Coal seam rock mass deformation and crack expansion detection device under different unloading conditions

Abstract

The present invention discloses a device for detecting deformation and crack expansion of coal seam rock mass under different unloading conditions, which comprises: a support machine platform; an upper fixing frame vertically arranged on one side of the upper end face of the support machine platform and capable of relatively rotating; an outer box body fixed on the side of the upper end face of the support machine platform away from the upper fixing frame for placing a coal seam rock mass sample; a plurality of symmetrically arranged stress loading and unloading components, each of the stress loading and unloading components being vertically fixed on the support machine platform, one end of the stress loading and unloading component passing through the outer box body and abutting against the coal seam rock mass sample; an external drilling device vertically arranged on the upper fixing frame, an inner hole position being opened in the middle of the upper end face of the outer box body, and the external drilling device vertically passing through the inner hole position for vertically drilling the coal seam rock mass sample; and a deformation and crack expansion detection component vertically arranged on the other side of the upper fixing frame.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine fission experiment simulation equipment, and specifically relates to a device for detecting the deformation and crack expansion of coal seam rock mass under different unloading conditions. Background Art

[0002] The existence of fractured coal and rock mass in coal mines seriously affects the strength characteristics and permeability characteristics of coal and rock mass. In the practice of coal mine rock mass engineering, the deformation of rock mass under stress affects the crack opening degree and its seepage properties, thereby also changing the permeability and deformation properties of the surrounding rock. Therefore, it is very necessary to study and analyze the influence of different stress loading and unloading on the mechanical properties of rock mass cracks; at present, most triaxial stress loading devices can realize the three-dimensional stress loading and unloading of fractured coal and rock mass, but it is relatively difficult in the detection of the deformation of fractured coal and rock mass or the detection of crack expansion. The subtle deformation generated by fractured coal and rock mass under different stress conditions is difficult to accurately detect by the naked eye or measuring equipment. Especially for some crack expansions in the middle of coal and rock mass, it is even more difficult to accurately locate. Therefore, those skilled in the art have provided a device for detecting the deformation and crack expansion of coal seam rock mass under different unloading conditions to solve the problems raised in the above background art. Summary of the Invention

[0003] To achieve the above object, the present invention provides the following technical solution: A device for detecting the deformation and crack expansion of coal seam rock mass under different unloading conditions, which includes:

[0004] A support machine platform;

[0005] An upper fixing frame, vertically arranged on one side of the upper end surface of the support machine platform and capable of rotating relatively. A driving motor is arranged in the support machine platform, and the output end of the driving motor is connected and driven with the upper fixing frame through the meshing of gears;

[0006] An outer box body, fixed on the side of the upper end surface of the support machine platform away from the upper fixing frame, for placing a coal seam rock mass sample;

[0007] A stress loading and unloading assembly, which is a plurality of symmetrically arranged ones. Each stress loading and unloading assembly is vertically fixed on the support machine platform. One end of the stress loading and unloading assembly penetrates through the outer box body and abuts against the coal seam rock mass sample;

[0008] An external drilling device, vertically arranged on the upper fixing frame. An inner hole position is opened in the middle of the upper end surface of the outer box body. The external drilling device vertically penetrates through the inner hole position for vertically drilling the coal seam rock mass sample; and

[0009] The deformation and crack expansion detection component is vertically arranged on the other side of the upper fixing frame. After the stress loading and unloading component completes the stress loading and unloading of the coal seam rock mass sample, it extends into the coal seam rock mass sample through a borehole and performs deformation and crack expansion detection on the coal seam rock mass sample in sections.

[0010] Furthermore, preferably, the stress loading and unloading component includes:

[0011] Side columns are vertically fixed on the support machine table, and guide rods are fixedly arranged in parallel on the side columns;

[0012] A driving member is slidably arranged on the guide rods. A transmission chain plate is arranged on the side column, and one end of the transmission chain plate is connected to the driving member;

[0013] A hydraulic telescopic cylinder is horizontally fixed on the driving member;

[0014] A bearing plate member is vertically fixed at the output end of the hydraulic telescopic cylinder; and

[0015] Stress loading rods are arranged in multiple vertical rows. Each stress loading rod horizontally penetrates and is fixed on the bearing plate member, and one end of the stress loading rod abuts against the coal seam rock mass sample.

