Shear creep test device capable of controlling water-containing state of rock structural surface and test method

Abstract

The invention provides a shear creep test device and test method capable of controlling the water-containing state of a rock structural plane, the device comprises a direct shear apparatus, a soaking device, an inflation device and a shear box, the direct shear apparatus comprises a loading frame, a loading device and a sliding device; the shear box comprises an upper shear box and a lower shear box, the upper shear box is provided with a first notch, and the lower shear box is provided with a second notch; the structural plane-containing rock sample comprises a hanging wall rock, a footwall rock and a structural plane, the hanging wall rock is placed in the first notch, the footwall rock is placed in the second notch, the lower shear box is placed on the sliding device, the hanging wall rock and the upper shear box are placed on the footwall rock, and the structural planes of the hanging wall rock and the footwall rock are aligned and contacted; the soaking device is arranged on the lower shear box, and the inflating device is connected to the upper shear box; and the loading device applies a normal load to the upper shear box and applies a transverse load to the lower shear box. The device and the method can be applied to research on shear mechanical characteristics and shear creep characteristics of the rock structural surface in different water-containing states.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mechanical property testing, and in particular to a shear creep testing device and a testing method capable of controlling the water content of a rock structural surface. Background Art

[0002] There are a large number of faults, joints and weak interlayers in engineering rock mass. These structural surfaces are the weak parts of rock mass engineering, and their mechanical properties have an important influence on the stability of rock mass. In the case of continuous precipitation or continuous rise of groundwater level, water intrusion will increase the bulk density of rock mass, weaken the friction and cohesion between particles inside the rock, and the chemical corrosion of water will have an irreversible effect on the strength and damage and fracture mechanism of rock. When the rock texture in the rock mass is hard or the water absorption rate is low, precipitation or groundwater mainly penetrates into the rock mass through the structural surface. Under the action of water-rock, the structural surface will gradually suffer surface damage and roughness degradation. The degree of structural surface weakening caused by different water content of the structural surface is also different. Generally, the greater the water content of the structural surface, the greater the degree of structural surface weakening. The deterioration of the structural surface will promote shear creep deformation, increase the creep rate, and reduce the long-term strength of the structural surface until shear slip instability occurs. Therefore, in order to more accurately predict and control the stability of rock mass with hard structural surfaces, it is necessary to study the shear creep characteristics of rock hard structural surfaces under different water content states. However, most of the current rock shear creep equipment can only perform shear creep tests on rock structural surfaces under dry or completely submerged conditions, and cannot control the water content of the rock structural surface. Although some scholars have slowed down the water loss of rock structural surfaces by controlling the temperature and humidity of the laboratory, it is still difficult to keep the rock structural surface in a certain water content state for a long time. Therefore, it is necessary to develop a shear creep test device that can control the water content of the rock structural surface. Summary of the invention

[0003] According to the technical problems raised above, a shear creep test device and test method for controlling the water content of rock structure surface are provided. The present invention mainly controls the water content of the structure surface by immersing the rock structure surface in water and locally inflating and pressurizing the structure surface, thereby realizing shear test and shear creep test of the structure surface under different water content states.

[0004] The technical means adopted by the present invention are as follows: A shear creep test device capable of controlling the water content of a rock structure surface comprises: a direct shear instrument, a water immersion device, an air filling device and a shear box, wherein the direct shear instrument comprises a loading frame and a loading device and a sliding device mounted on the loading frame; The shear box is used to accommodate a rock sample containing a structural surface, and comprises an upper shear box and a lower shear box arranged at intervals, a first notch is provided on one side of the upper shear box, a second notch is provided on one side of the lower shear box, and the first notch and the second notch are arranged oppositely; The rock sample containing the structural surface comprises an upper plate rock, a lower plate rock and a structural surface, the upper plate rock is placed in a first notch of an upper shear box, the lower plate rock is placed in a second notch of a lower shear box, the lower shear box is placed on a sliding device, the upper plate rock and the upper shear box are placed on the lower plate rock, the surface where the upper plate rock contacts the lower plate rock is the structural surface, the structural surfaces of the upper plate rock and the lower plate rock are aligned and contacted, the structural surface is located in a gap between the upper shear box and the lower shear box, and the total height of the upper plate rock and the lower plate rock is greater than the total height of the inner cavity of the upper shear box and the lower shear box; The water immersion device is arranged on the lower shear box and is used to immerse the structural surface; The inflation device is connected to the upper shear box and is used to inflate air into the structural surface; The loading device is used to apply a normal load to the top of the upper shear box and a lateral load to one side of the lower shear box.

