A system and method for simulating the structure of a collapsed body in a mine accident

Abstract

The present invention belongs to the field of similar simulation technology, and specifically relates to a system for simulating the structure of a collapsed body in a mine accident, comprising a main device, a formation model, a support model, a pressure loading module, a monitoring system and a resin filling module; the resin filling module is used to fill a transparent resin into a containing cavity after a simulated tunnel collapses; the present invention also proposes a method for simulating the structure of a collapsed body in a mine accident, wherein baffles are pasted in front and behind the collapsed area after the model collapses, and transparent resin is evenly injected from above the collapsed area; after all transparent resins are completely solidified, the baffles are removed, the solidified collapsed area is taken out, and three-dimensional reconstruction is performed after continuous slicing; the present invention can use a resin filling module to cast the gap formed by the collapsed body with a transparent resin material after the simulated tunnel collapses, and the model can be sliced ​​and three-dimensionally reconstructed after solidification, so that the internal structure of the mixed body after the collapse can be clearly obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of similar simulation, and in particular relates to a system and method for simulating a structure of a collapsed body in a mine accident. Background Art

[0002] Similar simulation experiment research in my country began in the late 1950s. The first similar simulation experiment frame was built by the Mine Pressure Laboratory of Beijing Institute of Mining in 1958. Subsequently, similar simulation technology was gradually extended to research in other fields. So far, there are many similar simulation experiment devices in underground engineering fields such as geotechnical engineering and mining engineering, ranging from plane to three-dimensional, from research tunnels to research stopes, each with its own characteristics.

[0003] Most of the existing tunnel similarity simulation experimental research in mining engineering focuses on the instability principle and the design of support to increase tunnel strength, but lacks research on mine collapse. However, casualties caused by tunnel collapse due to accidents are still the main cause of casualties in coal mines.

[0004] When the tunnel is used as the research object, there are still some contradictions in the existing models. When a large-scale model is used for experiment, the model tunnel is too short, which affects the effect; when a small-scale model is used for experiment, the model tunnel size will be very small. In order to study the structural laws of the mixed collapse body after the tunnel collapse, the tunnel size needs to be larger. According to past experience, the size of the experimental device needs to be large enough, which will result in a large test area, increased test costs, high labor intensity, and is not conducive to conducting experiments.

[0005] Moreover, most of the current related physical simulation experiments lack further analysis of the structural characteristics of the post-collapse mixture. During the simulation experiment, although an external or built-in camera is used to record the experimental process, this method can only record the model's appearance or the changes in the simulated tunnel, and cannot record the internal structure of the post-collapse rock mixture. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a mine accident collapse body structure simulation system and simulation method, which can realize the reconstruction and analysis of the internal structure of the mixed body after the collapse.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention proposes a mine accident collapse structure simulation system, which includes a main device, a stratum model, a support model, a pressure loading module, a monitoring system and a resin filling module;

[0009] The pressure loading module includes a hydraulic cylinder, a pressure plate and a hydraulic system connected to the hydraulic cylinder;

[0010] The main device comprises a rectangular accommodating cavity with an opening on the top, which is surrounded by a bottom plate, two side plates and two transparent plates. The two transparent plates can be removed from the bottom plate. A mounting plate is arranged above the accommodating cavity. The hydraulic cylinder is vertically mounted on the lower surface of the mounting plate. A pressing plate matching the accommodating cavity is arranged at the telescopic end of the hydraulic cylinder.

[0011] The support model includes a simulated anchor rod and a simulated anchor cable;

[0012] The monitoring system includes a high-speed camera, an infrared imager, a strain gauge for monitoring the stress change of the simulated overburden strata, a resistance strain gauge electrically connected to the strain gauge, a digital speckle monitoring system for monitoring the displacement of the strata, and a DS5 acoustic emission system for monitoring the time and location of the roof breakage;

[0013] The stratum model includes simulated rock layers arranged in sequence along the vertical direction, and adjacent simulated rock layers are artificially layered with mica powder; when paved to the tunnel and the monitoring instrument location, the support model and strain gauge are pre-buried in the rock layer;

[0014] The resin filling module is used to fill transparent resin into the accommodating cavity after the simulated tunnel collapses.

