CN115436191A - Test method for researching shear mechanical properties of rock structural surface by combining photoelastic test - Google Patents

Abstract

The invention provides a test method for researching the shearing mechanical property of a rock structural surface by combining a photoelastic test. The test method comprises the following steps: 1, adjusting a direct shear apparatus, and installing a sample; 2. adjusting the position of the shearing box, and performing test preparation work; 3. presetting target parameters and selecting a loading mode; 4. applying load, and collecting test images and data; 5. after the test is finished, the direct shear apparatus is reset, and data are stored; 6. and (5) image and data analysis work. The test method can be used for observing the changes of the stress field and the strain field of the test sample in the test process in real time according to various collected test data such as a stress optical diagram, load, displacement and the like and by combining preset target parameter values, drawing corresponding load-displacement curves and analyzing the influence of different loading conditions on the shearing mechanical property and the deformation characteristic of the rock structural plane.

Description

A test method combined with photoelastic test to study the shear mechanical properties of rock structural planes

technical field

The invention relates to a test method for studying the shear mechanical properties of a rock structural plane combined with a photoelastic test, and belongs to the technical field of rock mechanics engineering.

Background technique

Under the long-term geological action, the rock mass is cut by structural planes such as joints, faults, and fissures, showing extremely high discontinuity. The crisscross structural planes with complex origins control the mechanical behavior of the rock mass. In actual engineering practice, the shear deformation of the structural plane of the rock mass is a common failure mode in rock mass engineering. The shear deformation will lead to the instability of the rock mass structure, induce earthquakes, rockbursts and other geological disasters. Therefore, the study of the shear mechanical properties of rock mass discontinuities is conducive to revealing the instability mechanism and failure mechanism of fractured rock mass, and is of great significance to the whole process of rock mass engineering design, construction, operation and maintenance.

At present, there are many technical means for observing the stress state of rock joints. Among them, the photoelastic test method can directly simulate and study the stress field changes inside the rock joints, and observe the shear deformation characteristics of the rock mass structural plane in real time, which has a relatively strong advantage. Usually, the photoelasticity test is carried out on the photoelastic test platform, and the photoelastic test platform is composed of a complete set of devices, including laser, polarizer (1/4 wave plate), loading device, analyzer ( 1/4 wave plate) and cameras and other devices, but in the photoelastic test, due to the limitations of the test device or site conditions, most of the commonly used test methods are to test under constant force conditions, that is, when the test device remains constant Under the conditions of normal load and shear load, the study observes the shear mechanical properties of the rock mass structural plane, without considering the influence of loading rate and deformation rate. However, this method has strong limitations and is only suitable for simulating the failure and deformation process of anchored rock mass slopes and deep engineering rock masses when the structural plane is subjected to static loads. For engineering rock masses in different environments, the stress environments they are in are different, and when the structural plane fails and deforms, the normal loading conditions and shear loading conditions are varied. For example, for deep chambers Surrounding rock masses, anchored rock mass slopes, etc., due to the presence of free surfaces in the rock mass after the excavation of the chamber, under the action of in-situ stress, the initial shear deformation of the rock structural surface will occur, which will lead to shear and normal deformation of the structural surface. It may be affected by dynamic load at the same time, and it is in the process of dynamic change. In this case, it is more in line with engineering practice to adopt dynamic normal and shear loading conditions.

According to the above situation, during the process of shear failure and deformation of the rock mass structural surface, the normal and shear forces are not kept static, and the loading rate and deformation rate of the normal and shear loads are dynamic. changing. At present, when the laboratory conducts tests to study the shear mechanical properties of rock mass structural planes, the loading conditions considered are relatively simple, and the tests are not completely designed according to the actual engineering conditions. Therefore, there are inevitably some limitations in the application of research results.

Contents of the invention

The technical problem to be solved by the present invention is to provide a test method for studying the shear mechanical properties of the rock structural plane combined with the photoelastic test, aiming at the fact that the current common test methods cannot study and observe the dynamic failure and deformation characteristics of the structural plane of the rock mass. Through the self-developed direct shear instrument, different normal loading rates, normal deformation rates, shear loading rates and shear deformation rates can be set. According to the problem to be studied, choosing the appropriate loading rate and deformation rate can well simulate the different stress environments of the structural surface of the rock mass, so as to explore the shear mechanical properties of the structural surface of the rock mass under static load or dynamic load. and deformation characteristics provide the basis for the experiment.

