In-situ rock mass shear test method and device coupled with acoustic wave test

Abstract

The present application relates to the technical field of rock mass mechanics test, and discloses a kind of field rock mass shear test method and device coupled with acoustic wave test, the method is directly in the rock sample of the bottom surface and the rock of original rock is connected with original rock stripping, afterwards, ultrasonic emission probe and ultrasonic receiving probe are respectively arranged on the front side and rear side of rock sample, afterwards, set axial pressure is applied to the top surface of rock sample, afterwards, gradually increasing lateral load is applied to the left side or right side of rock sample, ultrasonic emission probe and ultrasonic receiving probe are uniformly reciprocated simultaneously when lateral load is applied, and ultrasonic wave data under different lateral loads are recorded in real time, the physical properties and structural characteristics of rock under different shear forces can be monitored in real time;The device comprises a uniform speed reciprocating movement mechanism, the uniform speed reciprocating movement mechanism comprises a housing, a transmission shaft and two lateral movement components, the lateral movement component comprises an incomplete gear, two racks, the device can drive each probe to complete coordinated motion, and control is convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock mass mechanics testing, in particular to a field rock mass shear experiment method and device coupled with acoustic wave testing. BACKGROUND

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

[0003] Rock mass shear experiments are to apply gradually increasing shear stress on rock samples and monitor the strain of the rock mass after shearing in real time to establish a stress-strain curve and determine the physical and mechanical parameters of the rock mass, such as elastic modulus, compressive strength, shear strength, and deformation characteristics. In order to accurately monitor the gradual change of the strain of the rock mass during the shearing process, current rock mass shear experiments need to be carried out on special experimental equipment. Usually, rock samples need to be transported to the laboratory for experiments, which is difficult to carry out experiments on field rock mass at the construction site. The shear experiment in the laboratory needs to collect or prepare a large number of rock samples, which has the problem of difficulty in preparing rock samples. The shear experiment is limited by the space of the experimental equipment, and cannot directly test large-size rock samples. In addition, it is limited by experimental time, experimental funds, and other aspects. The number of mechanical experiments in actual engineering is limited. In actual engineering, the determination of rock mass strength parameters is usually based on a small amount of experimental data, combined with geological investigation and engineering experience to determine the rock mass shear strength parameters, which is difficult to obtain design parameters that can truly reflect the engineering properties of the rock mass. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a field rock mass shear experiment method and device coupled with acoustic wave testing.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A field rock mass shear experiment method coupled with acoustic wave testing, comprising the following steps:

[0007] S1. A cubic rock sample is stripped from the original rock on site, the bottom surface of the rock sample is still connected to the original rock, and the top surface, left side surface, right side surface, front side surface, and rear side surface of the rock sample are all free surfaces;

[0008] S2. An axial pressure mechanism is arranged above the top surface of the rock sample, a lateral pressure mechanism is arranged on the left side surface or the right side surface of the rock sample, an ultrasonic receiving probe and an ultrasonic transmitting probe are arranged on the front side surface and the rear side surface of the rock sample respectively, and the ultrasonic receiving probe and the ultrasonic transmitting probe are connected with an acoustic wave testing device.

[0009] S3, the axial compression mechanism applies an axial load to the middle of the top surface of the rock sample to a set value;

[0010] S4, the acoustic wave testing device starts to record acoustic wave data continuously, and the lateral pressure mechanism applies a gradually increasing lateral load to the middle of the left side surface or the middle of the right side surface of the rock sample until the rock sample is destroyed, and the ultrasonic receiving probe and the ultrasonic transmitting probe move at a constant speed at the same time;

[0011] S5, the acoustic wave data recorded by the acoustic wave testing device is sorted and analyzed.

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

[0013] S401, the ultrasonic receiving probe and the ultrasonic transmitting probe are located at the left end of the rock sample, and the acoustic wave testing device is turned on to record acoustic wave data continuously;

[0014] 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;

[0015] S403, the ultrasonic receiving probe and the ultrasonic transmitting probe are moved to the right end of the rock sample at a constant speed synchronously;

[0016] S404, the lateral pressure mechanism applies a larger lateral load to the middle of the right side surface of the rock sample, and the load increase value is a set value;

[0017] S405, the ultrasonic receiving probe and the ultrasonic transmitting probe are moved to the left end of the rock sample at a constant speed synchronously;

[0018] S406, the lateral pressure mechanism applies a larger lateral load to the middle of the right side surface of the rock sample, and the load increase value is a set value;

[0019] S407, steps S403 to S406 are repeated until the rock sample is destroyed.

[0020] Specifically, the front side surface of the rock sample is provided with a first ultrasonic transmitting probe and a second ultrasonic receiving probe, and the back side surface of the rock sample is provided with a first ultrasonic receiving probe and a second ultrasonic transmitting probe. Another embodiment of the step S4 includes the following steps:

[0021] S411, the first ultrasonic emission probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic emission probe are located at the left end of the rock sample, the first ultrasonic emission probe and the first ultrasonic receiving probe are respectively located at the two ends of a diagonal line of the left end surface of the rock sample, the second ultrasonic emission probe and the second ultrasonic receiving probe are respectively located at the two ends of another diagonal line of the left end surface of the rock sample, and then the sound wave testing device is opened to continuously record sound wave data;

[0022] S412, the lateral pressure mechanism applies a set value of lateral load to the middle of the right side surface of the rock sample;

