A field rock mass compression test method and apparatus for coupled acoustic wave testing

Abstract

This invention relates to the field of rock mechanics testing technology, and discloses a field rock compression test method and apparatus using coupled acoustic wave testing. The method involves drilling four vertical holes downwards in the field to form a cubic rock sample. A first ultrasonic transmitting probe, a second ultrasonic receiving probe, and a second ultrasonic transmitting probe are sequentially installed in each vertical hole. During testing, a gradually increasing axial load is applied downwards to the center of the top surface of the rock sample. Simultaneously, each probe moves collaboratively to acquire ultrasonic test data under different loads. This allows for real-time monitoring of rock deformation and, combined with acoustic wave test data, inversion of the rock's physical and mechanical parameters and microstructural characteristics. The apparatus includes a reaction plate, an axial compression mechanism, and two symmetrically arranged uniform reciprocating mechanisms. Each uniform reciprocating mechanism includes an incomplete gear, a lower connecting rod, and two racks. The continuous uniform rotation of the two incomplete gears directly drives each probe to complete the collaborative movement, making control convenient.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, specifically to a field rock mass compression test method and apparatus using coupled acoustic wave testing. Background Technology

[0002] The mechanical properties of rock masses are generally described by the macroscopic characteristics exhibited by the rock mass under stress. This involves obtaining rock mass state parameters through experiments, establishing the stress-strain relationship, and deriving basic parameters of rock mass mechanical properties, such as compressive strength, elastic modulus, and Poisson's ratio, from the stress-strain curve. Traditional testing methods include thin-section tests, uniaxial compression tests, and shear tests. Among these, the uniaxial compression test is a commonly used in-situ testing method for determining rock mass deformation indices. It involves applying axial pressure to the rock mass, measuring the deformation value, and calculating the deformation modulus using the uniaxial compression formula in elastic mechanics.

[0003] Currently, uniaxial compression tests on rock masses typically require specialized laboratory equipment, making it impossible to test the mechanical properties of rock masses under axial compression in the field. Laboratory testing methods require the collection or simulation of large quantities of rock samples before testing, which presents challenges due to the difficulty of sample preparation. Furthermore, the accuracy of experimental results is limited by factors such as the precision of the sample loading position. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a field rock mass compression test method and device with coupled acoustic wave testing. This method can complete the mechanical property test of the rock mass under axial compression on site, monitor the deformation of the rock in real time, and obtain the physical and mechanical parameters and microstructure characteristics of the rock by combining the acoustic wave test data.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A field rock mass compression test method using coupled acoustic wave testing includes the following steps:

[0007] S1. Four vertical holes are drilled downwards from a flat rock surface selected on site. The four vertical holes enclose a cubic rock sample below the ground.

[0008] S2. Clean each vertical hole and fill each vertical hole with water;

[0009] S3. A first ultrasonic transmitting probe, a second ultrasonic receiving probe, a first ultrasonic receiving probe, and a second ultrasonic transmitting probe are respectively installed in the four vertical holes along the circumferential direction. The first ultrasonic transmitting probe and the second ultrasonic receiving probe are at the same height. 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 acoustic wave testing device.

[0010] S4. The acoustic wave testing device continuously records acoustic wave data to start 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 until the rock sample is destroyed and the test is stopped. At the same time as the axial load is applied, the first ultrasonic receiving probe and the second ultrasonic transmitting probe move up and down at a constant speed, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe move up and down at a constant speed in a coordinated manner.

[0011] S5. Organize and analyze the acoustic wave data recorded by the acoustic wave testing device.

[0012] Specifically, step S4 includes the following steps:

[0013] S41. Position the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe, and the second ultrasonic transmitting probe at the bottom of the vertical hole, and turn on the acoustic wave testing device to record acoustic wave data.

[0014] S42. Apply a vertically downward axial load to the central region of the top surface of the rock sample to a set value;

[0015] S43. Keep the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the bottom of the vertical hole, and make the first ultrasonic receiving probe and the second ultrasonic transmitting probe rise synchronously and at a constant speed to the top of the vertical hole.

[0016] S44. Keep the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the top of the vertical hole, and make the first ultrasonic transmitting probe and the second ultrasonic receiving probe rise synchronously and at a constant speed to the top of the vertical hole.