[0015] Furthermore, the mine accident collapse body structure simulation system also includes a water adding module, which includes a plurality of water inlet holes opened on the side plate, a plurality of water outlet holes opened on the bottom plate, and a pipeline system for realizing controllable water injection into the water inlet holes.

[0016] Furthermore, the simulated rock formation is made of several materials selected from gravel, river sand, barite powder, gypsum, rosin, and calcium carbonate as raw materials; and the proportion of each material in different simulated rock formations is determined according to the strength of coal rock.

[0017] The present invention also proposes a method for simulating the structure of a collapsed body caused by a mine accident, using the above-mentioned device for simulating the structure of a collapsed body caused by a mine accident, comprising the following steps:

[0018] Step 1: Prepare similar materials;

[0019] Step 2: Simulate rock stratum laying;

[0020] Step 3: Model maintenance and excavation simulation tunnel;

[0021] Step 4: Install the monitoring system;

[0022] Step 5: The pressure loading module increases pressure to cause the simulated tunnel to collapse;

[0023] Step 6: Remove the measuring instruments in the model, remove the simulated rock layer above the collapse range, stick baffles in front and behind the collapse area, and evenly inject transparent resin from above the collapse area;

[0024] Step 7: After all transparent resins are completely solidified, remove the baffle, take out the solidified collapsed area, and reconstruct it in three dimensions after continuous slicing;

[0025] Step 8: Analyze the structural characteristics of the collapsed body through the reconstructed three-dimensional model.

[0026] Furthermore, the viscosity of the transparent resin is 1200±100 Pa·s, and the transparent resin is poured at a minimum speed to ensure its fluidity.

[0027] Furthermore, the transparent resin is injected in batches, each time with a thickness of 5 cm, and the next injection of transparent resin is injected after the previous injection of transparent resin solidifies.

[0028] Furthermore, when slicing the solidified collapsed area, the tunnel length is used as the reference edge and slices are cut every 1 cm to 5 cm.

[0029] Furthermore, in step three, after the model has been cured for 7 days, the transparent plate is removed to allow the model to dry naturally; after 14 days, a simulated tunnel is excavated and the surface is brushed with lime; and displacement observation points are evenly placed on the surface of the collapse range.

[0030] Furthermore, between step 4 and step 5, if it is necessary to simulate water output from the rock formation, a water source is connected, and water is injected into the simulated rock formation through the water inlet holes opened on the side panels, and the injection amount is loaded according to the water output of the sandstone aquifer.

[0031] Furthermore, in step five, after the pressurization begins, the overburden pressure is loaded step by step, based on 2 tons. After each loading, it is left to stand for twenty minutes to observe the deformation of the simulated tunnel until the loading force reaches ten tons. The entire simulated tunnel deformation process is recorded using a high-speed camera.

[0032] The beneficial effects of the present invention are:

[0033] The device of the present invention includes a resin injection module, which can use a transparent resin material to pour the gap formed by the collapsed body after simulating the tunnel collapse. After the model solidifies, the model can be sliced ​​and three-dimensionally reconstructed to facilitate obtaining the spatial distribution characteristics inside the collapsed body;

[0034] The method of the present invention injects a transparent resin material into the collapsed model, slices the solidified model and reconstructs it in three dimensions through software, so that the internal structure of the mixed body after the collapse can be clearly obtained, the destruction process of the simulated tunnel after the collapse and the distribution of the blocks after the collapse can be more clearly observed, and the spatial distribution characteristics of the collapsed body can be clearly obtained, which is convenient for subsequent analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0036] Figure 1 Schematic diagram of the cross-sectional structure of the main device of an embodiment of the present invention.

[0037] Figure 2 Schematic diagram of the structure of the main device of an embodiment of the present invention.

[0038] Figure 3 FIG. 4 is a block diagram of a simulation system according to an embodiment of the present invention.

[0039] Figure 4 Schematic diagram of raw materials for simulating rock formations according to an embodiment of the present invention.

[0040] Figure 5 A stratigraphic column diagram of an application example of the present invention.

