulation box 102 and a water tank 103; the overburden geotechnical simulation box 102 is a transparent box with an open top; the interior of the overburden geotechnical simulation box 102 is filled with an overburden geotechnical body 104; the water tank 103 is installed inside the overburden geotechnical simulation box 102 and is located outside the overburden geotechnical body 104; a porous groundwater supply and drainage port 106 is provided at the bottom of the water tank 103; the water tank 103 is fitted with a One side of the covering rock and soil body 104 is configured with a porous permeable board and a geotextile 101; the water tank 103 is filled with porous groundwater 105; at least one first karst opening 107 is provided at the bottom of the covering rock and soil simulation box 102, the size and shape of which can be adjusted according to actual conditions, and the first karst opening 107 is located below the covering rock and soil body 104; a first karst control valve 108 is installed on the first karst opening 107; the first karst control valve 108 is connected to the karst fracture pipeline simulation module 5.

[0039] Furthermore, the karst fissure pipeline simulation module 5 is used to simulate deep karst geological environments such as long and deep karst fissures and pipelines; it includes a karst fissure pipeline mechanism 501, an upper flexible end 502, and a lower flexible end 503; the upper end of the upper flexible end 502 is connected to the first karst control valve 108, and the lower end is connected to the upper end of the karst fissure pipeline mechanism 501; the upper end of the lower flexible end 503 is connected to the lower end of the karst fissure pipeline mechanism 501, and the lower end is connected to the karst cave formation simulation module. Based on the results of the on-site investigation, karst structures such as dominant karst fissures and pipelines with good connectivity and a significant impact on karst collapse are selected, and a realistic karst fissure pipeline mechanism 501 is prepared using transparent materials and 3D printing technology. The shapes of the upper flexible end 502 and the lower flexible end 503 must be consistent with the actual karst structure.

[0040] Furthermore, the karst cave formation simulation module is used to simulate deep karst formation environments such as karst caves, caves and large karst pipelines; it includes a karst formation simulation box 6, a ground stress loading mechanism 7, and a first movable lifting mechanism 8; the karst formation simulation box 6 is an assembled metal box, the front of which is set to a high-strength transparent material, and the interior of the box is filled with rock fluid-solid coupling similarity materials prepared according to the physical and mechanical parameters of the real karst rock layer 601; the karst formation simulation box 6 is set on the first movable lifting mechanism 8; the interior of the karst formation simulation box 6 is filled with a karst rock layer 601; the interior of the karst rock layer 601 is provided with a karst cave underground space 602, which is prepared simultaneously by melting and dissolving methods (such as dry ice, paraffin, ice, salt) or air bags, splicing and other methods; the karst cave underground space 602 extends upward, and at least one is set on the top There is a second karst opening 603, which is connected to the lower flexible end 503; the ground stress loading mechanism 7 is arranged on the outer surface of the karst formation simulation box 6, including a reaction frame 701, a power device and a loading pressure plate 703; the reaction frame 701 is fixed on the first movable lifting mechanism 8; the loading pressure plate 703 is fitted on the inner side of the karst formation simulation box 6; the power device is placed between the reaction frame 701 and the loading pressure plate 703, one end of the power device is fixedly connected to the reaction frame 701, and the other end is fixedly connected to the loading pressure plate 703, and the loading plate 703 is a block loading form, which can flexibly simulate vertical ground stress and horizontal structural stress under various complex working conditions; the loading pressure plate 703 is provided with a first reserved hole 704 adapted to the second karst opening and a second reserved hole 705 adapted to the cross-section of the underground space.

[0041] Furthermore, the first movable lifting mechanism 8 includes a first movable trolley 801 and a first elevator 802; the first elevator 802 is installed on the first movable trolley 801; the karst formation simulation box 6 is hingedly installed on the first elevator 802; the horizontal position of the karst formation simulation box 6 is controlled by the first movable trolley 801, and the height and inclination angle of the karst formation simulation box 6 are controlled by the first elevator 802.

[0042] Furthermore, the power device is any one of a servo hydraulic loading cylinder or a high-power servo motor.

