LU500741B1 - An experimental device and working method for rock multi unit non-uniform uniaxial loading creep - Google Patents
An experimental device and working method for rock multi unit non-uniform uniaxial loading creep Download PDFInfo
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- 230000006835 compression Effects 0.000 claims description 11
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- 238000004088 simulation Methods 0.000 claims description 8
- 238000010586 diagram Methods 0.000 claims description 5
- 238000012937 correction Methods 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0071—Creep
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
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- G01N2203/02—Details not specific for a particular testing method
- G01N2203/0202—Control of the test
- G01N2203/0204—Safety arrangements, e.g. remote control, emergency stop
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N2203/022—Environment of the test
- G01N2203/023—Pressure
- G01N2203/0232—High pressure
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/025—Geometry of the test
- G01N2203/0252—Monoaxial, i.e. the forces being applied along a single axis of the specimen
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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Abstract
The invention relates to the technical field of rock mechanics experiment, in particular to a experimental device and working method of rock multi unit non-uniform uniaxial loading creep, the experimental device includes a high stiffness frame, a multi unit axial pressure loading module, an axial pressure Weibull distribution module, a voltage stabilizing control module, a data acquisition module, a video recording module, a safety protection grid and a hydraulic pump, the invention fully considers the real stress state of the engineering rock mass, and studies the influence of the anisotropy between each unit of the rock and the complex stress field of the crustal rock mass on the rock creep effect.
Description
[0001] The invention relates to the technical field of rock mechanics experiment, in particular to a experimental device and a working method for rock multi unit non-uniform uniaxial loading creep.
[0002] Due to the natural anisotropy of rocks and the complex geological structure in rock mass, the crustal rock mass is in a complex stress field. The stress characteristics of each unit in the rock mass under this complex stress field have obvious non-uniform distribution, and the creep effect of the rock mass under this non-uniform load is the main reason for the deformation and instability of underground engineering, and it is also an urgent problem to be solved in the design of rock mass engineering. The existing rock mechanics testing technology is generally measured by the overall loading method of applying uniform load (axial pressure or confining pressure) to the engineering rock specimen, which cannot reflect the non-uniform stress field of the rock mass, resulting in the impossibility of obtaining the real creep effect and creep failure mode of the rock mass, many engineering practice and theoretical research show that under the same working condition, the creep response of each element of engineering rock mass to non-uniform external load has different degrees, and the cumulative effect of the difference of creep response between each element has a great impact on the overall mechanical properties of rock mass structure. Although the experimental research of relevant scholars has achieved fruitful results, these experimental equipment and methods do not take into account the influence of rock anisotropy and complex stress field of crustal rock mass unit on rock creep effect, and there is few experimental equipment that can carry out rock multi-element non-uniform uniaxial loading creep experiment. There is also a lack of relevant rock mechanics experimental methods.
[0003] In order to solve the above technical problems, the invention proposes a rock multi-element non-uniform uniaxial loading creep experimental device and working method, fully considers the real stress condition of engineering rock mass, and studies the influence of anisotropy between rock units and complex stress field of crustal rock mass on rock creep effect.
[0004] The specific technical scheme is as follows:
[0005] The experimental device and a working method for rock multi unit non-uniform uniaxial loading creep, which comprises a high stiffness frame, a multi unit axial pressure loading module, an axial pressure Weibull distribution module, a voltage stabilizing control module, a data 1 acquisition module, a video recording module, a safety protection grid and a hydraulic pump. LUS00741
[0006] The high stiffness frame provides the installation position and low relative flexibility state of the whole device for the multi unit axial compression loading module, video recording module and safety protection grid in the experimental device, the multi unit axial pressure loading module provides multi unit non-uniform axial pressure for the experimental device, the axial pressure Weibull distribution module provides Weibull distributed pressure for the multi unit axial pressure loading module. The voltage stabilizing control module provides a stable pressure for the axial pressure Weibull distribution module, the data acquisition module is used to collect the stress and strain information during the experiment, the video recording module is used for real-time recording the dynamic changes of rock specimens during the experiment, the safety protection grid provides protection for personnel and equipment during the experiment, the hydraulic pump provides hydraulic power for the pressure stabilizing control module, the experimental device is equipped with a backup power supply, and the power capacity can be used for at least 48 hours, in the experimental device, the multi unit axial pressure loading module, axial pressure Weibull distribution module, voltage stabilizing control module and hydraulic pump are connected by high-pressure resistant hydraulic pipes.
