On-site rock mass shear experiment method and device for coupling sound wave test

Abstract

The invention relates to the technical field of rock mass mechanical testing, and discloses an on-site rock mass shearing experiment method and device for coupling sound wave testing, and the method comprises the following steps: directly stripping a rock sample of which the bottom surface is connected with a protolith from the protolith, and respectively arranging an ultrasonic transmitting probe and an ultrasonic receiving probe on the front side surface and the rear side surface of the rock sample; then, a set axial pressure is applied to the top surface of the rock sample, a gradually increasing transverse load is applied to the left side surface or the right side surface of the rock sample, the ultrasonic transmitting probe and the ultrasonic receiving probe cooperatively reciprocate at a constant speed while the transverse load is applied, and ultrasonic dynamic data under different transverse loads are recorded in real time; the physical properties and structural characteristics of the rock under different shearing force conditions can be monitored in real time; the device comprises a constant-speed reciprocating movement mechanism, the constant-speed reciprocating movement mechanism comprises a shell, a transmission shaft and two transverse movement assemblies, each transverse movement assembly comprises an incomplete gear and two racks, and the device can drive all probes to complete cooperative movement and is convenient to control.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass mechanics testing, in particular to a field rock mass shearing test method and device for coupled acoustic wave testing. Background Art

[0002] In geotechnical engineering, the determination of rock shear strength parameters is one of the key points restricting engineering design and construction. In actual engineering, the rock strength parameters obtained through on-site large-scale rock mechanics experiments can better reflect the engineering mechanics properties of rock.

[0003] The rock shear test is to apply gradually increasing shear stress to the rock sample, monitor the strain of the rock in real time after shearing, establish a stress-strain curve, and determine the physical and mechanical parameters of the rock such as elastic modulus, pressure strength, shear strength and deformation characteristics. In order to accurately monitor the gradual change of strain of the rock during shearing, the rock shear test needs to be carried out on special experimental equipment. Usually, the rock samples need to be transported to the laboratory for experiment, which makes it difficult to carry out experiments on the actual rock at the construction site. The way to carry out shear experiments in the laboratory requires the collection or preparation of a large number of rock samples, which has the problem of difficulty in preparing rock samples; when carrying out shear experiments, due to the space limitation of the experimental equipment, it is impossible to directly test large-sized rock samples. In addition, due to the experimental time and experimental funds, the number of mechanical experiments carried out in actual engineering is relatively limited. In actual engineering, the determination of rock strength parameters is usually based on a small amount of experimental data, combined with geological surveys and engineering experience to determine the rock shear strength parameters. It is difficult to obtain design parameters that can truly reflect the engineering characteristics of the rock mass. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a field rock shear test method and device for coupled acoustic wave testing.

[0005] The objective of the present invention is achieved through the following technical solutions: A field rock shear test method for coupled acoustic wave testing comprises the following steps: S1. Peel off a cubic rock sample from the original rock on site, wherein the bottom surface of the rock sample is still connected to the original rock, and the top surface, left surface, right surface, front side surface and rear side surface of the rock sample are all free-facing surfaces; S2, an axial pressure mechanism is arranged above the top surface of the rock sample, a transverse pressure mechanism is arranged on the left side or the right side of the rock sample, and an ultrasonic receiving probe and an ultrasonic transmitting probe are arranged on the front side and the rear side of the rock sample respectively, and the ultrasonic receiving probe and the ultrasonic transmitting probe are both connected to the acoustic wave testing device; S3, the axial pressure mechanism applies an axial load to the middle of the top surface of the rock sample to a set value; S4, the acoustic wave testing device continuously records the acoustic wave data and starts testing. During the test, the lateral pressure mechanism applies a gradually increasing lateral load to the middle of the left side or the middle of the right side of the rock sample until the rock sample is broken and the test is stopped. While applying the lateral load, the ultrasonic receiving probe and the ultrasonic transmitting probe coordinately reciprocate at a uniform speed. S5. Arrange and analyze the sound wave data recorded by the sound wave testing device.

[0006] Specifically, an implementation form of step S4 includes the following steps: S401, placing the ultrasonic receiving probe and the ultrasonic transmitting probe at the left end of the rock sample, and turning on the acoustic wave testing device to continuously record acoustic wave data; S402, the lateral pressure mechanism applies a lateral load of a set value to the middle of the right side surface of the rock sample; S403, moving the ultrasonic receiving probe and the ultrasonic transmitting probe synchronously and uniformly to the right end position of the rock sample; S404, the lateral pressure mechanism applies a greater lateral load to the middle portion of the right side surface of the rock sample, and the load increase value is a set value; S405, moving the ultrasonic receiving probe and the ultrasonic transmitting probe synchronously and uniformly to the left end position of the rock sample; S406, the lateral pressure mechanism applies a greater lateral load to the middle of the right side of the rock sample, and the load increase value is a set value; S407. Repeat steps S403 to S406 until the rock sample is destroyed.