[0016] Furthermore, preferably, it further includes:

[0017] Roof plate members are provided corresponding to each stress loading rod one by one. The stress loading rods are configured as two-stage telescopic structures, and a plurality of support springs are also connected between the roof plate members and the stress loading rods.

[0018] Furthermore, preferably, the deformation and crack expansion detection component includes:

[0019] A positioning seat is slidably arranged horizontally on the upper fixing frame;

[0020] A telescopic guide frame is vertically fixed in the middle of the positioning seat, and one end of the telescopic guide frame slides into the borehole of the coal seam rock mass sample;

[0021] An upper sealing disc and a lower sealing disc are coaxially fixed below the telescopic guide frame, and the upper sealing disc is located above the lower sealing disc;

[0022] An inline frame is vertically and symmetrically connected between the upper sealing disc and the lower sealing disc. An electric telescopic rod is also coaxially connected between the upper sealing disc and the lower sealing disc;

[0023] A main water inlet pipe is vertically connected to the upper sealing disc, and the other end of the main water inlet pipe is connected to an external water tank for draining and supplying the sealing gap between the upper sealing disc and the lower sealing disc; and

[0024] A drain main pipe is vertically connected to the lower sealing plate. Expansion pipes are provided on both the drain main pipe and the water inlet main pipe, and the drain main pipe is used to timely discharge the pumped water body.

[0025] Furthermore, as a preference, a plurality of side flow holes are circumferentially and arrayed in the borehole located in the coal seam rock mass sample, and the cross-section of each side flow hole is in an inverted trapezoid structure.

[0026] Furthermore, as a preference, the upper sealing plate and the lower sealing plate have the same composition structure. Among them, the upper sealing plate includes:

[0027] A fixed plate;

[0028] Positioning plates, a plurality of which are circumferentially arrayed, and each positioning plate is vertically arranged outside the fixed plate;

[0029] Fine-tuning telescopic rods are horizontally and symmetrically embedded and fixed in the fixed plate, and the output ends of each fine-tuning telescopic rod are fixedly connected to the positioning plate;

[0030] Main pressure plates, which are arranged corresponding to each positioning plate. An inner spring is horizontally connected between the main pressure plate and the positioning plate, and one end of the inner spring is connected to the main pressure plate through an inner connecting piece;

[0031] Linking rods are horizontally fixed in the fixed plate and are arranged corresponding to each main pressure plate. The cross-section of the linking rod is in a two-section telescopic structure; and

[0032] A sealing ring sleeve is connected below the fixed plate, and one end of the sealing ring sleeve passes through the linking rod and is connected to the main pressure plate.

[0033] Furthermore, as a preference, it further includes:

[0034] A stress detection piece is embedded between the main pressure plate and the inner connecting piece and is used to detect the contact stress between the coal seam rock mass sample and the positioning plate.

[0035] Furthermore, as a preference, it further includes:

[0036] Airbag ring pieces, a plurality of which are arranged. Each airbag ring piece is embedded and fixed on the main pressure plate. An air flow pipe is horizontally arranged on the fixed plate. One end of the air flow pipe is communicated with each airbag ring piece, and the other end of the air flow pipe is connected to an external air pump.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] In the present invention, the outer box body is used to hold the coal seam rock mass sample, and the stress loading and unloading assembly is used to apply stress loading or unloading at different intensities to the coal seam rock mass sample from all directions. Previously, the external drilling device can drill vertically into the coal seam rock mass sample. Preferably, the deformation and crack expansion detection assembly detects the shape of the drilled hole in the coal seam rock mass sample and the seepage characteristics of the coal seam rock mass sample through the drilled hole. After the stress loading and unloading assembly completes stress loading and unloading, the deformation and crack expansion detection assembly extends into the drilled hole again to detect the overall deformation of the coal seam rock mass sample and the expansion degree of internal cracks, so as to form a comparative experiment. Among them, a plurality of stress loading rods are arranged on the bearing plate member, and each stress loading rod can adjust the stress at different intensities from multiple positioning points, so as to truly restore and simulate the stress change of the mining face in the coal mine. The corresponding upper sealing disc and lower sealing disc can be expanded and framed in the drilled hole by the telescopic action of the fine-tuning telescopic rod. At this time, when the stress detection member reaches the warning value, the length of each fine-tuning telescopic rod is measured, and then the stress detection member reaches the limit value by the air supply and expansion and contraction action of the airbag ring member. At this time, the conveying air pressure in the airbag ring member is measured, so as to facilitate the deformation of the drilled hole of the coal seam rock mass sample obtained from the later comparative experiment. The water inlet main pipe supplies drainage to the sealing gap formed by the combination of the upper sealing disc and the lower sealing disc, and the internal crack expansion degree and expansion position are obtained by measuring the seepage velocity of the coal seam rock mass sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural diagram of the present invention;

