A method and equipment for testing multi-field coupled rheological tests of rocks under dynamic loads

Abstract

The present invention discloses a method and equipment for testing multi-field coupled rheological tests of rocks under dynamic loads, which belongs to the fields of rock mechanics, civil engineering, and geological disasters; the current test methods and equipment apply instantaneous loads to rocks, and simulate the impact of the instantaneous loads imposed on rocks by explosions in simulated working conditions, but cannot simulate the impact of the shock wave after the explosion on the rocks. The present invention places the rock sample in the sample chamber of a triaxial rheological test device, and converts the mechanical energy output by the motor into a dynamic load continuously applied to the rock sample through two hydraulic transmissions, simulating the impact of the shock wave of the explosive explosion on the rock; the load loading mechanism on the equipment above the sample chamber converts the rotational motion of the motor into linear reciprocating motion, and applies a continuous dynamic load to the rock sample through a cylinder, a power converter, and a hydraulic hose connecting them by hydraulic transmission; the test method and equipment provided by the present invention are convenient and flexible, and are suitable for a variety of test sites.

Description

Technical Field

[0001] The invention relates to a method and equipment for testing a multi-field coupled rheological test of rock under dynamic load, and belongs to the fields of rock mechanics, civil engineering and geological disasters. Background Art

[0002] The multi-field coupling problem of rock is an important research topic in rock mechanics at present, with very important engineering background and significance. In the central and southwestern regions of my country, such as Yunnan, Sichuan, Guizhou, Guangxi and other provinces (autonomous regions), there are large areas of Permian limestone strata. This stratum has rich high-quality limestone mineral resources and is an important source of building materials for a large number of infrastructure construction in my country. The distribution area of ​​Permian limestone strata is an area with frequent rainfall in my country. During the open-pit mining of limestone mines, micro-difference blasting will generate dynamic loads and produce continuous shock wave disturbance effects on rocks after blasting. Under the combined effects of blasting shock waves, freeze-thaw cycles and rainfall seepage, geological disasters such as landslides and collapses often occur in this area. Determining the long-term stability of rocks is an important prerequisite for solving disasters such as landslides and collapses from a mechanistic perspective.

[0003] The rheological mechanical property test of rock is one of the main means to determine the long-term stability of rock. It has become necessary to carry out multi-field coupled rheological test of rock under dynamic load. At present, the loading method of multi-field coupled rheological test under dynamic load is to load axial dynamic load on rock sample by intermittent impact or collision at the top of sample chamber to simulate the influence of instantaneous load on rock caused by explosive explosion. However, these two loading methods cannot simulate the continuous influence of shock wave generated by explosive explosion on rock. At the same time, loading in the form of impact and collision will also cause irregular vibration of equipment during the test, which will not only make the whole equipment easy to be damaged, but also affect the test data. In addition, in the current test method, the seepage system uses water as the permeation medium, which will cause water to freeze under low temperature conditions and cannot meet different permeation test conditions, thus failing to achieve the purpose and effect of the test. At the same time, in the current test equipment, the servo motor drives the piston, and the loading device driven by the force transmission rod fixedly connected to the piston impacts the rock sample. During the test, it is impossible to continuously apply dynamic load to the rock sample, and it is impossible to realize the function of continuously applying axial dynamic load. Summary of the invention

[0004] The purpose of the present invention is to address the problems of the prior art and provide a method and equipment for multi-field coupled rheological testing under dynamic loads. The method and equipment of the invention can apply continuous axial dynamic loads to rock samples, truly simulating the dynamic disturbance effect of shock waves generated by explosive explosions in actual working conditions on rocks, and the test data of the method of the present invention are highly accurate and the test equipment has good stability.

[0005] The technical solution adopted by the present invention to solve its technical problem is as follows: a rock sample is placed in a triaxial rheological test sample room, the temperature of the sample room is controlled at -30°C to 50°C, the confining pressure of the sample room is controlled at no more than 30Mpa, the osmotic pressure of the sample room is controlled at no more than 1MPa, a cyclic vibration dynamic load of no more than 100MPa in the axial direction and no more than 50Hz is applied to the top of the rock sample, and a triaxial rheological test is carried out; the dynamic stress strain and volume deformation of the rock sample under the dynamic load are measured with time; the cyclic vibration dynamic load is generated in the following way: the rotational motion of the motor is converted into a linear reciprocating motion through a crank-connecting rod mechanism, the crank-connecting rod mechanism drives a piston A located in a cylinder body A to apply force to the liquid in the cylinder body A, and the cyclic vibration dynamic load is applied to the rock sample by using hydraulic transmission, a cylinder body B and a piston B located in the cylinder body B.