[0041] Figure 6 This is a tunnel support arrangement diagram of an application example of the present invention.

[0042] Figure 7 Schematic diagram of the collapse range of an application example of the present invention.

[0043] Figure 8 Schematic diagram of the laying position of strain gauges in an application example of the present invention.

[0044] In the figure, 1-bottom plate, 2-side plate, 3-column, 4-mounting plate, 5-hydraulic cylinder, 6-pressure plate, 7-transparent plate, 8-water inlet hole, 9-water outlet hole, 10-simulated tunnel profile, 11-simulated rock formation, 12-strain gauge, 13-collapse range, 14-slot. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0046] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0048] like Figures 1 to 3 As shown, a mine accident collapse structure simulation system includes a main device, a formation model, a support model, a pressure loading module, a monitoring system and a resin filling module;

[0049] The pressure loading module includes a hydraulic cylinder 5, a pressure plate 6 and a hydraulic system connected to the hydraulic cylinder 5; the pressure loading module is used to provide ground stress simulation for the experiment; the pressure loading module is used to pressurize the model to simulate the ground stress of the overlying rock formation, the hydraulic system includes a hydraulic pump station and a regulating valve, etc., and the maximum range of the hydraulic cylinder 5 can provide a force of 50 tons to simulate the ground stress;

[0050] The main device comprises a rectangular accommodating cavity with an opening on the top, which is surrounded by a bottom plate 1, two side plates 2 and two transparent plates 7. The side plates 2 are provided with side grooves at both ends of the length thereof for inserting the transparent plates 7. The transparent plates 7 can be inserted into the side grooves to fix the positions, and the transparent plates 7 can also be pulled out from the side grooves to remove the two transparent plates 7 from the bottom plate 1. A mounting plate 4 is provided above the accommodating cavity. The hydraulic cylinder 5 is vertically mounted on the lower surface of the mounting plate 4. A pressing plate 6 matching the accommodating cavity is provided at the telescopic end of the hydraulic cylinder 5.

[0051] The support model includes a simulated anchor rod and a simulated anchor cable;

[0052] The monitoring system includes a high-speed camera, an infrared imager, a strain gauge 12 for monitoring the stress change of the simulated overlying rock strata, a resistance strain gauge electrically connected to the strain gauge 12, a digital speckle monitoring system for monitoring the displacement of the rock strata, and a DS5 acoustic emission system for monitoring the time and location of the roof break; the high-speed camera and the infrared imager can clearly observe the falling of blocks during the collapse process and determine the time and location of the collapse; the digital speckle monitoring system obtains the model structure strain result and determines the scope of the collapse damage; the strain gauge 12 can be used to monitor the stress conditions of each layer of rock strata before and after the collapse in real time; a video recording device can be placed in the simulated tunnel to observe the changes in the internal structure and record the destruction process of the direct roof when the collapse occurs;

[0053] The stratum model includes simulated rock layers 11 arranged in sequence along the vertical direction, and adjacent simulated rock layers 11 are artificially layered with mica powder; when paved to the tunnel and the monitoring instrument location, the support model and strain gauge 12 are pre-buried in the rock layer;

[0054] The resin filling module is used to fill transparent resin into the accommodating cavity after the simulated tunnel collapses.

[0055] Furthermore, the mine accident collapse body structure simulation system also includes a water adding module, which includes a plurality of water inlet holes 8 opened on the side panel 2, a plurality of water outlet holes 9 opened on the bottom plate 1, and a pipeline system for realizing controllable water injection into the water inlet holes 8, the pipeline system includes a water tank, and a water inlet pipe connecting the water tank and the water inlet hole 8, and the water inlet hole 8 is in a blocked state when not in use; a water collection tank for collecting seepage water can also be designed under the water outlet hole 9; the water adding module can add water influencing factors to the experiment.

[0056] Further, such as Figure 4 As shown, the simulated rock layer 11 is made of several materials selected from gravel, river sand, barite powder, gypsum, rosin, and calcium carbonate; the proportions of the various materials in the simulated rock layers 11 are determined according to the strength of the coal rock.

