A testing system for internal strain field in rock mass physics simulation test

Abstract

A testing system for internal strain field in rock mass physical simulation test involves the testing field of stress field in physical simulation test in geotechnical engineering, and can improve the installation efficiency and testing accuracy of strain bricks in rock mass physical simulation test. The present invention is composed of three parts: a sample stabilization system, a soil cutting system, and a motor system, wherein the sample stabilization system includes an outer frame column, a base plate, a base plate track, a transverse slide rail, and a longitudinal slide rail; the soil cutting system includes a disc, a rotating pressure rod, a pressure plate, a soil bucket, a fixed rod, a rotating bearing, a soil cutting line fixed rod, a soil cutting line fixed rod jack, and a soil cutting line; the motor system includes a motor and a motor controller. The present invention utilizes the synchronous deformation of strain bricks and simulated rock mass to study the changes in the internal stress and strain of the simulated rock mass under the action of external force, summarizes the changing laws of the internal stress field and strain field of the rock mass, and provides experimental references for basic research on related topics in rock mass physical simulation.

Description

Technical Field

[0001] The invention discloses a testing system for internal strain field in rock mass physical simulation test, mainly relates to the testing field of stress field in physical simulation test in geotechnical engineering, and can improve the placement efficiency and testing accuracy of strain bricks in rock mass physical simulation test. Background Art

[0002] In the long-term geological movement process, the stress concentration area inside the rock mass has a significant impact on seismic activity and active faults, and there are obvious differences in the damage of rock masses at different depths. Studies have shown that when the two sides of the strike-slip fault undergo relative displacement and deformation under the action of tectonic stress, the local stress field of the fault will produce a significant deflection. In order to characterize the relationship between this deflection and the activity of the fault, it is necessary to use physical simulation experiments to synchronously test the temporal and spatial evolution characteristics of the stress field inside the rock mass. However, since the measurement of internal stress in the rock mass is very difficult, it hinders the physical simulation research on seismic activity and strike-slip faults, and a method that can measure and simulate the internal stress of the rock mass is urgently needed.

[0003] The most widely used method at present is to make strain bricks similar to the simulation material. Before finding a suitable ratio of simulation materials, a large number of ratio tests are carried out, different ratios of similar materials are selected, and standard specimens are made in batches. The physical parameters of different ratios are determined through uniaxial compression tests, direct shear tests, etc., and then the final ratio is determined to make the required strain bricks.

[0004] Prior to the present invention, a patent application numbered CN201720279640.X disclosed a device for manufacturing strain bricks, which is characterized in that the manufacturing height of the strain brick test block can be adjusted to manufacture strain bricks of different specifications. The manufacturing technology of strain bricks has been perfected, but the installation process of strain bricks directly determines the coupling state of the strain bricks and the surrounding materials and the test accuracy.

[0005] Prior to the present invention, patent application number CN201620371052.4 disclosed a device for rapidly excavating strain brick embedding holes, which is characterized in that it consists of a soil sampler of the equipment main body, a top plate of air holes and scale lines. Its purpose is to rapidly excavate strain brick embedding holes to speed up the test. However, after taking out the soil sample, it is unable to control the stability of the excavation hole wall and destroys the physical structure of the excavation interface model material.

[0006] Therefore, under the premise of less disturbance to the physical structure of the simulated specimen, the present invention realizes the placement of strain bricks through static pressure and the elastic deformation characteristics of the soil, explores the changing law of the internal stress field of the fractured rock mass under the action of external force, and provides a reference for the physical simulation test of the fractured rock mass. Summary of the invention

[0007] In view of the shortcomings of existing devices for placing strain bricks, the present invention provides a testing system for the internal strain field in rock physics simulation tests. The device can reduce the end friction resistance when the soil bucket enters the simulated rock, and the predetermined position can be cut into a complete plane using the cutting line. The sample in the soil bucket can be backfilled to reduce the disturbance to the sample, thereby achieving the advantage of accurately placing strain bricks.

[0008] The invention comprises an outer frame column, a base plate, a base plate track, a transverse slide rail, a longitudinal slide rail, a disc, a rotating pressure rod, a motor, a motor controller, a pressure plate, a soil bucket, a fixing rod, a rotating bearing, a soil cutting line fixing rod jack, a soil cutting line fixing rod, a soil cutting line, a disc and a pressure plate.

[0009] The bottom track is used to hold the simulated sample box. Before pushing the sample box into the bottom track, first raise the soil bucket. After the sample box is pushed into the bottom track and fixed on the bottom plate, use the transverse and longitudinal slide rails to align the soil bucket with the preset position of the sample. Press the motor controller fixed on the outer frame column. At this time, the motor works on the rotating pressure rod to drive the soil bucket to take soil from the sample. After sampling is completed, put the strain brick in the corresponding position, then backfill, and cut off the excess sample. Since the sample itself has a certain rebound characteristic, after a short time of soil taking and cutting operation, the soil sample rebounds to make the sample and the strain brick reach a better coupling state.

