Device for testing bearing performance of coal rock structural body

Abstract

The invention discloses a coal rock structural body bearing performance testing device, and relates to the technical field of coal rock structural body bearing performance testing. One end of the rotating mechanism is fixedly connected with the loading disc, and through the synergistic effect of the integrated rotating mechanism, the radial extrusion mechanism, the axial extrusion mechanism and the heating plate, the porosity of a test sample can be actively regulated and increased, so that the porosity level of the test sample is higher than that of an original coal rock structure; the device can accurately simulate the porosity increase working condition of the coal rock caused by long-term erosion of gases such as H and CH, and realizes accurate prediction of the bearing capacity of the coal rock structure after long-term action of the gases by testing the bearing performance of the sample in different porosity states; according to the innovative design, the limitation that a traditional testing machine cannot simulate the pore evolution process is effectively solved, more reliable test data is provided for engineering evaluation, and the bearing capacity evaluation error caused by the change of the porosity is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-rock structure bearing performance testing, and in particular to a coal-rock structure bearing performance testing device. Background Art

[0002] Underground coal gasification technology is a new type of coal mining technology that heats and burns coal underground to produce combustible gas that can be used for industrial production and life. This technology can utilize the original production tunnels of the mine during mining, and use less equipment and personnel to mine legacy and difficult-to-mine coal resources. It has the advantages of high safety, low cost, and less waste of coal resources. It has become a major research direction for the development of coal technology in my country. Similar to traditional underground mining, underground coal resources will form a combustion zone after large-scale gasification mining. The high temperature generated by gasification causes the mechanical properties of structures such as isolation coal pillars, surrounding rocks and backfill bodies to deteriorate, causing thermal damage. When the isolation coal pillars, surrounding rocks or backfill bodies in the combustion zone become unstable, it will cause the overburden to collapse, resulting in the collapse of the combustion zone. In severe cases, it can cause the surface to sink, affecting the safety of surface buildings and personnel. In addition, the collapsed overburden will block the gasification channel, hinder the stable progress of the gasification process, and even cause gas leakage in the gasifier or groundwater intrusion into the gasifier, making it impossible for the subsequent gasification process to proceed smoothly. Therefore, it is urgent to carry out mechanical property tests on isolated coal pillars, surrounding rocks, filling bodies and other structures in the corresponding underground environment to explore the bearing capacity of coal-rock filling structures in the underground coal gasification environment.

[0003] In the laboratory, traditional rock rigidity testing machines can only achieve simple loading functions and cannot truly simulate the complex working conditions of coal rock structures in underground environments. In actual underground environments, gases such as H2 and CH4 will accumulate in the pores of coal rocks and generate internal pressures of several MPa. This pore pressure will significantly promote crack expansion, thereby changing the pore structure of the coal rock. As the porosity increases, the bearing capacity of the coal rock structure will change significantly. The testing machines currently used in laboratories can only test the bearing performance of coal rock at its current porosity state and cannot actively change its internal pore structure. This limitation results in the equipment being unable to simulate the working conditions of coal rock with increased porosity after long-term erosion by gases such as H2 and CH4, nor can it predict the impact of pore structure evolution on bearing capacity. Due to the lack of this key testing capability, serious misjudgments may occur in engineering assessments. Therefore, a coal rock structure bearing performance testing device is proposed to address the above issues. Summary of the Invention

[0004] The purpose of the present invention is to provide a coal rock structure bearing performance testing device to solve the problems in the background technology.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A coal-rock structure bearing performance testing device, comprising:

[0007] A support seat, the top end of which is fixedly connected to a base;

[0008] A cabinet body is fixedly mounted on the base, one end of the cabinet body is rotatably connected to a cabinet door for closing the cabinet body, a heating plate and a temperature sensor are fixedly connected to the inner side of the cabinet body, and an industrial computer is placed on one side of the cabinet body;

[0009] A perspective window, which is embedded on the inner side of the cabinet door;

[0010] A guide rail is fixedly mounted on the base, and a loading tray is rotatably connected to the outer side of the guide rail;

[0011] A rotating mechanism, one end of which is fixedly connected to the loading tray and is used to rotate with the loading tray;

[0012] A radial extrusion mechanism, one end of which is arranged on one side of the rotating mechanism; a longitudinal movement mechanism is arranged on one side of the radial extrusion mechanism;

[0013] An extrusion block is fixed to one end of the longitudinal moving mechanism, and a second through hole is formed on the inner side of the extrusion block;

[0014] Axial extrusion mechanism, with one end fixedly connected to the cabinet body.

[0015] Preferably, the top end of the loading tray is fixedly connected to a fixing seat, the inner side of the fixing seat is threadedly connected to a screw, and the other end of the screw is rotatably connected to a clamping block;

[0016] There are two clamping blocks, which are symmetrically distributed on both sides of the vertical center line of the loading plate.

