On-site rock mass compression 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 compression experiment method and device for coupling sound wave testing, and the method comprises the following steps: drilling four vertical holes downwards on site to form a cubic rock mass sample; a first ultrasonic transmitting probe, a second ultrasonic receiving probe, a first ultrasonic receiving probe and a second ultrasonic transmitting probe are sequentially arranged in each vertical hole, gradually increasing axial loads are downwards applied to the middle of the top surface of the rock sample during testing, and meanwhile, the probes cooperatively move to obtain ultrasonic detection data under different loads; the deformation condition of the rock can be monitored in real time, and the physical and mechanical parameters and the microstructure characteristics of the rock can be obtained through inversion in combination with sound wave test data; the device comprises a counter-force plate, an axial pressure mechanism and two constant-speed reciprocating mechanisms which are symmetrically arranged, each constant-speed reciprocating mechanism comprises an incomplete gear, a lower connecting rod and two racks, the two incomplete gears continuously rotate at a constant speed and can directly drive all probes to complete cooperative movement, and control is convenient.

Description

Technical Field

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

[0002] The mechanical properties of rock mass are generally described by the macroscopic characteristics of the rock mass after being subjected to stress, that is, the state parameters of the rock mass are obtained by experiments, the relationship between the stress and strain of the rock mass is established, and the basic parameters of the mechanical properties of the rock mass, such as compressive strength, elastic modulus and Poisson's ratio, are obtained according to the stress-strain curve. Traditional testing methods include thin section tests, uniaxial compression tests, shear tests, etc. Among them, uniaxial compression tests are a more common in-situ test method for measuring rock deformation indicators. It measures the deformation value of the rock mass by applying axial pressure to the rock mass, and calculates the deformation modulus according to the unidirectional compression formula of elastic mechanics.

[0003] At present, uniaxial compression tests on rock mass usually need to be completed in the laboratory using special experimental equipment, and it is impossible to test the mechanical properties of the rock mass on site when axial compression is applied. Before the laboratory test method is carried out, a large number of rock samples need to be collected or simulated, which has the problem of difficulty in preparing rock samples; in addition, during the test, the accuracy of the experimental results is also limited by the position accuracy of the loaded sample. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a field rock compression test method and device for coupled acoustic wave testing, which can complete the mechanical property test of the field rock mass when axial pressure is applied on site, monitor the deformation of the rock in real time, and obtain the physical and mechanical parameters and micro-structural characteristics of the rock by inverting the acoustic wave test data.

[0005] The objective of the present invention is achieved through the following technical solutions: A field rock mass compression test method for coupled acoustic wave testing comprises the following steps: S1. Drill four vertical holes downward from a flat rock surface on site, wherein the four vertical holes enclose a cubic rock sample below the ground; S2, cleaning each vertical hole and filling each vertical hole with water; S3, respectively arranging a first ultrasonic transmitting probe, a second ultrasonic receiving probe, a first ultrasonic receiving probe, and a second ultrasonic transmitting probe in the four vertical holes in sequence along the circumferential direction, wherein the first ultrasonic transmitting probe and the second ultrasonic receiving probe have the same height, the first ultrasonic receiving probe and the second ultrasonic transmitting probe have the same height, and the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe, and the second ultrasonic transmitting probe are all connected to the sound wave testing device; S4, the acoustic wave testing device continuously records the acoustic wave data and starts the test, during the test, an axial load is applied vertically downward and gradually increases to the middle area of ​​the top surface of the rock sample, and the test is stopped until the rock sample is destroyed, while the axial load is applied, the first ultrasonic receiving probe and the second ultrasonic transmitting probe are synchronously raised and lowered at a uniform speed, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously raised and lowered at a uniform speed in a coordinated manner; S5. Arrange and analyze the sound wave data recorded by the sound wave testing device.