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

A test method for studying the shear mechanical properties of rock structural planes combined with photoelastic tests, based on a photoelastic test platform and a direct shear instrument, the direct shear instrument includes: a base unit, a loading unit, a data acquisition unit, a control unit, and a shear box :

The base unit is arranged at the bottom of the direct shear instrument, and is used to bear and support the weight of the entire direct shear instrument, including a bottom support plate and a first height adjustment mechanism connected between the bottom of the bottom support plate and the ground, and the bottom support There is a first linear guide rail moving pair connected between the bottom of the plate and the photoelastic test platform, through which the position of the direct shear instrument on the photoelastic test platform is adjusted, and the first height adjustable mechanism Adjusting the height of the direct shear instrument, so that the light path can be aligned sequentially during the photoelastic test to form continuity;

The loading unit is arranged on the upper side of the base unit, and includes a rigid frame and a normal loading device, a shearing loading device and a supporting device arranged on the rigid frame, wherein the normal loading device and the shearing loading device Both adopt servo electric cylinders, the servo electric cylinder of the normal loading device is installed on the top of the rigid frame, and the servo electric cylinder of the shear loading device is installed on the left side of the rigid frame;

The support device is used to support the shear box during the test, including a first support device installed on the right side of the rigid frame and a second support device installed at the bottom of the rigid frame;

The right side of the rigid frame is provided with a vertical chute, and the first supporting device is fastened on the vertical chute by screws;

The second supporting device is on the same straight line as the normal loading device, and is connected to the bottom of the rigid frame through a second height adjustment mechanism;

The data monitoring and acquisition unit is arranged inside the loading unit for monitoring and collecting test data during the test, including a normal pressure sensor, a tangential pressure sensor, a normal displacement sensor and a tangential displacement sensor;

The control unit has a signal input terminal connected to the data monitoring and acquisition unit, and a signal output terminal connected to the loading unit;

The shearing box is used to place the test sample, including two parts of the upper shearing box and the lower shearing box with the same geometric size. There are no shields on the front and back of the shearing box, so that the light source can pass through the sample, ensuring the light path The continuity; the inner wall of the upper shear box and the inner wall of the lower shear box are provided with a groove that matches the size of the sample, and the sample is placed into the shear box along the groove and is tightly fixed;

Include the following steps:

Step 1: After the direct shear instrument is plugged in and started, adjust the working length of the normal servo electric cylinder and the shear servo electric cylinder to the shortest state, adjust the base unit to keep it flush with the bottom of the rigid frame, and turn the direct shear instrument Adjust to a suitable height and position, put the prepared photoelastic test sample into the shear box and fix it, and then install the upper shear box and the lower shear box on the first top plate and the second top plate respectively;

Step 2: Adjust the position of the shear box and the top plate so that the center of the upper surface of the upper shear box is on the same line as the center of the drive end of the normal servo electric cylinder, and the center of the left side of the lower shear box is in line with the center of the shear servo electric cylinder. The center of the driving end of the cylinder is at the same horizontal position, and the initial state of the joint surface is kept consistent;

Step 3: Select different loading modes by setting target parameters in advance through the control unit. The target parameters include: normal and shear target load values, loading rate and deformation rate, and control the normal servo electric cylinder and the shear servo electric cylinder respectively. Carry out preloading until the drive end of the servo electric cylinder is just in full contact with the end face of the shear box to keep the shear box stable. At this time, the upper shear box is fixed along the normal direction and the shear direction without displacement, and the lower shear box is fixed along the joint surface. The normal direction is fixed, and it can only move freely along the shear direction, but displacement along the normal direction of the joint surface is not allowed;