[0017] S45. Apply a larger axial load to the central region of the top surface of the rock sample, with the increased load being a set increment;

[0018] S46. Keep the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the top of the vertical hole, and make the first ultrasonic receiving probe and the second ultrasonic transmitting probe descend synchronously and at a uniform speed to the bottom of the vertical hole.

[0019] S47. Keep the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the bottom of the vertical hole, and make the first ultrasonic transmitting probe and the second ultrasonic receiving probe descend synchronously and uniformly to the bottom of the vertical hole.

[0020] S48. Apply a larger axial load to the central region of the top surface of the rock sample, with the increased load being a set increment;

[0021] S49. Repeat steps S43 to S48 until the rock sample is destroyed.

[0022] A field rock mass compression test device for coupled acoustic wave testing includes a reaction plate, an axial compression mechanism in the middle of the reaction plate, and uniform reciprocating mechanisms symmetrically arranged at both ends of the reaction plate. The axial compression mechanism includes 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 includes a drive mechanism, an incomplete gear, a lower connecting rod, and two racks. The racks are slidably connected to the reaction plate and are parallel to the extension and retraction direction of the hydraulic cylinder. The two racks are arranged opposite to each other. 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 and last teeth of the incomplete gear is 45°. When the incomplete gear rotates, it can mesh with the two racks respectively. The drive mechanism is used to drive the incomplete gear to rotate.

[0023] Specifically, the drive mechanism includes a housing and a motor. 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 inside the housing. A worm wheel is fixedly sleeved on the drive shaft. The worm meshes with the worm wheel. The output shaft of the motor is fixedly connected to one end of the worm. The incomplete gear is fixedly sleeved on the drive shaft.

[0024] Specifically, the uniform reciprocating mechanism further includes a pressure plate and a spring. The rack is slidably connected to the housing and is disposed between the pressure plate and the housing. The spring is used to provide the pressure plate with a spring force in the direction of the rack.

[0025] Specifically, the uniform reciprocating mechanism further includes two ultrasonic probe mounting mechanisms. Each ultrasonic probe mounting mechanism includes a slider, a sliding sleeve, a sliding rod, and a mounting rod. One end of the slider is slidably sleeved on the lower connecting rod, and the sliding rod is slidably inserted into the other end of the slider. The sliding sleeve is fixedly connected to one end of the sliding rod, and the mounting rod is slidably inserted into the sliding sleeve.

[0026] Specifically, 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 pin is fixedly provided at the end of the incomplete gear away from the reaction plate, the pin being compatible with both the upper and lower connecting rods.

[0027] The beneficial effects of this invention are:

[0028] The in-situ rock compression test method for coupled acoustic wave testing involves drilling four vertical holes directly into a flat rock surface, forming a cubic rock sample beneath the surface. A first ultrasonic transmitting probe and a first ultrasonic receiving probe are then installed in two diagonally opposite vertical holes, and a second ultrasonic transmitting probe and a second ultrasonic receiving probe are installed in the other two diagonally opposite vertical holes. Acoustic wave data is continuously recorded to begin the test. During the test, a gradually increasing axial load is applied vertically downwards to the central area of ​​the top surface of the rock sample until the sample fails. Simultaneously with the application of the axial load, acoustic wave data under different axial compression loads are acquired through the synchronized uniform reciprocating motion of the first ultrasonic receiving probe and the second ultrasonic transmitting probe, as well as their coordinated synchronous uniform reciprocating motion. The acoustic wave data is then processed and analyzed. This method allows for direct uniaxial compression testing of rocks on-site during construction. By monitoring the deformation of the rock under different axial compressions in real time and combining this data with acoustic wave testing, the physical and mechanical parameters and microstructural characteristics of the rock can be retrieved. It can accurately measure the physical and mechanical parameters of the rock (such as elastic modulus and Poisson's ratio) and also retrieve its microstructural characteristics (such as porosity and crack density). This method is accurate, reliable, and efficient, and is applicable to natural rock masses with various structural compositions. It is expected to be widely used in geotechnical engineering, providing reliable technical support for engineering safety.