[0006] Specifically, step S4 includes the following steps: S41, making the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic transmitting probe all be located at the bottom end of the vertical hole, and turning on the acoustic wave testing device to record acoustic wave data; S42, applying a vertical downward axial load to a set value to the middle area of ​​the top surface of the rock sample; S43, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the bottom end of the vertical hole, so that the first ultrasonic receiving probe and the second ultrasonic transmitting probe rise synchronously and uniformly to the top end of the vertical hole; S44, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the top position of the vertical hole, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe rise synchronously and uniformly to the top position of the vertical hole; S45, applying a greater axial load to the middle area of ​​the top surface of the rock sample, wherein the load increase portion is a set increment; S46, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the top end of the vertical hole, and making the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly descend to the bottom end of the vertical hole; S47, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the bottom end position of the vertical hole, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe synchronously and uniformly descend to the bottom end position of the vertical hole; S48, applying a greater axial load to the middle area of ​​the top surface of the rock sample, wherein the load increase portion is a set increment; S49. Repeat steps S43 to S48 until the rock sample is destroyed.

[0007] A field rock compression experimental device for coupled acoustic wave testing comprises a reaction plate, an axial pressure mechanism is arranged in the middle of the reaction plate, and uniform reciprocating mechanisms are symmetrically arranged at both ends of the reaction plate; the axial pressure mechanism comprises a hydraulic cylinder and a bearing plate, one end of the hydraulic cylinder is fixedly connected to the reaction plate, and the other end of the hydraulic cylinder is fixedly connected to the bearing plate; the uniform reciprocating mechanism comprises a driving mechanism, an incomplete gear, a lower connecting rod and two racks, the rack is slidably connected to the reaction plate, the rack is parallel to the telescopic direction of the hydraulic cylinder, the two racks are arranged opposite to each other, the two ends of the lower connecting rod are respectively fixedly connected to the two racks, the incomplete gear is rotatably connected to the reaction plate, 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, and the driving mechanism is used to drive the incomplete gear to rotate.

[0008] Specifically, the driving mechanism includes a shell and a motor, the shell is fixedly connected to the reaction plate, the motor is fixedly installed on the shell, a worm and a drive shaft are rotatably provided in the shell, a worm wheel is fixedly sleeved on the drive shaft, the worm is meshed with the worm wheel, the output shaft of the motor is fixedly connected to one end of the worm, and the incomplete gear is fixedly sleeved on the drive shaft.

[0009] Specifically, the uniform reciprocating mechanism further includes a pressure plate and a spring, the rack is slidably connected to the housing, the rack is arranged between the pressure plate and the housing, and the spring is used to provide an elastic force to press the pressure plate in the direction of the rack.

[0010] Specifically, the uniform reciprocating mechanism also includes two ultrasonic probe mounting mechanisms, which include a slider, a sleeve, a sliding rod and a mounting rod. One end of the slider can be slidably mounted on the lower connecting rod, and the sliding rod can be slidably inserted into the other end of the slider. The sleeve is fixedly connected to one end of the sliding rod, and the mounting rod can be slidably inserted into the sleeve.

[0011] Specifically, the uniform reciprocating mechanism also includes an upper connecting rod, both ends of which are fixedly connected to the two racks respectively, and a pin is fixedly provided at one end of the incomplete gear away from the reaction plate, and the pin is adapted to both the upper connecting rod and the lower connecting rod.

[0012] The beneficial effects of the present invention are: The field rock compression experimental method of the coupled acoustic wave test is to drill four vertical holes directly on the flat rock surface, and the four vertical holes enclose a cubic rock sample below the ground; then, a first ultrasonic transmitting probe and a first ultrasonic receiving probe are respectively arranged in two vertical holes in a diagonal direction, and a second ultrasonic transmitting probe and a second ultrasonic receiving probe are respectively arranged in two vertical holes in another diagonal direction; then, the acoustic wave data are continuously recorded to start the test, and during the test, an axial load that gradually increases vertically downward is applied to the middle area of ​​the top surface of the rock sample until the test is stopped when the rock sample is destroyed, and while applying the axial load, the acoustic wave data under different axial compressive loading forces are obtained through the coordinated action of the first ultrasonic receiving probe and the second ultrasonic transmitting probe being synchronously lifted and lowered at a uniform speed, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe being synchronously lifted and lowered at a uniform speed; and then the acoustic wave data are sorted and analyzed. This method can directly carry out uniaxial compression tests on actual rocks at the construction site. By real-time monitoring the deformation of rocks when different axial pressures are applied, the physical and mechanical parameters and micro-structural characteristics of rocks can be inverted in combination with acoustic test data. The physical and mechanical parameters of rocks (such as elastic modulus, Poisson's ratio, etc.) can be accurately measured, and the micro-structural characteristics of rocks (such as porosity, crack density, etc.) can also be inverted. This method has the advantages of accuracy, reliability, and efficiency when implemented. It is suitable for natural rock masses of various structural compositions and is expected to be widely used in the field of geotechnical engineering, providing reliable technical support for engineering safety.