[0043] Furthermore, the hydrodynamic condition simulation module is used to simulate the effects of groundwater, rainfall and other water environments on karst cover layers, karst fissure pipes, karst caves and underground spaces, including a porous groundwater control mechanism, a karst groundwater control mechanism and an atmospheric rainfall control mechanism; the porous groundwater control mechanism includes a first box 2, a first controller 3 and a first water pipe 4; one end of the first water pipe 4 is connected to the porous groundwater supply and drainage port 106, and the other end is connected to the first box 2; the first controller 3 is installed between the first water pipe 4 and the first box 2, and is used to control the amount of water supplied from the first box 2 to the water tank 103; the karst groundwater control mechanism has water supply, pumping and drainage, as well as booster pump and vacuum pump functions for selection, which can realize various working conditions such as karst groundwater level rise, fall and fluctuation at different rates and water level heights, and can simulate the high water pressure and strong vacuum environment of deep karst; the karst groundwater control mechanism is used to control the groundwater conditions of the karst cave underground space 602 and the karst fissure pipe simulation module; the karst groundwater control mechanism The mechanism includes a second box body 9, a second water pipe 11 and a funnel-shaped karst pipe 15; a second controller 10 is provided on the second box body 9; one end of the second water pipe 11 is connected to the second controller 10, and the other end is connected to the second karst opening 603; the funnel-shaped karst pipe 15 is vertically arranged above the second water pipe 11 to simulate the atmospheric rainfall environment. The transparent funnel-shaped karst pipe 15 is prepared by 3D printing according to the actual engineering geological sinkhole morphology and is arranged within the atmospheric rainfall range according to the actual position; a second karst control valve 16 is installed at the lower end of the funnel-shaped karst pipe 15; the second karst control valve 16 is connected to the second water pipe 11; the atmospheric rainfall control mechanism is used to simulate the atmospheric rainfall environment, including a third controller 12, a third water pipe 13 and an artificial rainfall sprinkler head 14; the third controller 12 is installed on the first box body 2; the third water pipe 13 is arranged above the covering layer geotechnical simulation box 102, and one end is connected to the third controller 12; the artificial rainfall sprinkler head 14 is installed on the third water pipe 13. It can simulate rainfall characteristics such as different rainfall patterns, rainfall duration, rainfall intensity, etc., and can realize the infiltration and replenishment of the karst cover rock and soil body 104 by atmospheric rainfall, as well as the vertical rapid replenishment of the karst groundwater.

[0044] Furthermore, the underground engineering excavation and load disturbance simulation module includes an underground engineering excavation mechanism 17, an underground space vibration loading mechanism 19, and a ground static and dynamic load and construction impact load loading mechanism 20; the underground engineering excavation mechanism 17 includes an excavation drill 1701, an excavation controller 1702, and a second movable lifting platform 18; the second movable lifting platform 18 includes a second movable trolley 1801 and a second elevator 1802; the second elevator 1802 is arranged on the second movable trolley 1801; the excavation drill 1701 is installed on the second elevator 1802, and the front end extends toward the karst formation simulation box 6; the excavation controller 1702 is electrically connected to the excavation drill 1701, and can adjust excavation characteristics such as excavation method, excavation position, cross-section size, excavation speed, and excavation angle; the underground space vibration loading mechanism 19 includes an underground space structure model 1904, a signal generator 190 1. Power amplifier 1902, vibrator 1903; underground space structure model 1904 is set in karst rock layer 601; vibrator 1903 is set in underground space structure model 1904 or karst rock layer 601, and can apply vibration loads of different modes, frequencies and amplitudes at different positions; one end of the power amplifier 1902 is electrically connected to the signal generator 1901, and the other end is electrically connected to the vibrator 1903; ground static and dynamic load and construction impact load loading mechanism 20 is set above the covering rock and soil body 104, including actuator 2002, ground static and dynamic load and construction impact load controller 2001, drilling simulation model drill rod / pile foundation simulation model pile 2003; drilling simulation model drill rod / pile foundation simulation model pile 2003 is installed on actuator 2002; actuator 2002 is electrically connected to ground static and dynamic load and construction impact load controller 2001. The drill rod of the drilling simulation model is made of steel pipe at a similar scale, and the pile of the pile foundation simulation model is made of concrete fluid-solid coupling similar materials at a similar scale. Different modes of ground static loads and pile foundation static loads, as well as ground dynamic loads of different frequencies and amplitudes, drilling / pile foundation dynamic loads, construction impact loads and other ground static and dynamic loads and construction impact load conditions can be applied at different locations.