[0007] The high stiffness frame is fixedly installed on the ground pedestal through thick bolts, and the ground pedestal is installed on the ground to support and fix the high stiffness frame; at the same time, it is used to connect the high-pressure resistant hydraulic pipe from the axial pressure Weibull distribution module; the stiffness value of materials used for high stiffness frame shall not be less than 5000kN/mm.
[0008] The multi unit axial pressure loading module is the moving part of the whole experimental device, which is directly connected with the data acquisition module through the data transmission line, connected with the axial pressure Weibull distribution module through the high-pressure hydraulic pipe in the ground pedestal, installed at the bottom of the high stiffness frame, longitudinally arranged, using the hydraulic pressure as the power source and adopting the servo control mode, the multi element axial compression loading module includes a centrally symmetrical porous shaft sleeve, a unit loading shaft, a loading head and a level gauge, which are used to apply vertical and upward multi element non-uniform axial stress to the test piece, the cross-sectional shape of the porous shaft sleeve can be a standard rectangle or a circle with different cross-sectional areas, which can meet the experimental requirements of specimens with different cross-sections and different cross-sectional areas. The unit loading shaft comprises a hydraulic cylinder, a liquid flowmeter, a liquid pressure gauge, an electromagnetic control valve and a check valve, all unit loading shafts are independent of each other, and the pressure is controlled by the electromagnetic control valve, the loading head has a variety of geometric shapes, which can meet the requirements of the test piece composed of different typical particle units, the loading head can move along the vertical direction to apply the normal multi-element non-uniform axial stress to the rock test piece, all liquid flow meters and liquid pressure gauges are connected to the computer through the data transmission line; the level is used for leveling before loading. 40 [0009] The axial pressure Weibull distribution module is installed on the shock absorption pad, 2 with a distance of 3M from the ground pedestal and 2m from the voltage stabilizing control mobHf00741 the axial pressure Weibull distribution module is directly connected with the data acquisition module through the data transmission line, the input end of the axial pressure Weibull distribution module is connected with the voltage stabilizing control module through the high-pressure resistant hydraulic pipe, and the output end is connected with the multi unit axial pressure loading module through the high-pressure resistant hydraulic pipe, the axial pressure Weibull distribution module includes a control module and an execution module, in which the control module is used to control the parameters of the axial pressure Weibull distribution, the execution module is used to conduct Weibull distribution processing on the stable hydraulic flow output through the pressure stabilizing control module according to the signal received by the control module, and transmit the hydraulic flow distributed through Weibull to the multi unit axial pressure loading module through the high-pressure resistant hydraulic pipe, the relevant parameters of Weibull distribution are input by computer and adjusted by electro-hydraulic servo valve.
[0010] The pressure stabilizing control module is installed on the shock absorbing pad, is directly connected with the data acquisition module through the data transmission line, is connected with the hydraulic pump through the front end of the high-pressure resistant hydraulic pipe, and the rear end is connected with the axial pressure Weibull distribution module, the pressure stabilizing control module includes a control module and an execution module, wherein the control module is used to control the accuracy of the output stable pressure, and the execution module is used to stabilize the fluctuating hydraulic flow from the hydraulic pump through electro-hydraulic pressure stabilizing valves with different accuracy according to the signals received by the control module, so as to eliminate the influence of instrument hydraulic fluctuation on the experimental data in the actual operation of the experiment, the accuracy of voltage stabilization is accurately controlled by computer.