[0007] Specifically, the front side of the rock sample is provided with a first ultrasonic transmitting probe and a second ultrasonic receiving probe, and the rear side of the rock sample is provided with a first ultrasonic receiving probe and a second ultrasonic transmitting probe. Another implementation form of step S4 includes the following steps: S411, make the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic transmitting probe all located at the left end of the rock sample, adjust the first ultrasonic transmitting probe and the first ultrasonic receiving probe to be located at the two ends of a diagonal line of the left end surface of the rock sample, respectively, adjust the second ultrasonic transmitting probe and the second ultrasonic receiving probe to be located at the two ends of another diagonal line of the left end surface of the rock sample, and then turn on the acoustic wave testing device to continuously record acoustic wave data; S412, the lateral pressure mechanism applies a lateral load of a set value to the middle of the right side surface of the rock sample; S413, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the left end position of the rock sample, and moving the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly to the right end position of the rock sample; S414, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the right end position of the rock sample, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously moved at a uniform speed to the right end position of the rock sample; S415, the lateral pressure mechanism applies a greater lateral load to the middle portion of the right side of the rock sample, and the load increase value is a set value; S416, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the right end position of the rock sample, and moving the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly to the left end position of the rock sample; S417, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the left end position of the rock sample, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously moved at a uniform speed to the left end position of the rock sample; S418, the lateral pressure mechanism applies a greater lateral load to the middle portion of the right side of the rock sample, and the load increase value is a set value; S419. Repeat steps S413 to S418 until the rock sample is destroyed.

[0008] A field rock shear test device for coupled acoustic wave testing comprises a uniform reciprocating mechanism, which comprises a shell, a transmission shaft and two transverse movement components; the transverse movement component comprises an incomplete gear, two racks and a plurality of connecting rods, the two racks are arranged opposite to each other, the two ends of the plurality of connecting rods are respectively fixedly connected to the two racks, the deflection angle between the first tooth and the last tooth of the incomplete gear is 45°, and the incomplete gear can be respectively meshed with the two racks when rotating; the two transverse movement components are arranged in parallel in the shell from top to bottom, the rack is slidably connected to the shell, the transmission shaft is rotatably connected to the shell, the two incomplete gears are fixedly sleeved on the transmission shaft, and the phase angle between the two incomplete gears differs by 90°.

[0009] Furthermore, it also includes an axial pressure mechanism, which includes an axial pressure hydraulic cylinder and an axial pressure pad. One end of the axial pressure hydraulic cylinder is fixedly connected to the bottom surface of the shell, and the axial pressure pad is fixedly connected to the other end of the axial pressure hydraulic cylinder. The extension and retraction direction of the piston rod of the axial pressure hydraulic cylinder is perpendicular to the sliding direction of the rack in the shell.

[0010] Furthermore, it also includes a transverse pressure mechanism, which includes a reaction plate, a transverse pressure hydraulic cylinder and a transverse pressure pad, one end of the transverse pressure hydraulic cylinder is fixedly connected to the reaction plate, and the other end of the transverse pressure hydraulic cylinder is fixedly connected to the transverse pressure pad; the reaction plate is arranged obliquely below the shell, and the transverse pressure pad is arranged on the side of the reaction plate close to the shell, and the extension and retraction direction of the piston rod of the transverse pressure hydraulic cylinder is parallel to the sliding direction of the rack in the shell.

[0011] Furthermore, the uniform reciprocating mechanism also includes a motor, a worm and a worm wheel, the worm is rotatably connected to the housing, the motor is used to drive the worm to rotate, the worm wheel is fixedly sleeved on the transmission shaft, and the worm is meshed with the worm wheel.

[0012] Furthermore, probe mounting mechanisms are provided on both sides of the shell, and the probe mounting mechanisms include an ear plate, a rod A and a plurality of mounting components, the rod A is movably inserted into one end of the ear plate, and the other end of the ear plate is detachably connected to the rack, and the mounting components include a slider and a rod B, one end of the slider is movably mounted on the rod A, and the rod B is movably inserted into the other end of the slider; the two probe mounting mechanisms are respectively connected to the two transverse movement components, or the two probe mounting mechanisms are connected to the same transverse movement component.

[0013] The beneficial effects of the present invention are: The field rock shear test method of the coupled acoustic wave test is to directly peel off a cubic rock sample from the original rock on site. During the peeling, the bottom surface of the rock sample is still connected to the original rock, and the other five surfaces of the rock sample are open surfaces; then an axial pressure mechanism is arranged on the top of the rock sample, a transverse pressure mechanism is arranged on the left or right side of the rock sample, and an ultrasonic transmitting probe and an ultrasonic receiving probe are respectively arranged on the front side and the rear side of the rock sample, so that the ultrasonic transmitting probe and the ultrasonic receiving probe are connected to the acoustic wave testing device; then a set axial pressure is applied to the middle area of ​​the top surface of the rock sample through the axial pressure mechanism; then a gradually increasing transverse load is applied to the middle of the left side or the middle of the right side of the rock sample through the transverse pressure mechanism for testing, while the transverse load is applied, the ultrasonic receiving probe and the ultrasonic transmitting probe move back and forth in coordination at a uniform speed, and the acoustic wave data are continuously recorded by the acoustic wave testing device; then the acoustic wave data recorded by the acoustic wave testing device are analyzed. The field rock shear test method of the coupled acoustic wave test can carry out direct shear tests on field rocks at the construction site, and use ultrasonic detection technology to monitor in real time the physical properties and structural characteristics of rocks under different shear conditions. It has the advantages of accuracy, reliability, and efficiency during implementation. The type and size of the peeled rock samples are not restricted, and it is suitable for natural rock masses with various structural compositions. It can realize direct experiments on large-size rock samples, and the obtained rock strength parameters can better reflect the engineering mechanical properties of the rock mass. It is expected to be widely used in the field of geotechnical engineering and provide reliable technical support for engineering safety.