[0017] Preferably, the rotating mechanism is fixed to a first hydraulic rod on the inner side of the base, the top of the first hydraulic rod is fixedly connected to a support plate, the top of the support plate is fixedly connected to a motor, the end of the main shaft of the motor is fixedly connected to a turntable, and the top of the turntable is fixedly connected to a second guide shaft on both sides of the vertical center line, and the outer side of the second guide shaft is slidably connected to a connecting column fixedly connected to the loading plate.

[0018] Preferably, both sides of the vertical center line of the bottom end of the support plate are fixedly connected with a first guide shaft that is slidably connected to the base.

[0019] Preferably, a dial plate is fixedly connected to the edge of the turntable.

[0020] Preferably, the radial extrusion mechanism includes a fixed plate fixedly connected to the loading plate, the inner side of the fixed plate is slidably connected to a third guide shaft, one end of the third guide shaft is fixedly connected to a push plate, the outer side of the third guide shaft is sleeved with a second spring whose two ends are respectively fixedly connected to the push plate and the fixed plate, and one end of the push plate is provided with a pushing assembly.

[0021] Preferably, the pushing assembly includes a second wedge block fixedly connected to the push plate, the inner side of the second wedge block is slidably connected to a first wedge block adapted thereto, the side end of the first wedge block is fixedly connected to a hollow connecting frame, and the end of the connecting frame is arranged at the top of the turntable, and the connecting frame is slidably connected to the loading plate.

[0022] Preferably, the longitudinal movement mechanism includes a connecting rod slidably connected to the loading plate, the top end of the connecting rod is fixedly connected to a transition plate, the inner side of the transition plate is slidably connected to an extrusion rod, one end of the extrusion rod is fixedly connected to the extrusion block, and a limit assembly is provided on one side of the extrusion rod;

[0023] A third spring is sleeved on the outer side of the extrusion rod, with two ends respectively fixedly connected to the extrusion block and the transition plate.

[0024] Preferably, the limiting assembly includes a connecting shell fixedly connected to the loading plate, a telescopic rod fixedly connected to the inner side of the connecting shell, the other end of the telescopic rod fixedly connected to a limiting block fitted with the connecting rod, and the outer side of the telescopic rod is sleeved with a first spring whose two ends are respectively fixedly connected to the extrusion block and the transition plate.

[0025] Preferably, the axial extrusion mechanism includes a second hydraulic rod fixedly connected to the cabinet body, a bearing is fixedly connected to the outer side of the telescopic end of the second hydraulic rod, an extrusion disk is fixedly connected to the outer ring of the bearing, and a first through hole is opened on the inner side of the extrusion disk.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. A coal rock structure bearing capacity testing device, which, through the synergistic action of an integrated rotation mechanism, radial extrusion mechanism, axial extrusion mechanism, and heating plate, can actively regulate and increase the porosity of the test sample to a level higher than that of the original coal rock structure. This device can accurately simulate the conditions in which the porosity of coal rock increases due to long-term erosion by gases such as H2 and CH4. By testing the bearing capacity of samples under different porosity conditions, it can accurately predict the bearing capacity of coal rock structures after long-term gas exposure. This innovative design effectively addresses the limitation of traditional testing machines in simulating the pore evolution process, provides more reliable test data for engineering evaluation, and significantly reduces the bearing capacity assessment error caused by porosity changes.

[0028] 2. A coal-rock structure bearing capacity testing device, which can precisely adjust the vertical position of the extrusion block through the action of a longitudinal moving mechanism, achieving targeted extrusion of different parts of the test sample, thereby ensuring that the overall porosity of the sample is effectively improved, simulating the distribution characteristics of the non-uniform stress field in the underground environment, and highly restoring the mechanical response of the coal-rock structure under actual working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Figure 1 This is a schematic diagram of the overall structure of a coal rock structure bearing performance testing device of the present invention.

[0031] Figure 2 This is a schematic diagram of the internal installation structure of a cabinet of a coal rock structure bearing performance testing device of the present invention.

[0032] Figure 3 This is a schematic diagram of the installation structure of a clamping block of a coal rock structure bearing performance testing device of the present invention.

[0033] Figure 4 This is a schematic diagram of the cross-section structure of the base of a coal rock structure bearing performance testing device of the present invention.

[0034] Figure 5 This is a schematic diagram of the installation structure of a coal rock structure bearing performance testing device of the present invention when the motor and the turntable are separated.

[0035] Figure 6 This is a schematic diagram of the installation structure of a push plate of a coal rock structure bearing performance testing device of the present invention.

[0036] Figure 7 This is a schematic structural diagram of the longitudinal movement mechanism of a coal-rock structure bearing performance testing device of the present invention.

[0037] Figure 8 This is a schematic diagram of the installation structure of a limit block of a coal rock structure bearing performance testing device of the present invention.

[0038] Figure 9 This is a structural schematic diagram of an extrusion plate of a coal rock structure bearing performance testing device of the present invention.