[0005] Furthermore, the direct shear apparatus further comprises a loading platform and a loading control system, wherein the loading platform is a concrete filling platform and is arranged below the loading frame, and the loading control system is arranged outside the loading frame; The loading device includes a vertical actuator, a first horizontal actuator, a second horizontal actuator, and a slide rail, each actuator is fixed to a loading frame and connected to a loading control system, wherein the vertical actuator is fixed above the loading frame to apply a normal load to the top of the upper shear box; the first horizontal actuator is fixed to one side of the loading frame to contact one side of the upper shear box; the second horizontal actuator is fixed to the other side of the loading frame to apply a lateral load to one side of the lower shear box; The sliding device comprises a slide rail, which is fixed on the loading platform and connected to the loading frame; the lower shear box is placed on the slide rail.

[0006] Furthermore, a plurality of hemispherical grooves are evenly arranged at the bottom of the lower shear box, steel balls are arranged in the grooves, the steel balls are connected with the slide rails, and the grooves at the bottom of the lower shear box and the surfaces of the steel balls are coated with lubricating oil.

[0007] Furthermore, the inflation device includes a high-pressure air pipe and an air pump, and a plurality of air inlet holes are evenly arranged on the front and back sides of the top of the upper shear box along the width of the rock, and the air inlet holes are connected to the first slot of the upper shear box, one side of the high-pressure air pipe is connected to the air inlet holes, and the other side extends to the outside of the loading frame and is connected to the air pump; a plurality of structural surface air inlet holes are provided on the upper plate rock according to the distribution positions of the air inlet holes, and one side of the plurality of structural surface air inlet holes is connected to the plurality of air inlet holes, and the other side is connected to the structural surface.

[0008] Furthermore, three air inlet holes are evenly arranged on the front of the top of the upper shear box along the direction of the rock width, and two air inlet holes are evenly arranged on the back of the top of the upper shear box along the direction of the rock width. The five air inlet holes are respectively connected to the first notch of the upper shear box, and the outlets of the five air inlet holes are evenly distributed along two diagonals on the upper shear box. The air inlet hole is provided with threads, and a threaded metal pipe is installed at the end of the high-pressure air pipe. The threaded metal pipe is screwed into the air inlet hole by using threads.

[0009] Further, the immersion device comprises a glass cylinder, a water pipe and a water pump, the glass cylinder is placed on the outer wall above the lower shear box, an opening is arranged in the middle of the bottom of the glass cylinder, the opening is aligned with the second notch of the lower shear box, the lower plate rock is placed in the opening and the second notch of the lower shear box, the upper part of the lower plate rock is located in the glass cylinder, and the length and width of the opening are equal to the length and width of the lower plate rock; A water inlet is provided at the bottom of the glass cylinder, and the water inlet is connected to a water pump through a water pipe, and is used to inject water into the glass cylinder, and the injected water submerges the structural surface.

[0010] Furthermore, the opening and the tiny gap between the second notch edge of the lower shear box and the lower plate rock are sealed by glass glue, the internal size of the glass cylinder is larger than the upper shear box, and the distance between the inner wall of the glass cylinder and the upper shear box is greater than the shear creep displacement of the rock sample containing the structural surface.

[0011] Furthermore, the rock sample containing the structural surface is a cubic sample with equal side lengths, and the structural surface is located at a 1 / 2 height position of the cubic sample, and the angle between the structural surface and the horizontal plane is 0°.

[0012] Furthermore, glass glue is applied to four sides of the rock sample containing the structural surface between the gap of the upper shear box and the lower shear box.