[0045] The monitoring and measurement module is used to monitor and collect multivariate information changes of the overburden, complex karst structure, karst stratum and underground space structure model 1904 during the experiment, including contact and non-contact methods. The contact methods include monitoring elements such as embedded earth pressure gauges, pore water pressure gauges, soil moisture gauges, water vapor pressure gauges, strain gauges, settlement markers, accelerometers, etc. arranged at key locations, as well as acoustic emission and high-density electrical methods; non-contact methods include laser displacement meters, digital photography measurement, geological radar and other means. According to different experimental requirements, multivariate information such as stress of the overburden rock and soil 104, pore water pressure, pore groundwater 105 water level, moisture content, strain, acceleration, ground displacement, ground deformation and collapse process, water and soil movement in karst fissure pipelines, soil cave development status and collapse process, cave water vapor pressure, karst groundwater level, cave surrounding rock stress and strain, underground space structure and surrounding rock fissure development and failure mode can be obtained.

[0046] A physical model experimental method for deep complex karst ground collapse, including:

[0047] 1) Based on the engineering site investigation data and the experimental design similarity ratio, fluid-solid coupling similarity materials for the overburden rock mass 104, fluid-solid coupling similarity materials for the karst rock layer 601, an underground space structure model 1904, and fluid-solid coupling similarity materials for pile foundation simulation model piles are prepared, and the prefabricated underground space structure model 1904 and the drilling simulation model drill rod / pile foundation simulation model pile 2003 are cast; dominant karst fissures, pipelines, and sinkholes with good connectivity and a significant impact on karst collapse are selected for 3D modeling, and a transparent karst fissure pipeline structure 501, a funnel-shaped karst pipeline 15, an upper flexible end 502, and a lower flexible end 503 based on real forms are produced using 3D printing technology;

[0048] 2) Assemble the overburden geotechnical simulation module 1, determine the plane position and height of the karst cave formation simulation module based on the actual karst morphology, secure it via the first movable lifting mechanism 8, close the first karst control valve 108, and respectively load the overburden soil fluid-solid coupling similarity material and the karst rock layer 601 fluid-solid coupling similarity material into the overburden geotechnical simulation box 102 and the karst formation simulation box 6 in layers. Simultaneously, bury the monitoring elements in the corresponding positions according to the experimental plan until the designed thickness is reached, completing the laying of the overburden soil and karst rock layer 601. When the rock layer is laid to the cave location, a melting dissolution method or an air bag or splicing method is used during the rock layer laying process to simultaneously prepare a cave underground space in the karst formation that meets the experimental morphology. During the laying process, the underground space structure model 1904 and the drilling simulation model drill rod / pile foundation simulation model pile 2003 are pre-buried according to the experimental plan.

[0049] 3) Install the in-situ stress loading mechanism 7 and the transparent karst fissure pipe mechanism 501, so that its upper flexible end 502 is correspondingly connected to the first karst control valve 108 below the overburden rock and soil simulation box 102, and the lower flexible end 503 is correspondingly connected to the second karst opening 603 at the top of the karst cave formation simulation module. The water tanks 103 on both sides of the overburden rock and soil simulation module 1 are connected to the porous groundwater control mechanism, and the bottom of the cave space of the karst cave formation simulation module is connected to the karst groundwater control mechanism. In-situ stress is applied to the karst rock layer 601 in the karst formation simulation box 6 according to the experimental design requirements. The sealing of the experimental system is checked. First, water is slowly supplied to the cave underground space and the karst fissure pipe mechanism 501 to a predetermined water level through the karst groundwater control mechanism. Then, water is slowly supplied to the overburden rock and soil body 104 to a predetermined water level through the porous groundwater control mechanism. The two water levels are maintained and left to stand.

[0050] 4) Select and install a dynamic coercion device according to the experimental requirements, connect and start the monitoring and measurement module, open the first karst control valve 108, conduct ambient acoustic emission, initial geological radar, and high-density electrical geophysical measurements, perform disturbances according to the experimental design parameters, record the parameters of the applied disturbance factors, and regularly conduct geological radar and high-density electrical geophysical measurements until the overburden rock mass 104 completely collapses;

[0051] 5) After the collapse develops stably and the monitoring data is stable, geological radar and high-density electrical geophysical prospecting measurements are carried out, the monitoring and measurement module is turned off, the dynamic coercion device is removed, and the groundwater in the overburden rock and soil simulation box 102, the water tank 103, the karst cave underground space 602, the funnel-shaped karst pipeline 15 and the karst fissure pipeline mechanism 501 is slowly drained. The soil in the overburden rock and soil simulation box 102 is excavated layer by layer and the shape of the collapse pit is recorded.

