TESTING DEVICE AND METHOD FOR SIMULATING COALBUMP OF PASSING THROUGH FAULT

A testing device for simulating coalbump includes a testing chamber. A first oil cylinder, a second oil cylinder and a third oil cylinder are provided within the testing chamber; each piston rod of each oil cylinder can stretch or retract. A first reaction seat, a second reaction seat and a third reaction seat are arranged opposite to a side of the first piston rod of the first oil cylinder, a side of the second piston rod of the second oil cylinder and a side of the third piston rod of the third oil cylinder respectively. The testing device includes a shear loading unit including a fourth oil cylinder and a fifth oil cylinder located on a same axis, and a side of a fourth piston rod of the fourth oil cylinder and a side of a fifth piston rod of the fifth oil cylinder are arranged opposite to each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Patent Application No. 202210690774.6, filed on Jun. 17, 2022, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the technical field of mines, particularly to a testing device and method for simulating coalbump of passing through fault.

BACKGROUND

Coalbump is a common dynamic disaster phenomenon in coal mine production and a major problem to be solved urgently in the mining industry. In complex geological structures such as faults and folds, coalbump frequently occurs due to stress concentration and severe strata behavior during mining. It is significant to carry out experimental research on the influence of faults and folds on coalbump. Coalbump of passing through fault is a phenomenon of rock burst caused by unstable sliding of the fault resulted from mining stress and release of concentrated stress near the fault, the stress concentration near the fault provides stress conditions for the fault coalbump and discontinuous structure of the fault provides geological structure conditions for the fault coalbump. The testing device in the prior art for simulating coalbump includes oil cylinders with piston rods along X, Y, and Z directions respectively. Pressure is applied onto a cube test specimen by hydraulic pressure of the oil cylinder to simulate ground stress. However, the testing device in the prior art cannot generate shearing force on the test specimen, resulting in that a physical simulation test of coalbump cannot be carried out under the condition of disturbed shear dynamic load caused by fault dislocation.

SUMMARY

An object of the present disclosure is to provide a testing device and method for simulating coalbump of passing through fault, aiming at a problem that the existing testing device for simulating coalbump cannot generate shearing force on a test specimen so that a physical simulation test of coalbump cannot be carried out under the condition of disturbed shear dynamic load caused by fault dislocation.

According to the first aspect of the present disclosure, the present disclosure provides a testing device for simulating coalbump of passing through fault. The technical solution of the testing device is provided as follows.

The testing device includes a testing chamber; a first oil cylinder, a second oil cylinder and a third oil cylinder are provided within the testing chamber; a first piston rod of the first oil cylinder, a second piston rod of the second oil cylinder and a third piston rod of the third oil cylinder stretch or retract respectively in an X direction, a Y direction and a Z direction; a first reaction seat, a second reaction seat and a third reaction seat are arranged opposite to a side of the first piston rod of the first oil cylinder, a side of the second piston rod of the second oil cylinder and a side of the third piston rod of the third piston rod respectively, and provided within the testing chamber. The testing device further includes a shear loading unit including a fourth oil cylinder and a fifth oil cylinder. The fourth oil cylinder and the fifth oil cylinder are located on a same axis, and a side of a fourth piston rod of the fourth oil cylinder and a side of a fifth piston rod of the fifth oil cylinder are arranged opposite to each other; the fourth piston rod of the fourth oil cylinder and the fifth piston rod of the fifth oil cylinder stretch or retract along the X direction, Y direction or Z direction.

Further, the testing chamber includes a fixed seat and a test specimen carrier for loading a cuboid test specimen, the fixed seat is of hexahedral structure, a space for accommodating the test specimen carrier is formed inside the fixed seat, and an inlet-outlet opening for entrance and exit of the test specimen carrier is formed on a surface of the fixed seat. The first oil cylinder is arranged on the test specimen carrier and located at an end of a length direction of the test specimen. The second oil cylinder, the third oil cylinder, the fourth oil cylinder, the fifth oil cylinder, the first reaction seat, the second reaction seat and the third reaction seat are all arranged on the fixed seat. The axis of the fourth oil cylinder and the fifth oil cylinder is along the Z direction, and the shear loading unit formed by the fourth oil cylinder and the fifth oil cylinder is arranged in parallel with the third oil cylinder; two second oil cylinders and two second reaction seats are, and six surfaces of the test specimen are covered with pressure bearing plates respectively. Conveying the test specimen out of or into a loading operation area by the test specimen carrier saves labor force.