[0014] The field rock shear test device of the coupled acoustic wave test includes a uniform reciprocating mechanism, which includes a housing, a transmission shaft and two transverse moving components; the transverse moving component includes an incomplete gear, two racks and a plurality of connecting rods, the two racks are arranged opposite to each other and connected to form a sliding mechanism through a plurality of connecting rods, and the incomplete gear can be respectively meshed with the two racks when rotating; the two transverse moving components are arranged in parallel in the housing from top to bottom, and the two incomplete gears are fixedly sleeved on the transmission shaft. The deflection angle between the first tooth and the last tooth of the incomplete gear is 45°, and when the incomplete gear rotates continuously, the sliding mechanism cyclically performs the action of uniform rightward movement-stop-uniform leftward movement-stop; the phase angle between the two incomplete gears is 90°, and when the driving shaft drives the two incomplete gears to rotate continuously at a uniform speed at the same time, one sliding mechanism cyclically performs the action of uniform rightward movement-stop-uniform leftward movement-stop, and the other sliding mechanism cyclically performs the action of stop-uniform rightward movement-stop-uniform leftward movement. Under different scanning modes, the ultrasonic transmitting probe and the ultrasonic receiving probe can be connected to one sliding mechanism, or the ultrasonic transmitting probe and the ultrasonic receiving probe can be connected to two sliding mechanisms respectively. When conducting experiments, only the transmission shaft continues to rotate at a uniform speed to achieve the coordinated uniform reciprocating motion of the ultrasonic transmitting probe and the ultrasonic receiving probe for ultrasonic scanning, and the control process is extremely convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of a field rock shear test device for coupled acoustic wave testing during an experiment of the present invention; Figure 2 A schematic diagram of scanning trajectories of an ultrasonic transmitting probe and an ultrasonic receiving probe in a top view plane of a rock sample when a field rock shear test method for coupled acoustic wave testing of the present invention is conducted according to Example 1; Figure 3 A schematic diagram of scanning trajectories of a first ultrasonic transmitting probe and a first ultrasonic receiving probe in a top view of a diagonal cross section of a rock sample when a field rock shear test method for coupled acoustic wave testing of the present invention is conducted according to Example 2; Figure 4 It is a structural schematic diagram of a field rock shear test device for coupled acoustic wave testing according to the present invention; Figure 5 It is a schematic diagram of the exploded structure of a uniform reciprocating motion mechanism in a field rock shear test device for coupled acoustic wave testing according to the present invention; Figure 6 It is a structural schematic diagram of a transverse movement component in a field rock shear experimental device for coupled acoustic wave testing of the present invention and a schematic diagram of the assembly structure of two transverse movement components; Figure 7 It is a structural schematic diagram of a probe installation mechanism in a field rock shear test device for coupled acoustic wave testing according to the present invention; In the figure, 1-rock sample, 2-ultrasonic transmitting probe, 3-ultrasonic receiving probe, 4-first ultrasonic transmitting probe, 5-first ultrasonic receiving probe, 6-second ultrasonic transmitting probe, 7-second ultrasonic receiving probe, 10-axial pressure mechanism, 11-axial pressure hydraulic cylinder, 12-axial pressure pad, 20-transverse pressure mechanism, 21-reaction plate, 22-transverse pressure hydraulic cylinder, 23-transverse pressure pad, 30-uniform reciprocating movement mechanism, 31-transmission shaft, 32-transverse movement assembly, 321-incomplete gear, 322-rack, 323-connecting rod, 33-motor, 34-worm, 35-worm wheel, 40-probe mounting mechanism, 41-ear plate, 42-rod A, 43-slider, 44-rod B. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0017] like Figures 1 to 3 As shown, a field rock shear test method for coupled acoustic wave testing includes the following steps: S1. Peel off a cubic rock sample 1 from the original rock on site. The bottom surface of the rock sample 1 is still connected to the original rock. The top surface, left surface, right surface, front side surface and rear side surface of the rock sample 1 are all free surfaces. Pay attention to reducing disturbance during peeling. After peeling, polish each free surface to make it smooth.

[0018] S2. An axial pressure mechanism 10 is arranged above the top surface of the rock sample 1, a lateral pressure mechanism 20 is arranged on the left side or the right side of the rock sample 1, and an ultrasonic receiving probe and an ultrasonic transmitting probe are respectively arranged on the front side and the rear side of the rock sample 1. The ultrasonic receiving probe and the ultrasonic transmitting probe are both connected to the ultrasonic wave testing device. The ultrasonic receiving probe is used to receive the ultrasonic vibration signal emitted by the ultrasonic transmitting probe and can be recorded in real time by the ultrasonic wave testing device.