Step 4: If it is a static loading mode, control the normal electric cylinder and the shear electric cylinder to apply the normal load and the shear load to the sample at a constant loading rate and deformation rate respectively, and then keep it static and constant; if it is In dynamic loading mode, after the normal load and shear load reach the target value, continue to control the normal electric cylinder or shear electric cylinder to load the sample according to the preset loading rate and deformation rate until the normal or shear displacement End the test when it reaches a certain value, the control unit collects the data of the sensor during the test and processes it into a corresponding curve, and uses a high-speed camera to shoot and record photos of the sample changes during the entire loading process in real time;

Step 5: After the loading is finished, return the loading device to its original position, unload the load in the shear direction first, and keep the normal load in place to prevent sudden deformation in the shear direction when the normal load is unloaded. After contact, unload the normal load; finally remove the shear box, remove and clean the sample, and then proceed to the next set of tests;

Step 6: After the test, based on the images and various data collected during the test, simulate and analyze the shear mechanical properties and deformation characteristics of the rock mass structural surface according to the principle of photoelastic test.

The first height adjustment mechanism includes a foot cup and a support column, and the support column is installed on the foot cup through a first screw rod on the foot cup.

Ribs are provided inside and outside the rigid frame to prevent vibration and shaking of the direct shear instrument during photoelastic test loading and ensure the stability of the test platform.

The driving end of the servo electric cylinder is connected with a floating joint to ensure full contact with the shear box when loading, and then completely transfer the load applied by the electric cylinder to the sample.

Both the servo electric cylinder of the normal loading device and the servo electric cylinder of the shear loading device are equipped with reducers

The first supporting device includes a screw, a first push rod and a first top plate; the first push rod is installed on the right side of the rigid frame through screws, and the top end of the first push rod is connected to the first top plate;

The second support device includes a second screw rod, a second top plate and a chute guide rail, the second top plate is installed on the low-resistance chute guide rail, and the low-resistance chute guide rail is fixed on the Bottom of rigid frame.

The right side of the upper shear box is provided with a first slide rail, and the first top plate has a first slide groove, and the upper shear box is installed on the first slide rail of the first top plate through the first slide rail. on the slot;

The bottom surface of the lower shearing box is provided with a second slide rail, and the second top plate is provided with a second chute, and the lower shearing box is installed on the second chute of the second top plate through the second slide rail superior.

The image taken refers to the stress light map used for photoelastic test analysis, and the collected test data includes normal load, normal displacement, shear load, and shear displacement;

The static loading mode refers to that the normal and shear loads applied to the sample remain unchanged until the end of the test after reaching the target value;

The dynamic loading mode is divided into static normal-dynamic shear loading mode, dynamic normal-static shear loading mode and dynamic normal-dynamic shear loading mode.

According to the recorded stress light map and the normal load, normal displacement, shear load and shear displacement data of the sample structure surface, the stress field and strain field of the sample are calculated according to the photoelastic test principle, and the normal load-normal The shear mechanical properties and deformation characteristics of the rock mass structural plane are obtained through analysis.

Compared with the prior art, the present invention adopts the above technical scheme and has the following technical effects:

First. According to the principle of photoelastic test, this test method can accurately analyze the shear mechanical properties and deformation characteristics of rock mass structural plane under different loading conditions based on the self-designed direct shear instrument, which ensures the accuracy and stability of photoelastic test.

second. Using the control system of the direct shear instrument, different loading rates and deformation rates can be set to achieve rock mass structural plane shear tests under different loading modes, such as static loading shear tests and dynamic loading shear tests. .

third. This test method takes into account the occurrence of rock structural planes under different loading modes (static loading mode or dynamic loading mode) by controlling the supporting control software to preset loading target parameters (normal and shear target load values, loading rate and deformation rate). Shear failure can more realistically reproduce the shear failure process of engineering rock mass, and the test method is simple and easy to operate, which can provide an experimental basis for the study of shear mechanical properties and deformation characteristics of rock structural planes.

Description of drawings

Fig. 1 is test method flow chart;

Fig. 2 is the front view of direct shear instrument;

Fig. 3 is the overall schematic diagram of the photoelastic test platform;

Fig. 4 is the detail drawing of the cutting box of the direct shearing instrument;

Fig. 5 is the control principle block diagram of direct shear instrument;

Fig. 6 is a control software interface diagram of the direct shear instrument.