Further, two first guide rails arranged in parallel for movement of the test specimen carrier are provided outside the inlet-outlet opening, and the two first guide rails are supported and fixed by a support frame. The test specimen carrier conveys the test specimen through the first guide rails, which ensures positioning precision of the test specimen.

Further, the test specimen carrier is of hexahedral structure, a test specimen loading space for accommodating the test specimen is provided through the test specimen carrier, a loading and unloading opening for loading and unloading the test specimen is provided on a surface of the test specimen carrier and arranged horizontally. The first oil cylinder is arranged on a side wall of the test specimen loading space far from the fixed seat; upper and lower side walls of the test specimen loading space are provided with through slots, and cushion blocks for transferring loading load or reaction force are slidably fitted in the through slots.

Further, the test specimen is loaded on the test specimen carrier through a test specimen preparation platform, and two second guide rails arranged in parallel for movement of the test specimen preparation platform are provided on the test specimen carrier; extension guide rails are provided outside the loading and unloading opening and form extension portions of the second guide rails. The extension guide rails are provided on a loading platform, which is not convenient for the test specimen to be directly placed into the test specimen carrier; however, placing the test specimen on the test specimen preparation platform and then transferring it into the test specimen carrier makes loading more convenient and much faster.

Further, the loading platform includes a test specimen preparation platform base, and four columns are provided on the test specimen preparation platform base. Each of the extension guide rails is fixed on two corresponding columns by two semicircular hoops and screws. The test specimen preparation platform is of “” shaped frame structure, and two hollow areas of the test specimen preparation platform form an avoidance space for avoiding the cushion blocks; a pressure bearing plate is arranged between the test specimen preparation platform and the test specimen. The extension guide rails are fixed firmly, and stable and reliable in structure; furthermore, because of designing the test specimen preparation platform with a “H” shaped frame structure, it is no necessary to unload the test specimen from the test specimen preparation platform, and the test specimen preparation platform and the test specimen enter the fixed seat together with the test specimen carrier, which is convenient and quick.

Further, each of piston rods of the first oil cylinder, the second oil cylinder, the third oil cylinder the fourth oil cylinder and the fifth oil cylinder is provided with a stress sensor and a displacement sensor. Change data of stress and displacement is collected from the surface of the test specimen during a process from loading of the oil cylinder to occurrence of rock bust, for subsequent analysis.

Further, the testing device further includes a monitoring system for detecting cracks in the test specimen, and the monitoring system includes an ultrasonic detection system, a thermal imaging detection system, an electromagnetic radiation detection system, a high-speed camera, a borehole imager, and a dynamic strain gauge, which are used for detecting whether the cracks occur in the test specimen during loading, positions where the cracks occur, extension directions and so on.

According to a second aspect of the present disclosure, the present disclosure provides a testing method for simulating coalbump by adopting the testing device. The testing method includes the following steps:S1, mounting a test specimen: mounting a prepared cuboid test specimen into place;S2, preliminary loading: synchronously loading the first oil cylinder (1), the second oil cylinder (2), the third oil cylinder (3), the fourth oil cylinder (4) and the fifth oil cylinder (5) to a first loading force, to clamp the test specimen by collaborating with the first reaction seat (6), the second reaction seat (7) and the third reaction seat (8);S3, fixing the test specimen: further loading all oil cylinders synchronously along a direction of the fourth piston rod of the fourth oil cylinder (4) to a second loading force, so as to further fasten the test specimen;S4, preloading: loading the first oil cylinder, the second oil cylinder, the third oil cylinder, the fourth oil cylinder and the fifth oil cylinder synchronously to respective target preloading forces on conditions that first target preloading forces of the fourth oil cylinder (4) and the fifth oil cylinder (5) are less than second target preloading forces of the first oil cylinder (1), the second oil cylinder (2) and the third oil cylinder (3);S5, keeping pressure stable: keeping pressure in a stable state for a period of time, after each oil cylinder reaches its target preloading force;S6, shearing test: keeping the second target preloading forces of the first oil cylinder (1), the second oil cylinder (2) and the third oil cylinder (3) stable, and controlling piston rods of the fourth oil cylinder (4) and the fifth oil cylinder (5) to move synchronously in a same direction until the test specimen is broken;S7, unloading and removing the test specimen: removing the test specimen and ending the test.