[0011] The data acquisition module comprises a sensor, a data transmission line, a computer and a display screen, the data acquisition module is respectively connected with a multi unit axial pressure loading module, an axial pressure Weibull distribution module, a voltage stabilizing control module, a video recording module and a hydraulic pump through the data transmission line, and its interfaces with the data transmission line are RS232 serial interfaces, all sensors have two groups; in the displacement sensor, the transverse displacement sensor adopts chain displacement meter, the data transmission line is a shielded line, which can effectively isolate the interference signals generated by other electronic equipment and greatly reduce the loss in the process of signal transmission, when recording the strain data in the experimental device, considering the flexibility influence of the device, the flexibility from the device itself is automatically subtracted for flexibility correction, the displacement of the loading head in the loading shaft of each unit is calculated through the reading of the liquid flowmeter, so as to verify the accuracy of the measured strain data.
[0012] The video recording module is installed on the upper part of the high stiffness frame and connected with the computer through a data transmission line, four cameras are installed on the 40 high stiffness frame through a magnetic meter base, the camera is equipped with a fill light, and 3 the angle and lens orientation can be adjusted arbitrarily, and the aperture size can be adjusté(P00741 the four cameras are respectively arranged in four directions of the tested specimen, the video recording frequency is adjustable, and the range is 0.01 - 50Hz, the video can be post processed into panoramic video, which is convenient for comparison with the results of numerical simulation.
[0013] The safety protection grid has four groups, which are respectively installed on the four columns of the high stiffness frame through hinges, and is composed of high-strength glass and steel wire mesh, which are respectively located in four directions to completely cover the experimental area in the high stiffness frame.
[0014] The hydraulic pump is installed on the shock absorbing pad, is directly connected with the data acquisition module through the data transmission line, and is connected with the pressure stabilizing control module through the high-pressure resistant hydraulic pipe; the hydraulic pump provides hydraulic power for the whole loading system and reduces the impact of the hydraulic pump on the experiment; the hydraulic modules contained in the experimental device are connected by high-pressure resistant hydraulic pipes.
[0015] The working method for rock multi unit non-uniform uniaxial loading creep, which comprises the following steps:
[0016] Step 1: For the specific engineering rock mass, a numerical model is established according to the geological conditions of the actual sampling area, and the loading parameters, Weibull distribution parameters and sensor acquisition frequency of the rock specimen used in the uniaxial loading creep experiment are determined through the results of numerical simulation and uniaxial compression experiment.
[0017] Step 2: Select the corresponding porous shaft sleeve, unit loading shaft and loading head according to the cross-sectional area shape, size and typical grain unit composition of the rock specimen, assemble the unit loading shaft, loading head and the selected porous shaft sleeve, connect the liquid flowmeter, liquid pressure gauge, electromagnetic control valve, check valve and data transmission line and test.
[0018] Step 3: Apply Vaseline evenly on the upper and lower loading surfaces of the rock specimen, level the loading head with a level gauge, and then place the rock specimen on the assembled lower loading surface, the upper loading surface can be determined to place a rigid loading plate or install the unit loading shaft as required, and make the upper and lower loading surfaces of the device in close contact with the upper and lower surfaces of the specimen, at the same time, install the chain extensometer and other sensors, and then apply an initial stress of about 5kN.
[0019] Step 4: Open the four cameras of the video recording module through the computer, adjust the camera to an appropriate angle according to the collected video picture, start video recording, and close all safety protection grids at the same time.
[0020] Step 5: Turn on the hydraulic pump and all sensors, and determine whether the sensors work normally by manually changing the sensor parameters, after ensuring that there is no error, set the parameters that need to be zeroed uniformly. 4
[0021] Step 6: Open the control software on the computer, input the loading parameters, Weibaf 0741 distribution parameters and sensor acquisition frequency parameters obtained in step 1 into the control software, and control the multi unit axial compression loading module through the software to start loading the rock specimen.
[0022] Step 7: Keep the load until the rock specimen is completely destroyed, in this process, the data acquisition module and video recording module record the stress and strain information of the specimen, the flow and pressure change data of each unit loading axis and the dynamic change diagram of the rock specimen in real time.
[0023] Step 8: After a single test, take out the damaged rock specimen, observe, photograph and record it.
[0024] Step 9: Select a new rock specimen, adjust the loading conditions according to the experimental scheme, and repeat steps 1 to 8.