In the figure: 1 is the foot cup, 2 is the support column, 3 is the bottom support plate, 4 is the rigid frame, 5 is the screw, 6 is the first ejector rod, 7 is the first top plate, 8 is the normal pressure sensor, 9 is the Normal floating joint, 10 is normal servo electric cylinder, 11 is normal displacement sensor, 12 is shear displacement sensor, 13 is shear servo electric cylinder, 14 is shear floating joint, 15 is shear pressure sensor, 16 17 is the second screw rod, 18 is the second top plate, 19 is the low-resistance chute guide rail, 20 is the lower shear box, 21 is the upper shear box, 22 is the slider, 23 is the rib, 24 is Computer, 25, amplifying circuit, 26, signal processing circuit, 27, control software, 28, display screen, 29, mouse, keyboard.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 and Fig. 6, the present invention provides a test method for studying the shear mechanical properties of rock structural planes in combination with photoelastic tests, based on a photoelastic test platform, on which A direct shear instrument is installed to study the shear mechanical properties of rock joints in combination with photoelastic tests, including a base unit, a loading unit, a data monitoring and acquisition unit, a control unit and a shear box. The loading unit is located on the upper part of the base unit, the base unit supports the weight of the entire direct shear instrument, the data monitoring and acquisition unit is installed inside the loading unit, and the control unit controls the operation of the direct shear instrument.

The base unit includes a first height adjustment mechanism and a bottom support plate 3 . The first height adjustment mechanism is made up of four foot cups 1 and four support posts 2 . The support column 2 is installed on the foot cup 1 through the first screw rod on the foot cup, the bottom support plate 3 is installed on the four support columns 2 through bolts, and the height of the base can be adjusted by rotating the foot cup screw rod, thereby It is ensured that the direct shear instrument can carry out photoelastic tests under different height conditions, and the support of the direct shear instrument is fixed on the ground. A first linear guide rail moving pair is connected between the bottom of the bottom support plate and the photoelastic test platform, through which the position of the direct shear instrument on the photoelastic test platform can be adjusted, and the first height can be adjusted The mechanism adjusts the height of the direct shear instrument so that the optical path can be aligned sequentially during the photoelastic test to form continuity. The materials are all made of stainless steel, and the maximum load-bearing capacity can reach 200kg, as shown in Figures 2 and 3.

The loading unit includes a normal loading device, a shear loading device and a supporting device. The loading rate and deformation rate of the loading unit can reach up to 5KN/s and 100mm/s respectively, the loading load can reach up to 10KN, and the test space can reach up to 100mm (normal direction) × 200mm (tangential direction). Both the normal loading device and the shearing loading device are composed of a servo electric cylinder and a floating joint. A reducer is installed on the servo electric cylinder to ensure that the electric cylinder can realize stable stepless speed regulation. The support device is divided into the first support device located on the right side of the rigid frame and the second support device located at the bottom of the rigid frame. The first support device is composed of screws 5, first push rod 6 and first top plate 7 from right to left. Two support devices are made up of the second top board 18 from top to bottom, the chute guide rail 19 and four second screw mandrels 17 .

The rigid frame 4 is made of multi-layer stainless steel, with triangular plates 16 on the inside, and reinforcing ribs 23 on the inside and outside for reinforcement, so as to ensure that the rigid frame will not be deformed during the test loading process, and prevent the vibration or vibration of the direct shear instrument from affecting the test results . The normal loading device and the shear loading device are respectively arranged on the top and left side of the rigid frame 4, and the floating joint is installed on the servo electric cylinder to ensure full contact with the shear box during loading, and then completely transfer the load applied by the electric cylinder to the sample. The top plate 7 of the first supporting device is installed on the first push rod 6, and the first push rod is fixed on the right side of the rigid frame 4 by the screw 5, and the first push rod 6 is a telescopic rod.