[0040] Figure 2 is a schematic structural diagram of the stress loading and unloading assembly in the present invention;

[0041] Figure 3 is a schematic structural diagram of the deformation and crack expansion detection assembly in the present invention;

[0042] Figure 4 is a schematic structural diagram of the upper sealing disc in the present invention;

[0043] In the figure: 1 support machine platform, 2 upper fixing frame, 3 outer box body, 4 drive motor, 5 stress loading and unloading assembly, 51 side vertical column, 52 transmission chain plate, 53 hydraulic telescopic cylinder, 54 bearing plate member, 55 stress loading rod, 56 top plate member, 57 support spring, 6 deformation and crack expansion detection assembly, 61 positioning seat, 62 telescopic guide frame, 63 water inlet main pipe, 64 drainage main pipe, 65 internal connection frame, 66 side flow hole, 7 upper sealing disc, 71 fixed disc, 72 positioning plate, 73 main pressure plate, 74 internal spring, 75 fine-tuning telescopic rod, 76 linkage rod, 77 sealing ring sleeve, 78 airbag ring member, 79 air flow pipe, 8 lower sealing disc. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Please refer to Figure 1, in the embodiments of the present invention, a deformation and cracking detection device for coal seam rock mass under different unloading conditions includes:

[0045] A support machine platform 1;

[0046] An upper fixing frame 2, vertically arranged on one side of the upper end face of the support machine platform 1 and capable of relative rotation. A driving motor 4 is arranged in the support machine platform 1, and the output end of the driving motor 4 is connected and driven with the upper fixing frame 2 through the meshing action of gears;

[0047] An outer box body 3, fixed on the upper end face of the support machine platform 1 on the side far from the upper fixing frame 2, for placing a coal seam rock mass sample;

[0048] A plurality of stress loading and unloading components 5, symmetrically arranged. Each stress loading and unloading component 5 is vertically fixed on the support machine platform 1. One end of the stress loading and unloading component 5 penetrates through the outer box body 3 and abuts against the coal seam rock mass sample;

[0049] An external drilling device (not shown in the figure), vertically arranged on the upper fixing frame 2. A central inner hole is opened on the upper end face of the outer box body 3, and the external drilling device vertically penetrates through the inner hole for vertically drilling the coal seam rock mass sample; and

[0050] A deformation and cracking detection component 6, vertically arranged on the other side of the upper fixing frame 2. After the stress loading and unloading component 5 completes the stress loading and unloading of the coal seam rock mass sample, the deformation and cracking detection component 6 extends into the coal seam rock mass sample through the drilled hole and segmentally detects the deformation and cracking of the coal seam rock mass sample.

[0051] In this embodiment, the stress loading and unloading component 5 includes:

[0052] A side column 51, vertically fixed on the support machine platform 1, and a guide rod is fixedly arranged in parallel on the side column 51;

[0053] A driving member, slidably arranged on the guide rod. A transmission chain plate 52 is arranged on the side column 51, and one end of the transmission chain plate 52 is connected to the driving member;

[0054] A hydraulic telescopic cylinder 53, horizontally fixed on the driving member;

[0055] A bearing plate member 54, vertically fixed on the output end of the hydraulic telescopic cylinder 53; and

[0056] A plurality of stress loading rods 55, arranged vertically. Each stress loading rod 55 horizontally penetrates and is fixed on the bearing plate member 54, and one end of the stress loading rod 55 abuts against the coal seam rock mass sample.