[0013] The present invention also provides a test method of a shear creep test device capable of controlling the water content of a rock structure surface, comprising the following steps: Step 1: Prepare a rock sample with a structural surface. The structural surface is located at 1 / 2 of the height of the sample and has an angle of 0° with the horizontal plane. Drill 1 to 5 structural surface air inlet holes on the upper plate rock according to the distribution of the air inlet holes of the upper shear box. Place the prepared rock sample with a structural surface in a drying oven and dry it to constant weight. Step 2: Place the first notch of the upper shear box and the second notch of the lower shear box on the workbench with the notch facing upwards, place the upper rock in the first notch of the upper shear box, place the lower rock in the second notch of the lower shear box, put the opening at the bottom of the glass cylinder over the lower rock, and place the glass cylinder on the outer wall of the second notch of the lower shear box; Step 3: Use glass glue to seal the small gap between the opening edge of the bottom of the glass cylinder and the second notch edge of the lower shear box and the rock sample with the structural surface to prevent water from penetrating into the shear box, and apply a layer of glass glue to the four sides of the rock sample with the structural surface between the notch edges of the upper shear box and the lower shear box to prevent water from penetrating into the rock sample with the structural surface from the side of the rock sample with the structural surface, and place the shear box and the rock sample with the structural surface coated with glue in a constant temperature curing box for curing; Step 4: After the glass glue is dried and solidified, combine the upper plate rock and the lower plate rock according to the contour of the rock structure surface, and place the shear box at the loading position on the slide rail, connect one end of the high-pressure air pipe to the air pump, and screw the other end of the high-pressure air pipe into the air inlet of the upper shear box corresponding to the required drying position of the rock sample with the structure surface, connect one end of the water pipe to the water pump, and connect the other end of the water pipe to the water inlet of the glass cylinder; Step 5: Use the loading control system to control the vertical actuator to apply preload force to the top surface of the upper shear box, turn on the air pump, adjust the air pressure to a predetermined value, inflate the structure surface, turn on the water pump to inject water into the glass cylinder, and do not cover the structure surface; Step 6: After the water completely infiltrates the structural surface, use the water pump to pump out the water in the glass cylinder, turn off the water pump and the air pump, control the vertical actuator to lift through the loading control system, remove the upper shear box and the upper plate rock, take pictures to record the dry and wet state of the structural surface, and calculate the infiltration area of ​​the structural surface. The moisture content of the structural surface is the ratio of the infiltration area of ​​the structural surface to the total area of ​​the structural surface. Reset the upper shear box and the upper plate rock, and repeat step 5; Step 7. Control the first horizontal actuator to contact the right side of the upper shear box through the loading control system, control the vertical actuator to apply a normal load to the top surface of the upper shear box to a set value, and control the second horizontal actuator to apply a lateral shear load to the left side of the lower shear box to a set value until the specimen undergoes shear creep failure or reaches a preset creep time. During the test, the water level in the glass cylinder is always kept above the structural surface, and the loading control system collects load and displacement data during the test in real time.

[0014] Compared with the prior art, the present invention has the following advantages: The shear creep test device provided by the present invention can control the water content of the rock structure surface. By immersing the rock structure surface in water and inflating and pressurizing it to control the water position and water content of the structure surface, shear tests and shear creep tests on the rock structure surface under different water content states are realized, and the problem of difficulty in controlling the water content of the structure surface during the shear creep test is solved. The device can be applied to the study of the shear mechanical properties and shear creep properties of the rock structure surface under different water content states.

[0015] Based on the above reasons, the present invention can be widely promoted in the fields of rock mechanical property testing and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0018] Figure 2 This is a partial enlarged view of the shear box of an embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the connection between the shear box, the air inlet and the high-pressure air pipe in an embodiment of the present invention.

[0020] Figure 4 It is a front view of the shear box according to an embodiment of the present invention.

[0021] Figure 5 It is a left view of the shear box according to an embodiment of the present invention.

[0022] Figure 6 1 is a top view of the shear box according to an embodiment of the present invention.

[0023] Figure 7 This is an example diagram of rocks containing structural surfaces according to an embodiment of the present invention.

[0024] Figure 8 for Figure 7 Top view of the .

[0025] Fig. 9 Schematic diagram of a glass cylinder according to an embodiment of the present invention.

[0026] Fig.10 This is a schematic diagram of controlling the water content of rock structural surfaces according to the present invention.

[0027] Fig.11 for Fig.10 A simplified schematic diagram of .

[0028] Fig.12 Inflatable air pressure Increase to Schematic diagram of the time.

[0029] In the figure: 1. loading frame; 2. vertical actuator; 31. first horizontal actuator; 32. second horizontal actuator; 4. slide rail; 5. concrete filling platform; 6. shear box; 61. upper shear box; 62. lower shear box; 63. air inlet; 7. rock sample with structural surface; 71. upper plate rock; 72. lower plate rock; 73. structural surface; 74. structural surface air inlet; 8. glass cylinder; 81. water inlet; 82. opening; 9. steel ball; 10. high-pressure air pipe; 11. water pipe; 12. loading control system; 13. air pump; 14. water pump. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0034] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0035] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0036] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0037] The present invention provides a shear creep test device capable of controlling the water content of a rock structure surface. Figure 1-9 As shown, it includes a shear box 6, a glass cylinder 8, a direct shear instrument, an air pump 13, a water pump 14, a water pipe 11, a high-pressure air pipe 10, etc. The direct shear instrument includes a loading control system 12, a loading frame 1, a vertical actuator 2, a horizontal actuator, a slide rail 4, and a concrete filling platform 5. The concrete filling platform 5 is arranged below the loading frame 1, and the loading control system 12 is arranged outside the loading frame 1. The horizontal actuator includes a first horizontal actuator 31 and a second horizontal actuator 32. The vertical actuator 2 and the horizontal actuator are fixed to the loading frame 1 and connected to the loading control system 12, wherein the vertical actuator 2 is fixed above the loading frame 1, and the existing actuator can be used to apply a normal load to the top of the upper shear box 61; the first horizontal actuator 31 is fixed to the right side of the loading frame 1, and the existing actuator can be used to achieve contact with the right side of the upper shear box 61; the second horizontal actuator 32 is fixed to the left side of the loading frame 1, and the existing actuator can be used to apply a lateral load to the left side of the lower shear box 62. The loading control system 12 can use the existing control system to control the vertical actuator 2, the first horizontal actuator 31 and the second horizontal actuator 32, and has the function of collecting data, collecting load and displacement data during the test. The slide rail 4 is fixed on the concrete filling platform 5 and connected to the right side of the loading frame 1, and the lower shear box 62 is placed on the slide rail 4. The present invention can be applied to the study of shear mechanical properties and shear creep properties of rock structural surfaces under different water content states.