The second supporting device is on the same straight line as the normal loading device, and the second top plate 18 is installed on the low-resistance chute guide rail 19, and is fixed on the bottom of the rigid frame 4 by the second screw mandrel 17 of four adjustable heights, both The shear box can slide left and right horizontally in the tangential direction, and the influence of friction force on the test is avoided to the greatest extent. The length and position of the first supporting device and the second supporting device can be adjusted to ensure that the light source can completely pass through the sample, ensure the continuity of the optical path and the stability of the test. The first top plate 7 and the second top plate 18 are provided with a chute, which coincides with the slide rails on the right side of the upper shear box 21 and the bottom surface of the lower shear box 20, which limits the shear box to only move along a certain direction during the test. Slide in the direction, as shown in Figure 2 and 3.

The data monitoring and acquisition unit includes a normal pressure sensor 8 , a normal displacement sensor 11 , a shear pressure sensor 15 , a shear displacement sensor 11 and a signal processing circuit 26 connected to a computer. The pressure sensor is set on the floating joint, which can monitor and collect the load applied to the sample in real time. Displacement sensors are respectively arranged on the servo electric cylinder, which can monitor and collect the deformation displacement of the sample in real time, as shown in Figure 2 and Figure 3.

The control unit includes a computer 24 , an amplifier circuit 25 , a signal processing circuit 26 , control software 27 and a display screen 28 . The data collected by the sensor is processed by the signal processing circuit 26, and then transmitted to the control software 27 through the amplification circuit 25. One end of the computer 24 is connected to the control software 27, and the other end is connected to the loading unit. The display screen 28 will display the self-designed supporting control software interface 27, through the control software to set the target parameter normal and shear target load values, loading rate and deformation rate in the test, different loading modes can be realized. Static loading mode and dynamic loading mode . The data and target parameters collected by the sensor are collected as output signals and stored in the computer 24, and after being processed by the computer 24, they are used as input signals of the servo loading mechanism to form a closed-loop control of the direct shear instrument. The display screen 28 can display parameters such as loading rate, deformation rate, displacement and load in real time, as well as load-time curve and displacement-time curve, etc. The control software 27 can be upgraded later to meet new loading modes or parameter requirements, as shown in FIGS. 5 and 6 .

The shearing box is used to place the photoelastic sample, and includes two parts, the upper shearing box 21 and the lower shearing box 20, which have the same geometric dimensions. Such deformation and destruction process. There are grooves on the inner wall of the upper and lower shear boxes, and the samples are put into the shear box along the grooves and fixed tightly to ensure that the samples will not be misplaced and slipped during the test. Both the right side of the upper shear box 21 and the bottom surface of the lower shear box 20 are provided with slide rails, which coincide with the slide grooves of the first top plate 7 and the second top plate 18 respectively. Ensure that the upper shear box 21 can move freely along the normal direction of the joint surface, but cannot be displaced along the shear direction; the lower shear box 20 can freely move along the shear direction, but cannot undergo displacement along the normal direction of the joint surface, Ensure that the test can be carried out stably, as shown in Figures 2, 3, and 4.

Embodiments of the present invention are as follows:

Example 1

This embodiment studies the test method of the shear mechanical properties of the rock mass structural plane under the static loading mode, and the test method includes the following steps:

Step 1: After the direct shear instrument is plugged in and started, adjust the working length of the normal servo electric cylinder and the shear servo electric cylinder to the shortest state, adjust the base unit to keep it flush with the bottom of the rigid frame, and turn the direct shear instrument Adjust to a suitable height and position, put the prepared photoelastic test sample into the shear box and fix it, and then install the upper shear box and the lower shear box on the first top plate and the second top plate respectively;

Step 2: Adjust the position of the shear box and the top plate so that the center of the upper surface of the upper shear box is on the same line as the center of the drive end of the normal servo electric cylinder, and the center of the left side of the lower shear box is in line with the center of the shear servo electric cylinder. The center of the driving end of the cylinder is at the same horizontal position, and the initial state of the joint surface is kept consistent;

Step 3: Set the target parameters in advance through the control unit. The target parameters include: normal and shear target load values, loading rate and deformation rate, and control the normal servo electric cylinder and the shear servo electric cylinder respectively to preload until the servo The driving end of the electric cylinder is just in full contact with the end face of the shear box to keep the shear box stable. At this time, the upper shear box is fixed along the normal direction and the shear direction without displacement, and the lower shear box is fixed along the normal direction of the joint surface. It can move freely along the shear direction, but the displacement along the normal direction of the joint surface is not allowed;