[0019] S3. The axial pressure mechanism 10 applies an axial load to the middle of the top surface of the rock sample 1 to a set value.

[0020] S4. The acoustic wave testing device continuously records the acoustic wave data and starts testing. During the test, the lateral pressure mechanism 20 applies a gradually increasing lateral load to the middle of the left side or the middle of the right side of the rock sample 1 until the rock sample 1 is destroyed and the test is stopped. While applying the lateral load, the ultrasonic receiving probe and the ultrasonic transmitting probe coordinately reciprocate at a uniform speed.

[0021] S5. Sort and analyze the sound wave data recorded by the sound wave testing device. According to the principle of ultrasonic testing, when conducting sound wave testing, the ultrasonic pulse transmitting source (ultrasonic transmitting probe) transmits high-frequency elastic pulse waves into the rock medium, so that the waves propagate in the rock medium, and the receiving system (ultrasonic receiving probe) records the wave characteristics of the waves propagating in the rock. Since there are a large number of random cracks, joints, pores and other interfaces in the rock mass, when the sound waves encounter these interfaces during the propagation process, they will produce reflection, scattering and diffraction effects, which will extend the propagation path of the wave and reduce the speed of the sound wave. For the same type of rock mass, the more cracks there are, the smaller the rock mass density and the lower the sound wave propagation speed. The rock mass structure and its corresponding mechanical properties can be inverted through the rock mass wave velocity. Based on the theoretical basis of the transmission of elastic waves in solid media, the wave equation of elastic waves in rock mass media can be obtained by the following formula: , In the formula, , , Represents the coordinate axis x , y , z Displacement in direction; is the Laplace operator; G is the shear modulus; λ is the Lame coefficient; is the volume strain symbol of the unit cell, .

[0022] In an infinite elastic space, the equation for the longitudinal wave velocity can be obtained as:

[0023] In the formula, V p is the longitudinal wave velocity; E d is the dynamic elastic modulus of the rock mass; ρ is the density of the rock mass; μ d is the dynamic Poisson's ratio.

[0024] Similarly, the shear wave velocity equation is:

[0025] In the formula, V s is the shear wave velocity; E d is the dynamic elastic modulus of the rock mass; ρ is the density of the rock mass; μ d is the dynamic Poisson's ratio.

[0026] From the expressions of longitudinal wave and shear wave velocities, it can be seen that the wave velocity is related to the elastic constant, density and Poisson's ratio of the rock medium.

[0027] In actual measurement, the rock wave velocity is:

[0028] In the formula, V is the longitudinal or transverse wave velocity; S is the distance of sound wave propagation; T It is the time difference between the receiving probe receiving the signal and the transmitting probe transmitting the signal.

[0029] In specific implementation, the above step S4 includes at least the following two implementation forms. Example 1

[0030] like Figure 2 As shown, the aforementioned step S4 includes the following steps: S401, the initial positions of the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are both located at the left end of the rock sample 1, and the acoustic wave testing device is turned on to continuously record acoustic wave data; S402, applying a lateral load of a set value to the middle of the right side of the rock sample 1 through the lateral pressing mechanism 20; S403, moving the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 synchronously and uniformly to the right end position of the rock sample; S404, the lateral pressing mechanism 20 applies a greater lateral load to the middle of the right side of the rock sample 1, and the load increase value is a set value; S405, moving the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 synchronously and uniformly to the left end of the rock sample 1; S406, the lateral pressing mechanism 20 applies a greater lateral load to the middle of the right side of the rock sample 1, and the load increase value is a set value; S407. Repeat steps S403 to S406 until the rock sample 1 is destroyed.

[0031] In the above step S403, the ultrasonic transmitting probe 2 continuously transmits ultrasonic vibration signals, which are received by the ultrasonic receiving probe 3 and recorded in real time by the ultrasonic detection device, and the ultrasonic detection data in the plane where the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are located in the rock sample 1 under the transverse pressure load applied in step S402 can be obtained. Similarly, in step S405, the ultrasonic detection data of the plane in the rock sample 1 under the transverse pressure load applied in step S404 can be obtained. Therefore, in the process of repeating steps S403 to S406, the ultrasonic detection data of the set test section in the rock sample 1 after each increase of the set value transverse load can be obtained.

[0032] The above test section can be set according to the detection needs. For example, in the scanning process of steps S403 and S405, the height of the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are kept the same, that is, the ultrasonic detection data of the section parallel to the top surface in the rock sample 1 under direct shear (lateral loading) is obtained; in the scanning process, the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are located at the height center of the rock sample 1, and the ultrasonic detection data of the section parallel to the top surface through the core of the rock sample 1 under direct shear (lateral loading) is obtained. It should be noted that since the acoustic wave testing device continuously records the acoustic wave data and converts it into a spectrum output, in order to linearize the data for easy analysis and processing, the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are kept at a constant speed when moving during implementation.