[0029] The field rock mass compression test device for coupled acoustic wave testing includes a reaction plate with an axial compression mechanism in the middle. The axial compression mechanism is used to apply axial compression to the rock sample during the experiment. A uniform reciprocating mechanism is symmetrically arranged at both ends of the reaction plate. This uniform reciprocating mechanism includes an incomplete gear, a lower connecting rod, and two racks. The two racks are arranged opposite each other, and the two ends of the lower connecting rod are fixedly connected to the two racks to form a rigid lifting mechanism. A first ultrasonic receiving probe and a 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 mesh with them respectively when rotating. When the incomplete gear rotates at a uniform speed, the lifting mechanism cyclically performs the action of uniform speed rise-high position stop-uniform speed descent-low position stop. In the field rock mass compression test device for coupled acoustic wave testing, the incomplete gears of the two uniform reciprocating mechanisms can achieve the coordinated action of synchronous uniform reciprocating lifting of the first ultrasonic receiving probe and the second ultrasonic transmitting probe, as well as the synchronous uniform reciprocating lifting of the first ultrasonic transmitting probe and the second ultrasonic receiving probe, making the control process extremely convenient. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the relative positions of each vertical hole and the structural diagram of the rock block sample enclosed by them in a field rock mass compression test method using coupled acoustic wave testing according to the present invention.

[0031] Figure 2 This is a schematic diagram of the coordinated motion process of the second ultrasonic transmitting probe and the second ultrasonic receiving probe in step S4 within the diagonal section of the rock block sample in a field rock mass compression test method of coupled acoustic wave testing according to the present invention.

[0032] Figure 3 This is a schematic diagram of the overall structure of a field rock mass compression test device for coupled acoustic wave testing according to the present invention.

[0033] Figure 4 This is a schematic diagram of the uniform reciprocating mechanism in a field rock mass compression test device for coupled acoustic wave testing according to the present invention.

[0034] Figure 5 for Figure 4 A schematic diagram of the internal structure of the back of the uniform reciprocating mechanism shown.

[0035] 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-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 gear, 28-worm wheel, 29-drive shaft, 30-pressure plate, 31-spring, 32-slider, 33-sliding sleeve, 34-sliding rod, 35-mounting rod, 36-pin. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0037] like Figure 1 As shown, a field rock mass compression test method using coupled acoustic wave testing includes the following steps:

[0038] S1. Select a flat rock block on site and drill four vertical holes 2 downwards. When drilling, the openings of the four vertical holes 2 are square, and the drilling depth is the same as the square, so that the four vertical holes 2 enclose a cubic rock block sample 1 below the ground.

[0039] S2. Clean each vertical hole 2 and fill each vertical hole 2 with water. The water is used to couple ultrasonic wave signals.

[0040] S3. A first ultrasonic transmitting probe 3, a second ultrasonic receiving probe 4, a first ultrasonic receiving probe 5, and a second ultrasonic transmitting probe 6 are sequentially installed in four vertical holes 2 along the circumference. All four probes are connected to an external acoustic wave testing device. The first ultrasonic transmitting probe 3 and the first ultrasonic receiving probe 5 constitute the first ultrasonic testing device, and the second ultrasonic transmitting probe 6 and the second ultrasonic receiving probe 4 constitute the second ultrasonic testing device. These two sets of ultrasonic testing devices are respectively arranged at the two diagonal cross-sections of the rock sample 1. The heights of the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4, and the heights of the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6, are always kept the same.

[0041] S4. The acoustic wave testing device continuously records acoustic wave data to start the test. During the test, a vertically downward axial load 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. At the same time as the axial load is applied, the acoustic wave test is carried out by the coordinated action of the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 moving up and down at a constant speed and the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 moving up and down at a constant speed.

[0042] S5. Organize and analyze the acoustic wave data recorded by the acoustic wave testing device.

[0043] In practical implementation, the collaborative action described in step S4 above can be performed as follows:

[0044] S41. Position 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 at the bottom of the corresponding vertical hole 2, and turn on the acoustic wave testing device to record acoustic wave data.

[0045] S42. Apply a vertically downward axial load to the middle region of the top surface of rock sample 1 to the set value;

[0046] S43. Keep the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 at the bottom 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 of the corresponding vertical hole 2.