[0039] In the figure: 1, rotating mechanism; 101, first hydraulic rod; 102, support plate; 103, first guide shaft; 104, motor; 105, turntable; 106, second guide shaft; 107, connecting column; 108, dial plate;

[0040] 2. Longitudinal movement mechanism; 201. Connecting rod; 202. Connecting housing; 203. First spring; 204. Telescopic rod; 205. Limit block; 206. Transition plate; 207. Extrusion rod; 208. Third spring;

[0041] 3. Radial extrusion mechanism; 301. Connecting frame; 302. First wedge block; 303. Second wedge block; 304. Push plate; 305. Third guide shaft; 306. Second spring; 307. Fixing plate;

[0042] 4. Axial extrusion mechanism; 401. Second hydraulic rod; 402. Bearing; 403. Extrusion plate; 404. First through hole;

[0043] 5. Loading tray; 6. Guide rail; 7. Base; 8. Support seat; 9. Extrusion block; 10. Fixing seat; 11. Screw; 12. Clamp; 13. Cabinet; 14. Heating plate; 15. Cabinet door; 16. Peripheral window; 17. Industrial computer; 18. Second through hole; 19. Temperature sensor. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with specific embodiments. The accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual drawings. They should not be understood as limiting the present invention. In order to better illustrate the specific embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted. Based on the specific embodiments of the present invention, all other specific embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, in the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The present invention will be further elaborated below in conjunction with specific embodiments.

[0046] Example

[0047] like Figures 1-9 As shown, a coal rock structure bearing performance testing device includes:

[0048] The support base 8 has a top end fixedly connected to the base 7. The support base 8 is arranged in a ring shape, with a space in the middle for the first guide shaft 103 to move;

[0049] The cabinet 13 is fixedly mounted on the base 7. One end of the cabinet 13 is rotatably connected to a cabinet door 15 for closing the cabinet 13. A heating plate 14 and a temperature sensor 19 are fixedly connected to the inside of the cabinet 13. An industrial computer 17 is placed on one side of the cabinet 13. When heating the test sample, closing the sealed cabinet door 15 can effectively reduce the heat loss inside the cabinet 13 and significantly improve the heating efficiency. The cabinet 13 is made of high-performance nickel-based alloy material with a temperature range of 1150°C-1300°C, far exceeding the maximum operating temperature of 600°C of the heating plate 14, ensuring structural stability under long-term high-temperature conditions. The temperature sensor 19 monitors the temperature changes inside the cabinet in real time and feeds the data back to the control system. The industrial computer 17 has a built-in pre-programmed PLC control program that can accurately coordinate the orderly operation of each electrical equipment to achieve fully automated control of the test process.

[0050] A perspective window 16 is embedded in the inner side of the cabinet door 15. The perspective window 16 is made of high-temperature resistant glass and can stably work in a high-temperature environment of 600°C for a long time, so that the staff can observe the working conditions inside the cabinet 13;

[0051] The guide rail 6 is fixedly mounted on the base 7. The outer side of the guide rail 6 is rotatably connected to the loading tray 5. The loading tray 5 is used to place the test sample. The test sample is cylindrical in shape. Under the action of the guide rail 6, the loading tray 5 can rotate along the guide rail 6 with the test sample.

[0052] The rotating mechanism 1 has one end fixedly connected to the loading tray 5 and is used to rotate with the loading tray 5;

[0053] A radial extrusion mechanism 3, one end of which is arranged on one side of the rotating mechanism 1; a longitudinal moving mechanism 2 is arranged on one side of the radial extrusion mechanism 3;

[0054] The extrusion block 9 is fixed to one end of the longitudinal moving mechanism 2. A second through hole 18 is provided on the inner side of the extrusion block 9. When the extrusion block 9 and the test sample are squeezed together, the gas can be discharged radially through the second through hole 18 to avoid disordered damage.

[0055] An axial extrusion mechanism 4, one end of which is fixedly connected to the cabinet body 13;

[0056] As a further improvement of the present invention, Figure 1 and Figure 2 As shown, the top of the loading plate 5 is fixedly connected to a fixing base 10, the inner side of the fixing base 10 is threadedly connected to a screw 11, and the other end of the screw 11 is rotatably connected to a clamping block 12; the clamping block 12 and the screw 11 are rotatably connected together in a detachable manner, for example, the clamping block 12 is sleeved on the end of the screw 11, and the size of the clamping block 12 can be customized or selected according to the actual specifications of the test sample to ensure stable clamping with the sample, maintain a stable clamping force during the porosity expansion process, and avoid loosening or displacement of the sample.

[0057] There are two clamping blocks 12 , which are symmetrically distributed on both sides of the vertical center line of the carrier plate 5 . The test sample can be clamped simultaneously by multiple clamping blocks 12 , which can improve the stability of the clamping.

[0058] To increase the porosity of the test sample, follow these steps:

[0059] Step 1: First, the test sample is clamped and fixed on the sample carrier 5 by the clamping block 12. Then, the heating plate 14 and the rotating mechanism 1 are started. The rotating mechanism 1 rotates the test sample rapidly at 0-3000 rpm, generating a centrifugal force exceeding 1000g (based on a rotation radius of 0.1m). The centrifugal force generated by the high-speed rotation promotes the directional migration of particles within the coal rock. The particle rearrangement causes the original pore structure to change. This migration process will produce a large number of new, small tensile microcracks within the sample, especially in weak areas such as primary microcracks and bedding planes, and expand existing pores, resulting in a "radial gradient distribution" of sample density (relatively loose in the center and relatively dense at the edge). This creates an anisotropic mechanical environment and an initial guide (radially outward) for subsequent shear failure.