[0033] It should be understood that during implementation, multiple groups of ultrasonic transmitting probes 2 and ultrasonic receiving probes 3 can be set up to simultaneously obtain ultrasonic detection data of different cross-sections of the rock sample 1 when subjected to direct shear (lateral loading) to explore the rock structure and mechanical properties of different cross-sectional positions within the rock sample 1 when subjected to different lateral loading forces. Example 2

[0034] A first ultrasonic transmitting probe 4 and a second ultrasonic receiving probe 7 are arranged on the front side of the rock sample 1, and a first ultrasonic receiving probe 5 and a second ultrasonic transmitting probe 6 are arranged on the rear side of the rock sample 1. The aforementioned step S4 includes the following steps: S411, make the first ultrasonic transmitting probe 4, the second ultrasonic receiving probe 7, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 all located at the left end of the rock sample 1, adjust the first ultrasonic transmitting probe 4 and the first ultrasonic receiving probe 5 to be located at the two ends of a diagonal line of the left end face of the rock sample 1, and adjust the second ultrasonic transmitting probe 6 and the second ultrasonic receiving probe 7 to be located at the two ends of another diagonal line of the left end face of the rock sample 1, and then turn on the acoustic wave testing device to continuously record acoustic wave data; S412, the lateral pressing mechanism 20 applies a lateral load of a set value to the middle of the right side surface of the rock sample 1; S413, keep the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 at the left end position of the rock sample, and make the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 move synchronously and uniformly to the right end position of the rock sample 1; S414, keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the right end position of the rock sample, and make the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 move synchronously and uniformly to the right end position of the rock sample 1; S415, the lateral pressing mechanism 20 applies a greater lateral load to the middle of the right side of the rock sample 1, and the load increase value is a set value; S416, keep the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 at the right end position of the rock sample, and make the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 move synchronously and uniformly to the left end position of the rock sample 1; S417, keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the left end position of the rock sample, and make the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 move synchronously and uniformly to the left end position of the rock sample 1; S418, the lateral pressing mechanism 20 applies a greater lateral load to the middle of the right side of the rock sample 1, and the load increase value is a set value; S419. Repeat steps S413 to S418 until the rock sample is destroyed.

[0035] In this embodiment, the ultrasonic wave signal emitted by the first ultrasonic transmitting probe 4 is received by the first ultrasonic receiving probe 5, which constitutes a first group of ultrasonic detection devices; the ultrasonic wave signal emitted by the second ultrasonic transmitting probe 6 is received by the second ultrasonic receiving probe 7, which constitutes a second group of ultrasonic detection devices.

[0036] Take the first set of ultrasonic detection devices as an example. Figure 3As shown, in the diagonal section of the rock sample 1 corresponding to the first group of ultrasonic detection devices, during steps S413 to S414, as the first ultrasonic receiving probe 5 and the first ultrasonic transmitting probe 4 move to the right successively, the ultrasonic waves emitted by the first ultrasonic transmitting probe 4 are continuously received by the first ultrasonic receiving probe 5 and continuously recorded by the acoustic wave testing device, and the ultrasonic detection data of the rock sample 1 passing through the diagonal section of the core under the transverse load state applied in step S412 can be obtained; similarly, during steps S416 to S417, as the first ultrasonic receiving probe 5 and the first ultrasonic transmitting probe 4 move to the left successively, the ultrasonic detection data of the rock sample 1 passing through the diagonal section of the core under the transverse load state applied in step S415 can be obtained. Thus, by repeating steps S413 to S418, the ultrasonic detection data of the rock sample 1 after each increase in the set transverse load can be obtained.

[0037] The ultrasonic detection process of the second ultrasonic detection device is the same as that of the first ultrasonic detection device. In the process of repeating steps S413 to S418, ultrasonic detection data of another diagonal section of the core of the rock sample 1 under different lateral loads can also be obtained. During implementation, the lifting and lowering movements of the first ultrasonic detection device and the second ultrasonic detection device are opposite. Taking step S413 as an example, the detection data obtained by the first ultrasonic detection device is that the first ultrasonic transmitting probe 4 is kept stationary and the first ultrasonic receiving probe 5 moves right at a constant speed. The detection data obtained by the second ultrasonic detection device is that the second ultrasonic receiving probe 7 is kept stationary and the second ultrasonic transmitting probe 6 moves right at a constant speed. The detection data under the axial pressure load state is obtained by averaging the two sets of data, which can reduce data errors.

[0038] It should be noted that since two sets of ultrasonic detection devices are set up, the interference problem between the two sets of ultrasonic detection devices must also be considered during data processing. Taking the first ultrasonic receiving probe 5 as an example, in addition to receiving the ultrasonic wave emitted by the first ultrasonic transmitting probe 4, it will also be affected by the ultrasonic wave emitted by the second ultrasonic transmitting probe 6. Since the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are located outside the rock sample 1, the distance between the two can be kept constant by keeping the two moving synchronously, which is conducive to eliminating interference effects during data processing. In addition, since the acoustic wave testing device continuously records acoustic wave data during the experiment, each ultrasonic transmitting probe and ultrasonic receiving probe maintains a uniform speed when moving during implementation to facilitate data processing.