In the present disclosure employing the above technical solutions, by newly providing a pair of coaxial oil cylinders on the basis of the existing testing device, on the premise that the loading force applied on the test specimen by other oil cylinders is kept stable, the piston rods of the newly provided pair of oil cylinders are controlled to clamp the test specimen and move in the same direction synchronously, so as to generate shear force on the test specimen. Compared with the problem that the existing testing device for simulating coalbump cannot generate shearing force on the test specimen so that the physical simulation test of coalbump cannot be carried out under the condition of disturbed shear dynamic load caused by fault dislocation, in the present disclosure, the shearing force can be generated on the test specimen so that the physical simulation test of coalbump can be carried out under the condition of disturbed shear dynamic load caused by fault dislocation.

Compared with the prior art, the present disclosure has the following technical effects. 1. The shearing force can be generated on the test specimen so that the physical simulation test of coalbump can be carried out under the condition of disturbed shear dynamic load caused by fault dislocation. 2. It is convenient and quick to load materials through the test specimen preparation platform and the test specimen carrier, saving workforce.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure will be described in detail in combination with the accompanying drawings.

In order to make the objects, the technical solutions and the advantages of the present disclosure much clearer, the present disclosure is further described in detail below in combination with the drawings and embodiments. It should be understood the specific embodiments described herein are only used to explain the present disclosure, not to limit the present disclosure.

An embodiment of the present disclosure provides a testing device for simulating coalbump. As shown inFIGS.1-3, the testing device includes a testing chamber, which is provided with a first oil cylinder1, a second oil cylinder2and a third oil cylinder3therein. A first piston rod of the first oil cylinder1, a second piston rod of the second oil cylinder2and a third piston rod of the third oil cylinder3stretch or retract in X, Y and Z directions respectively. A first reaction seat6, a second reaction seat7and a third reaction seat8arranged opposite to a side of the first oil cylinder1having the first piston rod arranged thereon, a side of the second oil cylinder2having the second piston rod arranged thereon and a side of the third oil cylinder3having the third piston rod arranged thereon respectively are provided within the testing chamber. The testing device further includes a shear loading unit including a fourth oil cylinder4and a fifth oil cylinder5. The fourth oil cylinder4and the fifth oil cylinder5are located on a same axis, and one side of the fourth oil cylinder4having a fourth piston rod provided thereon is arranged opposite to one side of the fifth oil cylinder5having a fifth piston rod provided thereon. The piston rods of the fourth oil cylinder4and the fifth oil cylinder5stretch or retract along the X direction, Y direction or Z direction.

The testing chamber includes a fixed seat11and a test specimen carrier12for loading a cuboid test specimen. The whole fixed seat11is of a hexahedral structure. A space for containing the test specimen carrier12is formed inside the fixed seat11. An inlet-outlet opening for entrance and exit of the test specimen carrier12is formed on one surface of the fixed seat11. The first oil cylinder1is arranged on the test specimen carrier12and located at one end of the test specimen in its length direction. The second oil cylinder2, the third oil cylinder3, the fourth oil cylinder4, the fifth oil cylinder5, the first reaction seat6, the second reaction seat7and the third reaction seat8are all arranged on the fixed seat11. The axes of the fourth oil cylinder4and the fifth oil cylinder5is along the Z direction, and the shear loading unit formed by the fourth oil cylinder4and the fifth oil cylinder5is arranged in parallel with the third oil cylinder3. Two second oil cylinder2and two second reaction seat7are provided, and the six surfaces of the test specimen are covered with pressure bearing plates9respectively.

Two first guide rails14arranged in parallel for moving the test specimen carrier12are provided outside the inlet-outlet opening, and supported and fixed by a support frame17.

The test specimen carrier12is of hexahedral structure. A test specimen loading space for accommodating the test specimen is arranged through the test specimen carrier12. One surface of the test specimen carrier12is provided with a loading and unloading opening for loading and unloading test specimens, and the loading and unloading opening is arranged horizontally. The first oil cylinder1is arranged on a side wall of the test specimen loading space far from the fixed seat11. Upper and lower side walls of the test specimen loading space are provided with through slots, and cushion blocks10for transferring the loading load or reaction force are slidably fitted in the through slots.