[0013] The field rock compression experimental device for coupled acoustic wave testing includes a reaction plate, an axial pressure mechanism is arranged in the middle of the reaction plate, and the axial pressure mechanism is used to load axial pressure on the rock sample when conducting the experiment; uniform reciprocating mechanisms are symmetrically arranged at both ends of the reaction plate, and the uniform reciprocating mechanism includes an incomplete gear, a lower connecting rod and two racks, the two racks are arranged opposite to each other, and the two ends of the lower connecting rod are respectively fixedly connected to the two racks to form a rigid lifting mechanism, the first ultrasonic receiving probe and the second ultrasonic transmitting probe are connected to the lifting mechanism of one of the uniform reciprocating mechanisms, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe are connected to the lifting mechanism of the other uniform reciprocating mechanism; the incomplete gear is adapted to the two racks, and can be respectively engaged with the two racks when it rotates, and when the incomplete gear rotates at a uniform speed, the lifting mechanism cyclically performs the actions of uniform rise-high position stop-uniform fall-low position stop. When the field rock compression experimental device of the coupled acoustic wave test is carried out, the uniform speed operation of the incomplete gears of the two uniform reciprocating mechanisms can realize the coordinated action of the synchronous uniform reciprocating lifting and lowering of the first ultrasonic receiving probe and the second ultrasonic transmitting probe and the synchronous uniform reciprocating lifting and lowering of the first ultrasonic transmitting probe and the second ultrasonic receiving probe, and the control process is extremely convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A schematic diagram of the relative positions of the vertical holes and the structure of the rock block sample surrounded by the vertical holes in a field rock compression test method for coupled acoustic wave testing according to the present invention; Figure 2 It is a schematic diagram of the coordinated movement process of the second ultrasonic transmitting probe and the second ultrasonic receiving probe in the diagonal cross section of the rock block sample in step S4 in a field rock compression experimental method for coupled acoustic wave testing of the present invention; Figure 3 It is a schematic diagram of the overall structure of a field rock mass compression experimental device for coupled acoustic wave testing according to the present invention; Figure 4 It is a structural schematic diagram of a uniform reciprocating mechanism in a field rock mass compression experimental device for coupled acoustic wave testing of the present invention; Figure 5 for Figure 4 The internal structure diagram of the back side of the uniform reciprocating mechanism shown; In the figure, 1-rock sample, 2-vertical hole, 3-first ultrasonic transmitting probe, 4-second ultrasonic receiving probe, 5-first ultrasonic receiving probe, 6-second ultrasonic transmitting probe, 10-reaction plate, 11-hydraulic cylinder, 12-load-bearing plate, 20-uniform reciprocating mechanism, 21-incomplete gear, 22-rack, 23-lower connecting rod, 24-upper connecting rod, 25-housing, 26-motor, 27-worm, 28-worm wheel, 29-driving shaft, 30-pressure plate, 31-spring, 32-slider, 33-sleeve, 34-sliding rod, 35-mounting rod, 36-pull pin. DETAILED DESCRIPTION

[0015] 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.

[0016] like Figure 1 As shown, a field rock mass compression test method for coupled acoustic wave testing includes the following steps: S1. Select a flat rock surface on site and drill four vertical holes 2 downward. When drilling, the openings of the four vertical holes 2 are square, and the drilling depth becomes the same as the square, so that the four vertical holes 2 enclose a cubic rock sample 1 below the ground.

[0017] S2, cleaning each vertical hole 2 and filling each vertical hole 2 with water, wherein the filled water is used for coupling the ultrasonic wave signal.

[0018] S3, respectively set the first ultrasonic transmitting probe 3, the second ultrasonic receiving probe 4, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 in the four vertical holes 2 in the circumferential direction, and the first ultrasonic transmitting probe 3, the second ultrasonic receiving probe 4, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are all connected to the external sound wave testing device. The first ultrasonic transmitting probe 3 and the first ultrasonic receiving probe 5 constitute a first group of ultrasonic detection devices, and the second ultrasonic transmitting probe 6 and the second ultrasonic receiving probe 4 constitute a second group of ultrasonic detection devices. The two groups of ultrasonic detection devices are respectively arranged at the two diagonal cross-section positions of the rock sample 1. The heights of the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are always kept the same, and the heights of the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are always kept the same.