[0039] According to the above, the field rock shear test method of the coupled acoustic wave test can be used to carry out direct shear tests on field rocks at the construction site, and use ultrasonic detection technology to monitor the physical properties and structural characteristics of rocks under different shear conditions in real time. When the method is implemented, the rock samples in the same original rock area can be ultrasonically scanned and tested in the manner of the above two embodiments, and the test data can be comprehensively analyzed, which has the advantages of accuracy, reliability, and efficiency; the type and size of the peeled rock samples are not restricted, and it is suitable for natural rock masses with various structural compositions, and can realize direct experiments on large-sized rock samples. The obtained rock strength parameters can better reflect the engineering mechanical properties of the rock mass, and it is expected to be widely used in the field of geotechnical engineering, providing reliable technical support for engineering safety.

[0040] like Figure 1 , Figures 4 to 7 As shown, a field rock shear test device for coupled acoustic wave testing includes a uniform reciprocating mechanism 30 , which includes a housing, a transmission shaft 31 and two transverse movement components 32 .

[0041] The traverse assembly 32 includes an incomplete gear 321, two racks 322 and a plurality of connecting rods 323. The two racks 322 are arranged opposite to each other, and the two ends of the plurality of connecting rods 323 are respectively fixedly connected to the two racks 322, and the two racks 322 form a rigid sliding mechanism through the connecting rods 323. The deflection angle between the first tooth and the last tooth of the incomplete gear 321 is 45°, and the incomplete gear 321 can mesh with the two racks 322 respectively when rotating. When the incomplete gear 321 rotates one circle, it can be equally divided into four rotation phases: when the incomplete gear 321 rotates through phase one (0-90°), it meshes with one of the racks 322, pushing the sliding mechanism to move in one direction; when the incomplete gear rotates through phase three (180-270°), it meshes with the other rack 322, pushing the sliding mechanism to slide in the opposite direction; when the incomplete gear rotates through phase two (90-180°) and phase four (270-360°), it does not mesh with the two racks 322, and the sliding mechanism remains stationary.

[0042] The two transverse shifting assemblies are arranged in parallel from top to bottom in the housing, the rack 322 is slidably connected to the housing (in implementation, the inner side wall of the housing is provided with a slide groove to guide the sliding of the rack 322, and the braking force on the rack 322 can be increased by providing a friction pad in the slide groove, etc.), the transmission shaft 31 is rotatably connected to the housing, and the two incomplete gears 321 are fixedly sleeved on the transmission shaft 31, and the phase angle between the two incomplete gears 321 differs by 90°. When the transmission shaft 31 rotates continuously at a uniform speed, the two incomplete gears 321 can be driven to rotate together. Since the phase angles of the two incomplete gears 321 differ by 90°, when the incomplete gear 321 in one transverse shifting assembly 32 is meshed with one of the racks 322, the incomplete gear 321 in the other transverse shifting assembly 32 is not meshed with both racks 322.

[0043] The field rock shear experimental device for coupled acoustic wave testing is used to implement the field rock shear experimental method for coupled acoustic wave testing described above, and the uniform reciprocating motion mechanism 30 is used to control the ultrasonic receiving probe and the ultrasonic transmitting probe to realize the coordinated uniform reciprocating motion in the aforementioned step S4. Specifically, when ultrasonic scanning is performed in the manner of the aforementioned embodiment 1, the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are both connected to the sliding mechanism of the same transverse movement component 32, and as the driving shaft 31 continues to rotate at a uniform speed, the sliding mechanism can drive the ultrasonic transmitting probe to cyclically execute the action of uniform right movement-stop-uniform left movement-stop, which can correspond to completing the aforementioned repeated steps S403 to S406 process; when ultrasonic scanning is performed in the manner of the aforementioned embodiment 2, the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 are connected to the sliding mechanism of the transverse movement component 32, and the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe The head 6 is connected to the sliding mechanism of another transverse moving assembly 32. Since the phase angles of the incomplete gears 321 in the two transverse moving assemblies 32 differ by 90°, as the driving shaft 31 continues to operate, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are driven by the sliding mechanism to which they are connected and cyclically perform the actions of uniform rightward movement-stop-uniform leftward movement-stop. In this process, the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 are driven by the sliding mechanism to which they are connected and cyclically perform the actions of stop-uniform rightward movement-stop-uniform leftward movement, which can correspond to the completion of the aforementioned repeated steps S413 to S418. It can be seen that when the field rock shear test device for coupled acoustic wave testing is conducting an experiment, the coordinated uniform reciprocating motion described in the aforementioned step S4 can be achieved by continuously operating the driving shaft 31 at a uniform speed, and the control process is extremely simple.

[0044] Specifically, the field rock shear test device of the coupled acoustic wave test also includes an axial pressure mechanism 10, which includes an axial pressure hydraulic cylinder 11 and an axial pressure pad 12. One end of the axial pressure hydraulic cylinder 11 is fixedly connected to the bottom surface of the shell, and the axial pressure pad 12 is fixedly connected to the other end of the axial pressure hydraulic cylinder 11. The extension direction of the piston rod of the axial pressure hydraulic cylinder 11 is perpendicular to the sliding direction of the rack 322 in the shell. When conducting the experiment, the shell is fixed directly above the rock sample 1 by anchoring or the like. When the piston rod of the axial pressure hydraulic cylinder 11 is extended, the axial load described in the aforementioned step S3 is applied to the middle area of ​​the top surface of the rock sample 1 through the axial pressure pad 12. The axial pressure pad 12 is used to make the axial load evenly distributed on the top surface of the rock sample 1.