[0025] Compared with the prior art, the invention has the following beneficial technical effects:
[0026] (1) The invention develops a rock multi-element non-uniform uniaxial loading creep experimental device, which can carry out rock multi-element non-uniform uniaxial loading creep mechanics experiment, and solves the problem of lack of rock multi-element non-uniform uniaxial loading creep experimental equipment for laboratory.
[0027] (2) The invention provides a rock multi-element non-uniform uniaxial loading creep experimental method, which provides multi-element non-uniform axial stress by Weibull distributing axial pressure, makes the rock specimen in the multi-element non-uniform uniaxial loading environment, and fully considers the anisotropy and actual stress state of the rock, it is beneficial to carry out more in-depth and scientific experimental research on the real creep effect and creep failure mode of rock mass in the environment of non-uniform stress field.
[0028] (3) According to different experimental requirements, the invention can implement multi element non-uniform uniaxial loading creep experiments under different Weibull distribution parameters, which is convenient to be combined with numerical simulation.
[0029] (4) Compared with the prior art, when recording strain data, the invention considers the flexibility influence of the device, automatically subtracts the strain value from the device itself, performs flexibility correction, and calculates the displacement of the loading head in each unit loading shaft according to the reading of the liquid flowmeter, which can verify the accuracy of the measured strain data.
[0030] (5) In the voltage stabilizing module of the invention, the voltage stabilizing technology and the arrangement distance between each module fully consider the impact of the external environment and the long-time operation of the pressure system on the experimental data during the actual operation of the experiment, and the accuracy of the voltage stabilizing is accurately controlled by the computer, which greatly improves the accuracy of the test data.
[0031] (6) The video recording module in the invention uses four angle cameras to record the dynamic changes of the rock specimen in the whole experimental process, and can process the data into panoramic video, which is very convenient for comparison and verification with the results 5 of numerical simulation. LU500741
[0042] The high stiffness frame 1 is fixedly installed on the ground pedestal 2 through thick bolts, and the ground pedestal 2 is installed on the ground to support and fix the high stiffness frame 1, at the same time, it is used to connect the high-pressure resistant hydraulic pipe 11 from the axial pressure Weibull distribution module 4; the stiffness value of materials used for high stiffness frame 1 shall not be less than 5000kN/mm.
[0043] The multi unit axial pressure loading module 3 is the moving part of the whole experimental device, which is directly connected with the data acquisition module 6 through the data transmission line 12, connected with the axial pressure Weibull distribution module 4 through the high-pressure hydraulic pipe 11 in the ground pedestal 2, installed at the bottom of the high stiffness frame 1, arranged longitudinally, using hydraulic pressure as the power source and adopting servo control mode, the multi unit axial compression loading module 3 includes a porous shaft sleeve 37 distributed symmetrically in the center, a unit loading shaft 32, a loading head 31 and a level gauge for applying a vertical multi unit non-uniform axial stress to the test piece, the cross-sectional shape of the porous shaft sleeve 37 can be a standard rectangle or circle with different cross-sectional areas, which can meet the experimental requirements of specimens with different cross-sections and different cross-sectional areas, the unit loading shaft 32 includes a hydraulic cylinder, a liquid flowmeter 33, a liquid pressure gauge 34, an electromagnetic control valve 35 and a check valve 36, all unit loading shafts 32 are independent of each other, and the pressure is controlled by the electromagnetic control valve 35, the loading head 31 has a variety of geometric shapes, which can meet the needs of the test piece composed of different typical particle units, the loading head 31 can move in the vertical direction to apply the normal multi-element non-uniform axial stress to the rock test piece 13, all liquid flow meters 33 and liquid pressure gauges 34 are connected to the computer 14 through a data transmission line; the level is used for leveling before loading.