[0006] The above technical solution is further implemented by obtaining a relationship function between the dynamic stress strain change, volume change and time based on the measured dynamic stress strain and volume change of the rock sample under the dynamic load over time.

[0007] The specific steps adopted in the above technical scheme are as follows: the temperature inside the sample chamber is adjusted by controlling the temperature at the top and bottom of the sample chamber, and the temperature inside the sample chamber is controlled at -30°C to 50°C; hydraulic fluid is input into the sample chamber to create a confining pressure, and the confining pressure is controlled to be no more than 30Mpa; a constant air pressure is applied to the top and bottom of the sample chamber, and the air pressure at the top is greater than the air pressure at the bottom, so as to generate a constant air pressure difference to form an osmotic pressure, and the osmotic pressure is controlled to be no more than 1MPa; an axial dynamic load of no more than 100MPa and a cyclic vibration load of no more than 50Hz is applied to the rock sample; and the change values ​​of the dynamic stress, strain and volume deformation of the rock sample under the dynamic load over time are measured.

[0008] The present invention provides a multi-field coupled rheological test device for rocks under dynamic load to solve the technical problems, which is as follows: a load loading mechanism is connected to the top of the sample chamber of the triaxial rheological test device, and the load loading mechanism includes a power output unit, a hydraulic transmission unit, and a load output unit;

[0009] The power output unit comprises at least an electric motor and a crank connected to the electric motor;

[0010] The load output unit at least includes a force transmission rod and a loading plate connected to the force transmission rod, and the loading plate is in contact with the upper surface of the sample chamber;

[0011] The hydraulic transmission unit at least includes a cylinder body A and a power converter. Hydraulic oil is filled in a liquid storage pressure chamber below the piston A in the cylinder body A. The piston rod fixed to the upper surface of the piston A is connected to the crank. A hydraulic valve is provided on the oil supply pipe on the side of the liquid storage pressure chamber. The oil supply pipe connects the liquid storage pressure chamber and the cylinder A. The power converter includes a cylinder body B and a piston B located in the cylinder body B. The lower surface of the piston B is connected to the force transmission rod. The lower part of the liquid storage pressure chamber and the upper part of the cylinder body B are connected through a hydraulic hose.

[0012] The further improvement to the above technical solution is as follows:

[0013] Aluminum pans for adjusting the temperature in the sample chamber are connected to the top and bottom of the sample chamber of the triaxial rheological test device. The top aluminum pan A is connected to a temperature circulation box A through two temperature circulation liquid hoses A, and the bottom aluminum pan B is connected to a temperature circulation box B through two temperature circulation liquid hoses B. The temperature circulation box at least includes: a cylinder body, a heating rod and a condenser.

[0014] The top and bottom of the sample chamber of the triaxial rheological test device are connected with ventilation pipes. The top ventilation pipe is connected with cylinder A, and an air pressure valve A is provided on the ventilation pipe. The bottom ventilation pipe is connected with cylinder B, and an air pressure valve B is provided on the ventilation pipe.

[0015] The side of the sample chamber of the triaxial rheological test device is connected with an oil pipe, which is communicated with the oil cylinder B and has a hydraulic valve on it.

[0016] In summary, the beneficial effects of the technical solution of the present invention are:

[0017] The method of the present invention generates power through an electric motor, utilizes hydraulic transmission to convert the mechanical energy of the electric motor into hydraulic energy, and then converts the hydraulic energy into mechanical energy. The power of the second conversion is hydraulic energy, and the power converted from the hydraulic energy can be continuously applied to the rock sample, which can well simulate the influence of the continuous disturbance of the shock wave after the explosion of the explosive on the rock; using gas instead of water as the permeation medium to apply osmotic pressure can solve the problem that under low temperature conditions, water is used as the permeation medium and causes water to freeze when flowing through the sample, thereby failing to meet the test conditions; the equipment of the present invention uses hydraulic transmission to convert the mechanical energy of the electric motor into hydraulic energy, and then converts the hydraulic energy into the kinetic energy of the loading plate on the upper part of the sample chamber. The loading plate is always in contact with the upper part of the sample chamber, and the converted kinetic energy is continuously applied to the rock sample, applying a continuous cyclic dynamic load to the rock sample; and the two power conversions minimize the destructive effect of high-frequency power on the instrument during the implementation process, effectively maintain the stability of the instrument, and avoid damage to the equipment by impact or collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Attached Figure 1 It is a structural schematic diagram of the device of the present invention;