[0057] Further, such as Figure 1 As shown, in order to facilitate observation and to ensure that the front and back surfaces of the main structure of the device will not bend due to the consolidation and expansion of the rock strata during the test, the transparent plate 7 is made of high-strength organic glass with a thickness of 15 mm or more; the bottom plate 1 and the side plate 2 are made of steel plates or stainless steel plates, and the columns 3 used to support the mounting plate 4 are made of stainless steel square tubes. The side plates 2 and the columns 3 are welded to the bottom as the main frame, which can not only fix the organic glass, but also withstand the gravity generated after the model is built.

[0058] Further, such as Figure 2As shown, two pairs of slots 14 into which the transparent plate 7 can be inserted are provided at the middle of the opposite sides of the side plate 2, and the spacing between the two sets of slots 14 is half the length of the side plate 2, so that when the transparent plate 7 is inserted into the two slots 14, the cross section of the accommodating cavity can be reduced by about half; thus, by adjusting the position of the transparent plate 7, the appropriate size of the accommodating cavity can be selected according to the experimental needs, in order to achieve the best experimental effect;

[0059] Furthermore, the maximum size of the rectangular accommodating cavity is 0.6m (length) * 0.5m (width) * 0.6m (height). The device has the characteristics of adjustable size and low production cost. Due to the smaller size, the workload required for the production of the stratum model and the support model simulation support is smaller, which is conducive to the rapid arrangement and cleaning of the model and the rapid implementation of the next simulation experiment. Compared with the width, the main device adopts a longer length, so it has a relatively deeper longitudinal direction, and can simulate the tunnel structure over a longer distance.

[0060] The device sent uses transparent resin material to cast the gaps formed by the collapsed body, and obtains a solidified model that simulates the fixation of the stratum, so that after the model solidifies, the model can be sliced ​​and three-dimensionally reconstructed, so as to obtain the spatial distribution characteristics inside the collapsed body.

[0061] The present invention also proposes a method for simulating the structure of a collapsed body caused by a mine accident, using the above-mentioned device for simulating the structure of a collapsed body caused by a mine accident, comprising the following steps:

[0062] Step 1: Preparation of similar materials: Determine the ratio according to the simulation object and the size of the main device, and calculate the amount of each similar material;

[0063] Step 2: Laying the simulated rock layer 11: The simulated rock layer 11 is laid in layers, and adjacent simulated rock layers 11 are artificially layered with mica powder. The simulated rock layer 11 with a thicker thickness needs to be laid in batches; when laying to the tunnel and the monitoring instrument position, the simulated support and strain gauge 12 are pre-buried, and the strain gauge 12 is placed in the rock layer above and below the simulated coal seam;

[0064] Step 3: Model maintenance and excavation of simulated tunnels; after the model is placed for 7 days, the transparent plate 7 is removed to allow the model to dry naturally; after 14 days, the simulated tunnel is excavated and the surface is brushed with lime; displacement observation points are evenly placed on the surface of the collapse range 13;

[0065] Step 4: Install the monitoring system;

[0066] Step 5: Pressurize the pressure loading module to cause the simulated tunnel to collapse: After starting to pressurize, gradually load the overburden pressure, based on 2 tons. After each loading, let it stand for 20 minutes to observe the deformation of the simulated tunnel until the loading force reaches 10 tons. The entire simulated tunnel deformation process is recorded using a high-speed camera;

[0067] Step 6: After collapse occurs, withdraw the measuring instruments in the model, remove the simulated rock layer 11 above the collapse range 13, stick baffles in front and behind the collapse area, and evenly inject transparent resin from above the collapse area; the viscosity of the transparent resin is 1200±100Pa·s, and the transparent resin is injected at the lowest speed to ensure its fluidity; according to the depth of the model, inject the transparent resin in batches, each time injecting 5cm thick transparent resin, and wait for the transparent resin injected last time to solidify before injecting the next transparent resin;

[0068] Step 7: After all transparent resins are completely solidified, remove the baffle, take out the solidified collapsed area, and reconstruct it in three dimensions after continuous slicing; when slicing, take the tunnel length as the reference edge and slice every 1 cm to 5 cm;

[0069] Step 8: Analyze the structural characteristics of the collapsed body through the reconstructed three-dimensional model.