[0044] The axial pressure Weibull distribution module 4 is installed on the shock absorbing pad 10, with a distance of 3m from the ground pedestal 2 and 2m from the voltage stabilizing control module
5. It is directly connected with the data acquisition module 6 through the data transmission line 12, the input end of the axial pressure Weibull distribution module 4 is connected with the voltage stabilizing control module 5 through the high-pressure resistant hydraulic pipe 11, and the output end is connected with the multi unit axial pressure loading module 33 through the high-pressure resistant hydraulic pipe 11, the axial pressure Weibull distribution module 4 includes a control module and an execution module, the control module is used to control the parameters of the axial pressure Weibull distribution, and the execution module is used to process the stable hydraulic flow output through the voltage stabilizing control module 5 according to the signal received by the control module, and transmit the hydraulic flow through the Weibull distribution to the multi unit axial pressure loading module 3 through the high-pressure resistant hydraulic pipe 11, the relevant parameters of Weibull distribution are input by computer 14 and adjusted by electro-hydraulic servo valve. 6
[0045] The pressure stabilizing control module 5 is installed on the shock absorbing pad 1GUR00741 directly connected with the data acquisition module 6 through the data transmission line 12, is connected with the hydraulic pump 9 through the front end of the high-pressure resistant hydraulic pipe 11, and is connected with the axial pressure Weibull distribution module 4 at the rear end. The pressure stabilizing control module 5 includes a control module and an execution module, wherein the control module is used to control the accuracy of the output stable pressure, and the execution module is used to stabilize the fluctuating hydraulic flow from the hydraulic pump through electro-hydraulic pressure stabilizing valves with different accuracy according to the signals received by the control module, so as to eliminate the influence of instrument hydraulic fluctuation on the experimental data during the actual operation of the experiment, the accuracy of voltage stabilization is accurately controlled by computer.
[0046] The data acquisition module 6 includes a sensor, a data transmission line, a computer and a display screen, the data acquisition module 6 is respectively connected with the multi unit axial pressure loading module 3, the axial pressure Weibull distribution module 4, the voltage stabilizing control module 5, the video recording module 7 and the hydraulic pump 9 through the data transmission line 12. Its interfaces with the data transmission line are RS232 serial interfaces, all sensors have two groups; In the displacement sensor, the transverse displacement sensor adopts chain displacement meter; the data transmission line is a shielded line, which can effectively isolate the interference signals generated by other electronic equipment and greatly reduce the loss in the process of signal transmission, when recording the strain data in the experimental device, considering the flexibility influence of the device, the flexibility from the device itself is automatically subtracted for flexibility correction, the displacement of the loading head in the loading shaft of each unit is calculated through the reading of the liquid flowmeter, so as to verify the accuracy of the measured strain data.
[0047] The video recording module 7 is installed on the upper part of the high stiffness frame and is connected with the computer 14 through a data transmission line, four cameras are installed on the high stiffness frame 1 through a magnetic meter base, the camera is equipped with a fill light, the angle and lens orientation can be adjusted arbitrarily, and the aperture size can be adjusted; the four cameras are respectively arranged in four directions of the tested specimen, the video recording frequency is adjustable, and the range is 0.01 ~ 50Hz, the video can be post processed into panoramic video, which is convenient for comparison with the results of numerical simulation.
[0048] The safety protection grid 8 has four groups, which are respectively installed on the four columns of the high stiffness frame through hinges, and is composed of high-strength glass and steel wire mesh, which are respectively located in four directions to completely cover the experimental area in the high stiffness frame.
[0049] The hydraulic pump 9 is installed on the shock absorbing pad 10, is directly connected with the data acquisition module 6 through the data transmission line 12, and is connected with the voltage stabilizing control module 5 through the high-pressure resistant hydraulic pipe 11, the hydraulic pump 9 provides hydraulic power for the whole loading system and reduces the impact of 40 the hydraulic pump on the experiment, the hydraulic modules included in the experimental device 7 are connected by high-pressure resistant hydraulic pipe 11. LUS00741
[0050] The invention relates to a working method of a rock multi-element non-uniform uniaxial loading creep experimental device, which comprises the following steps:
[0051] Step 1: For specific engineering rock mass, a numerical model is established according to the geological conditions of the actual sampling area, and the loading parameters, Weibull distribution parameters and sensor acquisition frequency of rock specimen 13 used in uniaxial loading creep experiment are determined through the results of numerical simulation calculation and uniaxial compression experiment.