[0023] S413, the first ultrasonic emission probe and the second ultrasonic receiving probe are kept at the left end of the rock sample, and the first ultrasonic receiving probe and the second ultrasonic emission probe are moved to the right end of the rock sample at a constant speed;

[0024] S414, the first ultrasonic receiving probe and the second ultrasonic emission probe are kept at the right end of the rock sample, and the first ultrasonic emission probe and the second ultrasonic receiving probe are moved to the right end of the rock sample at a constant speed;

[0025] S415, the lateral pressure mechanism applies a greater lateral load to the middle of the right side surface of the rock sample, and the load increase value is a set value;

[0026] S416, the first ultrasonic emission probe and the second ultrasonic receiving probe are kept at the right end of the rock sample, and the first ultrasonic receiving probe and the second ultrasonic emission probe are moved to the left end of the rock sample at a constant speed;

[0027] S417, the first ultrasonic receiving probe and the second ultrasonic emission probe are kept at the left end of the rock sample, and the first ultrasonic emission probe and the second ultrasonic receiving probe are moved to the left end of the rock sample at a constant speed;

[0028] S418, the lateral pressure mechanism applies a greater lateral load to the middle of the right side surface of the rock sample, and the load increase value is a set value;

[0029] S419, steps S413 to S418 are repeated until the rock sample is destroyed.

[0030] The utility model provides a kind of field rock mass shear test device of coupling acoustic wave test, including uniform velocity reciprocating movement mechanism, the uniform velocity reciprocating movement mechanism includes shell, transmission shaft and two horizontal shift components;The horizontal shift component includes incomplete gear, two racks and several connecting rods, two The rack is oppositely arranged, and the two ends of several connecting rods are fixedly connected with 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 engaged with two The rack is meshed when rotating;Two The horizontal shift component is arranged in parallel from top to bottom in the shell, the rack is slidably connected with the shell, the transmission shaft is rotatably connected with the shell, two The incomplete gear is fixedly sleeved on the transmission shaft, and the phase angle between two The incomplete gear is 90 °.

[0031] Further, it further includes shaft pressing mechanism, the shaft pressing mechanism includes shaft pressing hydraulic cylinder and shaft pressing backing plate, one end of the shaft pressing hydraulic cylinder is fixedly connected with the bottom surface of the shell, the shaft pressing backing plate is fixedly connected with the other end of the shaft pressing hydraulic cylinder, and the piston rod telescopic direction of the shaft pressing hydraulic cylinder is perpendicular to the sliding direction of the rack in the shell.

[0032] Further, it further includes horizontal pressure mechanism, the horizontal pressure mechanism includes counterforce plate, horizontal pressure hydraulic cylinder and horizontal pressure backing plate, one end of the horizontal pressure hydraulic cylinder is fixedly connected with the counterforce plate, the other end of the horizontal pressure hydraulic cylinder is fixedly connected with the horizontal pressure backing plate;The counterforce plate is arranged obliquely below the shell, the horizontal pressure backing plate is arranged on the side of the counterforce plate close to the shell, and the piston rod telescopic direction of the horizontal pressure hydraulic cylinder is parallel to the sliding direction of the rack in the shell.

[0033] Further, the uniform velocity reciprocating movement mechanism further includes motor, worm and worm wheel, the worm is rotatably connected with the shell, the motor is used to drive the worm to rotate, the worm wheel is fixedly sleeved on the transmission shaft, and the worm is engaged with the worm wheel.

[0034] Further, both sides of the shell are provided with probe mounting mechanism, the probe mounting mechanism includes lug plate, rod A and several mounting components, the rod A is movably penetrated in one end of the lug plate, the other end of the lug plate is detachably connected with the rack, the mounting component includes sliding block and rod B, one end of the sliding block is movably sleeved on the rod A, and the rod B is movably penetrated in the other end of the sliding block;Two The probe mounting mechanism is connected with two horizontal shift components respectively, or two The probe mounting mechanism is connected with the same horizontal shift component.

[0035] The beneficial effects of the utility model are:

[0036] The method comprises the following steps: a cubic rock sample is stripped from an original rock on site, the bottom surface of the rock sample is connected with the original rock, and the other five surfaces of the rock sample are free surfaces; an axial compression mechanism is arranged above the rock sample, a lateral compression mechanism is arranged on the left side or the right side of the rock sample, an ultrasonic emission probe and an ultrasonic receiving probe are arranged on the front side and the back side of the rock sample respectively, and the ultrasonic emission probe and the ultrasonic receiving probe are connected to an acoustic testing device; a set axial compression is applied to the middle region of the top surface of the rock sample by the axial compression mechanism; a gradually increasing lateral load is applied to the middle of the left side surface or the middle of the right side surface of the rock sample by the lateral compression mechanism for testing, the ultrasonic receiving probe and the ultrasonic emission probe are moved at a uniform speed at the same time when the lateral load is applied, and acoustic data is recorded by the acoustic testing device; and the acoustic data recorded by the acoustic testing device is analyzed. The method can perform a direct shear test on the rock on site, can monitor the physical properties and structural characteristics of the rock under different shear forces in real time by using the ultrasonic detection technology, has the advantages of accuracy, reliability and high efficiency, the types and sizes of the stripped rock samples are not restricted, the method is suitable for natural rock bodies with various structures, direct tests on large-size rock samples can be realized, and the rock strength parameters obtained can better reflect the rock engineering mechanical properties, so that the method can be widely applied in the field of geotechnical engineering and can provide reliable technical support for engineering safety.