[0070] Furthermore, whether to add water is selected according to experimental needs. For example, if water output from the rock layer 11 needs to be simulated, a water adding module is set up. Between step four and step five, the water inlet hole 8 is connected to the water inlet pipe, the water outlet hole 9 is opened, the water inlet volume is measured with a flow meter, and water is loaded according to the water output of the sandstone aquifer.

[0071] The method of the present invention injects a transparent resin material into the collapsed model, slices the solidified model and reconstructs it in three dimensions through software, so that the internal structure of the mixed body after the collapse can be clearly obtained, the destruction process of the simulated tunnel after the collapse and the distribution of the blocks after the collapse can be more clearly observed, and the spatial distribution characteristics of the collapsed body can be clearly obtained, which is convenient for subsequent analysis.

[0072] Application Examples

[0073] In this application example, the simulation object is a coal mine in Inner Mongolia with a burial depth of 500m. The first mining face of Bojiang Haizi Mine has an advancement length of 2603m and a face length of 200m. It mainly mines 3-1# coal seams with a mining area of ​​520,600m2. The coal seam is stable and is a nearly horizontal monocline structure with a thickness of 3.2 to 6.4m, an average of 5.4m, a strike of 30° to 60°, a dip of 300° to 330°, and a pseudo dip of 0 to 1.5° along the strike of the working face. It is accompanied by small fault structures in some areas. The cross-sectional shape of the first mining face roadway is a rectangle with cross-sectional dimensions: length × width = 5.6m × 3.6m. The stratigraphic column diagram is shown below. Figure 5 shown.

[0074] like Figure 6As shown, the coal mine roadway roof support uses 7 ф22mmx2500mm anchor rods, the spacing between the anchor rods is 850mmx900mm, the preload force is not less than 70kN, the matching steel belt is W3 steel belt, L=5.4m, the metal mesh is 8# diamond galvanized metal mesh with a specification of 6000mmx1100mm, the anchor cable specification is ф17.8mmx6300mm, the preload force is not less than 85kN, and the anchor cable is arranged in a "3-2-3" arrangement. Two-side support: 5 18mx2000mm anchor rods are used, the preload force is not less than 50kN, the metal mesh is 10# diamond galvanized metal mesh, the specification is 4400mmx1100mm. The roadway bottom slab is paved with a 200mm thick concrete floor, and the concrete strength is C30.

[0075] The immediate roof of the coal seam in the 3-1 section of the coal mine is sandy mudstone, which is brittle, low in strength and expands when exposed to water. The basic roof is coarse sandstone and gravel, which are rich in water. Affected by the tunnel excavation, the surrounding rock is loosened and cracks in the roof are developed, causing the pore water of the basic top sandstone to penetrate into the sandy mudstone from the crack channel. The participation of water causes the sandy mudstone on the roof to expand and mudify, and the strength is reduced. The tunnel has a large span and belongs to a large-section tunnel, which increases the exposed area of ​​the roof. When the top of the tunnel is stressed, the roof generates a large tensile stress. In addition, the roof structure is complex, containing multiple layers of coal lines, large rock phase changes, and low interlayer adhesion, which is very easy to delaminate. The sandy mudstone itself is brittle, the solid arch is unstable as a whole, and it is easy to form a loose roof fall outside the anchoring area. Therefore, the device and method of the present invention are intended to reveal the collapsed body structure of metal support components under roof fall (collapse) accidents.

[0076] In this application example, the maximum size of the accommodating chamber of the main device is: length×width×height=600mm×500mm×600mm.