[0057] As a preferred embodiment, it further includes:

[0058] A top plate member 56, which is provided in one-to-one correspondence with each of the stress loading rods 55. The stress loading rods 55 are configured as two-stage telescopic structures, and a plurality of support springs 57 are also connected between the top plate member 56 and the stress loading rods 55. Among them, preferably, the horizontal telescopic action of the hydraulic telescopic cylinder is used to drive the bearing plate member to displace towards the side close to the coal seam rock mass sample. At this time, the top plate member can abut against the coal seam rock mass sample, and then the support springs are compressed to different degrees by the telescopic adjustment action of each stress loading rod, so as to provide different stress loading and unloading actions at multiple points.

[0059] In this embodiment, the deformation and crack detection assembly 6 includes:

[0060] A positioning seat 61, which is slidably arranged on the upper fixing frame 2 relatively horizontally;

[0061] A telescopic guide frame 62, which is vertically fixed in the middle of the positioning seat 61, and one end of the telescopic guide frame 62 slides into the borehole of the coal seam rock mass sample;

[0062] An upper sealing disc 7 and a lower sealing disc 8, which are coaxially fixed below the telescopic guide frame 62, and the upper sealing disc 7 is located above the lower sealing disc 8;

[0063] An internal connection frame 65, which is vertically symmetrically connected between the upper sealing disc 7 and the lower sealing disc 8, and an electric telescopic rod is also coaxially connected between the upper sealing disc 7 and the lower sealing disc 8;

[0064] A main water inlet pipe 63, which is vertically connected to the upper sealing disc 7, and the other end of the main water inlet pipe 63 is connected to an external water tank for draining and supplying the sealing gap between the upper sealing disc 7 and the lower sealing disc 8; and

[0065] A main drain pipe 64, which is vertically connected to the lower sealing disc 8. Telescopic pipes are provided on both the main drain pipe 64 and the main water inlet pipe 63, and the main drain pipe 64 is used to discharge the pumped water in time. Especially for the detection of the crack expansion points and the degree of crack expansion of the coal seam rock mass sample, the upper sealing disc and the lower sealing disc are gradually driven by the telescopic guide frame to extend into the borehole. At this time, the upper sealing disc and the lower sealing disc can be hermetically attached to each other, and the internal injection is carried out through the main water inlet pipe to measure the seepage characteristics of the coal seam rock mass sample; the stress is adjusted by the stress loading and unloading assembly, and the seepage characteristics of the coal seam rock mass sample are measured again for comparison, so as to effectively locate the crack expansion points and the degree of crack expansion. Herein, the vertical distance between the upper sealing disc and the lower sealing disc can be adjusted by the telescopic movement of the electric telescopic rod, so as to improve the positioning detection accuracy.

[0066] In this embodiment, a plurality of side flow holes 66 are also circumferentially and arrayedly formed in the boreholes in the coal seam rock mass samples. The cross-section of each side flow hole 66 is in an inverted trapezoidal structure. Especially for some coal seam rock mass samples with relatively low overall seepage characteristics and relatively high internal compactness, in order to reduce the experimental difficulty, under different stress loading and unloading actions, the fissures generated inside can be preferentially connected to the side flow holes. Especially in the fissure expansion detection, water can directly flow into the fissures through the side flow holes and conduct seepage, so as to amplify the fissure points and facilitate detection.

[0067] In this embodiment, the upper sealing plate 7 and the lower sealing plate 8 have the same composition structure; among them, the upper sealing plate 7 includes:

[0068] A fixed plate 71;

[0069] Positioning plates 72, which are a plurality of circumferentially arrayed. Each positioning plate 72 is vertically arranged outside the fixed plate 71;

[0070] Fine-tuning telescopic rods 75 are symmetrically and horizontally embedded and fixed in the fixed plate 71. The output ends of each fine-tuning telescopic rod 75 are connected and fixed to the positioning plate 72;

[0071] Main pressure plates 73, which are arranged corresponding to each positioning plate 72. An inner spring 74 is horizontally connected between the main pressure plate 73 and the positioning plate 72. One end of the inner spring 74 is connected to the main pressure plate 73 through an inner connecting piece;

[0072] Linking rods 76 are horizontally fixed in the fixed plate 71 and are arranged corresponding to the main pressure plates 73 one by one. The cross-section of each linking rod 76 is in a two-stage telescopic structure; and

[0073] Sealing ring sleeves 77 are connected below the fixed plate 71. One end of the sealing ring sleeve 77 passes through the linking rod 76 and is connected to the main pressure plate 73.