[0038] The shear box 6 includes an upper shear box 61 and a lower shear box 62. Both the upper shear box 61 and the lower shear box 62 are open and arranged opposite to each other to form a cavity for accommodating the rock sample 7 containing the structural surface, wherein the opening is a first notch opened on one side of the upper shear box 61 and a second notch opened on one side of the lower shear box 62. The rock sample 7 containing the structural surface is a cubic sample with equal sides. The structural surface 73 is located at the 1 / 2 height position of the cubic sample and has an angle of 0° with the horizontal plane. The rock sample 7 containing the structural surface is divided into an upper plate rock 71 and a lower plate rock 72 by the structural surface 73. The upper plate rock 71 is placed in the first notch of the upper shear box 61, and the lower plate rock 72 is placed in the second notch of the lower shear box 62. The water absorption rates of the upper plate rock 71 and the lower plate rock 72 are both low and can be ignored. The total height of the upper plate rock 71 and the lower plate rock 72 is greater than the total height of the inner cavity of the upper shear box 61 and the lower shear box 62. The lower shear box 62 is placed on the slide rail 4, and the upper plate rock 71 and the upper shear box 61 are placed on the lower plate rock 72. The surface where the upper plate rock 71 and the lower plate rock 72 are in contact is the structural surface 73. The structural surfaces 73 of the two rocks are aligned and in contact. The structural surface 73 of the rock is located in the gap between the upper shear box 61 and the lower shear box 62. Three air inlet holes 63 are evenly arranged in front of the top of the upper shear box 61 along the direction of the rock width, and two air inlet holes 63 are arranged on the back of the top of the upper shear box 61. The five air inlet holes 63 of the upper shear box 61 are respectively connected to the opening of the upper shear box 61 and are evenly distributed along two diagonals in the opening of the upper shear box 61. 1-5 structural surface air inlet holes 74 can be drilled on the upper plate rock 71 according to the distribution position of the air inlet holes 63 in the opening of the upper shear box 61. One side of the structural surface air inlet hole 74 is connected to the air inlet hole 63, and the other side is connected to the structural surface 73. A plurality of hemispherical grooves are evenly arranged at the bottom of the lower shear box 62, and steel balls 9 are arranged in the grooves. The lower shear box 62 can be placed on the slide rail 4 of the direct shear instrument, and the steel balls 9 are connected with the slide rail 4. Lubricating oil is applied to the groove at the bottom of the lower shear box 62 and the surface of the steel balls 9. The direct shear instrument can apply a normal load to the top of the upper shear box 61 and a lateral load to the left side of the lower shear box 62.

[0039] An opening 82 is provided in the middle of the bottom of the glass cylinder 8, and the length and width of the opening 82 of the glass cylinder 8 are equal to the length and width of the lower plate rock 72 of the rock sample 7 containing the structural surface. A water inlet 81 is provided on the right side of the bottom of the glass cylinder 8, and the water inlet 81 is connected to the water pump 14 (placed outside the loading frame 1) through the water pipe 11, and is used to inject water into the glass cylinder 8, and the injected water submerges the structural surface 73. The glass cylinder 8 can be placed on the outer wall above the lower shear box 62, so that the opening 82 of the glass cylinder is aligned with the opening of the lower shear box 62, the lower plate rock 72 is placed in the opening 82 and the opening of the lower shear box 62, and the upper part of the lower plate rock 72 is located in the glass cylinder 8. The air pump 13 is placed outside the loading frame 1, and the air pump 13 can be connected to the air inlet 63 at the top of the upper shear box 61 through the high-pressure air pipe 10. The air inlet 63 of the upper shear box 61 is provided with threads, and a threaded metal pipe can be installed at the end of the high-pressure air pipe 10, and the threaded metal pipe can be screwed into the air inlet 63 of the upper shear box 61 by using the threads.

[0040] The opening 82 at the bottom of the glass cylinder 8 and the small gap between the open edge of the shear box 6 and the rock sample 7 with a structural surface are sealed by glass glue. The inner size of the glass cylinder 8 is larger than the upper shear box 61. The glass cylinder 8 can be surrounded by the outside of the upper shear box 61. The distance between the inner wall of the glass cylinder 8 and the upper shear box 61 is much larger than the shear creep displacement of the rock sample 7 with a structural surface. A layer of glass glue is applied to the four sides of the rock sample between the gap between the upper shear box 61 and the lower shear box 62.