[0077] The method for simulating the structure of a mine accident collapse body specifically includes the following steps:

[0078] Step 1: Preparation of similar materials: The similar materials selected for the simulation test mainly include fine sand, gravel, gypsum, barite powder, rosin and water. A proper amount of ink is added to the materials to simulate the coal seam, according to the strength of the coal rock;

[0079] According to the occurrence state of the coal seam and the roof and floor of the working face, as well as the size of the similar simulation test frame, taking into account the actual required 3-1 coal thickness and tunnel height, the model geometric similarity ratio is determined to be α L =30, then the model tunnel section is 0.187m×0.12m (the actual tunnel size is 5.6m×3.6m);

[0080] The volume-to-weight ratio of similar model materials is: α γ =1.2;

[0081] Therefore, the stress similarity ratio is: a σ =aL ×a γ =36;

[0082] The thickness of each simulated rock layer is shown in the following table:

[0083] Table 1 Thickness of each simulated rock layer relative to the actual rock layer

[0084] Lithological characteristics Model layer thickness mm Actual layer thickness m Coarse-grained sandstone 70 2.1 Sandy mudstone 80 2.4 coal 6.67 0.2 Sandy mudstone 10 0.3 Siltstone 13.33 0.4 coal 10 0.3 Sandy mudstone 33.33 1 3-1 Coal 180 5.4 Sandy mudstone 50 1.5 medium sandstone 30 0.9 Siltstone 50 1.5

[0085] The simulated rock layer is mainly designed with the 3-1 coal seam in the middle as the core area, and the rock layer below the siltstone layer is discarded; at the same time, since the height of this device is 600mm, in order to reserve operating space, the thickness of the first layer of simulated rock layer (coarse-grained sandstone) and the last layer of simulated rock layer (siltstone) are reduced as appropriate.

[0086] The properties of rock formations and simulated rock formations are detailed in Table 2 and Table 3:

[0087] Table 2 Properties of rock formations

[0088] Rock Type <![CDATA[Unit weight kn / m 3 > Compressive strengthMpa Tensile strengthMpa Elastic modulus Siltstone 24.30 23.9 1.33 3.29 Fine sandstone 24.70 21.9 1.41 3 medium sandstone 24.20 29.5 1.23 3.2 Sandy mudstone 24.79 4.1 0.21 0.9 3-1 Coal 11.62 25.25 1.18 1.99

[0089] In Table 2, the compressive strength, tensile strength and elastic modulus of sandy mudstone are the properties after the rock formation is softened.

[0090] Table 3 Properties of simulated rock formations

[0091] Model <![CDATA[Unit weight kn / m 3 > Compressive strengthMpa Tensile strengthMpa Elastic modulus Siltstone 20.253 0.498 0.028 0.069 Fine sandstone 20.58 0.456 0.029 0.063 medium sandstone 20.171 0.615 0.026 0.067 Sandy mudstone 20.661 0.085 0.004 0.019 coal 9.685 0.526 0.025 0.041

[0092] The geometric similarity of the support materials is taken as the first consideration. According to the similarity criterion and previous research experience, solder wire and thin iron wire are selected as similar simulation materials for anchor rods and anchor cables respectively; the comparison table of simulated support materials is as follows:

[0093] Table 4 Comparison of simulated support materials and support prototypes

[0094]

[0095] This simulation mainly observes the structure formed after the tunnel roof collapse.

[0096] The tunnel is buried at a depth of 532.3m, the simulation scheme is set at 1:30, the model laying height is 530mm, the simulated top rock layer height is 8.5m, and the remaining 519.2m height is simulated to generate pressure. The bulk density of the overburden model is 23.45kN / m 3 , the pressure generated at a depth of 519m is:

[0097] σ=γh=23.4kN / m 3 ×519.2m=12.15MPa.

[0098] According to the size of the model, and the predetermined ratio, the actual loading pressure is:

[0099]

[0100] That is, the force required to overlay the model is 10.125 tons;

[0101] In addition, according to the surrounding rock loosening circle theory and the estimated collapse range based on the on-site situation, the collapse range is: with the center of the top plate as the center of the circle and a radius of 5.4m (0.18m in the model), Figure 7 The circle in the figure schematically depicts the theoretical collapse range of the model;

[0102] Step 2: Simulated rock strata laying: Lay the simulated rock strata according to Table 1, and use mica powder as artificial stratification between adjacent layers; thicker simulated rock strata need to be laid in batches;

