Deflective stress loading device and method for coal seam water injection analog simulation

Abstract

The invention belongs to the technical field of coal seam water injection similar simulation, and relates to a deviating stress loading device and method for coal seam water injection similar simulation, and the device comprises a loading frame, a deviating stress loading device, a water injection system and a data acquisition system. The loading frame is used for fixing the coal seam model, the deviating stress loading device applies deviating stress in different directions and sizes on the coal seam model by accurately controlling loading force, and the complex stress state in an actual coal seam is simulated. The water injection system is used for injecting water into the coal seam model and simulating the coal seam water injection process. The data acquisition system records data such as loading force, water injection rate and coal seam deformation in real time. According to the method, loading parameters are changed by adjusting the deviating stress loading device, coal seam water injection similar simulation under different deviating stress conditions is achieved, and an effective experimental means is provided for research of the coal seam water injection technology.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam water injection similarity simulation, and relates to a deviatoric stress loading device and method for coal seam water injection similarity simulation. Background Art

[0002] Due to the random distribution of internal cracks and joints, anisotropy of mechanical properties, etc., the various properties and laws of rock mass are quite different from those of rocks. As a research method, similarity simulation, supported by the similarity principle, can scientifically simulate the properties of rock mass and the various working conditions and disturbances faced by rock mass underground to a certain extent. Coal mass, as a type of rock mass, is also suitable for similar research methods. And with the rapid development of technology, a variety of three-dimensional similarity simulation experimental systems have gradually developed.

[0003] In order to simulate the actual stress field underground, the three-dimensional experimental system currently loads external stress boundary conditions on the experimental model in a symmetrical manner. The loading methods are generally divided into three-way loading and two-way loading, that is, orthogonal loading of external stress in the three directions of XYZ or in the two directions of YZ. Coal seam water injection is generally divided into shallow hole water injection and deep hole water injection, and the injection locations are respectively the mining working face and the working face tunnel. Under this working state, at least one face of the coal body will be liberated from the original rock environment. Obviously, the mechanical state under this condition is an asymmetric stress boundary state. Obviously, the existing three-dimensional experimental system does not meet the experimental requirements of coal seam water injection.

[0004] Therefore, in order to simulate the actual working conditions of coal seam water injection at the working face, a new experimental device and method need to be proposed. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a deviatoric stress loading device and method for similar simulation of coal seam water injection, so as to solve the problem that the existing similar simulation devices for deep earth engineering are symmetrically loaded and cannot meet the experimental requirements of similar simulation of coal seam water injection, so as to meet the experimental requirements of similar simulation of coal seam water injection.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a deviatoric stress loading device for similar simulation of coal seam water injection, comprising an ordinary reaction frame, a plurality of loading jacks arranged in the ordinary reaction frame, and a test model arranged on the ordinary reaction frame through a shear support, wherein a model water injection interface is arranged on the test model for injecting water into the test model; a deviatoric stress reaction frame is also arranged at the front of the test model for cooperating with the shear support to provide asymmetric stress in a unidirectional Y direction.

[0007] Optionally, the common reaction frame is composed of a common reaction frame left beam, a common reaction frame upper beam, a common reaction frame right beam and a common reaction frame lower beam to form a frame structure, which is used to constrain the loading system to load symmetrical stress.

[0008] Optionally, a first X-direction loading jack and a second X-direction loading jack are respectively provided on the left beam and the right beam of the ordinary reaction frame, for providing loading pressure in the X direction; a Z-direction loading jack is provided on the top beam of the ordinary reaction frame, for providing loading pressure in the Z direction.

[0009] Optionally, shear supports are set at the upper and lower ends of the test model using high-strength adhesives and work in conjunction with the deviatoric stress reaction frame to simulate the interaction force between the coal body and the upper and lower rock strata.

[0010] Optionally, a first X-axis rubber oil pressure loading support and a second X-axis rubber oil pressure loading support are respectively arranged on the left and right sides of the test model, and are used to offset the mutual extrusion between the loading supports by flexible deformation and provide uniform loading pressure; a Z-axis rubber oil pressure loading support is arranged on the top of the shear support above the test model.