[0041] The method for using the shear creep test device capable of controlling the water content of a rock structure surface comprises the following test steps: Step 1: Prepare a rock sample 7 containing a structural surface. The structural surface 73 is located at 1 / 2 of the height of the sample, with an angle of 0° with the horizontal plane. Drill 1-5 structural surface air inlet holes 74 on the upper plate rock 71 according to the distribution of the air inlet holes 63 of the upper shear box 61. The number and specific positions of the holes can be determined according to the water content of the rock structural surface 73 required for the test. For example, if the test needs to obtain the shear creep characteristics of the rock sample 7 containing a structural surface when the structural surface 73 is dry in the middle and moist all around, it is only necessary to drill a hole at the top center of the upper plate rock 71. Then place the prepared rock sample in a drying oven, set the temperature to 105°C, and bake to constant weight; Step 2: Place the upper shear box 61 and the lower shear box 62 on the workbench with their openings facing upwards, place the upper rock 71 in the opening of the upper shear box 61, and the lower rock 72 in the opening of the lower shear box 62, then put the opening 82 at the bottom of the glass cylinder 8 over the lower rock 72, and place the glass cylinder 8 on the outer wall of the opening of the lower shear box 62; Step 3: Use glass glue to seal the edge of the opening 82 at the bottom of the glass cylinder 8 and the small gap between the open edge of the shear box 6 and the rock sample 7 containing the structural surface to prevent water from penetrating into the shear box 6, and apply a layer of glass glue to the four sides of the rock sample above the open edges of the upper shear box 61 and the lower shear box 62 to prevent water from penetrating into the rock sample from the side of the rock sample 7 containing the structural surface, and then place the shear box 6 and the rock sample 7 containing the structural surface coated with glue in a constant temperature curing box for curing; Step 4: After the glass glue is dried and solidified, the upper rock 71 and the lower rock 72 are combined according to the contour of the rock structure surface 73, and the shear box 6 is placed at the loading position on the direct shear instrument slide rail 4. One end of the high-pressure air pipe 10 is connected to the air pump 13, and the other end is screwed into the air inlet 63 of the upper shear box 61 corresponding to the required drying position of the rock sample 7 containing the structure surface. Then, one end of the water pipe 11 is connected to the water pump 14, and the other end is connected to the water inlet 81 of the glass cylinder 8; Step 5: Control the vertical actuator 2 to apply a preload force to the top surface of the upper shear box 61 through the loading control system 12, turn on the air pump 13, adjust the air pressure to a predetermined value, and inflate the rock structure surface 73. During the inflation process, the gas enters the pores and cracks of the rock structure surface 73 under pressure, occupying the space that water could originally enter. If the air pressure is increased, this displacement effect will be enhanced, thereby reducing the area of ​​the structure surface that can be infiltrated by water; then turn on the water pump 14 to inject water into the glass cylinder 8, and the water does not exceed a certain height of the structure surface 73; Step 6: After the water completely infiltrates the structural surface 73, use the water pump 14 to pump out the water in the glass cylinder 8, turn off the water pump 14 and the air pump 13, control the vertical actuator 2 to lift to a certain height through the loading control system 12, remove the upper shear box 61 and the upper plate rock 71, take photos to record the dry and wet state of the structural surface 73, and calculate the infiltration area of ​​the structural surface 73. The moisture content of the structural surface 73 can be expressed by the ratio of the infiltration area of ​​the structural surface 73 to the total area of ​​the structural surface 73, reset the upper shear box 61 and the upper plate rock 71, and repeat step 5; Step seven, control the first horizontal actuator 31 to contact the right side of the upper shear box 61 through the loading control system 12, control the vertical actuator 2 to apply a normal load to the top surface of the upper shear box 61 to a set value, and then control the second horizontal actuator 32 to apply a lateral shear load to the left side of the lower shear box 62 to a set value until the sample undergoes shear creep failure or reaches a preset creep time. During the test, the water level in the glass cylinder 8 is always kept above the rock structure surface 73, and the loading control system 12 can collect load and displacement data during the test in real time.

[0042] In the present invention, the relationship between the wetted area and the air pressure is: (1) In the rock structure, there are microstructures such as pores and cracks, which are the main channels for water to seep and diffuse in the structure. When the structure is inflated, the gas will enter the pores and cracks. When water is injected into the glass cylinder and the water is allowed to cover the structure to a certain height, the water will flow into the structure along the water-conducting channels formed by the pores and cracks. According to the principles of fluid mechanics, the flow of water in the pores follows Darcy's law and satisfies equation (1): (1) in Q is the seepage flow rate, K is the permeability coefficient, A is the seepage cross-sectional area, i is the hydraulic gradient, that is, the head loss per unit length along the seepage direction.