[0037] The device comprises a uniform-speed reciprocating movement mechanism, the uniform-speed reciprocating movement mechanism comprises a shell, a transmission shaft and two lateral movement assemblies, each lateral movement assembly comprises an incomplete gear, two racks and a plurality of connecting rods, the two racks are oppositely arranged and connected into a sliding mechanism through the plurality of connecting rods, and the incomplete gear can be engaged with the two racks when rotating; the two lateral movement assemblies are arranged in parallel from top to bottom in the shell, 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 the sliding mechanism cyclically performs the action of uniform-speed right movement-stop-uniform-speed left movement-stop when the incomplete gear continuously rotates; the phase angle between the two incomplete gears is 90°, and when the driving shaft drives the two incomplete gears to continuously rotate at a uniform speed, one sliding mechanism cyclically performs the action of uniform-speed right movement-stop-uniform-speed left movement-stop, and the other sliding mechanism cyclically performs the action of stop-uniform-speed right movement-stop-uniform-speed left movement. In different scanning modes, the ultrasonic emission probe and the ultrasonic receiving probe can be connected to one sliding mechanism or connected to two sliding mechanisms respectively, and when the experiment is performed, only the transmission shaft continuously rotates, so that the ultrasonic emission probe and the ultrasonic receiving probe can be moved at a uniform speed for ultrasonic scanning, and the control process is extremely convenient. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of a field rock mass shear experiment device of the application for coupling acoustic wave testing in the experiment;

[0039] Figure 2 It is a schematic diagram of scanning tracks of the ultrasonic emission probe and the ultrasonic receiving probe in the plane of the top view of the rock sample when the field rock mass shear experiment method of the application for coupling acoustic wave testing is experimented according to the embodiment 1;

[0040] Figure 3 It is a schematic diagram of scanning tracks of the first ultrasonic emission probe and the first ultrasonic receiving probe in the diagonal cross-section of the rock sample when the field rock mass shear experiment method of the application for coupling acoustic wave testing is experimented according to the embodiment 2;

[0041] Figure 4 It is a structural schematic diagram of a field rock mass shear experiment device of the application for coupling acoustic wave testing;

[0042] Figure 5 It is a disassembled structural schematic diagram of the uniform speed reciprocating movement mechanism in the field rock mass shear experiment device of the application for coupling acoustic wave testing;

[0043] Figure 6 It is a structural schematic diagram of the horizontal movement assembly and an assembled structural schematic diagram of two horizontal movement assemblies in the field rock mass shear experiment device of the application for coupling acoustic wave testing;

[0044] Figure 7 It is a structural schematic diagram of the probe mounting mechanism in the field rock mass shear experiment device of the application for coupling acoustic wave testing;

[0045] In the figure, 1 is a rock sample, 2 is an ultrasonic emission probe, 3 is an ultrasonic receiving probe, 4 is a first ultrasonic emission probe, 5 is a first ultrasonic receiving probe, 6 is a second ultrasonic emission probe, 7 is a second ultrasonic receiving probe, 10 is an axial pressure mechanism, 11 is an axial pressure hydraulic cylinder, 12 is an axial pressure backing plate, 20 is a horizontal pressure mechanism, 21 is a counterforce plate, 22 is a horizontal pressure hydraulic cylinder, 23 is a horizontal pressure backing plate, 30 is a uniform speed reciprocating movement mechanism, 31 is a transmission shaft, 32 is a horizontal movement assembly, 321 is an incomplete gear, 322 is a rack, 323 is a connecting rod, 33 is a motor, 34 is a worm, 35 is a worm wheel, 40 is a probe mounting mechanism, 41 is an ear plate, 42 is a rod A, 43 is a sliding block, and 44 is a rod B. DETAILED DESCRIPTION

[0046] The technical solutions of the application are described in further detail below in combination with the drawings, but the protection scope of the application is not limited to the following description.

[0047] As Figures 1 to 3As shown, a field rock mass shear test method of coupling acoustic wave test comprises the following steps:

[0048] S1, stripping a cubic rock sample 1 from the original rock in the field, the bottom surface of the rock sample 1 is still connected with the original rock, the top surface, left side surface, right side surface, front side surface and rear side surface of the rock sample 1 are all free surfaces, and attention is paid to reduce disturbance during stripping, and the free surfaces are polished smooth after stripping.

[0049] 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 surface or the right side surface of the rock sample 1, an ultrasonic receiving probe and an ultrasonic emitting probe are arranged on the front side surface and the rear side surface of the rock sample 1 respectively, the ultrasonic receiving probe and the ultrasonic emitting probe are connected with an acoustic wave testing device, and the ultrasonic receiving probe is used for receiving the ultrasonic wave signal emitted by the ultrasonic emitting probe and can be recorded in real time by the acoustic wave testing device.

[0050] S3, the axial pressure mechanism 10 applies an axial load to the middle part of the top surface of the rock sample 1 to a set value.

[0051] S4, the acoustic wave testing device starts to record acoustic wave data for testing, the lateral pressure mechanism 20 applies a gradually increasing lateral load to the middle part of the left side surface or the middle part of the right side surface of the rock sample 1 during testing, and the testing is stopped when the rock sample 1 is damaged, and the ultrasonic receiving probe and the ultrasonic emitting probe move at a uniform speed at the same time.