[0045] Specifically, the field rock shear test device of the coupled acoustic wave test also includes a transverse pressure mechanism 20, which includes a reaction plate 21, a transverse pressure hydraulic cylinder 22 and a transverse pressure pad 23. One end of the transverse pressure hydraulic cylinder 22 is fixedly connected to the reaction plate 21, and the other end of the transverse pressure hydraulic cylinder 22 is fixedly connected to the transverse pressure pad 23. The reaction plate 21 is fixedly arranged at the oblique lower part of the shell by anchoring or the like, and the transverse pressure pad 23 is arranged on the side of the reaction plate 21 close to the shell. The extension and retraction direction of the piston rod of the transverse pressure hydraulic cylinder 22 is parallel to the sliding direction of the rack 322 in the shell. When the piston rod of the transverse pressure hydraulic cylinder 22 is extended, the transverse load described in the aforementioned step S4 can be applied to the left side or right side of the rock sample 1 through the transverse pressure pad 23 to complete the direct shear test. The transverse pressure pad 23 is used to make the transverse load evenly distributed on the side of the rock sample 1.

[0046] Specifically, the uniform reciprocating motion mechanism 30 also includes a motor 33, a worm 34 and a worm wheel 35. The worm 34 is rotatably connected to the shell, and the worm wheel 35 is fixedly mounted on the transmission shaft 31. The worm 34 is meshed with the worm wheel 35. The motor 33 is used to drive the worm 34 to rotate. When the motor 33 continues to run at a uniform speed, the transmission shaft 31 can be driven to rotate continuously at a uniform speed after deceleration through the worm gear mechanism, thereby driving the two incomplete gears 321 to rotate continuously at a uniform speed.

[0047] Specifically, probe mounting mechanisms 40 are provided on both sides of the housing. Figure 7As shown, the probe installation mechanism 40 includes an ear plate 41, a rod A42 and a plurality of installation components. The rod A42 is movably inserted into one end of the ear plate 41, and the other end of the ear plate 41 is detachably connected to the rack 322. The installation component includes a slider 43 and a rod B44. One end of the slider 43 is movably sleeved on the rod A42, and the rod B44 is movably inserted into the other end of the slider 43. One end of the rod B44 is used to install an ultrasonic receiving probe or an ultrasonic transmitting probe. The height of the ultrasonic receiving probe or the ultrasonic transmitting probe can be adjusted by sliding the rod A42 relative to the ear plate 41 and the slider 43 on the rod A42; the distance of the ultrasonic transmitting probe or the ultrasonic receiving probe relative to the rock sample 1 can be adjusted by sliding the rod B44 relative to the slider 43. Through the above adjustment, the ultrasonic transmitting probe and the ultrasonic receiving probe can be adjusted to a set height and close to the side wall of the rock sample 1. After the adjustment is completed, they can be locked by the locking screw. The two probe mounting mechanisms 40 are respectively connected to the two transverse movement components 32, and ultrasonic scanning detection can be implemented in the form of the aforementioned embodiment 2. The two probe mounting mechanisms 40 are both connected to the same transverse movement component 32, and ultrasonic scanning can be implemented in the form of the aforementioned embodiment 1.

[0048] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A field rock shear test method for coupled acoustic wave testing, characterized in that: The steps include: S1. Peel off a cubic rock sample from the original rock on site, wherein the bottom surface of the rock sample is still connected to the original rock, and the top surface, left surface, right surface, front side surface and rear side surface of the rock sample are all free-facing surfaces; S2, an axial pressure mechanism is arranged above the top surface of the rock sample, a transverse pressure mechanism is arranged on the left side or the right side of the rock sample, and an ultrasonic receiving probe and an ultrasonic transmitting probe are arranged on the front side and the rear side of the rock sample respectively, and the ultrasonic receiving probe and the ultrasonic transmitting probe are both connected to the acoustic wave testing device; S3, the axial pressure mechanism applies an axial load to the middle of the top surface of the rock sample to a set value; S4, the acoustic wave testing device continuously records the acoustic wave data and starts testing. During the test, the lateral pressure mechanism applies a gradually increasing lateral load to the middle of the left side or the middle of the right side of the rock sample until the rock sample is broken and the test is stopped. While applying the lateral load, the ultrasonic receiving probe and the ultrasonic transmitting probe coordinately reciprocate at a uniform speed. S5. Arrange and analyze the sound wave data recorded by the sound wave testing device.