[0043] After water is injected, the glass cylinder, the water channel on the structural surface, water, and gas together form a fluid system. Figure 10-12 As shown in the figure, the air pressure in the pores of the structural surface is equal to the pressure input by the external air pump. The existence of air pressure in the pores will reduce the hydraulic gradient and hinder the seepage of water. When the air pressure in the pores increases, the hydraulic gradient will decrease, and the seepage resistance of water in the pores will increase. When the gas pressure in the pores increases to a certain value, it is difficult for water to further diffuse in the structural surface, thereby reducing the infiltration area. The above analysis shows that when the air pressure is large enough, a dry area will be formed in the flooded structural surface.

[0044] Will Fig.10 Further simplified to Fig.11 According to the principle of connected vessels and Pascal's law, when the influence of the structure on the head loss is not considered, Fig.11 The system in satisfies equation (2): (2) in is the density of water, is the standard atmospheric pressure, is the acceleration due to gravity, is the vertical distance from the liquid surface in the glass cylinder to the structural surface, is the inflation pressure. Increase to When Fig.12 As shown, the system satisfies equation (3): (3) in is the density of water, is the standard atmospheric pressure, is the acceleration due to gravity, is the vertical distance from the liquid surface in the glass cylinder to the structural surface, Inflation pressure.

[0045] Compared with equation (2) and equation (3), due to > ,so > , that is, the water level in the glass cylinder rises, and because the total volume of water in the system remains unchanged, the volume of water in the water channel decreases, that is, the volume of gas increases ( > ), which indicates that the increase of air pressure will increase the radius of the dry area, thereby increasing the area of ​​the dry area of ​​the structural surface and reducing the area of ​​the wet area of ​​the structural surface.

[0046] In addition, the shape, size, spatial distribution and other characteristics of the water-conducting channels within the structural surface are extremely random, which leads to different resistances for each water-conducting channel. When the air pump input pressure is increased, the gas tends to flow preferentially to the channel with less resistance. As the gas pressure continues to increase and reaches a certain value, the gas in the channel with the least resistance will first reach the edge of the structural surface. At this time, if the pressure continues to increase, it will be difficult to further expand the area of ​​the dry area. Therefore, only by increasing the pressure within a specific air pressure range can the area of ​​the dry area be expanded. If the test requirements for the dry area cannot be met by increasing the air pressure, the method of inflating in multiple air holes can be used to obtain the required water content of the structural surface.

[0047] (2) From a microscopic perspective, there are many tiny pores in the rock structure surface. Water can infiltrate these pores through capillary action when there is no air pressure. However, when the air pressure increases, the filling and pressure of the pores by gas will change the pressure balance in the pores, making it difficult for water to enter some pores, thereby reducing the infiltration area of ​​the structure surface.

[0048] After inflation and water injection according to the method of the present invention, the structural surface infiltration stability is maintained, mainly based on the following aspects: (1) This test device and test method are mainly used for the shear creep study of low permeability rocks with hard structural surfaces. For such rocks, the diffusion of water in the rock matrix can be ignored at the laboratory shear creep time scale, and only the seepage and diffusion of water in the pores or cracks of the rock structural surface are considered. The air pressure formed during the inflation process forms a relatively stable pressure field in the pores and cracks in the structural surface. When the water level in the glass cylinder does not change, this pressure field hinders the flow of water, making the distribution of water in the structural surface relatively fixed.

[0049] (2) In the shear creep test of rock structural surface, the creep rate of the structural surface is extremely low. According to previous studies, the creep rate of rock structural surface in the stable creep stage is usually no more than 10 -4 s -1, the final displacement usually does not exceed 5mm. In view of such a small creep rate and creep displacement, the change in the moisture content of the structural surface caused by the relative displacement of the upper and lower wall rocks can be basically ignored.