[0074] As a preferred embodiment, it further includes:

[0075] A stress detection piece, which is embedded between the main pressure plate 73 and the inner connecting piece and is used to detect the contact stress between the coal seam rock mass sample and the positioning plate 72. It should be noted that the warning value and the limit value of the stress detection piece are preferably determined in advance. The warning value is the initial warning when the inner wall of the borehole of the coal seam rock mass sample is under the pressure of the main pressure plate; while the limit value is the pressure bearing limit when the inner wall of the borehole of the coal seam rock mass sample is under the pressure of the main pressure plate.

[0076] In this embodiment, it further includes:

[0077] The airbag ring members 78, a plurality of which are arranged in a row, are each embedded and fixed on the main pressing plate 73. A gas flow pipe 79 is horizontally arranged on the fixed disk 71. One end of the gas flow pipe 79 is communicated with each of the airbag ring members 78, and the other end of the gas flow pipe 79 is connected to an external air pump (not shown in the figure). Among them, the upper sealing disk and the lower sealing disk are expanded and framed in the drilling hole by the telescopic action of the fine-tuning telescopic rod. At this time, when the stress detection member reaches the warning value, the lengths of the fine-tuning telescopic rods are measured. Then, the stress detection member reaches the limit value due to the air supply expansion and contraction action of the airbag ring member. At this time, the conveying air pressure in the airbag ring member is measured, so as to facilitate the comparison of the deformation of the coal seam rock mass sample borehole obtained from the later comparative experiment; at the same time, the airbag ring member has a high waterproof isolation effect and improves the sealing performance.

[0078] Specifically, in the coal and rock mass deformation and crack expansion detection experiment under different unloading conditions, coal and rock mass samples are extracted from the coal mining face in the coal mine and placed in the outer box body. The coal seam rock mass sample is vertically drilled through an external drilling device. At this time, the deformation and crack expansion detection component can preferentially detect the preliminary seepage characteristics of the coal and rock mass sample. The stress loading and unloading component abuts against the coal seam rock mass sample and adjusts the stress loading and unloading of different intensities; the deformation and crack expansion detection component extends into the drilling hole again to detect the overall deformation of the coal seam rock mass sample and the expansion degree of the internal cracks, so as to form a comparative experiment, thereby simulating the change of the internal structure of the coal seam and the generation of cracks under the stress change of the coal mining face in the coal mine.

[0079] As mentioned above, only the preferred specific embodiments of the present invention are described, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. Coal seam rock mass deformation and crack expansion detection device under different unloading conditions, characterized in that: Comprising: A support machine platform (1); An upper fixing frame (2), vertically arranged on one side of the upper end face of the support machine platform (1) and rotatable relative to each other. A driving motor (4) is arranged in the support machine platform (1), and the output end of the driving motor (4) is connected and driven with the upper fixing frame (2) through the meshing of gears; An outer box body (3), fixed on the upper end face of the support machine platform (1) on the side away from the upper fixing frame (2) for placing coal seam rock mass samples; A plurality of stress loading and unloading components (5) are symmetrically arranged. Each stress loading and unloading component (5) is vertically fixed on the support machine platform (1). One end of the stress loading and unloading component (5) penetrates through the outer box body (3) and abuts against the coal seam rock mass sample; An external drilling device, vertically arranged on the upper fixing frame (2). An inner hole position is opened in the middle of the upper end face of the outer box body (3). The external drilling device vertically penetrates through the inner hole position for vertically drilling the coal seam rock mass sample; A deformation and fracture expansion detection component (6), vertically arranged on the other side of the upper fixing frame (2). After the stress loading and unloading component (5) completes the stress loading and unloading of the coal seam rock mass sample, the deformation and fracture expansion detection component (6) extends into the coal seam rock mass sample through the drilled hole and segments the coal seam rock mass sample for deformation and fracture expansion detection; The deformation and fracture expansion detection component (6) comprises: A positioning seat (61), arranged on the upper fixing frame (2) and slidable relative to each other horizontally; A telescopic guide frame (62), vertically fixed in the middle of the positioning seat (61). One end of the telescopic guide frame (62) slides into the drilled hole of the coal seam rock mass sample; An upper sealing disc (7) and a lower sealing disc (8), coaxially fixed below the telescopic guide frame (62), and the upper sealing disc (7) is located above the lower sealing disc (8); A main water inlet pipe (63), vertically communicated with the upper sealing disc (7); A main drain pipe (64), vertically communicated with the lower sealing disc (8); The upper sealing disc (7) and the lower sealing disc (8) have the same composition structure; The upper sealing disc (7) comprises: A fixed disc (71); A plurality of positioning plates (72) are arranged in a circumferential array. Each positioning plate (72) is vertically arranged outside the fixed disc (71); A fine adjustment telescopic rod (75), horizontally and symmetrically embedded and fixed in the fixed disc (71). The output end of each fine adjustment telescopic rod (75) is connected and fixed to the positioning plate (72); A main pressure plate (73), arranged corresponding to each positioning plate (72). An inner spring (74) is horizontally connected between the main pressure plate (73) and the positioning plate (72). One end of the inner spring (74) is connected to the main pressure plate (73) through an inner connecting piece; A linkage rod (76), horizontally fixed in the fixed disc (71) and arranged corresponding to the main pressure plate (73). The cross section of the linkage rod (76) is a two-section telescopic structure; A sealing ring sleeve (77), connected below the fixed disc (71). One end of the sealing ring sleeve (77) passes through the linkage rod (76) and is connected to the main pressure plate (73); Airbag ring members (78), a plurality of which are arranged, and each airbag ring member (78) is embedded and fixed on the main pressing plate (73). An air flow pipe (79) is horizontally arranged on the fixed disk (71), and one end of the air flow pipe (79) is communicated with each airbag ring member (78).