[0052] Furthermore, the dynamic coercion device is at least one of an underground engineering excavation mechanism 17, an underground space vibration loading mechanism 19, a ground static and dynamic load and construction impact load loading mechanism 20, a porous groundwater control mechanism, a karst groundwater control mechanism, and an atmospheric rainfall control mechanism.

Claims

1. A physical model experimental system for deep complex karst ground collapse, characterized by: include: The invention relates to a covering layer geotechnical simulation module (1), a karst fracture pipeline simulation module (5), a karst cave formation simulation module, a hydrodynamic condition simulation module, an underground engineering excavation and load disturbance simulation module, and a monitoring and measurement module; the karst cave formation simulation module is arranged below the covering layer geotechnical simulation module (1), and the karst fracture pipeline simulation module (5) is arranged between the karst cave formation simulation module and the covering layer geotechnical simulation module (1); the top end of the karst fracture pipeline simulation module (5) is connected to the bottom end of the covering layer geotechnical simulation module (1), and the bottom end is connected to the karst cave formation simulation module, forming a covering layer of deep karst collapse. The cover layer-karst fracture pipeline-karst cave formation structure; the hydrodynamic condition simulation module is used to control the groundwater level in the cover layer geotechnical simulation module (1), the karst fracture pipeline simulation module (5) and the karst cave formation simulation module, as well as rainfall recharge; the underground engineering excavation and load disturbance simulation module includes an underground engineering excavation mechanism (17) and an underground space vibration loading mechanism (19) arranged in the karst cave formation simulation module, as well as a ground static and dynamic load and construction impact load loading mechanism arranged above the cover layer geotechnical simulation module (1); the monitoring and measurement module is used to obtain multivariate information data during the experiment.

2. A physical model experimental system for deep complex karst ground collapse according to claim 1, characterized in that: The overburden rock and soil simulation module (1) comprises an overburden rock and soil simulation box (102) and a water tank (103); the interior of the overburden rock and soil simulation box (102) is filled with an overburden rock and soil body (104); the water tank (103) is installed inside the overburden rock and soil simulation box (102) and is located outside the overburden rock and soil body (104); a porous groundwater supply and drainage port (106) is provided at the bottom of the water tank (103); the water tank (103) is attached to one side of the overburden rock and soil body (104); The side is configured with a porous permeable plate and a geotextile (101); the water tank (103) is filled with porous groundwater (105); the bottom of the overburden rock and soil simulation box (102) is provided with at least one first karst opening (107), and the first karst opening (107) is located below the overburden rock and soil body (104); a first karst control valve (108) is installed on the first karst opening (107); and the first karst control valve (108) is connected to the karst fracture pipeline simulation module (5).

3. A physical model experimental system for deep complex karst ground collapse according to claim 2, characterized in that: The karst fissure pipeline simulation module (5) is used to simulate a deep karst geological environment; it comprises a karst fissure pipeline mechanism (501), an upper flexible end (502), and a lower flexible end (503); the upper end of the upper flexible end (502) is connected to the first karst control valve (108), and the lower end is connected to the upper end of the karst fissure pipeline mechanism (501); the upper end of the lower flexible end (503) is connected to the lower end of the karst fissure pipeline mechanism (501), and the lower end is connected to the karst cave formation simulation module.

4. A physical model experimental system for deep complex karst ground collapse according to claim 3, characterized in that: The karst cave formation simulation module is used to simulate a deep karst formation environment; it comprises a karst formation simulation box (6), a ground stress loading mechanism (7), and a first movable lifting mechanism (8); the karst formation simulation box (6) is arranged on the first movable lifting mechanism (8); the interior of the karst formation simulation box (6) is filled with a karst rock layer (601); a karst cave underground space (602) is arranged inside the karst rock layer (601); the karst cave underground space (602) extends upward, and a second karst opening (603) is arranged on the top, and the second karst opening (603) is connected to the lower flexible end (503); the ground stress loading mechanism (7) is arranged The invention relates to a device for karst formation simulation box (6) and comprises a reaction frame (701), a power device and a loading plate (703); the reaction frame (701) is fixed on a first movable lifting mechanism (8); the loading plate (703) is arranged in close contact with the inner side of the karst formation simulation box (6); the power device is placed between the reaction frame (701) and the loading plate (703), one end of the power device is fixedly connected to the reaction frame (701), and the other end is fixedly connected to the loading plate (703); the loading plate (703) is provided with a first reserved hole (704) adapted to the second karst opening and a second reserved hole (705) adapted to the cross section of the underground space.