[0060] Step 2: After the longitudinal moving mechanism 2 adjusts the extrusion block 9 to an appropriate height, the radial extrusion mechanism 3 squeezes the extrusion block 9 and the test sample together. The radial extrusion of the extrusion block 9 (5-20 MPa) can generate shear stress, destroy the cementation between particles, promote the initiation and expansion of microcracks, and synergize with the centrifugal force to form a through-going crack network.

[0061] The reasons for the formation of the through-going fracture network are as follows:

[0062] Guiding crack initiation and propagation paths: Centrifugal force establishes a radial "tension background field" and microcrack guidance; when the radial compressive shear stress field is superimposed on this background field, its energy is no longer used to uniformly compress the dense coal rock mass, but is preferentially used to expand existing, favorable-directed (radial) microcracks; this greatly reduces the energy required to generate new cracks;

[0063] From isolated cracks to connected networks: The microcracks produced by centrifugal force alone are mostly isolated and unconnected; radial extrusion alone may only produce a local, single fracture zone; but when the two work together, the shear force of radial extrusion will expand and connect along the path pre-weakened by centrifugal force (radial microcrack group), like "beads on a string", connecting isolated defects and eventually forming a through-going crack network that runs through the entire specimen or most areas.

[0064] At the same time, the relationship between centrifugal force (Fc) and radial extrusion force (Fr) is not a fixed numerical ratio, but a dynamic functional relationship related to the mechanical properties of the coal rock itself. The quantitative criteria for their coordinated work are as follows:

[0065] 1) Core mechanics principles:

[0066] The main function of radial extrusion force is to generate shear stress sufficient to cause shear failure of coal rock, and its effectiveness depends on the shear strength of coal rock under the current experimental temperature (T) and stress state.

[0067] Therefore, the basic mechanical inequality that must be satisfied for synergy is:

[0068] τ(Fr)>S(T)

[0069] Where: τ(Fr) is the maximum shear stress (unit: MPa) generated inside the coal rock by the radial extrusion force Fr. Its specific value can be obtained through Hertz contact theory or finite element simulation and is positively correlated with Fr.

[0070] S(T) is the shear strength of the coal rock sample at the current heating temperature (T) (unit: MPa). The increase in temperature (T) will significantly soften the organic matter, resulting in a sharp drop in the S(T) value.

[0071] Therefore, the value of the radial extrusion force Fr must be large enough so that the generated shear stress τ(Fr) can exceed the shear strength S(T) of the coal rock at the current temperature, which is a necessary condition for the generation of cracks.

[0072] 2) Empirical range of numerical ratios:

[0073] Although it is not a fixed value, according to a large number of experiments conducted by the applicant, in order to form an optimized through-fracture network rather than local crushing, there is an effective empirical magnitude range between the centrifugal force and the radial extrusion force:

[0074] (Fc / m*g):(Fr / A)≈(100-1000g):(5-20MPa)

[0075] That is, when the centrifugal force field intensity is 100-1000 times the acceleration of gravity, the radial extrusion stress should be controlled within the range of 5-20 MPa.

[0076] This represents a matching relationship in terms of magnitude. For example, under a high centrifugal force field of 500g, if the radial compressive stress is too low (e.g., <2MPa), the pre-expansion effect caused by centrifugation cannot be effectively utilized; if it is too high (e.g., >30MPa), the sample may be directly crushed, forming a single crushing zone rather than a network of cracks.

[0077] 3) Dynamic adjustment strategy:

[0078] In actual experiments, the operation process is usually:

[0079] Start heating and centrifugation first to allow the sample to preheat and reach a certain pre-expansion state.

[0080] Then, the radial extrusion force is applied step by step while the force-displacement curve is monitored on the industrial computer 17 .

[0081] When the force-displacement curve shows obvious yield, it indicates that shear cracks are being generated on a large scale, and at this time the optimal Fr value under the current conditions is reached.

[0082] Therefore, the coordination between centrifugal force and radial extrusion force is not a simple numerical ratio, but a process that follows the "τ(Fr)>S(T)" failure criterion and is dynamically optimized based on experimental feedback within the empirical range of (100-1000g):(5-20MPa). Those skilled in the art can determine the optimal parameter combination through a limited number of routine experiments based on the above criteria and range.

[0083] Step 3: The end of the test sample is squeezed by the axial squeezing mechanism 4. The axial load (0-20 MPa) can change the effective stress field, suppress excessive expansion caused by centrifugation, maintain structural stability, and guide the directional expansion of the crack through the stress concentration effect;

[0084] The core role of the axial load (Fa) is to provide a controllable confining pressure (the confining pressure is defined in the existing technology and will not be elaborated here). Its "threshold" and "balance mechanism" need to be determined according to the stability requirements of the specimen under complex loads.