Step 4: Control the normal electric cylinder and the shear electric cylinder to apply the normal load and shear load to the sample at a constant loading rate and deformation rate respectively, and then keep it static and constant until the predetermined time is reached. The unit collects the data of the sensor during the test and processes it into a corresponding curve, and uses a high-speed camera to take real-time photos of the changes in the sample during the entire loading process;

Step 5: After the loading is finished, return the loading device to its original position, unload the load in the shear direction first, and keep the normal load in place to prevent sudden deformation in the shear direction when the normal load is unloaded. After contact, unload the normal load; finally remove the shear box, remove and clean the sample, and then proceed to the next set of tests;

Step 6: After the test, based on the images and various data collected during the test, simulate and analyze the shear mechanical properties and deformation characteristics of the rock mass structural surface according to the principle of photoelastic test.

Example 2

This embodiment studies the test method of the shear mechanical properties of the rock mass structural plane under the dynamic normal direction-dynamic shear loading mode, and the test method includes the following steps:

Step 1: After the direct shear instrument is plugged in and started, adjust the working length of the normal servo electric cylinder and the shear servo electric cylinder to the shortest state, adjust the base unit to keep it flush with the bottom of the rigid frame, and turn the direct shear instrument Adjust to a suitable height and position, put the prepared photoelastic test sample into the shear box and fix it, and then install the upper shear box and the lower shear box on the first top plate and the second top plate respectively;

Step 2: Adjust the position of the shear box and the top plate so that the center of the upper surface of the upper shear box is on the same line as the center of the drive end of the normal servo electric cylinder, and the center of the left side of the lower shear box is in line with the center of the shear servo electric cylinder. The center of the driving end of the cylinder is at the same horizontal position, and the initial state of the joint surface is kept consistent;

Step 3: Set the target parameters in advance through the control unit. The target parameters include: normal and shear target load values, loading rate and deformation rate, and control the normal servo electric cylinder and the shear servo electric cylinder respectively to preload until the servo The driving end of the electric cylinder is just in full contact with the end face of the shear box to keep the shear box stable. At this time, the upper shear box is fixed along the normal direction and the shear direction without displacement, and the lower shear box is fixed along the normal direction of the joint surface. It can move freely along the shear direction, but the displacement along the normal direction of the joint surface is not allowed;

Step 4: Control the normal direction electric cylinder and the shear electric cylinder to apply the normal load and shear load to the sample at a constant loading rate and deformation rate respectively to the target value, then continue to control the normal direction electric cylinder and the shear electric cylinder according to Load the sample at the preset loading rate and deformation rate until the test ends when the normal direction and shear displacement reach a certain value. The control unit collects the data of the sensor during the test and processes it into a corresponding curve. At the same time, a high-speed camera is used to shoot and record in real time Photographs of specimen changes throughout the loading process;

Step 5: After the loading is finished, return the loading device to its original position, unload the load in the shear direction first, and keep the normal load in place to prevent sudden deformation in the shear direction when the normal load is unloaded. After contact, unload the normal load; finally remove the shear box, remove and clean the sample, and then proceed to the next set of tests.

Step 6: After the test, based on the images and various data collected during the test, simulate and analyze the shear mechanical properties and deformation characteristics of the rock mass structural surface according to the principle of photoelastic test.

Example 3

This embodiment studies the test method of the shear mechanical properties of the rock mass structural plane under the static normal direction-dynamic shear loading mode, and the test method includes the following steps:

Based on embodiment 2, and, in step 4, after the normal load and the shear load are applied to the sample at a constant loading rate and deformation rate respectively by the direct shear instrument normal loading device and the shear loading device to reach the target value, The normal loading device keeps the load target value unchanged, and only the shear loading device continues to load the sample according to the preset loading rate and deformation rate.

Example 4

This embodiment studies the test method of the shear mechanical properties of the rock mass structural plane under the dynamic normal direction-static shear loading mode, and the test method includes the following steps:

Based on embodiment 2, and, in step 4, after the normal load and the shear load are applied to the sample at a constant loading rate and deformation rate respectively by the direct shear instrument normal loading device and the shear loading device to reach the target value, The shear loading device keeps the load target value unchanged, and only the normal loading device continues to load the sample according to the preset loading rate and deformation rate.

Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and unless defined as herein, are not to be interpreted in an idealized or overly formal sense Explanation.

The above embodiments are only to illustrate the technical ideas of the present invention, and can not limit the protection scope of the present invention with this. All technical ideas proposed in accordance with the present invention, any changes made on the basis of technical solutions, all fall within the protection scope of the present invention. Inside. The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the scope of knowledge of those skilled in the art. .

Claims (9)

1. A test method combined with photoelastic test to study the shear mechanical properties of rock structural planes, based on a photoelastic test platform and a direct shear instrument, the direct shear instrument includes: a base unit, a loading unit, a data acquisition unit, a control unit and a shear Cut box: The base unit is arranged at the bottom of the direct shear instrument, and is used to bear and support the weight of the entire direct shear instrument, including a bottom support plate and a first height adjustment mechanism connected between the bottom of the bottom support plate and the ground, and the bottom support There is a first linear guide rail moving pair connected between the bottom of the plate and the photoelastic test platform, through which the position of the direct shear instrument on the photoelastic test platform is adjusted, and the first height adjustable mechanism Adjusting the height of the direct shear instrument, so that the light path can be aligned sequentially during the photoelastic test to form continuity; The loading unit is arranged on the upper side of the base unit, and includes a rigid frame and a normal loading device, a shearing loading device and a supporting device arranged on the rigid frame, wherein the normal loading device and the shearing loading device Both adopt servo electric cylinders, the servo electric cylinder of the normal loading device is installed on the top of the rigid frame, and the servo electric cylinder of the shear loading device is installed on the left side of the rigid frame; The support device is used to support the shear box during the test, including a first support device installed on the right side of the rigid frame and a second support device installed at the bottom of the rigid frame; The right side of the rigid frame is provided with a vertical chute, and the first supporting device is fastened on the vertical chute by screws; The second supporting device is on the same straight line as the normal loading device, and is connected to the bottom of the rigid frame through a second height adjustment mechanism; The data monitoring and acquisition unit is arranged inside the loading unit for monitoring and collecting test data during the test, including a normal pressure sensor, a tangential pressure sensor, a normal displacement sensor and a tangential displacement sensor; The control unit has a signal input terminal connected to the data monitoring and acquisition unit, and a signal output terminal connected to the loading unit; The shearing box is used to place the test sample, including two parts of the upper shearing box and the lower shearing box with the same geometric size. There are no shields on the front and back of the shearing box, so that the light source can pass through the sample, ensuring the light path The continuity; the inner wall of the upper shear box and the inner wall of the lower shear box are provided with a groove that matches the size of the sample, and the sample is placed into the shear box along the groove and is tightly fixed; It is characterized in that, comprising the following steps: Step 1: After the direct shear instrument is plugged in and started, adjust the working length of the normal servo electric cylinder and the shear servo electric cylinder to the shortest state, adjust the base unit to keep it flush with the bottom of the rigid frame, and turn the direct shear instrument Adjust to a suitable height and position, put the prepared photoelastic test sample into the shear box and fix it, and then install the upper shear box and the lower shear box on the first top plate and the second top plate respectively; Step 2: Adjust the position of the shear box and the top plate so that the center of the upper surface of the upper shear box is on the same line as the center of the drive end of the normal servo electric cylinder, and the center of the left side of the lower shear box is in line with the center of the shear servo electric cylinder. The center of the driving end of the cylinder is at the same horizontal position, and the initial state of the joint surface is kept consistent; Step 3: Select different loading modes by setting target parameters in advance through the control unit. The target parameters include: normal and shear target load values, loading rate and deformation rate, and control the normal servo electric cylinder and the shear servo electric cylinder respectively. Carry out preloading until the drive end of the servo electric cylinder is just in full contact with the end face of the shear box to keep the shear box stable. At this time, the upper shear box is fixed along the normal direction and the shear direction without displacement, and the lower shear box is fixed along the joint surface. The normal direction is fixed, and it can only move freely along the shear direction, but the displacement along the normal direction of the joint surface is not allowed; Step 