5. A physical model experimental system for deep complex karst ground collapse according to claim 4, characterized in that: The first movable lifting mechanism (8) comprises a first movable trolley (801) and a first elevator (802); the first elevator (802) is mounted on the first movable trolley (801); the karst formation simulation box (6) is hingedly mounted on the first elevator (802); the horizontal position of the karst formation simulation box (6) is controlled by the first movable trolley (801), and the height and inclination angle of the karst formation simulation box (6) are controlled by the first elevator (802).

6. A physical model experimental system for deep complex karst ground collapse according to claim 4, characterized in that: The power device is any one of a servo hydraulic loading cylinder and a high-power servo motor.

7. A physical model experimental system for deep complex karst ground collapse according to claim 2, characterized in that: The hydrodynamic condition simulation module includes a porous groundwater control mechanism, a karst groundwater control mechanism, and an atmospheric rainfall control mechanism; the porous groundwater control mechanism includes a first box (2), a first controller (3), and a first water pipe (4); one end of the first water pipe (4) is connected to the porous groundwater supply and drainage port (106), and the other end is connected to the first box (2); the first controller (3) is installed between the first water pipe (4) and the first box (2), and is used to control the water supply amount from the first box (2) to the water tank (103); the karst groundwater control mechanism is used to control the groundwater conditions of the karst cave underground space (602) and the karst fissure pipeline simulation module (5), and includes a second box (9), a second water pipe (11), and a funnel-shaped karst pipeline (15); the second box (9) is provided with a second controller (10); one end of the second water pipe (11) is connected to the second controller (10), and the other end is connected to the second karst opening (603); the funnel-shaped karst pipe (15) is vertically arranged above the second water pipe (11); the lower end of the funnel-shaped karst pipe (15) is installed with a second karst control valve (16); the second karst control valve (16) is connected to the second water pipe (11); the atmospheric rainfall control mechanism is used to simulate the atmospheric rainfall environment, including a third controller (12), a third water pipe (13) and an artificial rainfall sprinkler head (14); the third controller (12) is installed on the first box (2); the third water pipe (13) is arranged above the cover layer rock and soil simulation box (102), and one end is connected to the third controller (12); the artificial rainfall sprinkler head (14) is installed on the third water pipe (13).

8. A physical model experimental system for deep complex karst ground collapse according to claim 4, characterized in that: The underground engineering excavation and load disturbance simulation module comprises an underground engineering excavation mechanism (17), an underground space vibration loading mechanism (19), and a ground static and dynamic load and construction impact load loading mechanism (20); the underground engineering excavation mechanism (17) comprises an excavation drill (1701), an excavation controller (1702), and a second movable lifting platform (18); the second movable lifting platform (18) comprises a second movable trolley (1801) and a second elevator (1802); the second elevator (1802) is arranged on the second movable trolley (1801); the excavation drill (1701) is installed on the second elevator (1802), and the front end extends toward the karst formation simulation box (6); the excavation controller (1702) is electrically connected to the excavation drill (1701); the underground space vibration loading mechanism (19) comprises an underground space structure model (1904), a signal generator (1901), a power An amplifier (1902), an exciter (1903); an underground space structure model (1904) is arranged in a karst rock layer (601); the exciter (1903) is arranged in the underground space structure model (1904) or the karst rock layer (601); one end of the power amplifier (1902) is electrically connected to the signal generator (1901), and the other end is electrically connected to the exciter (1903); a ground static and dynamic load and construction impact load loading mechanism (2 0) is arranged above the covering rock and soil mass (104), comprising an actuator (2002), a ground static and dynamic load and construction impact load controller (2001), and a drilling simulation model drill rod / pile foundation simulation model pile (2003); the drilling simulation model drill rod / pile foundation simulation model pile (2003) is installed on the actuator (2002); and the actuator (2002) is electrically connected to the ground static and dynamic load and construction impact load controller (2001).