[0085] 1) The axial load setting is not a fixed value, but is intended to ensure that the specimen does not experience structural instability (i.e., "over-expansion" or brittle fracture) under the combined action of centrifugal force and radial extrusion force. Its effectiveness follows the following stability criteria:

[0086] Pa>Pc

[0087] Where: Pa is the axial stress applied by the axial extrusion mechanism (unit: MPa); Pc is the critical stress at which the specimen undergoes structural instability under specific centrifugal force (Fc) and radial extrusion force (Fr) conditions.

[0088] Therefore, the axial stress Pa must always be greater than the critical instability stress Pc, which is the lower threshold for maintaining structural stability.

[0089] 2) Dynamic balance mechanism - "optimal confining pressure range":

[0090] However, the greater the axial force, the better. Excessive confining pressure will inhibit the expansion of all cracks, including the through-going cracks we hope to generate. Therefore, there is an upper threshold for the axial force. This requires an "optimal confining pressure range":

[0091] PC <Pa<Ps

[0092] Where: Ps is the axial stress value that begins to significantly inhibit the expansion of the target crack.

[0093] The dynamic balance mechanism is reflected in the regulation of Pa within this range:

[0094] When the deformation rate of the sample is monitored to be too fast or the acoustic emission signal surges, it indicates that there is a risk of instability (approaching Pc), and the system should dynamically increase Pa.

[0095] When the crack expands too slowly or stops, it indicates that the confining pressure may be too high (close to Ps), and the system should dynamically reduce Pa to allow the crack to continue to expand optimally.

[0096] 3) The linkage relationship with centrifugal force (Fc) and radial force (Fr):

[0097] Pc is not a constant, it is mainly positively correlated with the centrifugal force Fc. This is because the centrifugal force is the main driving force that causes the radial "expansion" of the specimen and the loosening of the structure. Its empirical relationship can be expressed as:

[0098] Pc∝Fc

[0099] That is, the higher the rotational speed (centrifugal force), the greater the minimum axial confining pressure (Pa) required to prevent instability.

[0100] The radial force Fr mainly affects the efficiency of crack expansion. In the axial force balance mechanism, it is more of an object that needs to be "stabilized" rather than a factor that directly determines Pc.

[0101] 4) Empirical parameter range and examples:

[0102] Based on experiments, for most bituminous coal and anthracite samples, under the conditions of a centrifugal force field of 100-1000g and a radial extrusion stress of 5-20MPa, the optimal axial confining pressure (Pa) range is usually 1-10MPa.

[0103] Specific Example 1 (suppressing expansion): Under the severe conditions of 2000 rpm and radial extrusion of 15 MPa, setting the axial stress Pa to 5 MPa can effectively prevent the overall crushing of the sample in the middle of the test, while allowing a large number of microcracks to expand in an orderly manner.

[0104] Specific Example 2 (Providing Stability): Under mild conditions of 1500 rpm and radial extrusion of 10 MPa, setting the axial stress Pa to 2-3 MPa can provide sufficient lateral constraint to maintain the smooth progress of the latter part of the test.

[0105] Therefore, the dynamic balance mechanism of the axial extrusion mechanism can be summarized as follows:

[0106] Within the empirical range of 1-10 MPa, with the goal of "maintaining structural stability without significantly inhibiting crack expansion", the basic value of the axial stress Pa is positively adjusted according to the magnitude of the centrifugal force Fc, and closed-loop fine-tuning is performed based on the real-time monitored specimen response (deformation, acoustic emission).

[0107] Those skilled in the art can fully realize effective control of the axial load according to the above criteria, ranges and feedback mechanisms.

[0108] When the test sample is subjected to radial and axial compression, the temperature inside the cabinet 13 is gradually raised to 600°C by the heating plate 14. The high temperature induces the following physical and chemical changes:

[0109] a) Pyrolysis and volatilization of organic matter (300-500℃)

[0110] b) Mineral phase change and shrinkage (such as dehydration of clay minerals)

[0111] c) Thermal stress leads to the proliferation of microcracks.

[0112] At the same time, the porosity increases by an average of 3-5% for every 100°C increase in temperature.

[0113] After the porosity increase operation of the test sample is completed, the rotation mechanism 1, the radial extrusion mechanism 3 and the extrusion block 9 can be stopped, and then the bearing capacity of the test sample is tested by the axial extrusion mechanism 4, and the test parameters will be displayed on the display of the industrial computer 17.

[0114] Experiments show that at 1500rpm+10MPa radial force+3MPa axial pressure+400℃, the porosity of coal rock can be increased from 12.4% to 35±2%;

[0115] Under the conditions of 2000rpm+15MPa radial pressure+5MPa axial pressure+500℃, the porosity of coal rock can be increased from 11.8% to 38.9%±2%.