[0052] S5, the acoustic wave data recorded by the acoustic wave testing device is arranged and analyzed. According to the ultrasonic detection principle, the wave propagation characteristics in the rock mass are recorded by the receiving system (ultrasonic receiving probe) when the high-frequency elastic pulse wave is emitted by the ultrasonic pulse emitting source (ultrasonic emitting probe) to the rock mass medium, and the wave propagation characteristics in the rock mass are recorded by the receiving system (ultrasonic receiving probe) when the high-frequency elastic pulse wave is emitted by the ultrasonic pulse emitting source (ultrasonic emitting probe) to the rock mass medium. Due to the existence of a large number of random cracks, joints and pores in the rock mass, when the wave encounters these interfaces during propagation, reflection, scattering and diffraction of the wave will occur, the propagation path of the wave will be lengthened, and the speed of the wave will be reduced. For the same rock mass, the more cracks, the smaller the density of the rock mass, and the lower the speed of the wave propagation, and the wave velocity of the rock mass can be used to obtain the structure and corresponding mechanical properties of the rock mass. Based on the transmission of elastic wave in solid medium, the wave equation of elastic wave in rock mass medium can be obtained from the following formula:

[0053] ,

[0054] In the formula, , , represents the displacement in the direction of the coordinate axis x , y , z ​is the Laplace operator; G is the shear modulus; Lambda is the Lame coefficient; is the volume strain tensor of the unit body, .

[0055] In an infinite elastic body space, the equation of the longitudinal wave velocity can be obtained as:

[0056]

[0057] In the formula, V p is the longitudinal wave velocity; E d is the dynamic elastic modulus of the rock mass; Rho is the density of the rock mass; Mu d is the dynamic Poisson's ratio.

[0058] Similarly, the equation of the transverse wave velocity is:

[0059]

[0060] In the formula, V s is the transverse wave velocity; E d is the dynamic elastic modulus of the rock mass; Rho is the density of the rock mass; Mu d is the dynamic Poisson's ratio.

[0061] From the expressions of the longitudinal wave and transverse wave velocities, it can be seen that the wave velocity is related to the elastic constants, density and Poisson's ratio of the rock mass medium.

[0062] In actual measurement, the wave velocity of the rock mass is:

[0063]

[0064] In the formula, V is the longitudinal or transverse wave velocity; S is the sound wave propagation distance; T is the time difference between the receiving signal received by the receiving probe and the transmitting signal transmitted by the transmitting probe.

[0065] In specific implementation, the above step S4 at least includes the following two implementation forms. Embodiment 1

[0066] As Figure 2 shown, the foregoing step S4 includes the following steps:

[0067] S401, the initial positions of the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are 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;

[0068] S402, the lateral pressure mechanism 20 applies a set value of lateral load to the middle of the right side of the rock sample 1;

[0069] S403, the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are moved synchronously and uniformly to the right end of the rock sample;

[0070] S404, the lateral pressure 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;

[0071] S405, the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are moved synchronously and uniformly to the left end of the rock sample 1;

[0072] S406, the lateral pressure 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;

[0073] S407, repeat steps S403 to S406 until the rock sample 1 is destroyed.

[0074] In the above step S403, the ultrasonic transmitting probe 2 continuously emits ultrasonic wave signals, which are received by the ultrasonic receiving probe 3 and continuously recorded in real time by the ultrasonic detection device, so that the ultrasonic detection data of the plane in which the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are located in the rock sample 1 under the lateral 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 lateral pressure load applied in step S404 can be obtained. Thus, during the repeated steps S403 to S406, the ultrasonic detection data of the test section in the rock sample 1 after each increase of the lateral load by a set value can be obtained.

[0075] The test section can be set according to the detection needs. For example, the heights of the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are kept the same during the scanning process in steps S403 and S405, i.e. the ultrasonic detection data of the section parallel to the top surface of the rock sample 1 under the direct shear (lateral loading) is obtained; the ultrasonic transmitting probe 2 and the ultrasonic receiving probe 3 are located at the height center of the rock sample 1 during the scanning process, and thus the ultrasonic detection data of the section parallel to the top surface of the rock core under the direct shear (lateral loading) is obtained. It should be noted that, since the acoustic wave testing device continuously records acoustic wave data and converts it into a graph 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 uniform during movement.

[0076] It should be understood that in the implementation, a plurality of sets of ultrasonic emission probe 2 and ultrasonic receiving probe 3 can also be arranged to simultaneously obtain ultrasonic detection data of different cross sections of the rock sample 1 under direct shear (lateral loading) to explore the rock mass structure and mechanical properties of different cross section positions of the rock sample 1 under different lateral loading forces. Embodiment 2

[0077] The first ultrasonic emission probe 4 and the second ultrasonic receiving probe 7 are arranged on the front side of the rock sample 1, and the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are arranged on the back side of the rock sample 1. The foregoing step S4 includes the following steps:

[0078] S411, the first ultrasonic emission probe 4, the second ultrasonic receiving probe 7, the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are all located at the left end position of the rock sample 1, and the first ultrasonic emission probe 4 and the first ultrasonic receiving probe 5 are adjusted to be located at both ends of one diagonal line of the left end surface of the rock sample 1, and the second ultrasonic emission probe 6 and the second ultrasonic receiving probe 7 are adjusted to be located at both ends of another diagonal line of the left end surface of the rock sample 1, and then the sound wave testing device is turned on to continuously record sound wave data;

[0079] S412, the lateral pressure mechanism 20 applies a set value of lateral load to the middle of the right side surface of the rock sample 1;