[0047] S44. Keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the top of the corresponding vertical hole 2, and make the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 rise synchronously and uniformly to the top of the corresponding vertical hole 2.

[0048] S45. Apply a larger axial load to the middle region of the top surface of rock sample 1, with the increased load being the set increment.

[0049] S46. Keep the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 at the top of the corresponding vertical hole 2, and make the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 descend synchronously and at a uniform speed to the bottom of the corresponding vertical hole 2.

[0050] S47. Keep the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 at the bottom of the corresponding vertical hole 2, and make the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 descend synchronously and at a uniform speed to the bottom of the corresponding vertical hole 2.

[0051] S48. Apply a larger axial load to the middle region of the top surface of rock sample 1, with the increased load being the set increment;

[0052] S49. Repeat steps S43 to S48 until rock sample 1 is destroyed.

[0053] Taking the second group of ultrasonic testing devices as an example, such as Figure 2As shown, within the diagonal section corresponding to the rock sample 1 in the second set of ultrasonic testing devices, 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, thus obtaining the ultrasonic testing data of the rock sample 1 under the axial compression state applied in step S42. 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 compression state applied in step S45 can be obtained. Therefore, by repeating steps S43 to S48, the ultrasonic testing data of the rock sample 1 after each increase in the set value of axial load can be obtained.

[0054] The ultrasonic testing process of the first group of ultrasonic testing devices is the same as that of the second group of ultrasonic testing devices. During the repetition of steps S43 to S48, a set of ultrasonic testing data can also be obtained. In practice, the lifting and lowering movements of the first and second groups of ultrasonic testing devices are opposite. Taking step S43 as an example, the testing data obtained by the second group of ultrasonic testing devices is obtained by keeping the second ultrasonic receiving probe 4 stationary and the second ultrasonic transmitting probe 6 rising at a constant speed; while the testing data obtained by the first group of ultrasonic testing devices is obtained by keeping the first ultrasonic transmitting probe 3 stationary and rising at a constant speed. By averaging the two sets of data, the testing data under the axial compression load condition can be obtained, thus reducing data errors.

[0055] It should be noted that, due to the presence of two sets of ultrasonic testing devices, interference between the two sets must be considered during data processing. Taking the second ultrasonic receiving probe 4 as an example, in addition to receiving the ultrasonic waves emitted by the second ultrasonic transmitting probe 6, it is also affected by the ultrasonic waves emitted by the first ultrasonic transmitting probe 3. For example... Figure 1 As shown, since the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are located in the right edge region of the rock sample 1, far from the center of the rock sample 1 subjected to axial loading, the rock in this region is less affected by axial compression as the loading force gradually increases. Therefore, during implementation, the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are raised and lowered synchronously and always kept at the same height, which helps to reduce or eliminate interference during data processing. Furthermore, since the acoustic wave testing device continuously records acoustic wave data during the experiment, it is required that each ultrasonic transmitting probe and ultrasonic receiving probe maintain a uniform speed during ascent or descent to facilitate data processing.

[0056] In acoustic wave testing, a high-frequency elastic pulse wave is emitted from an ultrasonic pulse transmitter into the rock mass, allowing the wave to propagate within the rock mass. A receiving system records the wave propagation characteristics within the rock mass. Because rock masses contain numerous random fissures, joints, pores, and other interfaces, sound waves encountering these interfaces during propagation experience reflection, scattering, and diffraction, which lengthen the wave propagation path and reduce the sound wave velocity. For the same type of rock mass, the more fissures, the lower 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.

[0057] The aforementioned step S5 involves organizing and analyzing the acoustic data recorded by the acoustic testing device. This includes inverting the microstructural characteristics of the rock mass at different locations during loading, such as porosity and crack density, based on the change in wave velocity with compression time. The rock mass undergoes four stages during loading: compaction stage, stable crack development stage, unstable fracture stage, and post-fracture stage. Time-wave velocity curves are plotted based on the ultrasonic testing data obtained under each axial pressure. As the loading axial pressure gradually increases, the time-wave velocity curves correspond to the following processes: when the wave velocity is stable and without fluctuation, the rock mass is not disturbed, which is a safe state; when the wave velocity begins to increase, the rock mass is in the compaction stage, meaning that the original open structural surfaces or micro-cracks within the rock mass are under stress. The wave gradually closes, and the propagation speed of the wave in the rock mass increases after closure. When the wave velocity reaches its maximum value, the rock mass also reaches its densest stage, at which point the volume of pores and fissures within the rock mass is at its smallest. As the wave velocity gradually decreases, the volume of pores and fissures inside the rock mass begins to develop. When the wave velocity curve is in a fluctuating state, the rock mass expands from internal fissures to macroscopic fissures on the surface, and the rock mass deformation gradually increases. The fissures develop rapidly, intersect, and combine to form macroscopic fracture surfaces. When the wave velocity decreases rapidly, the rock mass is damaged, relative slip occurs, and the rock mass becomes unstable.