9. A physical model experimental method for deep complex karst ground collapse, characterized by: include: 1) Based on the engineering site investigation data and the experimental design similarity ratio, the fluid-solid coupling similarity material of the overburden rock mass (104), the fluid-solid coupling similarity material of the karst rock layer (601), the underground space structure model (1904), and the fluid-solid coupling similarity material of the pile foundation simulation model pile are prepared, and the prefabricated underground space structure model (1904) and the drilling simulation model drill rod / pile foundation simulation model pile (2003) are cast; the advantageous karst fissures, pipelines, and sinkhole karst structures with good connectivity and a greater impact on karst collapse are selected, and 3D modeling is performed, and a transparent karst fissure pipeline structure (501), a funnel-shaped karst pipeline (15), an upper flexible end (502), and a lower flexible end (503) based on the real form are manufactured by 3D printing technology; 2) Assembling the overburden geotechnical simulation module (1), determining the plane position and height of the karst cave formation simulation module according to the actual karst morphology, fixing it by a first movable lifting mechanism (8), closing the first karst control valve (108), and respectively filling the overburden soil fluid-solid coupling similar material and the karst rock layer (601) fluid-solid coupling similar material into the overburden geotechnical simulation box (102) and the karst formation simulation box (6) in layers, and simultaneously burying the monitoring elements at corresponding positions according to the experimental plan until the designed thickness is reached, thereby completing the laying of the overburden soil and the karst rock layer (601); wherein when the rock layer is laid to the cave position, a melting dissolution method or an air bag or splicing method is used to simultaneously prepare a cave underground space in the karst formation that meets the experimental morphology during the rock layer laying process, and pre-burying the underground space structure model (1904) and the drilling simulation model drill rod / pile foundation simulation model pile (2003) according to the experimental plan during the laying process; 3) Installing the ground stress loading mechanism (7), installing the transparent karst fissure pipe mechanism (501), so that the upper flexible end (502) thereof is correspondingly connected to the first karst control valve (108) below the overburden rock and soil simulation box (102), and the lower flexible end (503) is correspondingly connected to the second karst opening (603) at the top of the karst cave formation simulation module, the water tanks (103) on both sides of the overburden rock and soil simulation module (1) are connected to the porous groundwater control mechanism, and the bottom of the cave space of the karst cave formation simulation module is connected to the karst groundwater control mechanism, applying ground stress to the karst rock layer (601) in the karst formation simulation box (6) according to the experimental design requirements, checking the sealing of the experimental system, first slowly supplying water to the cave underground space and the karst fissure pipe mechanism (501) to a predetermined water level through the karst groundwater control mechanism, and then slowly supplying water to the overburden rock and soil body (104) to a predetermined water level through the porous groundwater control mechanism, maintaining the two water levels and allowing it to stand; 4) selecting and installing a dynamic coercion device according to the experimental requirements, connecting and starting the monitoring and measurement module, opening the first karst control valve (108), performing environmental acoustic emission, initial geological radar, and high-density electrical geophysical survey measurements, performing disturbances according to the experimental design parameters, recording the parameters of the applied disturbance factors, and regularly performing geological radar and high-density electrical geophysical survey measurements until the overburden rock and soil body (104) completely collapses; 5) After the collapse develops steadily and the monitoring data is stable, geological radar and high-density electrical geophysical prospecting measurements are carried out, the monitoring and measurement module is turned off, the dynamic coercion device is removed, and the groundwater in the overburden rock and soil simulation box (102), the water tank (103), the karst cave underground space (602), the funnel-shaped karst pipeline (15) and the karst fissure pipeline mechanism (501) is slowly discharged, and the soil in the overburden rock and soil simulation box (102) is excavated layer by layer and the shape of the collapse pit is recorded.

10. A physical model experimental method for deep complex karst ground collapse according to claim 9, characterized in that: The dynamic coercion device is at least one of an underground engineering excavation mechanism (17), an underground space vibration loading mechanism (19), a ground static and dynamic load and construction impact load loading mechanism (20), a porous groundwater control mechanism, a karst groundwater control mechanism, and an atmospheric rainfall control mechanism.

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