[0080] S413, the first ultrasonic emission probe 4 and the second ultrasonic receiving probe 7 are kept at the left end position of the rock sample, and the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are synchronously moved at a uniform speed to the right end position of the rock sample 1;

[0081] S414, the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are kept at the right end position of the rock sample, and the first ultrasonic emission probe 4 and the second ultrasonic receiving probe 7 are synchronously moved at a uniform speed to the right end position of the rock sample 1;

[0082] S415, the lateral pressure mechanism 20 applies a larger lateral load to the middle of the right side surface of the rock sample 1, and the load increase value is a set value;

[0083] S416, the first ultrasonic emission probe 4 and the second ultrasonic receiving probe 7 are kept at the right end position of the rock sample, and the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are synchronously moved at a uniform speed to the left end position of the rock sample 1;

[0084] S417, the first ultrasonic receiving probe 5 and the second ultrasonic emission probe 6 are kept at the left end position of the rock sample, and the first ultrasonic emission probe 4 and the second ultrasonic receiving probe 7 are synchronously moved at a uniform speed to the left end position of the rock sample 1;

[0085] S418, the lateral pressure mechanism 20 applies a greater lateral load to the middle of the right side surface of the rock sample 1, and the load increase value is a set value;

[0086] S419, repeating steps S413 to S418 until the rock sample is destroyed.

[0087] In this embodiment, the ultrasonic wave signals emitted by the first ultrasonic emission probe 4 are received by the first ultrasonic receiving probe 5, which constitutes the first group of ultrasonic detection devices; the ultrasonic wave signals emitted by the second ultrasonic emission probe 6 are received by the second ultrasonic receiving probe 7, which constitutes the second group of ultrasonic detection devices.

[0088] Taking the first group of ultrasonic detection devices as an example, as shown in Figure 3 During the steps S413 to S414, as the first ultrasonic receiving probe 5 and the first ultrasonic emission probe 4 move rightward in turn, the ultrasonic waves emitted by the first ultrasonic emission probe 4 are continuously received by the first ultrasonic receiving probe 5 and recorded by the acoustic wave testing device, and the ultrasonic detection data of the rock sample 1 passing through the core diagonal cross section under the lateral load applied in step S412 can be obtained; similarly, during the steps S416 to S417, as the first ultrasonic receiving probe 5 and the first ultrasonic emission probe 4 move leftward in turn, the ultrasonic detection data of the rock sample 1 passing through the core diagonal cross section under the lateral load applied in step S415 can be obtained. Thus, by repeating the steps S413 to S418, the ultrasonic detection data of the rock sample 1 after each increase of the lateral load by the set value can be obtained.

[0089] The ultrasonic detection process of the second group of ultrasonic detection devices is the same as that of the first group of ultrasonic detection devices, and during the repetition of the steps S413 to S418, the ultrasonic detection data of another diagonal cross section of the rock sample 1 passing through the core under different lateral loads can also be obtained. In practice, the lifting movements of the first group of ultrasonic detection devices and the second group of ultrasonic detection devices are opposite, taking step S413 as an example, the detection data obtained by the first group of ultrasonic detection devices is that the first ultrasonic emission probe 4 is kept stationary and the first ultrasonic receiving probe 5 moves rightward at a constant speed, while the detection data obtained by the second group of ultrasonic detection devices is that the second ultrasonic receiving probe 7 is kept stationary and the second ultrasonic emission probe 6 moves rightward at a constant speed, and the detection data under the axial pressure load can be obtained by averaging the two groups of data, which can reduce the data error.

[0090] It should be noted that, due to the setting of two groups of ultrasonic detection devices, the interference problem between the two groups of ultrasonic detection devices needs to 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 emitting probe 4, it will also be affected by the ultrasonic wave emitted by the second ultrasonic emitting probe 6. Since the first ultrasonic receiving probe 5 and the second ultrasonic emitting probe 6 are located outside the rock sample 1, by keeping them in synchronous motion, the distance between them can be kept constant at all times, which is beneficial to eliminating the interference effect during data processing. In addition, since the acoustic wave testing device continuously records acoustic wave data during the experiment, the ultrasonic emitting probes and the ultrasonic receiving probes all maintain a constant speed when moving, so as to facilitate data processing.

[0091] According to the above, the in-situ rock mass shear experiment method of coupled acoustic wave testing can carry out direct shear test on in-situ rock at the construction site, and use ultrasonic detection technology to monitor the physical properties and structural characteristics of rock under different shear forces in real time. This method has the advantages of accuracy, reliability and high efficiency when implemented on rock samples in the same original rock area by ultrasonic scanning detection in the above two embodiments; the types and sizes of stripped rock samples are not restricted, and it is suitable for various natural rock masses with different structural compositions, and can realize direct experiment on large-size rock samples. The rock mass strength parameters obtained can better reflect the rock mass engineering mechanical properties, and will be widely used in geotechnical engineering field to provide reliable technical support for engineering safety.

[0092] As shown in Figure 1 , Figures 4 to 7 , a kind of in-situ rock mass shear experiment device of coupled acoustic wave testing, including uniform speed reciprocating movement mechanism 30, uniform speed reciprocating movement mechanism 30 including shell, transmission shaft 31 and two lateral displacement components 32.