[0011] Optionally, a rubber cavity is provided inside the first X-axis rubber oil pressure loading support, the second X-axis rubber oil pressure loading support and the Z-axis rubber oil pressure loading support, and the cavity is filled with hydraulic oil. When loading, the hydraulic oil pressure changes synchronously with the pressure of the loading jack in proportion; the contact surface between the support and the loading jack is a rubber-steel plate composite material, and the remaining surfaces are pressure-bearing rubber.

[0012] Optionally, the deviatoric stress reaction frame is reinforced with rectangular grid-shaped reinforcement ribs, and an arc-shaped cross-section is used on the side to naturally transition with the side plate to prevent concentrated stress.

[0013] A deviator stress loading method for coal seam water injection similarity simulation, using a deviator stress loading device for coal seam water injection similarity simulation as described above, comprises the following steps:

[0014] a) Bond the test model to the upper and lower shear supports using a high-strength adhesive;

[0015] b) After the adhesive solidifies, place the combination of the test model and the shear support into a common reaction frame;

[0016] c) combining the first X-direction rubber oil pressure loading support, the second X-direction rubber oil pressure loading support and the Z-direction rubber oil pressure loading support with the test model;

[0017] d) Install the deviator stress reaction frame and ensure that it fits tightly with the shear support;

[0018] e) firstly, symmetrical loading of the Z-axis and the X-axis is performed by using the Z-direction loading jack, the first X-direction loading jack, and the second X-direction loading jack;

[0019] f) Then, the Y-axis direction is loaded through the deviator stress reaction frame and the corresponding loading mechanism, so that the test model is loaded under asymmetric stress in the unidirectional Y direction;

[0020] g) Inject water into the test model through the model water injection interface to conduct a similar simulation experiment of coal seam water injection.

[0021] Optionally, in step f, when loading is performed in the Y-axis direction, the combination formed by the test model and the upper and lower shear supports begins to move forward naturally due to the unidirectional force of the rear loading jack until the upper and lower shear supports contact the deviatoric stress reaction frame and stop moving under its constraint. At this time, the constraint reaction force on the upper and lower shear supports is balanced with the deviatoric stress loading pressure, and a deviatoric stress loading state is formed in the test model.

[0022] The beneficial effects of the present invention are as follows: the deviator stress loading device and method for similar simulation of coal seam water injection of the present invention can make up for the deficiency that only stress boundary conditions can be loaded symmetrically in the current three-dimensional deep rock mass physical similar simulation; the device is simple to operate and has strong reusability, and can not only simulate the deviator stress boundary conditions during water injection, but also conduct simulation research on other deep coal and rock problems.

[0023] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the installation of the shear support of the present invention;

[0027] Figure 3 It is a schematic diagram of the assembly of the present invention;

[0028] Figure 4 It is a schematic diagram of the position of the deviator stress reaction frame of the present invention;

[0029] Figure 5 It is a schematic diagram of the deviatoric stress reaction frame mechanism of the present invention;

[0030] Figure 6 It is a schematic diagram of the deviator stress loading process of the present invention;

[0031] Figure 7 It is a schematic diagram of the structure of the rubber oil pressure support of the present invention.

[0032] Figure markings: 1. Left beam of ordinary reaction frame; 2. First X-direction loading jack; 3. Upper beam of ordinary reaction frame; 4. Z-direction loading jack; 5. Eccentric stress reaction frame; 6. Right beam of ordinary reaction frame; 7. Second X-direction loading jack; 8. First X-direction rubber oil pressure loading support; 9. Lower beam of ordinary reaction frame; 10. Shear support; 11. Model water injection interface; 12. Second X-direction rubber oil pressure loading support; 13. Test model; 14. Rubber; 15. Rubber-steel plate composite material; 16. Hydraulic oil; 17. Z-direction rubber oil pressure loading support. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] See also Figure 1 to Figure 7 , is a deviatoric stress loading device for similar simulation of coal seam water injection, the device comprises:

[0037] Ordinary reaction frame: The frame structure is composed of ordinary reaction frame left beam 1, ordinary reaction frame upper beam 3, ordinary reaction frame right beam 6 and ordinary reaction frame lower beam 9. This structure is used to constrain the loading system to achieve symmetrical stress loading.

[0038] Loading jacks: including a first X-direction loading jack 2 arranged on the left beam 1 of the common reaction frame, a second X-direction loading jack 7 arranged on the right beam 6 of the common reaction frame, and a Z-direction loading jack 4 arranged on the top beam 3 of the common reaction frame. These jacks are used to provide loading pressure in the X direction and the Z direction respectively.