[0058] The aforementioned step S5, which involves organizing and analyzing the acoustic data recorded by the acoustic testing device, also includes inverting the physical and mechanical parameters of the rock under various axial loads based on the acoustic test data, such as elastic modulus and Poisson's ratio. The calculation formulas are as follows.

[0059] ,

[0060] In the formula: V P V is the longitudinal wave velocity. S For transverse wave velocity, ρ Let E be the density of the rock mass, E be the elastic modulus, and μ be Poisson's ratio.

[0061] This coupled acoustic wave testing method for in-situ rock compression experiments allows for uniaxial compression tests on rocks at construction sites. By monitoring the deformation of the rock under different axial compressions in real time and combining the acoustic wave test data, the physical and mechanical parameters and microstructural characteristics of the rock can be retrieved. This method can accurately measure the physical and mechanical parameters of the rock (such as elastic modulus and Poisson's ratio) and also retrieve its microstructural characteristics (such as porosity and crack density). This method is accurate, reliable, and efficient, and is applicable to natural rock masses with various structural compositions. It is expected to be widely used in geotechnical engineering, providing reliable technical support for engineering safety.

[0062] 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 compression mechanism in the middle of the reaction plate, and uniform reciprocating mechanisms 20 symmetrically arranged at both ends of the reaction plate. The axial compression 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 drive 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, and the racks 22 are parallel to the extension and retraction direction of the hydraulic cylinder 11. The two racks 22 are arranged opposite each other. The two ends of the lower connecting rod 23 are fixedly connected to the two racks 22 respectively, forming a rigid lifting mechanism. The incomplete gear 21 is rotatably connected to the reaction plate 10. The deflection angle between the first and last teeth of the incomplete gear 21 is 45°. When the incomplete gear 21 rotates, it can mesh with the two racks 22 respectively. Figure 2 As shown, the drive mechanism is used to drive the incomplete gear 21 to rotate. During the process of the drive mechanism rotating at a constant speed for one revolution, when the incomplete gear 21 rotates from 0-90°, it meshes with the rack 22 on the left side of the figure (the moment when the first tooth of the incomplete gear 21 just enters the mesh with the rack 22 on the left side is defined as the starting point of the rotation of the incomplete gear 21 at 0°. Since the deflection angle between the first and last teeth of the incomplete gear 21 is 45°, when the incomplete gear 21 rotates 90°, its last tooth disengages from the rack 22 on the left side). This rotation process can drive the lifting mechanism to rise at a constant speed. When the incomplete gear 21 rotates from 90-180°, the incomplete gear 21 does not mesh with either rack 22, and the lifting mechanism remains stationary. When the incomplete gear 21 rotates from 180-270°, it meshes with the rack 22 on the right side of the figure. This rotation process can drive the lifting mechanism to descend at a constant speed. When the incomplete gear 21 rotates from 270-360°, it does not mesh with either rack 22, and the lifting mechanism remains stationary.