[0103] The compressive failure of continuous medium similar materials is characterized by shear fracture; the failure mode of discontinuous medium similar materials is shear and tensile cracking along the structural surface; the rock and coal seams within the collapse range have cracks, so discontinuous medium materials are used, stone is used to characterize the structure, river sand and gypsum film binder are used to characterize the structure, and barite powder is used to adjust the bulk density of discontinuous, heterogeneous, anisotropic similar materials; the aggregate of the rock similar materials outside the collapse range is selected according to experience as sand, and the binder is gypsum and calcium carbonate;

[0104] When laying to the tunnel and monitoring instrument location, simulated support and strain gauges are pre-buried to simulate the placement of strain gauges in the rock layers above and below the coal seam; Figure 8 As shown, the strain gauges include horizontally placed strain gauges and vertically placed strain gauges;

[0105] Step 3: Model maintenance and excavation of simulated tunnels; after the model is placed for 7 days of maintenance, the transparent plate is removed to allow the model to dry naturally; after 14 days, the simulated tunnel is excavated, and lime or putty powder is brushed on the outer surface of the model, preferably white paint or other paint with a large color difference from the model. After brushing lime, only the outer surface is adhered to the white paint, and the cracked gaps in the model are not adhered to white, so that the crack characteristics and crack range can be more clearly observed;

[0106] Displacement observation points are evenly placed on the surface of the collapse range, and the displacement observation points are evenly arranged at 0.06*0.06;

[0107] Step 4: Install the monitoring system; the monitoring system includes a digital speckle monitoring system, a resistance strain gauge, a Thousand Eye Wolf 2F04 high-speed camera, and a Soft Island DS5 acoustic emission system;

[0108] Step 5: Pressurize the pressure loading module to cause the simulated tunnel to collapse: After starting to pressurize, gradually load the overburden pressure, based on 2 tons. After each loading, let it stand for 20 minutes to observe the deformation of the simulated tunnel until the loading force reaches 10 tons. The entire simulated tunnel deformation process is recorded using a high-speed camera;

[0109] Step 6: After collapse occurs, withdraw the measuring instruments in the model, remove the simulated rock layer above the collapse range, and stick baffles in front and behind the collapse area. The baffles are foam plastic boards. The resin solidifies with a small amount of viscosity. The foam board is rough on the surface, so it is easy to peel off the resin from the foam plastic board after the resin solidifies. Inject transparent resin evenly from the top of the collapse area. The viscosity of the transparent resin is 1200±100Pa·s. When pouring the transparent resin, pour it at the lowest speed to ensure its fluidity to maintain the structural integrity of the collapsed body. Because the model is too thick, inject 5cm at a time and solidify it in four times, and the time used is 2d*4.

[0110] Step 7: After all transparent resins are completely solidified, let them stand for another day, then remove the baffle, take out the solidified collapsed area, slice it with a cutting machine, and reconstruct it in three dimensions using C4D software after continuous slicing; when slicing, take the length of the lane as the reference edge and slice every 5 cm;

[0111] Step 8: Analyze the structural characteristics of the collapsed body through the reconstructed three-dimensional model.

[0112] It is to be understood that the above description is only exemplary and the embodiments of the present application do not limit this. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A mine accident collapse structure simulation system, characterized by: It includes main device, formation model, support model, pressure loading module, monitoring system and resin injection module; The pressure loading module comprises a hydraulic cylinder (5), a pressure plate (6) and a hydraulic system connected to the hydraulic cylinder (5); The main device comprises a rectangular accommodating cavity with an opening on the top, which is surrounded by a bottom plate (1), two side plates (2) and two transparent plates (7); the two transparent plates (7) can be removed from the bottom plate (1); a mounting plate (4) is arranged above the accommodating cavity; the hydraulic cylinder (5) is vertically mounted on the lower surface of the mounting plate (4); a pressing plate (6) matching the accommodating cavity is arranged at the telescopic end of the hydraulic cylinder (5); two pairs of slots (14) into which the transparent plates (7) can be inserted are arranged in the middle of the opposite sides of the side plate (2); the spacing between the two groups of slots (14) is half the length of the side plate (2); The support model includes a simulated anchor rod and a simulated anchor cable; solder wire and thin iron wire are selected as similar simulation materials for the simulated anchor rod and the simulated anchor cable respectively; The monitoring system comprises a high-speed camera, an infrared imager, a strain gauge (12) for monitoring stress changes of simulated overburden strata, a resistance strain gauge electrically connected to the strain gauge (12), a digital speckle monitoring system for monitoring stratum displacement, and a DS5 acoustic emission system for monitoring the time and location of roof fracture; The stratum model comprises simulated rock layers (11) arranged in sequence along the vertical direction, and adjacent simulated rock layers (11) are artificially layered using mica powder; When laying to the tunnel and the monitoring instrument location, a support model and strain gauges (12) are pre-buried in the rock formation; The resin injection module is used to inject transparent resin into the accommodating cavity after collapse of the simulated tunnel; after collapse, the simulated rock layer (11) above the collapse range (13) is removed, and the resin injection module uniformly injects transparent resin from above the collapse area; the transparent resin has a viscosity of 1200±100 Pa·s, and the transparent resin is injected at a minimum speed to ensure its fluidity; according to the depth of the model, the transparent resin is injected in batches, and the next transparent resin is injected after the previous transparent resin is solidified; after all the transparent resins are completely solidified, the solidified collapse area is taken out, and three-dimensional reconstruction is performed after continuous slicing.