2. The coal seam rock mass deformation and crack expansion detection device under different unloading conditions according to claim 1, characterized in that: The stress loading and unloading assembly (5) includes: Side columns (51), vertically fixed on the support machine table (1), and guide rods are fixedly arranged in parallel on the side columns (51); A driving member, slidably arranged on the guide rods, and a transmission chain plate (52) is arranged on the side column (51), and one end of the transmission chain plate (52) is connected to the driving member; A hydraulic telescopic cylinder (53), horizontally fixed on the driving member; A receiving plate member (54), vertically fixed on the output end of the hydraulic telescopic cylinder (53); Stress loading rods (55), a plurality of which are arranged vertically, and each stress loading rod (55) horizontally penetrates and is fixed on the receiving plate member (54), and one end of the stress loading rod (55) abuts against the coal seam rock mass sample.

3. The coal seam rock mass deformation and crack expansion detection device under different unloading conditions according to claim 2, characterized in that: The stress loading and unloading assembly (5) further includes: A top plate member (56), corresponding to each stress loading rod (55) one by one. The stress loading rod (55) is configured as a two-stage telescopic structure, and a plurality of support springs (57) are also connected between the top plate member (56) and the stress loading rod (55).

4. The device for detecting the deformation and crack expansion of coal seam rock mass under different unloading conditions according to claim 1, characterized in that: The deformation and crack expansion detection assembly (6) further includes: An internal connection frame (65), vertically and symmetrically connected between the upper sealing disk (7) and the lower sealing disk (8). An electric telescopic rod is also coaxially connected between the upper sealing disk (7) and the lower sealing disk (8); The other end of the water inlet main pipe (63) is communicated with an external water tank, which is used for draining and supplying the sealing gap between the upper sealing disk (7) and the lower sealing disk (8); Expansion pipes are arranged on both the drain main pipe (64) and the water inlet main pipe (63), and the drain main pipe (64) is used for timely discharging the discharged water body.

5. The coal seam rock mass deformation and crack expansion detection device under different unloading conditions according to claim 4, characterized in that: A plurality of side flow holes (66) are also circumferentially arrayed in the borehole in the coal seam rock mass sample, and the cross-section of each side flow hole (66) is in an inverted trapezoidal structure.

6. The coal seam rock mass deformation and crack expansion detection device under different unloading conditions according to claim 1, characterized in that: The upper sealing disk (7) further includes: A stress detection member, embedded between the main pressing plate (73) and the internal connection member, which is used for detecting the contact stress between the coal seam rock mass sample and the positioning plate (72).

7. The coal seam rock mass deformation and crack expansion detection device under different unloading conditions according to claim 1, characterized in that: The other end of the air flow pipe (79) is connected to an external air pump.

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