[0116] From the above, it can be seen that through the synergistic effect of the integrated extrusion block 9, the rotating mechanism 1, the radial extrusion mechanism 3, the axial extrusion mechanism 4 and the heating plate 14, the porosity of the test sample can be actively regulated and increased to make it higher than the porosity level of the original coal rock structure. The device can simulate the working conditions of coal rock with increased porosity caused by long-term erosion of gases such as H2 and CH4. By testing the bearing performance of the sample under different porosity states, the bearing capacity of the coal rock structure after long-term gas action can be accurately predicted. This innovative design effectively solves the limitation of traditional testing machines that cannot simulate the pore evolution process, provides more reliable test data for engineering evaluation, and significantly reduces the bearing capacity evaluation error caused by porosity changes.

[0117] "Active control" means that before the test, the staff places the test sample on the loading plate 5, and then expands the porosity of the sample through the coordinated action of the extrusion block 9, the rotating mechanism 1, the radial extrusion mechanism 3, the axial extrusion mechanism 4 and the heating plate 14. This is human active participation. Since the predetermined program has been written into the industrial computer 17, the staff only needs to operate the corresponding control buttons and programs.

[0118] As a further improvement of the present invention, Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 As shown, the rotating mechanism 1 is fixed to the first hydraulic rod 101 inside the base 7, the top of the first hydraulic rod 101 is fixedly connected to the support plate 102, the top of the support plate 102 is fixedly connected to the motor 104, the spindle end of the motor 104 is fixedly connected to the turntable 105, the top of the turntable 105 is fixedly connected to the two sides of the vertical center line, and the outer side of the second guide shaft 106 is slidably connected to the connecting column 107 fixedly connected to the loading plate 5; when it is necessary to rotate the loading plate 5 with the test sample, the motor 104 drives the turntable 105 to rotate. 5 rotates, and then the turntable 105 rotates along the guide rail 6 with the loading tray 5 through the second guide shaft 106 and the connecting column 107. At the same time, the loading tray 5 also rotates with the test sample. When the turntable 105 needs to move in the vertical direction, the first hydraulic rod 101 moves the turntable 105 in the vertical direction through the support plate 102 and the motor 104. At the same time, since the second guide shaft 106 slides on the inner side of the connecting column 107, the turntable 105 can continue to rotate with the connecting column 107 through the second guide shaft 106 when moving in the vertical direction.

[0119] As a further improvement of the present invention, Figure 4 and Figure 5As shown, both sides of the vertical center line of the bottom end of the support plate 102 are fixedly connected with the first guide shaft 103 which is slidably connected to the base 7. The first guide shaft 103 plays the role of guiding and limiting to ensure the stability of the support plate 102 when moving in the vertical direction.

[0120] As a further improvement of the present invention, Figure 4 and Figure 5 As shown, a dial plate 108 is fixedly connected to the edge of the rotary disk 105. When the dial plate 108 needs to be positioned above the bottom of the connecting rod 201, the rotary disk 105 first causes the dial plate 108 to be offset from the bottom of the connecting rod 201. Then, the rotary disk 105 moves the dial plate 108 upwards, causing the dial plate 108 to be positioned above the bottom of the connecting rod 201. Then, the rotary disk 105 rotates the dial plate 108 to be directly above the bottom of the connecting rod 201.

[0121] When the dial plate 108 needs to be located below the bottom of the connecting rod, the rotary disk 105 first moves the dial plate 108 away from the bottom of the connecting rod 201, and then the rotary disk 105 moves the dial plate 108 downward to position the dial plate 108 below the bottom of the connecting rod 201. Then, the rotary disk 105 rotates the dial plate 108 to just above the bottom of the connecting rod 201.

[0122] When the turntable 105 moves in the vertical direction with the dial plate 108, when the dial plate 108 is above the bottom of the connecting rod 201, the turntable 105 moves downward with the dial plate 108, and the connecting rod 201 can be moved downward. When the dial plate 108 is below the connecting rod 201, the turntable 105 moves upward with the dial plate 108, and the connecting rod 201 can be moved upward. Under the action of the up and down movement of the connecting rod 201, the vertical adjustment of the extrusion block 9 is achieved, so that the extrusion block 9 can be squeezed together with the test sample at different positions in the vertical direction.

[0123] As a further improvement of the present invention, Figure 2 、 Figure 3 、 Figure 4 、 Figure 6 and Figure 7As shown, the radial extrusion mechanism 3 includes a fixed plate 307 fixedly connected to the loading plate 5, and a third guide shaft 305 is slidably connected to the inner side of the fixed plate 307, and one end of the third guide shaft 305 is fixedly connected to the push plate 304, and the outer side of the third guide shaft 305 is sleeved with a second spring 306 whose two ends are respectively fixedly connected to the push plate 304 and the fixed plate 307, and one end of the push plate 304 is provided with a pushing component, and the second spring 306 gives the push plate 304 a pulling force to make the push plate 304 approach the fixed plate 307. When the push plate 304 is pushed by the pushing force of the pushing component, the push plate 304 will be squeezed together with the extrusion block 9 and the test sample through the extrusion rod 207. When the push plate 304 is not pushed by the pushing force of the pushing component, the push plate 304 will be separated from the extrusion rod 207 under the pulling force of the second spring 306.