[0010] The upper part of the soil bucket is provided with a rotating bearing. Since the downward power of the soil bucket is provided by a rotating pressure rod or manually through a disc, a rotating bearing and a fixing rod are required to fix the soil bucket to ensure that it will not rotate due to the influence of the upper part.

[0011] When the soil bucket penetrates into the simulated sample, since the sample itself has a certain strength, in order to reduce the end friction resistance of the soil bucket when entering the soil, the soil cutting mouth of the soil bucket is bladed with reference to the ring knife in geotechnical test.

[0012] If the soil bucket is directly pulled during sampling, the sample at the preset position will produce a jagged tensile cross-section due to the tensile force, so that the sample and the strain brick cannot be fully contacted, thereby causing excessive test errors due to uncoordinated deformation under stress.

[0013] The cutting edge foot is provided with cutting line fixing rod insertion holes around the cutting edge. The two cutting line fixing rod insertion holes on the left are used to insert the cutting line fixing rods, and the two cutting line fixing rod insertion holes on the right are used to insert the two ends of the cutting line from the bottom. Before the soil bucket enters the soil, the cutting line is first wound around the cutting line fixing rod on the left. After the cutting bucket reaches the predetermined position, the cutting line fixing rod releases the cutting line, and the two ends of the cutting line are pinched by hand on the upper part of the cutting line fixing rod insertion hole on the right, and the cutting line is slowly tightened to cut the soil, so as to ensure that the incision is a complete plane.

[0014] Beneficial results

[0015] The device can effectively reduce the disturbance to the physical structure of the simulated test when taking soil. The preset position is cut into a complete plane using the soil cutting line to make the simulated sample and the strain gauge surface fully contact. The sample with the same height as the strain brick is cut out of the soil column, and the original soil column is placed above the strain brick according to the original position, so that the strain brick is placed quickly and efficiently. The device can be used to explore the influence characteristics of different fractures on the local stress field of rocks, and can more intuitively show the influence trend of the occurrence on stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Placement device for strain bricks;

[0017] Figure 2 Rotating pressure rod diagram;

[0018] Figure 3 To take the earth bucket diagram;

[0019] Figure 4 It is a diagram of the cut-out.

[0020] Figure 5 Sectional view of the fixing rod for cutting line DETAILED DESCRIPTION

[0021] The present invention provides a testing system for the internal strain field in a rock mass physical simulation test. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the device is described in detail below in conjunction with the accompanying drawings.

[0022] As shown in the attached drawings, the patent of the present invention includes 16 parts: 1. outer frame column, 2. base plate, 3. base plate track, 4. horizontal slide rail, 5. longitudinal slide rail, 6. rotating pressure rod, 7. motor, 8. motor controller, 9. soil bucket, 10. fixed rod, 11. rotating bearing, 12. soil cutting line fixed rod jack, 13. soil cutting line fixed rod, 14. soil cutting line, 15. disc, and 16. pressure plate.

[0023] The base plate (2) is made of stainless steel. A rubber anti-skid pad is installed under the base plate (2) to maintain the overall stability of the device. The four corners of the base plate (2) have reserved screw holes for installing and fixing the outer frame column (1); the longitudinal slide rail (5) is made of stainless steel, and two longitudinal slide rails (5) form a group to provide a sliding channel for the rotating pressure rod (6); the transverse slide rail (4) is made of stainless steel, and two transverse slide rails (4) form a group to provide a sliding channel for the longitudinal slide rail (5).

[0024] First, the soil bucket (9) and the rotating pressure rod (6) are connected together by rotating threads, and then the motor (7) and the pressure plate (16) are fixed together with screws, and then the pressure plate (16) is placed in the longitudinal slide rail (5), and the two longitudinal slide rails (5) are fixed so that the pressure plate (16) can move freely along the track, and then the longitudinal slide rail (5) is placed in the transverse slide rail (4), and the two transverse slide rails (4) are fixed so that the longitudinal slide rail (5) can slide freely along the track of the transverse slide rail (4); secondly, the outer frame column (1) is aligned with the screw hole reserved on the bottom plate and fixed to the bottom plate with screws, and then the transverse slide rail (4) and the longitudinal slide rail (5) are fixed with screws; finally, the motor controller (8) is fixed to the outer frame column (4) with screws.