[0039] Shear support 10: A high-strength adhesive is used to set it at the upper and lower ends of the test model 13. The shear support 10 works in conjunction with the deviatoric stress reaction frame 5 to simulate the interaction force between the coal body and the upper and lower rock layers.

[0040] The test model 13 is used for conducting a similar simulation experiment of coal seam water injection, and is provided with a model water injection interface 11 for injecting water into the test model 13 .

[0041] The deviator stress reaction frame 5 is arranged at the front of the test model 13, and is used to cooperate with the shear support 10 to provide asymmetric stress in the unidirectional Y direction. The deviator stress reaction frame 5 is reinforced with rectangular grid-shaped reinforcement ribs, and has an arc-shaped cross-section at the side to naturally transition with the side plate to prevent concentrated stress.

[0042] Rubber oil pressure loading support: including a first X-axis rubber oil pressure loading support 8, a second X-axis rubber oil pressure loading support 12 and a Z-axis rubber oil pressure loading support 17 arranged on the top of the shear support 10. These supports are provided with a rubber cavity inside, and the cavity is filled with hydraulic oil 16. When loading, the pressure of the hydraulic oil 16 changes synchronously in proportion to the pressure of the loading jack. The contact surface between the support and the loading jack is a rubber steel plate composite material 15, and the remaining surface is a pressure-bearing rubber 14. This design can offset the mutual extrusion between the loading seats with flexible deformation and provide uniform loading pressure. In this embodiment, on the one hand, the pressure in the cavity can resist the external pressure to prevent the rubber support from excessive deformation, and on the other hand, the rubber in contact with the model can produce uniform pressure due to the pressure tightly fitting the model load surface. And due to the close fit of the rubber, the model can be in a better sealing environment, which can provide conditions for similar simulation of coal seam water injection. In addition, the mutual contact of the rubber bearings during the three-way loading process is flexible contact, which can prevent the mutual bite and extrusion of the loading bearings caused by the deformation of the model from causing damage.

[0043] By using the above-mentioned deviator stress loading device for similar simulation of coal seam water injection, the present invention also provides a deviator stress loading method for similar simulation of coal seam water injection, which method comprises the following steps:

[0044] a) The test model 13 and the upper and lower shear supports 10 are bonded together using a high-strength adhesive to ensure that the adhesive has a high shear strength, which can be used to simulate the interaction force between the coal body and the upper and lower rock layers.

[0045] b) After the adhesive is solidified, the combination of the test model 13 and the shear support 10 is placed in a common reaction frame.

[0046] c) The first X-direction rubber oil pressure loading support 8, the second X-direction rubber oil pressure loading support 12 and the Z-direction rubber oil pressure loading support (not separately marked in the figure) are combined with the test model 13.

[0047] d) Install the deviator stress reaction frame 5 and ensure that it fits tightly with the shear support 10.

[0048] e) Symmetrical loading of the Z-axis and the X-axis is performed by the Z-direction loading jack 4, the first X-direction loading jack 2 and the second X-direction loading jack 7.

[0049] f) Then, the Y-axis direction is loaded through the deviator stress reaction frame 5 and the corresponding loading mechanism. In this process, the joint body formed by the test model 13 and the upper and lower shear supports 10 begins to move forward naturally due to the unidirectional force of the rear loading jack, until the upper and lower shear supports 10 contact the deviator stress reaction frame 5 and stop moving under its constraint. At this time, the constraint reaction force on the upper and lower shear supports 10 is balanced with the deviator stress loading pressure, and a deviator stress loading state is formed in the test model 13.

[0050] g) Water is injected into the test model 13 through the model water injection interface 11 to conduct a similar simulation experiment of coal seam water injection. During the experiment, the water injection effect of the coal body under the deviatoric stress state can be observed, and the influence of water injection on the physical and mechanical properties of the coal body can be analyzed.

[0051] In this embodiment, since the deviatoric stress constraint reaction frame does not contact the coal model, the concentrated stress damage to the coal model is avoided. The contact of the adhesion force of the upper and lower shear supports with the coal model naturally simulates the mutual friction and connection between the sedimentary rock layers, and does not affect the final experimental results.