4: If it is a static loading mode, control the normal electric cylinder and the shear electric cylinder to apply the normal load and the shear load to the sample at a constant loading rate and deformation rate respectively, and then keep it static and constant; if it is In dynamic loading mode, after the normal load and shear load reach the target value, continue to control the normal electric cylinder or shear electric cylinder to load the sample according to the preset loading rate and deformation rate until the normal or shear displacement End the test when it reaches a certain value, the control unit collects the data of the sensor during the test and processes it into a corresponding curve, and uses a high-speed camera to shoot and record photos of the sample changes during the entire loading process in real time; Step 5: After the loading is finished, return the loading device to its original position, unload the load in the shear direction first, and keep the normal load in place to prevent sudden deformation in the shear direction when the normal load is unloaded. After contact, unload the normal load; finally remove the shear box, remove and clean the sample, and then proceed to the next set of tests; Step 6: After the test, based on the images and various data collected during the test, simulate and analyze the shear mechanical properties and deformation characteristics of the rock mass structural surface according to the principle of photoelastic test. 2. The test method for studying the shear mechanical properties of rock structural planes according to claim 1, characterized in that: the first height adjustment mechanism includes a foot cup and a support column, and the support column passes through the foot cup The first screw rod on the top is installed on the foot cup. 3. according to claim 1 in conjunction with the test method of photoelastic test research rock structural plane shear mechanical properties, it is characterized in that: described rigid framework inside and outside are all provided with stiffeners, prevents from directly when carrying out photoelastic test loading. The shearing instrument vibrates and shakes to ensure the stability of the test platform. 4. The test method for studying the shear mechanical properties of the rock structural surface in combination with the photoelastic test according to claim 1, characterized in that: the driving end of the servo electric cylinder is connected with a floating joint to ensure that it is compatible with the shear box when loading. Sufficient contact, thereby completely transferring the load applied by the electric cylinder to the specimen. 5. the test method according to claim 1 in conjunction with photoelastic test research rock structural plane shear mechanical properties, it is characterized in that: the servo electric cylinder of described normal direction loading device and the servo electric cylinder of shear loading device are all A reducer is installed. 6. the test method of combining photoelastic test according to claim 1 to study the shear mechanical properties of rock structure plane, is characterized in that: described first supporting device comprises screw, the first push rod and the first top plate; The rod is installed on the right side of the rigid frame through screws, and the top of the first push rod is connected to the first top plate; The second support device includes a second screw rod, a second top plate and a chute guide rail, the second top plate is installed on the low-resistance chute guide rail, and the low-resistance chute guide rail is fixed on the Bottom of rigid frame. 7. The right side of the upper shear box is provided with a first slide rail, and the first top plate has a first chute, and the upper shear box is installed on the first slide rail of the first top plate through the first slide rail. on a chute; The bottom surface of the lower shearing box is provided with a second slide rail, and the second top plate is provided with a second chute, and the lower shearing box is installed on the second chute of the second top plate through the second slide rail superior. 8. the test method according to claim 5 in conjunction with photoelastic test research rock structural plane shear mechanical properties, it is characterized in that: the image of described shooting refers to the stress light map that is used for photoelastic test analysis, the test data of collection Including, normal load, normal displacement, shear load, shear displacement; The static loading mode refers to that the normal and shear loads applied to the sample remain unchanged until the end of the test after reaching the target value; The dynamic loading mode is divided into static normal-dynamic shear loading mode, dynamic normal-static shear loading mode and dynamic normal-dynamic shear loading mode. 9. the test method according to claim 1 in conjunction with photoelastic test research rock structural plane shear mechanical properties, it is characterized in that: according to the stress photogram of shooting record and sample structural plane normal load, normal displacement, shear Shear load and shear displacement data, calculate the stress field and strain field of the sample according to the photoelastic test principle, and draw the normal load-normal displacement curve, normal displacement-shear displacement curve, and shear load-shear displacement curve , through the analysis, the shear mechanical properties and deformation characteristics of the structural plane of the rock mass are obtained.

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