[0019] S4, the acoustic wave testing device continuously records the acoustic wave data and starts the test. During the test, an axial load that gradually increases vertically downward is applied to the middle area of ​​the top surface of the rock sample 1 until the rock sample 1 is destroyed and the test is stopped. While applying the axial load, the acoustic wave test is performed by the coordinated action of the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 synchronously and uniformly lifting and lowering, and the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 synchronously and uniformly lifting and lowering.

[0020] S5. Arrange and analyze the sound wave data recorded by the sound wave testing device.

[0021] In specific implementation, the collaborative action described in step S4 above can be performed as follows: S41, making the first ultrasonic transmitting probe 3, the second ultrasonic receiving probe 4, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 all located at the bottom end of the corresponding vertical hole 2, and turning on the acoustic wave testing device to record acoustic wave data; S42, applying a vertical downward axial load to a set value to the middle area of ​​the top surface of the rock sample 1; S43, keep the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 at the bottom end position of the corresponding vertical hole 2, and make the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 rise synchronously and uniformly to the top end position of the corresponding vertical hole 2; S44, keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the top position of the corresponding vertical hole 2, so that the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 rise synchronously and uniformly to the top position of the corresponding vertical hole 2; S45, applying a greater axial load to the middle area of ​​the top surface of the rock sample 1, and the load increase portion is the set increment; S46, keep the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 at the top position of the corresponding vertical hole 2, and make the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 synchronously and uniformly descend to the bottom position of the corresponding vertical hole 2; S47, keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the corresponding bottom end position of the vertical hole 2, and make the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 synchronously and uniformly descend to the corresponding bottom end position of the vertical hole 2; S48, applying a greater axial load to the middle area of ​​the top surface of the rock sample 1, and the load increase portion is the set increment; S49. Repeat steps S43 to S48 until the rock sample 1 is destroyed.

[0022] Take the second set of ultrasonic detection devices as an example. Figure 2 As shown, in the diagonal section of the second group of ultrasonic testing devices corresponding to the rock sample 1, during steps S43 to S44, as the second ultrasonic transmitting probe 6 and the second ultrasonic receiving probe 4 rise successively, the ultrasonic waves emitted by the second ultrasonic transmitting probe 6 are continuously received by the second ultrasonic receiving probe 4 and continuously recorded by the acoustic wave testing device, and the ultrasonic testing data of the rock sample 1 under the axial pressure state applied in step S42 can be obtained; similarly, during steps S46 to S47, as the second ultrasonic transmitting probe 6 and the second ultrasonic receiving probe 4 descend successively, the ultrasonic testing data of the rock sample 1 under the axial pressure state applied in step S45 can be obtained. Thus, by repeating steps S43 to S48, the ultrasonic testing data of the rock sample 1 after each increase in the set value axial load can be obtained.

[0023] The ultrasonic detection process of the first ultrasonic detection device is the same as that of the second ultrasonic detection device. In the process of repeating steps S43 to S48, a set of ultrasonic detection data 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 S43 as an example, the detection data obtained by the second ultrasonic detection device is that the second ultrasonic receiving probe 4 is kept stationary and the second ultrasonic transmitting probe 6 is raised at a constant speed; while the detection data obtained by the first ultrasonic detection device is that the first ultrasonic transmitting probe 3 is kept stationary and the first ultrasonic transmitting probe 3 is raised 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.

[0024] It should be noted that since two sets of ultrasonic detection devices are provided, the interference between the two sets of ultrasonic detection devices needs to be considered during data processing. Taking the second ultrasonic receiving probe 4 as an example, in addition to receiving the ultrasonic wave emitted by the second ultrasonic transmitting probe 6, it will also be affected by the ultrasonic wave emitted by the first ultrasonic transmitting probe 3. Figure 1As shown, since the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are located at the right edge area of ​​the rock sample 1, they are far away from the central part of the rock sample 1 subjected to axial loading. In the process of gradually increasing loading force, the rock in this part is less affected by the axial compression loading. In implementation, the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are synchronously raised and lowered and always maintained at the same height, which is conducive to reducing or eliminating interference effects during data processing. In addition, since the acoustic wave test device continuously records acoustic wave data during the experiment, each ultrasonic transmitting probe and ultrasonic receiving probe are required to maintain a uniform speed when rising or falling in implementation to facilitate data processing.