The test specimen is loaded on the test specimen carrier12through a test specimen preparation platform15, and two second guide rails18arranged parallel for movement of the test specimen preparation platform12are provided on the test specimen carrier12. Extension guide rails16are provided outside the loading and unloading opening; the extension guide rails16form extension portions of the second guide rails18and are arranged on a loading platform.

The loading platform includes a test specimen preparation platform base13which is provided with four columns Each extension guide rail16is fixed on two columns by two semicircular hoops and screws. The test specimen preparation platform15is of “H” shaped frame structure, and two hollow areas of the test specimen preparation platform15form an avoidance space for avoiding the cushion blocks10. A pressure bearing plate9is arranged between the test specimen preparation platform15and the test specimen.

The piston rods of the first oil cylinder1, the second oil cylinder2, the third oil cylinder3, the fourth oil cylinder4and the fifth oil cylinder5are provided with stress sensors and displacement sensors.

The testing device also includes a monitoring system for detecting cracks in the test specimen. The monitoring system includes an ultrasonic detection system, a thermal imaging detection system, an electromagnetic radiation detection system, a high-speed camera, a borehole imager and a dynamic strain gauge.

An embodiment of the present disclosure provides a testing method for simulating coalbump with the above testing device. The testing method includes the following steps:S1, loading a test specimen: a prepared cuboid test specimen is placed on the test specimen preparation platform15, the test specimen preparation platform15is driven along the extension guide rails16to enter the test specimen carrier12until the pressure bearing plate9on the test specimen preparation platform15is aligned with the underlying cushion block10, and then the test specimen carrier12is driven along the first guide rails14to enter the fixed seat11until it contacts the first reaction seat6;S2, preliminary loading: the first oil cylinder1, the second oil cylinder2, the third oil cylinder3, the fourth oil cylinder4and the fifth oil cylinder5are synchronously loaded to a first loading force (the loading force is enough to make the pressure bearing plate contact tightly the test specimen), so as to clamp the test specimen together with the first reaction seat6, the second reaction seat7and the third reaction seat8;S3, fixing the test specimen: all the oil cylinders along the direction of the piston rod of the fourth oil cylinder4are further synchronously loaded to a second loading force (the second loading force is greater than the first loading force in S2 and less than the target preloading forces in S4), so as to further stabilize the test specimen;S4, preloading: on the premise that the first target preloading forces of the fourth oil cylinder4and the fifth oil cylinder5are less than second target preloading forces of the first oil cylinder1, the second oil cylinder2and the third oil cylinder3, the above oil cylinders are loaded synchronously to respective target preloading forces (the target preloading force is determined according to the working conditions required to be simulated);S5, keeping pressure stable: after each oil cylinder reaches its target preloading force, the state of stable pressure is kept for a period of time;S6, shearing test: the second target preloading forces of the first oil cylinder1, the second oil cylinder2and the third oil cylinder3are kept stable, and the piston rods of the fourth oil cylinder4and the fifth oil cylinder5are controlled to move in the same direction synchronously until the test specimen cracks;S7, unloading and taking the test specimen: the first oil cylinder1, the second oil cylinder2, the third oil cylinder3, the fourth oil cylinder4and the fifth oil cylinder5are unloaded at a certain rate until there is no loading force, and the test specimen carrier12is driven along the first guide rails11to exit the fixed seat11, and the test specimen is taken out.

In the present disclosure employing the above technical solutions, by newly providing a pair of coaxial oil cylinders on the basis of the existing testing device, on the premise that the loading force applied on the test specimen by other oil cylinders is kept stable, the piston rods of the newly provided pair of oil cylinders are controlled to clamp the test specimen and move in the same direction synchronously, so as to produce shear force on the test specimen. Compared with the problem that the existing testing device for simulating coalbump cannot generate shearing force on the test specimen so that the physical simulation test of coalbump cannot be carried out under the condition of disturbed shear dynamic load caused by fault dislocation, in the present disclosure, the shearing force can be generated on the test specimen so that the physical simulation test of coalbump can be carried out under the condition of disturbed shear dynamic load caused by fault dislocation. Furthermore, it is convenient and quick to load materials through the test specimen preparation platform and the test specimen carrier, saving manpower.

The above is only a preferred embodiment of the present disclosure, and does not limit the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.