[0050] (3) Sealing measures (such as glass glue sealing) are used for the tiny gaps between the glass cylinder, the shear box and the rock, as well as the sides of the rock specimens. These sealing measures effectively prevent lateral water leakage and avoid external interference. Through these sealing measures, water can only interact with the rock in a predetermined manner within the structural surface, thereby further improving the stability of infiltration.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shear creep test device capable of controlling the water content of a rock structure surface, characterized in that: include: A direct shear apparatus, a water immersion device, an air filling device and a shear box (6), wherein the direct shear apparatus comprises a loading frame (1) and a loading device and a sliding device mounted on the loading frame (1); The shear box (6) is used to accommodate a rock sample (7) containing a structural surface, and comprises an upper shear box (61) and a lower shear box (62) arranged at intervals, a first notch being provided on one side of the upper shear box (61), a second notch being provided on one side of the lower shear box (62), and the first notch and the second notch being arranged opposite to each other; The rock sample (7) containing a structural surface comprises an upper plate rock (71), a lower plate rock (72) and a structural surface (73); the upper plate rock (71) is placed in a first notch of an upper shear box (61); the lower plate rock (72) is placed in a second notch of a lower shear box (62); the lower shear box (62) is placed on a sliding device; the upper plate rock (71) and the upper shear box (61) are placed on the lower plate rock (72); the surface where the upper plate rock (71) and the lower plate rock (72) are in contact is the structural surface (73); the structural surfaces (73) of the upper plate rock (71) and the lower plate rock (72) are aligned and in contact; the structural surface (73) is located in a gap between the upper shear box (61) and the lower shear box (62); the total height of the upper plate rock (71) and the lower plate rock (72) is greater than the total height of the inner cavities of the upper shear box (61) and the lower shear box (62); The water immersion device is arranged on the lower shear box (62) and is used to immerse the structural surface (73); The inflation device is connected to the upper shear box (61) and is used to inflate air into the structural surface (73); The loading device is used to apply a normal load to the top of the upper shear box (61) and a lateral load to one side of the lower shear box (62).

2. The shear creep test device capable of controlling the water content of rock structure surface according to claim 1, characterized in that: The direct shear apparatus further comprises a loading platform and a loading control system (12); the loading platform adopts a concrete filling platform (5) and is arranged below the loading frame (1); and the loading control system (12) is arranged outside the loading frame (1); The loading device comprises a vertical actuator (2), a first horizontal actuator (31), a second horizontal actuator (32), and a slide rail (4), each actuator being fixed to a loading frame (1) and connected to a loading control system (12), wherein the vertical actuator (2) is fixed above the loading frame (1) and is used to apply a normal load to the top of the upper shear box (61); the first horizontal actuator (31) is fixed to one side of the loading frame (1) and is used to contact one side of the upper shear box (61); the second horizontal actuator (32) is fixed to the other side of the loading frame (1) and is used to apply a lateral load to one side of the lower shear box (62); The sliding device comprises a slide rail (4), wherein the slide rail (4) is fixed on the loading platform and connected to the loading frame (1); the lower shear box (62) is placed on the slide rail (4).

3. The shear creep test device capable of controlling the water content of rock structure surface according to claim 2, characterized in that: A plurality of hemispherical grooves are evenly arranged at the bottom of the lower shear box (62), and steel balls (9) are arranged in the grooves. The steel balls (9) are matched and connected to the slide rails (4), and the grooves at the bottom of the lower shear box (62) and the surfaces of the steel balls (9) are coated with lubricating oil.

4. The shear creep test device capable of controlling the water content of rock structure surface according to claim 1, characterized in that: The inflation device comprises a high-pressure air pipe (10) and an air pump (13); a plurality of air inlet holes (63) are evenly arranged on the front and back sides of the top of the upper shear box (61) along the direction of the rock width; the air inlet holes (63) are connected to the first notch of the upper shear box (61); one side of the high-pressure air pipe (10) is connected to the air inlet holes (63), and the other side extends to the outside of the loading frame (1) and is connected to the air pump (13); a plurality of structural surface air inlet holes (74) are provided on the upper plate rock (71) according to the distribution positions of the air inlet holes (63); one side of the plurality of structural surface air inlet holes (74) is connected to the plurality of air inlet holes (63), and the other side is connected to the structural surface (73).

5. The shear creep test device capable of controlling the water content of rock structure surface according to claim 4, characterized in that: The top front of the upper shear box (61) is evenly arranged with three air inlet holes (63) along the direction of the rock width, and the top back of the upper shear box (61) is evenly arranged with two air inlet holes (63) along the direction of the rock width. The five air inlet holes (63) are respectively connected to the first notch of the upper shear box (61), and the outlets of the five air inlet holes (63) are evenly distributed along two diagonal lines on the upper shear box (61); The air inlet hole (63) is provided with a thread, and a threaded metal pipe is installed at the end of the high-pressure air pipe (10), and the threaded metal pipe is screwed into the air inlet hole (63) by means of a thread.

6. The shear creep test device capable of controlling the water content of rock structure surface according to claim 1, characterized in that: The immersion device comprises a glass cylinder (8), a water pipe (11) and a water pump (14); the glass cylinder (8) is placed on the outer wall above the lower shear box (62); an opening (82) is provided in the middle of the bottom of the glass cylinder (8); the opening (82) is aligned with the second notch of the lower shear box (62); the lower plate rock (72) is placed in the opening (82) and the second notch of the lower shear box (62); the upper part of the lower plate rock (72) is located in the glass cylinder (8); the length and width of the opening (82) are equal to the length and width of the lower plate rock (72); A water inlet (81) is provided at the bottom of the glass cylinder (8), and the water inlet (81) is connected to a water pump (14) via a water pipe (11) and is used to inject water into the glass cylinder (8), and the injected water submerges the structural surface (73).