[0063] This coupled acoustic wave testing field rock mass compression experimental device can be used to carry out the aforementioned experimental methods. When implemented in the field, it can be combined with... Figure 1 , Figure 3As 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 a vertically downward gradually increasing axial load to the central area of ​​the top surface of the rock sample 1, and the load-bearing plate 12 is used to evenly distribute the axial load on 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... Figure 3 The lifting mechanism of the left-side uniform reciprocating mechanism 20 is connected, and the first ultrasonic transmitting probe 3 and the second ultrasonic receiving probe 4 are connected to... Figure 3 The lifting mechanism of the uniform reciprocating mechanism 20 on the right is connected. Adjusting the initial positions of the two uniform reciprocating mechanisms 20 so that the initial positions of the two incomplete gears 21 are 90° out of phase, allows the test to begin. During testing, the hydraulic cylinder 11 gradually increases the axial load according to the set load increments in the program. Regarding the motion control of the two sets of ultrasonic testing devices, the drive mechanisms of the two uniform reciprocating mechanisms 20 operate simultaneously at the same speed. Figure 3 As shown, when the incomplete gear 21 on the left rotates through its 0-90° phase range, the incomplete gear 21 on the right rotates through its 270-360° phase range, thus completing the aforementioned action S43. When the incomplete gear 21 on the left rotates through its 90-180° phase range, the incomplete gear 21 on the right rotates through its 0-90° phase range, thus completing the aforementioned action S43. This process continues, and as the drive mechanisms of the two uniform reciprocating mechanisms 20 continue to operate, the aforementioned action S43 is completed. Figure 2 The diagram shows the cyclic operation process from S43 to S47. It is evident that during the experiment, the two uniform reciprocating mechanisms 20 can complete the coordinated action described in step S4 simply by operating their drive mechanisms at the same speed simultaneously; the control process is extremely simple.

[0064] It should be understood that, during implementation, by ensuring the initial positions of the two incomplete gears 21 are identical, the two lifting mechanisms can synchronously and cyclically perform uniform reciprocating lifting 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 reciprocate. At this time, the two sets of ultrasonic detection devices switch to parallel scanning mode. In practical applications, this device can be used to scan the actual rock mass on-site using both the aforementioned parallel scanning mode and the aforementioned cyclic mode (S43 to S47), and the detection results can be comprehensively analyzed to obtain more accurate experimental results.

[0065] In specific implementation, such as Figure 4 , Figure 5As shown, the aforementioned drive 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 gear 27 and a drive shaft 29 are rotatably disposed within the housing 25. A worm wheel 28 is fixedly sleeved on the drive shaft 29, and the worm gear 27 meshes with the worm wheel 28. The output shaft of the motor 26 is fixedly connected to one end of the worm gear 27. An incomplete gear 21 is fixedly sleeved on the drive shaft 29. When the motor 26 continuously rotates at a constant speed, the worm gear 27 rotates along with it, thereby driving the worm wheel 28 and the drive shaft 29 to rotate, which in turn drives the incomplete gear 21 to rotate at a constant speed.

[0066] In specific implementation, such as 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 disposed between the pressure plate 30 and the housing 25. The spring 31 is used to provide the pressure plate 30 with a spring force 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.

[0067] In specific implementation, such as Figure 4 As shown, the uniform reciprocating mechanism 20 also includes two ultrasonic probe mounting mechanisms. Each ultrasonic probe mounting mechanism includes a slider 32, a sliding sleeve 33, a sliding rod 34, and a mounting rod 35. One end of the slider 32 is slidably fitted onto the lower connecting rod 23, and the sliding rod 34 is slidably inserted into the other end of the slider 32. The sliding sleeve 33 is fixedly connected to one end of the sliding rod 34, and the mounting rod 35 is slidably inserted into the sliding sleeve 34. The bottom end of the mounting rod 35 is used to mount an ultrasonic transmitting probe or an ultrasonic receiving probe. Since errors are inevitable when drilling the vertical hole 2 in the field during step S2, the initial position of the ultrasonic transmitting probe or ultrasonic receiving probe can be finely adjusted by sliding the slider 32 on the lower connecting rod 23, sliding the sliding rod 34 within the slider 32, and sliding the mounting rod 35 within the sliding sleeve 33. After adjustment, the position can be locked using a locking screw.

[0068] In specific implementation, such as Figure 4 As shown, the uniform reciprocating mechanism 20 also includes an upper connecting rod 24, the two ends of which are fixedly connected to two racks 22 respectively, making the lifting mechanism a frame structure and enhancing its structural rigidity; a pin 36 is fixedly provided at the end of the incomplete gear 21 away from the reaction plate 10. The 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 engage, the 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 engage smoothly with the rack 22, avoiding tooth backing.