[0124] As a further improvement of the present invention, Figure 4 and Figure 6 When the cam 310 is in the closed position, the push rod 304 is in the closed position, and the push rod 304 is in the open position, so that the push rod 304 and the push rod 304 can be adjusted. As shown in FIG, the pushing assembly includes a second wedge block 303 fixedly connected to the push plate 304, the inner side of the second wedge block 303 is slidably connected to the first wedge block 302 adapted therewith, the side end of the first wedge block 302 is fixedly connected to the hollow connecting frame 301, and the end of the connecting frame 301 is set at the top of the turntable 105, and the connecting frame 301 is slidably connected to the loading plate 5. When the extrusion block 9 and the test sample need to be squeezed together, the turntable 105 moves upward, and when the turntable 105 moves upward, the connecting frame 301 will be pushed up, and then the connecting frame 301 will bring the first wedge block 302 and the second wedge block 303 to produce relative movement. Under the interaction between the first wedge block 302 and the second wedge block 303, the second wedge block 303 will bring the push plate 304 to move in the lateral direction close to the extrusion rod 207, so that the push plate 304 can squeeze the test sample with the extrusion block 9 through the extrusion rod 207.

[0125] As a further improvement of the present invention, Figure 4 、 Figure 6 and Figure 7 As shown, the longitudinal moving mechanism 2 includes a connecting rod 201 slidably connected to the loading plate 5, the top of the connecting rod 201 is fixedly connected to a transition plate 206, the inner side of the transition plate 206 is slidably connected to an extrusion rod 207, one end of the extrusion rod 207 is fixedly connected to the extrusion block 9, and a limit assembly is provided on one side of the extrusion rod 207.

[0126] The outer side of the extrusion rod 207 is sleeved with a third spring 208 at both ends which are fixedly connected to the extrusion block 9 and the transition plate 206 respectively. The third spring 208 applies a pulling force to the extrusion block 9, so that the extrusion block 9 moves toward the transition plate 206 when it is not subjected to a thrust, so that the extrusion block 9 is separated from the test sample. When the extrusion block 9 needs to move in the vertical direction, for example, when it moves upward, when the dial plate 108 is directly below the bottom of the connecting rod 201, the turntable 105 brings the dial plate 108 to lift the connecting rod 201 upward, and then the connecting rod 201 passes through the transition plate 206 and the extrusion rod 207 and moves upward with the extrusion block 9. When the extrusion block 9 moves upward to a suitable position, the limiting action of the limiting assembly realizes the limiting fixation of the connecting rod 201, ensuring that the connecting rod 201 does not move arbitrarily.

[0127] Only after the extrusion block 9 is adjusted to a suitable position in the vertical direction can the extrusion block 9 and the test sample be squeezed together through the radial extrusion mechanism 3. When the connecting frame 301 inside the radial extrusion mechanism 3 needs to be moved upward, the position of the dial plate 108 needs to be staggered with the bottom of the connecting rod 201 to ensure that when the turntable 105 moves upward with the connecting frame 301, the dial plate 108 will not move with the connecting rod 201.

[0128] As a further improvement of the present invention, Figure 7 and Figure 8 As shown, the limit assembly includes a connecting shell 202 fixedly connected to the loading tray 5, a telescopic rod 204 fixedly connected to the inner side of the connecting shell 202, the other end of the telescopic rod 204 fixedly connected to a limit block 205 fitted with the connecting rod 201, and a first spring 203 is sleeved on the outer side of the telescopic rod 204, both ends of which are respectively fixedly connected to the extrusion block 9 and the transition plate 206. The first spring 203 gives the limit block 205 a thrust, and under the thrust of the first spring 203, the limit block 205 and the connecting rod 201 can be fitted together. The friction between the limit block 205 and the connecting rod 201 can achieve the limit fixation of the connecting rod 201. When the dial plate 108 moves in the vertical direction, the dial plate 108 will overcome the friction between the limit block 205 and the connecting rod 201 and move the connecting rod 201 in the vertical direction.

[0129] As a further improvement of the present invention, Figure 2 and Figure 9As shown, the axial extrusion mechanism 4 includes a second hydraulic rod 401 fixedly connected to the cabinet 13, a bearing 402 is fixedly connected to the outer side of the telescopic end of the second hydraulic rod 401, and an extrusion plate 403 is fixedly connected to the outer ring of the bearing 402. A first through hole 404 is opened on the inner side of the extrusion plate 403. During the centrifugal rotation of the test sample, the second hydraulic rod 401 carries the extrusion plate 403 through the bearing 402 to axially extrude the test sample from the top of the test sample. Under the action of the bearing 402, the extrusion plate 403 can move together with the test sample. At the same time, under the action of the first through hole 404, the gas can be guided to be discharged radially to avoid disorderly damage.

[0130] At the same time, the squeezing plate 403 can also press the test sample to perform a load-bearing capacity test on the test sample.

[0131] Moreover, all parts of the device that come into contact with high temperature are made of high temperature resistant materials to ensure that all parts can work normally.