[0052] Step 2: Select the corresponding porous shaft sleeve 37, unit loading shaft 32 and loading head 31 according to the cross-sectional area shape, size and typical grain unit composition of the rock specimen, assemble the unit loading shaft 32, loading head 31 and the selected porous shaft sleeve 37, connect the liquid flowmeter 33, liquid pressure gauge 34, solenoid control valve 35, check valve 36 and data transmission line 12 and test.
[0053] Step 3: Apply Vaseline evenly on the upper and lower loading surfaces of the rock specimen 13, level the loading head 31 with a level gauge, and then place the rock specimen 13 on the assembled lower loading surface, the upper loading surface can be determined to place a rigid loading plate or install the unit loading shaft as required, then make the upper and lower loading surfaces of the device in close contact with the upper and lower surfaces of the specimen, at the same time, install the chain extensometer and other sensors, and then apply an initial stress of about 5kN.
[0054] Step 4: Open the four cameras of the video recording module 7 through the computer 14, adjust the camera to an appropriate angle according to the collected video picture, start video recording, and close all safety protection grids 8 at the same time.
[0055] Step 5: Turn on the hydraulic pump 9 and all sensors, and determine whether the sensors work normally by manually changing the sensor parameters, after ensuring that there is no error, set the parameters that need to be zeroed uniformly.
[0056] Step 6: Open the control software on the computer 14, input the loading parameters, Weibull distribution parameters and sensor acquisition frequency parameters obtained in step 1 into the control software, and start loading the rock specimen 13 through the software control multi unit axial compression loading module 3.
[0057] Step 7: Maintain the load until the rock specimen 13 is destroyed. In this process, the data acquisition module 6 and video recording module 7 record the stress and strain information of the specimen, the flow and pressure change data of each unit loading axis and the dynamic change diagram of the rock specimen 13 in real time.
[0058] Step 8: After a single test, take out the damaged rock specimen 13, observe, photograph and record it.
[0059] Step 9: Select a new rock specimen, adjust the loading conditions according to the experimental scheme, and repeat steps 1 to 8.
[0060] Fig. 4 is the stress diagram of the specimen in the example (uniaxial loading creep test). As 40 shown in Fig. 4, the loading force on the specimen is the axial loading force after Weibull distribution, 8 compared with the traditional loading method, discretizing a total axial loading force F into HiR00741 resultant force of F1, F2, F3, F4, F5, F6..., which can provide more real stress conditions for the rock specimen.
[0061]Fig. 5 is the schematic diagram of Weibull distribution under different parameter conditions in the embodiment (uniaxial loading creep test), as shown in Fig. 5, under different environmental conditions of different rock samples, different Weibull distribution parameters can be selected, and the influence of the anisotropy of rock samples and the actual loading environment on the creep test results can be fully considered, the creep test results are closer to the actual situation.
9
Claims (10)
1. A experimental device of rock multi unit non-uniform uniaxial loading creep, which is characterized in that it comprises a high stiffness frame, a multi unit axial pressure loading module, an axial pressure Weibull distribution module, a voltage stabilizing control module, a data acquisition module, a video recording module, a safety protection grid and a hydraulic pump.
The high stiffness frame provides the installation position and low relative flexibility state of the whole device for the multi unit axial compression loading module, video recording module and safety protection grid in the experimental device, the multi unit axial pressure loading module provides multi unit non-uniform axial pressure for the experimental device, the axial pressure Weibull distribution module provides Weibull distributed pressure for the multi unit axial pressure loading module, the voltage stabilizing control module provides stable pressure for the axial pressure Weibull distribution module, and the data acquisition module is used to collect stress and strain information during the experiment, the video recording module is used for real-time recording the dynamic changes of rock specimens during the experiment, the safety protection grid provides protection for personnel and equipment during the experiment, and the hydraulic pump provides hydraulic power for the pressure stabilizing control module, the experimental device is equipped with a backup power supply, and the power capacity can be used for at least 48 hours. In the experimental device, the multi unit axial pressure loading module, axial pressure Weibull distribution module, voltage stabilizing control module and hydraulic pump are connected by high-pressure resistant hydraulic pipes.
2. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the high stiffness frame is fixedly installed on the ground pedestal through thick bolts, and the ground pedestal is installed on the ground to support and fix the high stiffness frame, at the same time, it is used to connect the high-pressure resistant hydraulic pipe from the axial pressure Weibull distribution module; the stiffness value of materials used for high stiffness frame shall not be less than 5000kN/mm.
3. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the multi unit axial pressure loading module is the moving part of the whole experimental device, which is directly connected with the data acquisition module through the data transmission line, connected with the axial pressure Weibull distribution module through the high-pressure hydraulic pipe in the ground pedestal, installed at the bottom of the high stiffness frame, longitudinally arranged, using the hydraulic pressure as the power source and adopting the servo control mode, the multi element axial compression loading module includes a centrally symmetrical porous shaft sleeve, a unit loading shaft, a loading head and a level gauge, which are used to apply vertical and upward multi element non-uniform axial stress to the test piece, the cross-sectional shape of the porous shaft sleeve can be a standard rectangle or a circle with different cross-sectional areas, which can meet the experimental requirements of specimens with different cross-sections and different cross-sectional areas. The unit loading shaft comprises a 40 hydraulic cylinder, a liquid flowmeter, a liquid pressure gauge, an electromagnetic control valve and 10
CLAIMS - LU5OO741 a check valve, all unit loading shafts are independent of each other, and the pressure is controlled by the electromagnetic control valve, the loading head has a variety of geometric shapes, which can meet the requirements of the test piece composed of different typical particle units, the loading head can move along the vertical direction to apply the normal multi-element non-uniform axial stress to the rock test piece, all liquid flow meters and liquid pressure gauges are connected to the computer through the data transmission line, the level gauge is used for leveling before loading.
4. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the axial pressure Weibull distribution module is installed on the shock absorption pad, with a distance of 3m from the ground pedestal and 2m from the voltage stabilizing control module, it is directly connected with the data acquisition module through the data transmission line, the input end of the axial pressure Weibull distribution module is connected with the voltage stabilizing control module through the high-pressure resistant hydraulic pipe, and the output end is connected with the multi unit axial pressure loading module through the high-pressure resistant hydraulic pipe, the axial pressure Weibull distribution module includes the control module and the execution module, the control module is used to control the parameters of the Weibull distribution of the axial pressure, and the execution module is used to process the Weibull distribution of the stable hydraulic flow output through the pressure stabilizing control module according to the signal received by the control module, and transmit the Weibull distributed hydraulic flow to the multi unit axial pressure loading module through the high-pressure resistant hydraulic pipe, the relevant parameters of Weibull distribution are input by computer and adjusted by electro-hydraulic servo valve.
5. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the pressure stabilizing control module is installed on the shock absorbing pad, is directly connected with the data acquisition module through the data transmission line, is connected with the hydraulic pump through the front end of the high-pressure resistant hydraulic pipe, and the rear end is connected with the axial pressure Weibull distribution module, the pressure stabilizing control module includes a control module and an execution module, wherein the control module is used to control the accuracy of the output stable pressure, and the execution module is used to stabilize the fluctuating hydraulic flow from the hydraulic pump through electro-hydraulic pressure stabilizing valves with different accuracy according to the signals received by the control module, so as to eliminate the influence of instrument hydraulic fluctuation on the experimental data in the actual operation of the experiment, the accuracy of voltage stabilization is accurately controlled by computer.
6. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the data acquisition module comprises a sensor, a data transmission line, a computer and a display screen, the data acquisition module is respectively connected with a 40 multi unit axial pressure loading module, an axial pressure Weibull distribution module, a voltage 11
CLAIMS - LU5OO741 stabilizing control module, a video recording module and a hydraulic pump through the data transmission line, and its interfaces with the data transmission line are RS232 serial interfaces, all sensors have two groups; in the displacement sensor, the transverse displacement sensor adopts chain displacement meter, the data transmission line is a shielded line, which can effectively isolate the interference signals generated by other electronic equipment and greatly reduce the loss in the process of signal transmission, when recording the strain data in the experimental device, considering the flexibility influence of the device, the flexibility from the device itself is automatically subtracted for flexibility correction, the displacement of the loading head in the loading shaft of each unit is calculated through the reading of the liquid flowmeter, so as to verify the accuracy of the measured strain data.
7. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the video recording module is installed on the upper part of the high stiffness frame, connected with the computer through a data transmission line, and four cameras are installed on the high stiffness frame through a magnetic meter base, the camera is equipped with a fill light, and the angle and lens orientation can be adjusted arbitrarily, and the aperture size can be adjusted, the four cameras are respectively arranged in four directions of the tested specimen, the video recording frequency is adjustable, and the range is 0.01~50Hz, the video can be post processed into panoramic video, which is convenient for comparison with the results of numerical simulation.
8. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the safety protection grid has four groups, which are respectively installed on the four columns of the high stiffness frame through hinges, and is composed of high-strength glass and steel wire mesh, which are respectively located in four directions to completely cover the experimental area in the high stiffness frame.
9. The experimental device of rock multi unit non-uniform uniaxial loading creep according to claim 1, which is characterized by: the hydraulic pump is installed on the shock absorbing pad, is directly connected with the data acquisition module through the data transmission line, and is connected with the pressure stabilizing control module through the high-pressure resistant hydraulic pipe, the hydraulic pump provides hydraulic power for the whole loading system and reduces the impact of the hydraulic pump on the experiment, the hydraulic modules contained in the experimental device are connected by high-pressure resistant hydraulic pipes.
10. A working method of The experimental device of rock multi unit non-uniform uniaxial loading creep, which is characterized in that it comprises the following steps: Step 1: For the specific engineering rock mass, a numerical model is established according to the geological conditions of the actual sampling area, and the loading parameters, Weibull distribution 40 parameters and sensor acquisition frequency of the rock specimen used in the uniaxial loading 12
CLAIMS - LU5OO741 creep experiment are determined through the results of numerical simulation and uniaxial compression experiment.
Step 2: Select the corresponding porous shaft sleeve, unit loading shaft and loading head according to the cross-sectional area shape, size and typical grain unit composition of the rock specimen, assemble the unit loading shaft, loading head and the selected porous shaft sleeve, connect the liquid flowmeter, liquid pressure gauge, solenoid control valve, check valve and data transmission line and test.
Step 3: Apply Vaseline evenly on the upper and lower loading surfaces of the rock specimen, level the loading head with a level gauge, and then place the rock specimen on the assembled lower loading surface, the upper loading surface can be determined to place a rigid loading plate or install the unit loading shaft as required, and make the upper and lower loading surfaces of the device in close contact with the upper and lower surfaces of the specimen, at the same time, install the chain extensometer and other sensors, and then apply an initial stress of about 5kN. Step 4: Open the four cameras of the video recording module through the computer, adjust the camera to an appropriate angle according to the collected video picture, start video recording, and close all safety protection grids at the same time.
Step 5: Turn on the hydraulic pump and all sensors, and determine whether the sensors work normally by manually changing the sensor parameters, after ensuring that there is no error, set the parameters that need to be zeroed uniformly.
Step 6: Open the control software on the computer, input the loading parameters, Weibull distribution parameters and sensor acquisition frequency parameters obtained in step 1 into the control software, and control the multi unit axial compression loading module through the software to start loading the rock specimen.
Step 7: Keep the load until the rock specimen is destroyed. In this process, the data acquisition module and video recording module record the stress and strain information of the specimen, the flow and pressure change data of each unit loading axis and the dynamic change diagram of the rock specimen in real time.
Step 8: After a single test, take out the damaged rock specimen, observe, photograph and record it. Step 9: Select a new rock specimen, adjust the loading conditions according to the experimental scheme, and repeat steps 1 to 8. 13
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| LU500741A LU500741B1 (en) | 2021-10-18 | 2021-10-18 | An experimental device and working method for rock multi unit non-uniform uniaxial loading creep |
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