[0025] During the acoustic wave test, an ultrasonic pulse transmitter emits a high-frequency elastic pulse wave into the rock medium, causing the wave to propagate in the rock medium, and a receiving system is used to record the wave characteristics of the wave 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 wave encounters these interfaces during the propagation process, it will produce reflection, scattering and diffraction effects, which will extend the wave propagation path and reduce the sound wave speed. 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. Therefore, the rock mass wave velocity can reflect the rock mass structure and its corresponding mechanical properties.

[0026] The aforementioned step S5 describes the sorting and analysis of the acoustic wave data recorded by the acoustic wave testing device, including inverting the microstructural characteristics of the rock at different positions during the loading process, such as porosity, crack density, etc., based on the change in wave velocity with compression time. The rock mass is divided into four stages during the loading process, namely, the compaction stage, the stable development stage of cracks, the unstable rupture stage, and the post-rupture stage. Time-wave velocity curves are drawn based on the ultrasonic detection data obtained under the aforementioned axial pressures. As the loading axial pressure gradually increases, the time-wave velocity curve corresponds to the following processes in sequence: when the wave velocity is stable and unchanged without fluctuations, the rock mass is not disturbed and is in a safe state; when the wave velocity begins to increase, the rock mass is in the compaction stage, that is, the original open structural surfaces or microcracks in the rock mass are stressed. After closure, the wave propagation speed in the rock mass increases; when the wave speed reaches the maximum value, the rock mass also reaches the densest stage, at which time the volume of pores and cracks in the rock mass is the smallest; when the wave speed gradually decreases, the volume of pores and cracks inside the rock mass begins to develop; when the wave speed curve is in a fluctuating state, the rock mass changes from internal cracks to surface macroscopic cracks, the rock mass deformation also gradually increases, the cracks develop rapidly, cross and combine with each other to form a macroscopic fracture surface; when the wave speed decreases rapidly, the rock mass is destroyed, relative slip occurs, and the rock mass becomes unstable.

[0027] The aforementioned step S5 of sorting and analyzing the acoustic wave data recorded by the acoustic wave testing device also includes inverting the physical and mechanical parameters of the rock under various axial loads, such as elastic modulus, Poisson's ratio, etc., according to the acoustic wave test data. The calculation formula is as follows: , Where: V P is the longitudinal wave velocity, V S is the shear wave velocity, ρ is the density of the rock mass, E is the elastic modulus, and μ is the Poisson's ratio.

[0028] The field rock mass compression test method of the coupled acoustic wave test can carry out uniaxial compression tests on field rocks at the construction site. By real-time monitoring the deformation of the rock when different axial pressures are applied, the physical and mechanical parameters and micro-structural characteristics of the rock can be inverted in combination with the acoustic wave test data. The physical and mechanical parameters of the rock (such as elastic modulus, Poisson's ratio, etc.) can be accurately measured, and the micro-structural characteristics of the rock (such as porosity, crack density, etc.) can also be inverted. This method has the advantages of accuracy, reliability, and efficiency when implemented. It is suitable for natural rock masses of various structural compositions and is expected to be widely used in the field of geotechnical engineering, providing reliable technical support for engineering safety.