[0132] The above is a preferred embodiment of the present invention. The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only illustrate the principles of the present invention. Without departing from the scope of protection of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A coal rock structure bearing performance testing device, characterized in that: include: A support seat (8), the top end of which is fixedly connected to the base (7); A cabinet (13) is fixedly mounted on the base (7), one end of the cabinet (13) is rotatably connected to a cabinet door (15) for closing the cabinet (13), a heating plate (14) and a temperature sensor (19) are fixedly connected to the inner side of the cabinet (13), and an industrial computer (17) is placed on one side of the cabinet (13); A perspective window (16) is embedded in the inner side of the cabinet door (15); A guide rail (6) is fixedly mounted on the base (7), and the outer side of the guide rail (6) is rotatably connected to the loading tray (5); A rotating mechanism (1), one end of which is fixedly connected to the loading tray (5) and is used to rotate the loading tray (5); A radial extrusion mechanism (3), one end of which is arranged on one side of the rotating mechanism (1); a longitudinal movement mechanism (2) is arranged on one side of the radial extrusion mechanism (3); An extrusion block (9) is fixed to one end of the longitudinal moving mechanism (2), and a second through hole (18) is provided on the inner side of the extrusion block (9); An axial extrusion mechanism (4) is provided, and one end is fixedly connected to the cabinet body (13).

2. A coal-rock structure bearing capacity testing device according to claim 1, characterized in that: The top end of the loading plate (5) is fixedly connected to a fixing seat (10), the inner side of the fixing seat (10) is threadedly connected to a screw rod (11), and the other end of the screw rod (11) is rotatably connected to a clamping block (12); There are two clamping blocks (12), which are symmetrically distributed on both sides of the vertical center line of the loading plate (5).

3. The coal-rock structure bearing capacity testing device according to claim 1, characterized in that: The rotating mechanism (1) is fixed to a first hydraulic rod (101) on the inner side of the base (7); the top end of the first hydraulic rod (101) is fixedly connected to a support plate (102); the top end of the support plate (102) is fixedly connected to a motor (104); the end of the main shaft of the motor (104) is fixedly connected to a turntable (105); the top of the turntable (105) is fixedly connected to a second guide shaft (106) on both sides of the vertical center line; the outer side of the second guide shaft (106) is slidably connected to a connecting column (107) fixedly connected to the loading plate (5).

4. A coal-rock structure bearing capacity testing device according to claim 3, characterized in that: A first guide shaft (103) slidably connected to the base (7) is fixedly connected to both sides of the vertical center line of the bottom end of the support plate (102).

5. A coal-rock structure bearing performance testing device according to claim 3 or 4, characterized in that: A dial plate (108) is fixedly connected to the edge of the turntable (105).

6. The coal-rock structure bearing capacity testing device according to claim 1, characterized in that: The radial extrusion mechanism (3) comprises a fixed plate (307) fixedly connected to the loading plate (5); a third guide shaft (305) is slidably connected to the inner side of the fixed plate (307); one end of the third guide shaft (305) is fixedly connected to the push plate (304); the outer side of the third guide shaft (305) is sleeved with a second spring (306) whose two ends are respectively fixedly connected to the push plate (304) and the fixed plate (307); and one end of the push plate (304) is provided with a pushing component.

7. The coal-rock structure bearing capacity testing device according to claim 6, characterized in that: The pushing assembly includes a second wedge block (303) fixedly connected to the push plate (304), the inner side of the second wedge block (303) is slidably connected to a first wedge block (302) adapted thereto, the side end of the first wedge block (302) is fixedly connected to a hollow connecting frame (301), and the end of the connecting frame (301) is arranged at the top end of the turntable (105), and the connecting frame (301) is slidably connected to the loading plate (5).

8. The coal-rock structure bearing capacity testing device according to claim 1, characterized in that: The longitudinal movement mechanism (2) comprises a connecting rod (201) slidably connected to the loading plate (5), a top end of the connecting rod (201) is fixedly connected to a transition plate (206), an inner side of the transition plate (206) is slidably connected to an extrusion rod (207), one end of the extrusion rod (207) is fixedly connected to an extrusion block (9), and a limit assembly is provided on one side of the extrusion rod (207); The outer side of the extrusion rod (207) is sleeved with a third spring (208) whose two ends are respectively fixedly connected to the extrusion block (9) and the transition plate (206).

9. The coal-rock structure bearing capacity testing device according to claim 8, characterized in that: The limiting assembly comprises a connecting shell (202) fixedly connected to the loading plate (5); a telescopic rod (204) is fixedly connected to the inner side of the connecting shell (202); the other end of the telescopic rod (204) is fixedly connected to a limiting block (205) that fits with the connecting rod (201); and the outer side of the telescopic rod (204) is sleeved with a first spring (203) whose two ends are respectively fixedly connected to the extrusion block (9) and the transition plate (206).

10. The coal-rock structure bearing performance testing device according to claim 1, characterized in that: The axial extrusion mechanism (4) comprises a second hydraulic rod (401) fixedly connected to the cabinet (13); a bearing (402) is fixedly connected to the outer side of the telescopic end of the second hydraulic rod (401); an extrusion disc (403) is fixedly connected to the outer ring of the bearing (402); and a first through hole (404) is provided on the inner side of the extrusion disc (403).

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