2. A field rock shear test method for coupled acoustic wave testing according to claim 1, characterized in that: The step S4 comprises the following steps: S401, placing the ultrasonic receiving probe and the ultrasonic transmitting probe at the left end of the rock sample, and turning on the acoustic wave testing device to continuously record acoustic wave data; S402, the lateral pressure mechanism applies a lateral load of a set value to the middle of the right side surface of the rock sample; S403, moving the ultrasonic receiving probe and the ultrasonic transmitting probe synchronously and uniformly to the right end position of the rock sample; S404, the lateral pressure mechanism applies a greater lateral load to the middle portion of the right side surface of the rock sample, and the load increase value is a set value; S405, moving the ultrasonic receiving probe and the ultrasonic transmitting probe synchronously and uniformly to the left end position of the rock sample; S406, the lateral pressure mechanism applies a greater lateral load to the middle of the right side of the rock sample, and the load increase value is a set value; S407. Repeat steps S403 to S406 until the rock sample is destroyed.

3. The field rock shear test method of coupled acoustic wave testing according to claim 1, characterized in that: The front side of the rock sample is provided with a first ultrasonic transmitting probe and a second ultrasonic receiving probe, and the rear side of the rock sample is provided with a first ultrasonic receiving probe and a second ultrasonic transmitting probe, and the step S4 comprises the following steps: S411, make the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic transmitting probe all located at the left end of the rock sample, adjust the first ultrasonic transmitting probe and the first ultrasonic receiving probe to be located at the two ends of a diagonal line of the left end surface of the rock sample, respectively, adjust the second ultrasonic transmitting probe and the second ultrasonic receiving probe to be located at the two ends of another diagonal line of the left end surface of the rock sample, and then turn on the acoustic wave testing device to continuously record acoustic wave data; S412, the lateral pressure mechanism applies a lateral load of a set value to the middle of the right side surface of the rock sample; S413, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the left end position of the rock sample, and moving the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly to the right end position of the rock sample; S414, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the right end position of the rock sample, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously moved at a uniform speed to the right end position of the rock sample; S415, the lateral pressure mechanism applies a greater lateral load to the middle of the right side of the rock sample, and the load increase value is a set value; S416, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the right end position of the rock sample, and moving the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly to the left end position of the rock sample; S417, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the left end position of the rock sample, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously moved at a uniform speed to the left end position of the rock sample; S418, the lateral pressure mechanism applies a greater lateral load to the middle portion of the right side surface of the rock sample, and the load increase value is a set value; S419. Repeat steps S413 to S418 until the rock sample is destroyed.

4. A field rock shear test device for coupled acoustic wave testing, characterized in that: It includes a uniform reciprocating motion mechanism, which includes a housing, a transmission shaft and two transverse movement components; The transverse shift assembly includes an incomplete gear, two racks and a plurality of connecting rods, the two racks are arranged opposite to each other, the two ends of the plurality of connecting rods are respectively fixedly connected to the two racks, the deflection angle between the first tooth and the last tooth of the incomplete gear is 45°, and the incomplete gear can mesh with the two racks respectively when rotating; The two transverse shift assemblies are arranged in parallel from top to bottom in the shell, the rack is slidably connected to the shell, the transmission shaft is rotatably connected to the shell, the two incomplete gears are fixedly mounted on the transmission shaft, and the phase angle between the two incomplete gears differs by 90°.

5. The field rock shear test device for coupled acoustic wave testing according to claim 4, characterized in that: It also includes an axial pressure mechanism, which includes an axial pressure hydraulic cylinder and an axial pressure pad. One end of the axial pressure hydraulic cylinder is fixedly connected to the bottom surface of the shell, and the axial pressure pad is fixedly connected to the other end of the axial pressure hydraulic cylinder. The extension and retraction direction of the piston rod of the axial pressure hydraulic cylinder is perpendicular to the sliding direction of the rack in the shell.

6. A field rock shear test device for coupled acoustic wave testing according to claim 5, characterized in that: It also includes a lateral pressing mechanism, which includes a reaction plate, a lateral pressing hydraulic cylinder and a lateral pressing pad, one end of the lateral pressing hydraulic cylinder is fixedly connected to the reaction plate, and the other end of the lateral pressing hydraulic cylinder is fixedly connected to the lateral pressing pad; The reaction plate is arranged obliquely below the housing, the lateral pressure pad is arranged on one side of the reaction plate close to the housing, and the extension and retraction direction of the piston rod of the lateral pressure hydraulic cylinder is parallel to the sliding direction of the rack in the housing.

7. The field rock shear test device for coupled acoustic wave testing according to claim 4, characterized in that: The uniform reciprocating mechanism also includes a motor, a worm and a worm wheel. The worm is rotatably connected to the housing. The motor is used to drive the worm to rotate. The worm wheel is fixedly sleeved on the transmission shaft, and the worm is meshed with the worm wheel.

8. The field rock shear test device for coupled acoustic wave testing according to claim 4, characterized in that: Both sides of the shell are provided with probe mounting mechanisms. The probe mounting mechanism comprises an ear plate, a rod A and a plurality of mounting components, wherein the rod A is movably inserted into one end of the ear plate, and the other end of the ear plate is detachably connected to the rack, and the mounting component comprises a slider and a rod B, wherein one end of the slider is movably sleeved on the rod A, and the rod B is movably inserted into the other end of the slider; The two probe mounting mechanisms are respectively connected to two transverse movement components, or the two probe mounting mechanisms are both connected to the same transverse movement component.

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