[0029] like Figures 3 to 5 As shown, a field rock mass compression test device for coupled acoustic wave testing includes a reaction plate 10, an axial pressure mechanism is arranged in the middle of the reaction plate, and uniform reciprocating mechanisms 20 are symmetrically arranged at both ends of the reaction plate. The axial pressure mechanism includes a hydraulic cylinder 11 and a bearing plate 12, one end of the hydraulic cylinder 11 is fixedly connected to the reaction plate 10, and the other end of the hydraulic cylinder 11 is fixedly connected to the bearing plate 12. The uniform reciprocating mechanism 20 includes a driving mechanism, an incomplete gear 21, a lower connecting rod 23 and two racks 22. The racks 22 are slidably connected to the reaction plate 10. The racks 22 are parallel to the extension and contraction direction of the hydraulic cylinder 11. The two racks 22 are arranged opposite to each other. The two ends of the lower connecting rod 23 are respectively fixedly connected to the two racks 22 so that the two racks 22 are connected to form a rigid lifting mechanism. The incomplete gear 21 is rotatably connected to the reaction plate 10. The deflection angle between the first tooth and the last tooth of the incomplete gear 21 is 45°. When the incomplete gear 21 rotates, it can mesh with the two racks 22 respectively. Figure 2As shown, the driving mechanism is used to drive the incomplete gear 21 to rotate. When the driving mechanism rotates at a uniform speed for one circle, the incomplete gear 21 rotates 0-90° and meshes with the rack 22 on the left side of the figure (the moment when the first tooth of the incomplete gear 21 and the left rack 22 just enter into meshing is defined as the rotation starting point 0° of the incomplete gear 21. Since the deflection angle between the first tooth and the last tooth of the incomplete gear 21 is 45°, when the incomplete gear 21 rotates 90°, its last tooth disengages from the left rack 22). This rotation process can drive the lifting mechanism to rise at a uniform speed; when the incomplete gear 21 rotates 90-180°, the incomplete gear 21 is not meshed with the racks 22 on both sides, and the lifting mechanism remains stationary; when the incomplete gear 21 rotates 180-270°, it meshes with the rack 22 on the right side of the figure, and this rotation process can drive the lifting mechanism to descend at a uniform speed. When the incomplete gear 21 rotates 270-360°, it is not meshed with the racks 22 on both sides, and the lifting mechanism remains stationary.

[0030] The field rock compression experimental device of the coupled acoustic wave test can be used to carry out the above-mentioned experimental method. When it is implemented in the field, combined with Figure 1 , Figure 3 As shown, the reaction plate 10 can be fixed directly above the rock sample 1 by being mounted on a heavy vehicle or connected to a ground anchor, etc., the hydraulic cylinder 11 is used to apply an axial load that gradually increases vertically downward to the middle area of ​​the top surface of the rock sample 1, and the bearing plate 12 is used to evenly distribute the axial load in the loaded area of ​​the top surface of the rock sample 1; the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are connected to the Figure 3 The lifting mechanism of the left uniform reciprocating mechanism 20 is connected, and the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are connected. Figure 3 The lifting mechanism of the uniform reciprocating mechanism 20 on the right side is connected, and the initial positions of the two uniform reciprocating mechanisms 20 are adjusted so that the initial positions of the two incomplete gears 21 are 90° apart in phase, and then the test can be started. During the test, the hydraulic cylinder 11 can gradually increase the axial load according to the set load increment according to the program; in terms of the motion control of the two sets of ultrasonic testing devices, the driving mechanisms of the two uniform reciprocating mechanisms 20 operate at the same speed at the same time, such as Figure 3 As shown, when the left incomplete gear 21 in the figure rotates through its 0-90° phase range, the right incomplete gear 21 in the figure rotates through its 270-360° phase range, and the aforementioned S43 action process is completed at this time. When the left incomplete gear 21 in the figure rotates through its 90-180° phase range, the right incomplete gear 21 in the figure rotates through its 0-90° phase range, and the aforementioned S43 action process is completed at this time. By analogy, as the driving mechanisms of the two uniform reciprocating mechanisms 20 continue to operate, the above-mentioned S43 action process can be completed. Figure 2The cyclic action process from S43 to S47 is shown. It can be seen that when the field rock mass compression experimental device for coupled acoustic wave testing is tested, the driving mechanisms of the two uniform reciprocating mechanisms 20 can simultaneously operate at the same speed to complete the coordinated action described in the aforementioned step S4, and the control process is extremely simple.

[0031] It should be understood that, when implemented, the initial positions of the two incomplete gears 21 are made the same, so that the two lifting mechanisms can synchronously and cyclically perform uniform reciprocating lifting and lowering actions, driving the first ultrasonic transmitting probe 3, the second ultrasonic receiving probe 4, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 to synchronously and uniformly lift and lower, and at this time, the two sets of ultrasonic detection devices switch to the parallel scanning mode. In practical applications, the device can be used to scan the on-site rock mass in the above-mentioned parallel scanning mode and the aforementioned cyclic mode of S43 to S47, respectively, and the detection results can be comprehensively analyzed to obtain more accurate experimental results.