[0025] The bottom track (3) is used to hold a box for simulating rock samples. Before the sample box is pushed into the bottom track (3), the soil bucket (9) is first raised. After the box is held, the soil bucket (9) is aligned with the position preset in the design scheme during the sample test using the transverse slide rail (4) and the longitudinal slide rail (5). The motor controller (8) is turned on. At this time, the motor (7) works on the rotating pressure rod (6) to drive the soil bucket (9) to take soil from the sample. After the soil bucket (9) reaches the specified position, it is slightly rotated to cut the sample. The soil line fixing rod (13) is slowly pulled out from the soil cutting line fixing rod insertion hole (12), so that the soil cutting line (14) and the soil cutting line fixing rod (13) are separated from each other and no longer entangled; the two ends of the soil cutting line are pinched by hand on the upper part of the right soil cutting line fixing rod insertion hole (12), and the soil cutting line (14) is slowly tightened to cut the soil. After the soil cutting is completed, the soil bucket is taken out, and the strain brick is placed at the corresponding position, and the sample with the same height as the strain brick is cut out of the soil column, and the original soil column is placed above the strain brick according to the original position to backfill the sample. Since the soil sample itself has viscoelasticity, the sample can be restored to its original approximate state in a short time.

[0026] Soil bucket (9) Figure 3 As shown, a rotating bearing (11) is provided on the upper part of the soil bucket (9). Since the downward power of the soil bucket is provided by the rotating pressure rod (6), the rotating bearing (11) and the fixing rod (10) are required to fix the soil bucket (9) to ensure that it will not rotate due to the influence of the upper part.

[0027] During the design, it was considered that when the soil bucket (9) penetrates deep into the material, the simulated specimen itself has a certain strength. Therefore, the cutting opening of the soil bucket (9) was chamfered with reference to the ring knife in the geotechnical test, thereby reducing the end friction resistance when the soil bucket enters the soil. If the soil bucket (9) is directly pulled when taking soil, the soil may produce a jagged tensile cross-section due to the tensile stress. During the test, the uncoupled contact between the strain brick and the upper and lower surfaces of the soil will cause excessive test errors. Therefore, the design reserves cutting line fixing rod sockets (12) at the four corners of the cutting edge. Figure 4 As shown in the soil cutting opening, the two soil cutting line fixing rod insertion holes (12) on the left are used to insert the soil cutting line fixing rod (13), and the two soil cutting line fixing rod insertion holes (12) on the right are used to insert the two ends of the soil cutting line (14) from the bottom into the upper part and out. During the test, the soil cutting line (14) is firstly wound around the lower part of the soil cutting line fixing rod (13) for 2 to 3 turns; after the soil taking bucket (9) enters the specified position depth of the soil body, the upper part of the soil cutting line fixing rod (13) is slightly rotated to make the soil cutting line (14) and the soil cutting line fixing rod (13) separate from each other and no longer entangled, and the soil cutting line fixing rod (13) is slowly pulled out from the soil cutting line fixing rod insertion hole (12); the two ends of the soil cutting line are pinched at the upper part of the soil cutting line fixing rod insertion hole (12) on the right side, and the soil cutting line (14) is slowly pulled out to cut the soil, so as to ensure that the upper and lower contact surfaces of the strain brick and the soil body are complete planes.

Claims

1. A method for testing internal strain field in a rock mass physical simulation test, characterized in that: The system used in this method is as follows: The bottom plate rail (3) is located on the bottom plate (2). The bottom plate (2) has reserved screw holes at four corners for mounting and fixing the outer frame column (1). The two longitudinal slide rails (5) form a group to provide a sliding channel for the pressure plate (16). The two transverse slide rails (4) form a group to provide a sliding channel for the longitudinal slide rails (5). A rotating bearing (11) is provided on the upper part of the soil bucket (9), and the rotating bearing (11) and the fixing rod (10) fix the soil bucket (9); the soil bucket (9) and the rotating pressure rod (6) are connected together by a rotating thread, and then the motor (7) and the pressure plate (16) are fixed together by screws, the pressure plate (16) is placed in the longitudinal slide rail (5), and the two longitudinal slide rails (5) are fixed so that the pressure plate (16) can move freely along the track, and the longitudinal slide rail (5) is placed in the transverse slide rail (4) so ​​that the longitudinal slide rail (5) can slide freely along the track of the transverse slide rail (4); the transverse slide rail (4) and the longitudinal slide rail (5) are fixed by screws; the motor controller (8) is fixed to the outer frame column by screws; The bottom plate track (3) is used to clamp a box of simulated rock samples. Before the sample box is pushed into the bottom plate track (3), the soil bucket (9) is first raised. After the box is clamped, the soil bucket (9) is aligned with the preset position of the sample test using the transverse slide rail (4) and the longitudinal slide rail (5). The motor controller (8) is turned on. At this time, the motor (7) performs work on the rotating pressure rod (6), driving the soil bucket (9) to take soil from the sample. After the soil bucket (9) reaches the specified position, soil is cut. After the soil cutting is completed, the soil bucket is raised, and a strain brick is placed at the corresponding position. The sample with the same height as the strain brick is cut out of the soil column, and the original soil column is placed above the strain brick according to the original position to backfill the sample. A rotating bearing (11) is provided on the upper part of the soil bucket (9). The downward power of the soil bucket is provided by a rotating pressure rod (6). The rotating bearing (11) and the fixing rod (10) are used to fix the soil bucket (9).

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