[0093] Lateral displacement component 32 includes incomplete gear 321, two racks 322 and several connecting rods 323. Two racks 322 are oppositely arranged, and the two ends of several connecting rods 323 are fixedly connected with two racks 322 respectively, and two racks 322 form a rigid sliding mechanism through connecting rod 323. The deflection angle between the first tooth and the last tooth of incomplete gear 321 is 45°, and incomplete gear 321 can be engaged with two racks 322 respectively when rotating. When incomplete gear 321 rotates one revolution, it can be divided into four rotation phases: when incomplete gear 321 rotates through phase one (0-90°), it is engaged with one of the two racks 322, and the sliding mechanism is pushed to move in one direction; when incomplete gear rotates through phase three (180-270°), it is engaged with the other rack 322, and the sliding mechanism is pushed to slide in the opposite direction; when incomplete gear rotates through phase two (90-180°) and phase four (270-360°), it is not engaged with two racks 322, and the sliding mechanism remains stationary at this time.

[0094] Two horizontal movement assemblies are arranged in parallel from top to bottom in the shell, the rack 322 is in sliding connection with the shell (in the implementation, the inner side wall of the shell is provided with a sliding groove to guide the sliding of the rack 322, and the braking force on the rack 322 can be increased by arranging a friction pad in the sliding groove), the transmission shaft 31 is rotatably connected with the shell, the two incomplete gears 321 are both fixedly sleeved on the transmission shaft 31, and the phase angles of the two incomplete gears 321 are different by 90°. When the transmission shaft 31 continuously rotates at a constant speed, the two incomplete gears 321 are driven to rotate together, and since the phase angles of the two incomplete gears 321 are different by 90°, when the incomplete gear 321 in one horizontal movement assembly 32 meshes with one of the racks 322, the incomplete gear 321 in the other horizontal movement assembly 32 does not mesh with the two racks 322.

[0095] The in-situ rock shear test device for the coupled acoustic wave test is used to implement the in-situ rock shear test method for the coupled acoustic wave test, and the uniform speed reciprocating movement mechanism 30 is used to control the ultrasonic receiving probe and the ultrasonic transmitting probe to realize the coordinated uniform speed reciprocating movement in the foregoing step S4. Specifically, when the ultrasonic scanning is performed in the manner of the foregoing embodiment 1, the ultrasonic receiving probe 3 and the ultrasonic transmitting probe 2 are both connected with the sliding mechanism of the same horizontal movement assembly 32, and as the driving shaft 31 continuously rotates at a constant speed, the sliding mechanism can drive the ultrasonic transmitting probe to cyclically perform the action of uniform speed right movement-stop-uniform speed left movement-stop, which can correspond to the completion of the foregoing repeated steps S403 to S406; when the ultrasonic scanning is performed in the manner of the foregoing embodiment 2, the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 are connected with the sliding mechanism of the horizontal movement assembly 32, and the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 are connected with the sliding mechanism of the other horizontal movement assembly 32, and since the phase angles of the incomplete gears 321 in the two horizontal movement assemblies 32 are different by 90°, as the driving shaft 31 continuously rotates, the first ultrasonic receiving probe 5 and the second ultrasonic transmitting probe 6 cyclically perform the action of uniform speed right movement-stop-uniform speed left movement-stop under the driving of the sliding mechanism connected therewith, while in the process, the first ultrasonic transmitting probe 4 and the second ultrasonic receiving probe 7 cyclically perform the action of stop-uniform speed right movement-stop-uniform speed left movement under the driving of the sliding mechanism connected therewith, which can correspond to the completion of the foregoing repeated steps S413 to S418. As can be seen, when the in-situ rock shear test device for the coupled acoustic wave test is used to perform the test, the coordinated uniform speed reciprocating movement in the foregoing step S4 can be realized by continuously rotating the driving shaft 31 at a constant speed, and the control process is extremely simple.

[0096] Specifically, the in-situ rock mass shear experiment device for coupled acoustic wave testing further comprises an axial pressure mechanism 10, the axial pressure mechanism 10 comprising an axial pressure hydraulic cylinder 11 and an axial pressure pad 12, one end of the axial pressure hydraulic cylinder 11 being fixedly connected with the bottom surface of the shell, the axial pressure pad 12 being fixedly connected with the other end of the axial pressure hydraulic cylinder 11, the piston rod of the axial pressure hydraulic cylinder 11 being perpendicular to the sliding direction of the rack 322 in the shell. During the experiment, the shell is fixed above the rock sample 1 by means of a ground anchor or the like, and the piston rod of the axial pressure hydraulic cylinder 11 is extended to apply the axial load described in the aforementioned step S3 to the middle area of the top surface of the rock sample 1 through the axial pressure pad 12, and the axial pressure pad 12 is used to uniformly distribute the axial load on the top surface of the rock sample 1.

[0097] Specifically, the in-situ rock mass shear experiment device for coupled acoustic wave testing further comprises a lateral pressure mechanism 20, the lateral pressure mechanism 20 comprising a counterforce plate 21, a lateral pressure hydraulic cylinder 22 and a lateral pressure pad 23, one end of the lateral pressure hydraulic cylinder 22 being fixedly connected with the counterforce plate 21, the other end of the lateral pressure hydraulic cylinder 22 being fixedly connected with the lateral pressure pad 23. The counterforce plate 21 is fixedly arranged obliquely below the shell by means of a ground anchor or the like, the lateral pressure pad 23 is arranged on the side of the counterforce plate 21 close to the shell, and the piston rod of the lateral pressure hydraulic cylinder 22 is parallel to the sliding direction of the rack 322 in the shell. When the piston rod of the lateral pressure hydraulic cylinder 22 is extended, the lateral load described in the aforementioned step S4 can be applied to the left or right side surface of the rock sample 1 through the lateral pressure pad 23 to complete the direct shear experiment, and the lateral pressure pad 23 is used to uniformly distribute the lateral load on the side surface of the rock sample 1.