7. The shear creep test device capable of controlling the water content of rock structure surface according to claim 6, characterized in that: The opening (82) and the small gap between the second notch edge of the lower shear box (62) and the lower plate rock (72) are sealed by glass glue, the inner size of the glass cylinder (8) is larger than the upper shear box (61), and the distance between the inner wall of the glass cylinder (8) and the upper shear box (61) is larger than the shear creep displacement of the rock sample (7) containing the structural surface.

8. The shear creep test device capable of controlling the water content of rock structure surface according to claim 1, characterized in that: The rock sample (7) containing a structural surface is a cubic sample with equal side lengths, and the structural surface (73) is located at a half height position of the cubic sample and has an angle of 0° with the horizontal plane.

9. The shear creep test device capable of controlling the water content of rock structure surface according to claim 1, characterized in that: Glass glue is applied to the four side surfaces of the rock sample (7) containing the structural surface between the gaps of the upper shear box (61) and the lower shear box (62).

10. A test method for a shear creep test device capable of controlling the water content of a rock structure surface according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Prepare a rock sample (7) containing a structural surface, wherein the structural surface (73) is located at a half height of the sample and has an angle of 0° with the horizontal plane. Drill 1 to 5 structural surface air inlet holes (74) on the upper plate rock (71) according to the distribution positions of the air inlet holes (63) of the upper shear box (61). Place the prepared rock sample (7) containing a structural surface in a drying oven and dry it to a constant weight. Step 2: Place the first notch of the upper shear box (61) and the second notch of the lower shear box (62) on a workbench with the notch facing upward, place the upper rock (71) in the first notch of the upper shear box (61), place the lower rock (72) in the second notch of the lower shear box (62), put the opening (82) at the bottom of the glass cylinder (8) over the lower rock (72), and place the glass cylinder (8) on the outer wall of the second notch of the lower shear box (62); Step 3: Use glass glue to seal the small gap between the edge of the opening (82) at the bottom of the glass cylinder (8) and the edge of the second notch of the lower shear box (62) and the rock sample (7) containing the structural surface, so as to prevent water from penetrating into the shear box (6), and apply a layer of glass glue to the four sides of the rock sample (7) containing the structural surface between the notch edges of the upper shear box (61) and the lower shear box (62), so as to prevent water from penetrating into the rock sample (7) containing the structural surface from the side of the rock sample (7), and place the shear box (6) and the rock sample (7) containing the structural surface, which have been coated with glue, in a constant temperature curing box for curing; Step 4: After the glass glue is dried and solidified, the upper rock (71) and the lower rock (72) are combined according to the contour of the rock structural surface (73), and the shear box (6) is placed at the loading position on the slide rail (4). One end of the high-pressure air pipe (10) is connected to the air pump (13), and the other end of the high-pressure air pipe (10) is screwed into the air inlet (63) of the upper shear box (61) corresponding to the required drying position of the rock sample (7) containing the structural surface. One end of the water pipe (11) is connected to the water pump (14), and the other end of the water pipe (11) is connected to the water inlet (81) of the glass cylinder (8); Step 5: Control the vertical actuator (2) through the loading control system (12) to apply a pre-tightening force to the top surface of the upper shear box (61), turn on the air pump (13), adjust the air pressure to a predetermined value, inflate the structural surface (73), turn on the water pump (14) to inject water into the glass cylinder (8) so as not to cover the structural surface (73); Step 6: After the water completely infiltrates the structural surface (73), use the water pump (14) to pump out the water in the glass cylinder (8), turn off the water pump (14) and the air pump (13), control the vertical actuator (2) to lift up through the loading control system (12), remove the upper shear box (61) and the upper plate rock (71), take photos to record the dry and wet state of the structural surface (73), and calculate the infiltration area of ​​the structural surface (73). The water content of the structural surface (73) is the ratio of the infiltration area of ​​the structural surface (73) to the total area of ​​the structural surface (73), reset the upper shear box (61) and the upper plate rock (71), and repeat step 5; Step 7: Control the first horizontal actuator (31) to contact the right side of the upper shear box (61) through the loading control system (12), control the vertical actuator (2) to apply a normal load to the top surface of the upper shear box (61) to a set value, and control the second horizontal actuator (32) to apply a transverse shear load to the left side of the lower shear box (62) to a set value until the specimen undergoes shear creep failure or reaches a preset creep time. During the test, the water level in the glass cylinder (8) is always kept above the structural surface (73), and the loading control system (12) collects load and displacement data during the test in real time.

Images