2. The mine accident collapse structure simulation system according to claim 1, characterized in that: It also comprises a water adding module, which comprises a plurality of water inlet holes (8) provided on the side plate (2), a plurality of water outlet holes (9) provided on the bottom plate (1), and a pipeline system for realizing controllable water injection into the water inlet holes (8).

3. The mine accident collapse structure simulation system according to claim 1, characterized in that: The simulated rock layer (11) is made of several materials selected from the group consisting of gravel, river sand, barite powder, gypsum, rosin and calcium carbonate. The proportions of the various materials in different simulated rock layers (11) are determined according to the strength of the coal rock.

4. A method for simulating the structure of a collapsed body in a mine accident, characterized in that: Using the mine accident collapse structure simulation device as claimed in claim 1, comprising the following steps: Step 1: Prepare similar materials; Step 2: laying the simulated rock layer (11); Step 3: Model maintenance and excavation simulation tunnel; Step 4: Install the monitoring system; Step 5: The pressure loading module increases pressure to cause the simulated tunnel to collapse; Step 6: Remove the measuring instruments in the model, remove the simulated rock layer (11) above the collapse range (13), stick baffles in front and behind the collapse area, and evenly inject transparent resin from above the collapse area; Step 7: After all transparent resins are completely solidified, remove the baffle, take out the solidified collapsed area, and reconstruct it in three dimensions after continuous slicing; Step 8: Analyze the structural characteristics of the collapsed body through the reconstructed three-dimensional model.

5. The method for simulating the structure of a mine accident collapse body according to claim 4, characterized in that: Inject the transparent resin in batches, with a thickness of 5 cm each time. Wait until the previous injection of transparent resin solidifies before injecting the next injection of transparent resin.

6. The method for simulating the structure of a mine accident collapse body according to claim 4, characterized in that: When slicing the solidified collapsed area, use the tunnel length as the reference edge and slice every 1cm to 5cm.

7. The method for simulating the structure of a mine accident collapse body according to claim 4, characterized in that: In step 3, after the model is cured for 7 days, the transparent plate (7) is removed to allow the model to dry naturally; after 14 days, a simulated tunnel is excavated and the surface is painted with lime; and displacement observation points are evenly placed on the surface of the collapse range (13).

8. The method for simulating the structure of a mine accident collapse body according to claim 4, characterized in that: Between step 4 and step 5, if it is necessary to simulate water output from the rock layer (11), a water source is connected and water is injected into the simulated rock layer (11) through the water inlet hole (8) opened on the side plate (2). The amount of water injected is loaded according to the water output of the sandstone aquifer.

9. The method for simulating the structure of a mine accident collapse body according to claim 4, characterized in that: In step five, after the pressurization begins, the overburden pressure is loaded step by step, based on 2 tons. After each loading, it is left to stand for 20 minutes to observe the deformation of the simulated tunnel until the loading force reaches 10 tons. The entire simulated tunnel deformation process is recorded using a high-speed camera.

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