[0098] Specifically, the uniform-speed reciprocating movement mechanism 30 further comprises a motor 33, a worm 34 and a worm gear 35, the worm 34 being rotatably connected with the shell, the worm gear 35 being fixedly sleeved on the transmission shaft 31, the worm 34 being engaged with the worm gear 35, and the motor 33 being used to drive the worm 34 to rotate. When the motor 33 continuously operates at a uniform speed, the transmission shaft 31 can be continuously driven to rotate at a uniform speed through the worm and gear mechanism, so as to continuously drive the two incomplete gears 321 to rotate at a uniform speed.

[0099] Specifically, a probe mounting mechanism 40 is arranged on each side of the shell, as shown in Figure 7As shown, the probe mounting mechanism 40 comprises an ear plate 41, a rod A 42 and several mounting assemblies. The rod A 42 movably penetrates one end of the ear plate 41, and the other end of the ear plate 41 is detachably connected with the rack 322. The mounting assemblies comprise a slider 43 and a rod B 44. One end of the slider 43 movably penetrates the rod A 42, and the rod B 44 movably penetrates the other end of the slider 43. One end of the rod B 44 is used for mounting the ultrasonic receiving probe or the ultrasonic transmitting probe. The height of the ultrasonic receiving probe or the ultrasonic transmitting probe can be adjusted by sliding the rod A 42 relative to the ear plate 41 and sliding the slider 43 on the rod A 42. The distance between the ultrasonic transmitting probe or the ultrasonic receiving probe and the rock sample 1 can be adjusted by sliding the rod B 44 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, and then locked by locking screws. The two probe mounting mechanisms 40 are connected with the two transverse moving assemblies 32, and the ultrasonic scanning detection can be performed in the form of the above-mentioned embodiment 2. The two probe mounting mechanisms 40 are connected with the same transverse moving assembly 32, and the ultrasonic scanning can be performed in the form of the above-mentioned embodiment 1.

[0100] The above description is only the preferred embodiments of the present application, and it should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concepts described herein by the above-mentioned teaching or related technical or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims of the present application.

Claims

1. A method for in-situ rock mass shear test coupled with acoustic wave test, characterized in that, It comprises the following steps: S1, stripping out a cubic rock sample from the original rock in the field, the bottom surface of the rock sample is still connected with the original rock, the top surface, left side surface, right side surface, front side surface and back side surface of the rock sample are all free surfaces; S2, setting an axial pressure mechanism above the top surface of the rock sample, setting a lateral pressure mechanism on the left side surface or the right side surface of the rock sample, setting an ultrasonic receiving probe and an ultrasonic emitting probe on the front side surface and the back side surface of the rock sample respectively, the ultrasonic receiving probe and the ultrasonic emitting probe are connected with an acoustic wave testing device; S3, the axial pressure mechanism applies an axial load to the middle part of the top surface of the rock sample to a set value; S4, the acoustic wave testing device starts testing by continuously recording acoustic wave data, during the testing, the lateral pressure mechanism applies gradually increasing lateral load to the middle part of the left side surface or the middle part of the right side surface of the rock sample until the rock sample is destroyed, at the same time of applying the lateral load, the ultrasonic receiving probe and the ultrasonic emitting probe move at a uniform speed in a reciprocating manner; S5, the acoustic wave data recorded by the acoustic wave testing device is sorted and analyzed; The step S4 comprises the following steps: S401, the ultrasonic receiving probe and the ultrasonic emitting probe are located at the left end position of the rock sample, and the acoustic wave testing device is turned on to continuously record acoustic wave data; S402, the lateral pressure mechanism applies a set value of lateral load to the middle part of the right side surface of the rock sample; S403, the ultrasonic receiving probe and the ultrasonic emitting probe are moved synchronously and uniformly to the right end position of the rock sample; S404, the lateral pressure mechanism applies a larger lateral load to the middle part of the right side surface of the rock sample, the load increase value is a set value; S405, the ultrasonic receiving probe and the ultrasonic emitting probe are moved synchronously and uniformly to the left end position of the rock sample; S406, the lateral pressure mechanism applies a larger lateral load to the middle part of the right side surface of the rock sample, the load increase value is a set value; S407, repeating steps S403 to S406 until the rock sample is destroyed.