[0032] In specific implementation, Figure 4 , Figure 5 As shown, the driving mechanism includes a housing 25 and a motor 26, the housing 25 is fixedly connected to the reaction plate 10, and the motor 26 is fixedly mounted on the housing 25. A worm 27 and a drive shaft 29 are rotatably arranged in the housing 25, a worm wheel 28 is fixedly sleeved on the drive shaft 29, the worm 27 meshes with the worm wheel 28, the output shaft of the motor 26 is fixedly connected to one end of the worm 27, and the incomplete gear 21 is fixedly sleeved on the drive shaft 29. When the motor 26 continues to run at a uniform speed, the worm 27 rotates together, thereby driving the worm wheel 28 and the drive shaft 29 to rotate, and then driving the incomplete gear 21 to rotate at a uniform speed.

[0033] When implementing it, Figure 4 As shown, the above-mentioned uniform reciprocating mechanism 20 also includes a pressure plate 30 and a spring 31. The rack 22 is slidably connected to the housing 25. The rack 22 is arranged between the pressure plate 30 and the housing 25. The spring 31 is used to provide an elastic force to the pressure plate 30 in the direction of pressing the rack 22, so as to clamp and brake the rack 22 when the incomplete gear 21 is not engaged with the racks 22 on both sides.

[0034] When implementing it, Figure 4As shown, the uniform reciprocating mechanism 20 also includes two ultrasonic probe mounting mechanisms, which include a slider 32, a sleeve 33, a slide bar 34 and a mounting rod 35. One end of the slider 32 is slidably mounted on the lower connecting rod 23, the slide bar 34 is slidably inserted into the other end of the slider 32, the sleeve 33 is fixedly connected to one end of the slide bar 34, the mounting rod 35 is slidably inserted into the sleeve 34, and the bottom end of the mounting rod 35 is used to install an ultrasonic transmitting probe or an ultrasonic receiving probe. Since errors are inevitable when drilling the vertical hole 2 in the field in the aforementioned step S2, the initial position of the ultrasonic transmitting probe or the ultrasonic receiving probe can be fine-tuned by sliding the slider 32 on the lower connecting rod 23, sliding the slide bar 34 in the slider 32, and sliding the mounting rod 35 in the sleeve 33 in the above-mentioned setting, and the position can be locked by a locking screw after the adjustment is completed.

[0035] When implementing it, Figure 4 As shown, the uniform reciprocating mechanism 20 also includes an upper connecting rod 24, and the two ends of the upper connecting rod 24 are respectively fixedly connected to the two racks 22, so that the lifting mechanism has a frame structure, thereby enhancing its structural rigidity; a detent pin 36 is fixedly provided at one end of the incomplete gear 21 away from the reaction plate 10, and the detent pin 36 is adapted to both the upper connecting rod 24 and the lower connecting rod 23. Before the incomplete gear 21 and the rack 22 enter into meshing, the detent pin 36 first contacts the upper connecting rod 24 or the lower connecting rod 23 to push the lifting mechanism to move, so that the first tooth of the incomplete rack 21 can mesh smoothly with the rack 22 to avoid the occurrence of top tooth phenomenon.

[0036] 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 mass compression test method for coupled acoustic wave testing, characterized in that: The steps include: S1. Drill four vertical holes downward from a flat rock surface on site, wherein the four vertical holes enclose a cubic rock sample below the ground; S2, cleaning each vertical hole and filling each vertical hole with water; S3, respectively arranging a first ultrasonic transmitting probe, a second ultrasonic receiving probe, a first ultrasonic receiving probe, and a second ultrasonic transmitting probe in the four vertical holes in sequence along the circumferential direction, wherein the first ultrasonic transmitting probe and the second ultrasonic receiving probe have the same height, the first ultrasonic receiving probe and the second ultrasonic transmitting probe have the same height, and the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe, and the second ultrasonic transmitting probe are all connected to the sound wave testing device; S4, the acoustic wave testing device continuously records the acoustic wave data and starts the test, during the test, an axial load is applied vertically downward and gradually increases to the middle area of ​​the top surface of the rock sample, and the test is stopped until the rock sample is destroyed, while the axial load is applied, the first ultrasonic receiving probe and the second ultrasonic transmitting probe are synchronously raised and lowered at a uniform speed, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe are synchronously raised and lowered at a uniform speed in a coordinated manner; S5. Arrange and analyze the sound wave data recorded by the sound wave testing device.