[0052] Through the above implementation modes, the present invention can realize a deviatoric stress loading experiment similar to the simulation of coal seam water injection, and provide an effective experimental means for the research of coal seam water injection technology.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A deviatoric stress loading device for similar simulation of coal seam water injection, characterized in that: It includes an ordinary reaction frame, a plurality of loading jacks arranged in the ordinary reaction frame, and a test model arranged on the ordinary reaction frame through a shear support. The test model is provided with a model water injection interface for injecting water into the test model; a deviatoric stress reaction frame is also provided at the front of the test model for cooperating with the shear support to provide asymmetric stress in the unidirectional Y direction.

2. A deviatoric stress loading device for similar simulation of coal seam water injection according to claim 1, characterized in that: The ordinary reaction frame is composed of an ordinary reaction frame left beam, an ordinary reaction frame upper beam, an ordinary reaction frame right beam and an ordinary reaction frame lower beam to form a frame structure, which is used to constrain the loading system to load symmetrical stress.

3. A deviatoric stress loading device for similar simulation of coal seam water injection according to claim 2, characterized in that: The left beam and the right beam of the ordinary reaction frame are respectively provided with a first X-direction loading jack and a second X-direction loading jack for providing loading pressure in the X direction; the top beam of the ordinary reaction frame is provided with a Z-direction loading jack for providing loading pressure in the Z direction.

4. The deviator stress loading device for similar simulation of coal seam water injection according to claim 1, characterized in that: Shear supports are set at the upper and lower ends of the test model with high-strength adhesives and work in conjunction with the deviatoric stress reaction frame to simulate the interaction force between the coal body and the upper and lower rock strata.

5. The deviatoric stress loading device for similar simulation of coal seam water injection according to claim 1, characterized in that: The first X-axis rubber oil pressure loading support and the second X-axis rubber oil pressure loading support are respectively arranged on the left and right sides of the test model, and are used to offset the mutual extrusion between the loading supports by flexible deformation and provide uniform loading pressure; a Z-axis rubber oil pressure loading support is arranged on the top of the shear support above the test model.

6. The deviator stress loading device for similar simulation of coal seam water injection according to claim 1, characterized in that: A rubber cavity is provided inside the first X-direction rubber oil pressure loading support, the second X-direction rubber oil pressure loading support and the Z-direction rubber oil pressure loading support, and the cavity is filled with hydraulic oil. When loading, the pressure of the hydraulic oil changes synchronously in proportion to the pressure of the loading jack; The contact surface between the support and the loading jack is a rubber-steel plate composite material, and the remaining surfaces are pressure-bearing rubber.

7. The deviator stress loading device for similar simulation of coal seam water injection according to claim 1, characterized in that: The deviatoric stress reaction frame is reinforced with rectangular grid-shaped reinforcing ribs, and the side edges are naturally transitioned with the side panels using arc-shaped sections to prevent concentrated stress.

8. A deviator stress loading method for similar simulation of coal seam water injection, using a deviator stress loading device for similar simulation of coal seam water injection as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: a) Bond the test model to the upper and lower shear supports using a high-strength adhesive; b) After the adhesive solidifies, place the combination of the test model and the shear support into a common reaction frame; c) combining the first X-direction rubber oil pressure loading support, the second X-direction rubber oil pressure loading support and the Z-direction rubber oil pressure loading support with the test model; d) Install the deviator stress reaction frame and ensure that it fits tightly with the shear support; e) firstly, symmetrical loading of the Z-axis and the X-axis is performed by using the Z-direction loading jack, the first X-direction loading jack, and the second X-direction loading jack; f) Then, the Y-axis direction is loaded through the deviator stress reaction frame and the corresponding loading mechanism, so that the test model is loaded under asymmetric stress in the unidirectional Y direction; g) Inject water into the test model through the model water injection interface to conduct a similar simulation experiment of coal seam water injection.

9. A deviatoric stress loading method for similar simulation of coal seam water injection according to claim 8, characterized in that: In step f, when loading is performed in the Y-axis direction, the combination formed by the test model and the upper and lower shear supports begins to move forward naturally due to the unidirectional force of the rear loading jack until the upper and lower shear supports contact the deviatoric stress reaction frame and stop moving under its constraint. At this time, the constraint reaction force on the upper and lower shear supports is balanced with the deviatoric stress loading pressure, and a deviatoric stress loading state is formed in the test model.

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