2. A method for in-situ rock mass shear test coupled with acoustic wave test, characterized in that, It comprises the following steps: S1, stripping out a cubic rock sample from the original rock in the field, the bottom surface of the rock sample is still connected with the original rock, the top surface, left side surface, right side surface, front side surface and back side surface of the rock sample are all free surfaces; S2, setting an axial pressure mechanism above the top surface of the rock sample, setting a lateral pressure mechanism on the left side surface or the right side surface of the rock sample, setting an ultrasonic receiving probe and an ultrasonic emitting probe on the front side surface and the back side surface of the rock sample respectively, the ultrasonic receiving probe and the ultrasonic emitting probe are connected with an acoustic wave testing device; S3, the axial pressure mechanism applies an axial load to the middle part of the top surface of the rock sample to a set value; S4, the acoustic wave testing device starts testing by continuously recording acoustic wave data, during the testing, the lateral pressure mechanism applies gradually increasing lateral load to the middle part of the left side surface or the middle part of the right side surface of the rock sample until the rock sample is destroyed, at the same time of applying the lateral load, the ultrasonic receiving probe and the ultrasonic emitting probe move at a uniform speed in a reciprocating manner; S5, the acoustic wave data recorded by the acoustic wave testing device is sorted and analyzed; The front side of the rock sample is provided with a first ultrasonic emission probe and a second ultrasonic receiving probe, and the back side of the rock sample is provided with a first ultrasonic receiving probe and a second ultrasonic emission probe, and the step S4 comprises the following steps: S411, the first ultrasonic emission probe, the second ultrasonic receiving probe, the first ultrasonic receiving probe and the second ultrasonic emission probe are located at the left end of the rock sample, the first ultrasonic emission probe and the first ultrasonic receiving probe are respectively located at the two ends of a diagonal line of the left end surface of the rock sample, the second ultrasonic emission probe and the second ultrasonic receiving probe are respectively located at the two ends of another diagonal line of the left end surface of the rock sample, and then the acoustic wave testing device is turned on to continuously record acoustic wave data; S412, the lateral pressure mechanism applies a set value of lateral load to the middle of the right side of the rock sample; S413, the first ultrasonic emission probe and the second ultrasonic receiving probe are kept at the left end of the rock sample, and the first ultrasonic receiving probe and the second ultrasonic emission probe are moved to the right end of the rock sample at a constant speed; S414, the first ultrasonic receiving probe and the second ultrasonic emission probe are kept at the right end of the rock sample, and the first ultrasonic emission probe and the second ultrasonic receiving probe are moved to the right end of the rock sample at a constant speed; S415, the lateral pressure mechanism applies a larger lateral load to the middle of the right side of the rock sample, and the load increase value is a set value; S416, the first ultrasonic emission probe and the second ultrasonic receiving probe are kept at the right end of the rock sample, and the first ultrasonic receiving probe and the second ultrasonic emission probe are moved to the left end of the rock sample at a constant speed; S417, the first ultrasonic receiving probe and the second ultrasonic emission probe are kept at the left end of the rock sample, and the first ultrasonic emission probe and the second ultrasonic receiving probe are moved to the left end of the rock sample at a constant speed; S418, the lateral pressure mechanism applies a larger lateral load to the middle of the right side of the rock sample, and the load increase value is a set value; S419, steps S413 to S418 are repeated until the rock sample is destroyed.

3. A field rock mass shear test device coupled with acoustic wave testing, characterized in that, The method for implementing the shear experiment of the rock mass in the field by the coupled acoustic wave test according to claim 1 or 2, wherein the device for implementing the shear experiment of the rock mass in the field by the coupled acoustic wave test comprises a uniform speed reciprocating movement mechanism, and the uniform speed reciprocating movement mechanism comprises a shell, a transmission shaft and two lateral movement assemblies; The lateral movement assembly comprises an incomplete gear, two racks and a plurality of connecting rods, the two racks are oppositely arranged, the two ends of the plurality of connecting rods are fixedly connected with the two racks respectively, the deflection angle between the first tooth and the last tooth of the incomplete gear is 45°, and the incomplete gear can be engaged with the two racks respectively when the incomplete gear rotates; The two lateral movement assemblies are arranged in parallel from top to bottom in the shell, the rack is slidably connected with the shell, the transmission shaft is rotatably connected with the shell, the two incomplete gears are fixedly sleeved on the transmission shaft, and the phase angle difference between the two incomplete gears is 90°.

4. The in-situ rock mass shear test device of claim 3, wherein, The shaft pressing mechanism comprises a shaft pressing hydraulic cylinder and a shaft pressing pad plate, one end of the shaft pressing hydraulic cylinder is fixedly connected with the bottom surface of the shell, the shaft pressing pad plate is fixedly connected with the other end of the shaft pressing hydraulic cylinder, and the piston rod of the shaft pressing hydraulic cylinder is perpendicular to the sliding direction of the rack in the shell.

5. The in-situ rock mass shear test device coupled with acoustic wave test according to claim 4, characterized in that, The lateral pressing mechanism comprises a counterforce plate, a lateral pressing hydraulic cylinder and a lateral pressing pad plate, one end of the lateral pressing hydraulic cylinder is fixedly connected with the counterforce plate, and the other end of the lateral pressing hydraulic cylinder is fixedly connected with the lateral pressing pad plate. The counterforce plate is arranged obliquely below the shell, the lateral pressing pad plate is arranged on the side of the counterforce plate close to the shell, and the piston rod of the lateral pressing hydraulic cylinder is parallel to the sliding direction of the rack in the shell.

6. The in-situ rock mass shear test device of claim 3, wherein, The uniform-speed reciprocating movement mechanism further comprises a motor, a worm and a worm wheel, the worm is rotatably connected with the shell, the motor is used for driving the worm to rotate, the worm wheel is fixedly sleeved on the transmission shaft, and the worm is engaged with the worm wheel.

7. The apparatus according to claim 3, wherein, 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 assemblies, the rod A is movably arranged in one end of the ear plate, the other end of the ear plate is detachably connected with the rack, the mounting assembly comprises a sliding block and a rod B, one end of the sliding block is movably sleeved on the rod A, and the rod B is movably arranged in the other end of the sliding block. Two probe mounting mechanisms are respectively connected with two lateral movement assemblies, or two probe mounting mechanisms are connected with the same lateral movement assembly.

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