2. The field rock mass compression test method of coupled acoustic wave testing according to claim 1 is characterized in that: The step S4 comprises the following steps: S41, making the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic transmitting probe all be located at the bottom end of the vertical hole, and turning on the acoustic wave testing device to record acoustic wave data; S42, applying a vertical downward axial load to a set value to the middle area of ​​the top surface of the rock sample; S43, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the bottom end of the vertical hole, so that the first ultrasonic receiving probe and the second ultrasonic transmitting probe rise synchronously and uniformly to the top end of the vertical hole; S44, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the top position of the vertical hole, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe rise synchronously and uniformly to the top position of the vertical hole; S45, applying a greater axial load to the middle area of ​​the top surface of the rock sample, wherein the load increase portion is a set increment; S46, keeping the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the top end of the vertical hole, and making the first ultrasonic receiving probe and the second ultrasonic transmitting probe synchronously and uniformly descend to the bottom end of the vertical hole; S47, keeping the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the bottom end position of the vertical hole, so that the first ultrasonic transmitting probe and the second ultrasonic receiving probe synchronously and uniformly descend to the bottom end position of the vertical hole; S48, applying a greater axial load to the middle area of ​​the top surface of the rock sample, wherein the load increase portion is a set increment; S49. Repeat steps S43 to S48 until the rock sample is destroyed.

3. A field rock compression test device for coupled acoustic wave testing, characterized in that: It comprises a reaction plate, wherein an axial pressure mechanism is arranged in the middle of the reaction plate, and uniform reciprocating mechanisms are symmetrically arranged at both ends of the reaction plate; The axial pressure mechanism comprises a hydraulic cylinder and a bearing plate, one end of the hydraulic cylinder is fixedly connected to the reaction plate, and the other end of the hydraulic cylinder is fixedly connected to the bearing plate; The uniform reciprocating mechanism comprises a driving mechanism, an incomplete gear, a lower connecting rod and two racks. The rack is slidably connected to the reaction plate, and the rack is parallel to the extension and contraction direction of the hydraulic cylinder. The two racks are arranged opposite to each other, and the two ends of the lower connecting rod are fixedly connected to the two racks respectively. The incomplete gear is rotatably connected to the reaction plate, 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 driving mechanism is used to drive the incomplete gear to rotate.

4. The field rock mass compression test device for coupled acoustic wave testing according to claim 3 is characterized in that: The driving mechanism comprises a housing and a motor, wherein the housing is fixedly connected to the reaction plate, and the motor is fixedly mounted on the housing. A worm and a drive shaft are rotatably arranged in the shell, a worm wheel is fixedly sleeved on the drive shaft, the worm is meshed with the worm wheel, the output shaft of the motor is fixedly connected to one end of the worm, and the incomplete gear is fixedly sleeved on the drive shaft.

5. The field rock mass compression test device for coupled acoustic wave testing according to claim 4, characterized in that: The uniform reciprocating mechanism further comprises a pressure plate and a spring. The rack is slidably connected to the housing. The rack is arranged between the pressure plate and the housing. The spring is used for providing an elastic force to press the pressure plate in the direction of the rack.

6. The field rock mass compression test device for coupled acoustic wave testing according to claim 3, characterized in that: The uniform reciprocating mechanism also includes two ultrasonic probe mounting mechanisms, which include a slider, a sleeve, a slide rod and a mounting rod. One end of the slider is slidably mounted on the lower connecting rod, and the slide rod is slidably inserted into the other end of the slider. The sleeve is fixedly connected to one end of the slide rod, and the mounting rod is slidably inserted into the sleeve.

7. The field rock mass compression test device for coupled acoustic wave testing according to claim 3, characterized in that: The uniform reciprocating mechanism also includes an upper connecting rod, the two ends of which are fixedly connected to the two racks respectively, and a detent pin is fixedly provided at one end of the incomplete gear away from the reaction plate, and the detent pin is adapted to both the upper connecting rod and the lower connecting rod.

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