[0069] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A field rock mass compression test method using coupled acoustic wave testing, characterized in that, Includes the following steps: S1. Select a flat rock block on site and drill four vertical holes downwards. The four vertical holes enclose a cubic rock block sample below the ground. S2. Clean each vertical hole and fill each vertical hole with water; S3. A first ultrasonic transmitting probe, a second ultrasonic receiving probe, a first ultrasonic receiving probe, and a second ultrasonic transmitting probe are respectively installed in the four vertical holes along the circumferential direction. The first ultrasonic transmitting probe and the second ultrasonic receiving probe are at the same height. 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 acoustic wave testing device. S4. The acoustic wave testing device continuously records acoustic wave data to start 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 until the rock sample is destroyed and the test is stopped. At the same time as the axial load is applied, the first ultrasonic receiving probe and the second ultrasonic transmitting probe move up and down at a constant speed, and the first ultrasonic transmitting probe and the second ultrasonic receiving probe move up and down at a constant speed in a coordinated manner. S5. Organize and analyze the acoustic wave data recorded by the acoustic wave testing device.

2. The field rock mass compression test method for coupled acoustic wave testing according to claim 1, characterized in that, Step S4 includes the following steps: S41. Position the first ultrasonic transmitting probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe, and the second ultrasonic transmitting probe at the bottom of the vertical hole, and turn on the acoustic wave testing device to record acoustic wave data. S42. Apply a vertically downward axial load to the central region of the top surface of the rock sample to a set value; S43. Keep the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the bottom of the vertical hole, and make the first ultrasonic receiving probe and the second ultrasonic transmitting probe rise synchronously and at a constant speed to the top of the vertical hole. S44. Keep the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the top of the vertical hole, and make the first ultrasonic transmitting probe and the second ultrasonic receiving probe rise synchronously and at a constant speed to the top of the vertical hole. S45. Apply a larger axial load to the central region of the top surface of the rock sample, with the increased load being a set increment; S46. Keep the first ultrasonic transmitting probe and the second ultrasonic receiving probe at the top of the vertical hole, and make the first ultrasonic receiving probe and the second ultrasonic transmitting probe descend synchronously and at a uniform speed to the bottom of the vertical hole. S47. Keep the first ultrasonic receiving probe and the second ultrasonic transmitting probe at the bottom of the vertical hole, and make the first ultrasonic transmitting probe and the second ultrasonic receiving probe descend synchronously and uniformly to the bottom of the vertical hole. S48. Apply a larger axial load to the central region of the top surface of the rock sample, with the increased load being a set increment; S49. Repeat steps S43 to S48 until the rock sample is destroyed.

3. A field rock mass compression test apparatus for coupled acoustic wave testing, characterized in that, The reaction plate includes a reaction plate, a axial compression mechanism is provided in the middle of the reaction plate, and uniform reciprocating mechanisms are symmetrically provided at both ends of the reaction plate; The axial pressure mechanism includes 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 includes a drive 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 retraction direction of the hydraulic cylinder. The two racks are arranged opposite each other, and 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 and last teeth of the incomplete gear is 45°. When the incomplete gear rotates, it can mesh with the two racks respectively. The drive mechanism is used to drive the incomplete gear to rotate.

4. The field rock mass compression test apparatus for coupled acoustic wave testing according to claim 3, characterized in that, The drive mechanism includes a housing and a motor. The housing is fixedly connected to the reaction plate, and the motor is fixedly mounted on the housing. The housing contains a worm gear and a drive shaft that are rotatably mounted. A worm wheel is fixedly mounted on the drive shaft. The worm gear meshes with the worm wheel. The output shaft of the motor is fixedly connected to one end of the worm gear. The incomplete gear is fixedly mounted on the drive shaft.

5. The field rock mass compression test apparatus for coupled acoustic wave testing according to claim 4, characterized in that, The uniform reciprocating mechanism further includes a pressure plate and a spring. The rack is slidably connected to the housing and is disposed between the pressure plate and the housing. The spring is used to provide the pressure plate with a spring force in the direction of the rack.

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

7. The field rock mass compression test apparatus 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. The end of the incomplete gear away from the reaction plate is fixedly provided with a pin, which is adapted to both the upper and lower connecting rods.

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