[0019] In the figure: 1. rock sample; 11. temperature circulation box A; 12. temperature circulation liquid hose A; 13. aluminum plate A; 21. air pressure valve A; 22. cylinder A; 23. air pressure valve B; 24. cylinder B; 31. oil cylinder B; 32. hydraulic valve; 41. electric motor; 42. piston rod; 43. piston; 44. liquid storage pressure chamber; 45. hydraulic valve; 46. oil cylinder A; 47. hydraulic hose; 48. power converter; 49. force transmission rod; 410. loading plate; 411. rigid pressure head. DETAILED DESCRIPTION

[0020] The method of the present invention is further described below with reference to the embodiments.

[0021] The method of the present invention is tested by taking end values ​​and intermediate values ​​within the range of test temperature, confining pressure and osmotic pressure, and three embodiments are provided.

[0022] The test method for the multi-field coupled rheological test of rock under dynamic load provided in Example 1 is as follows: a rock sample is placed in a sample chamber of a triaxial rheological device, the temperature in the sample chamber is adjusted to -28°C, the confining pressure is controlled to 3Mpa, and this state is maintained for 30 minutes, a constant air pressure is applied to the top and bottom of the sample chamber, the top air pressure is greater than the bottom air pressure, and a constant air pressure difference is generated, the air pressure difference is the osmotic pressure of this embodiment, and the osmotic pressure is controlled to 0.2Mpa; the temperature, confining pressure, and osmotic pressure are kept stable until the end of the test, and a cyclic vibration dynamic load is applied to the rock sample, which changes once per second in the range of no more than 100Mpa and no more than 50hz in the axial direction, and the temperature value, confining pressure value, osmotic pressure value, load change value, and rock sample volume change value data in the sample chamber are collected by sensors, and the dynamic stress change value and volume change value of the rock sample under different test conditions are recorded once per second;

[0023] The test method for the multi-field coupled rheological test of rock under dynamic load provided in Example 2 is as follows: the temperature in the sample chamber is controlled at 10°C, the confining pressure in the sample chamber is controlled at 15 MPa, and this state is maintained for 30 minutes, the osmotic pressure in the sample chamber is controlled at 0.5 MPa, and the temperature, confining pressure, and osmotic pressure are kept stable until the end of the test, and a cyclic vibration dynamic load is applied to the rock sample with an axial value of no more than 100 MPa and a range of no more than 50 Hz that changes once per second, and the temperature value, confining pressure value, osmotic pressure value, load change value, and rock sample volume change value data of the sample chamber are collected through sensors, and the dynamic stress change value and volume change value of the rock sample under different test conditions are recorded once per second;

[0024] The test method for the multi-field coupled rheological test of rock under dynamic load provided in Example 3 is as follows: the temperature in the sample chamber is controlled at 50°C, the confining pressure in the sample chamber is controlled at 30 MPa, and this state is maintained for 30 minutes, the osmotic pressure in the sample chamber is controlled at 1 MPa, and the temperature, confining pressure, and osmotic pressure are kept stable until the end of the test, and a cyclic vibration dynamic load is applied to the rock sample with an axial range of no more than 100 MPa and a change of once per second within a range of no more than 50 Hz, and the temperature value, confining pressure value, osmotic pressure value, load change value, and rock sample volume change value data of the sample chamber are collected through sensors, and the dynamic stress change value and volume change value of the rock sample under different test conditions are recorded once per second;

[0025] The dynamic stress-strain changes and volumetric strain changes of the rock samples measured by the above three embodiments are used to obtain the relationship function between the dynamic stress-strain changes, volumetric strain changes and time; the temperature values, confining pressure values ​​and osmotic pressure values ​​selected in the three embodiments are the end values ​​and intermediate values ​​of the test conditions, and in the actual test process, the values ​​taken are all possible values ​​within the range.

[0026] The dynamic load of the test method is generated in the following way: the rotational motion of the motor is converted into a linear reciprocating motion through a crank-connecting rod mechanism, the crank-connecting rod mechanism drives the piston in the cylinder to apply force to the liquid in the cylinder, and the hydraulic transmission is used to apply a cyclic vibration dynamic load to the rock sample; the kinetic energy of the first conversion is an impact effect, and the kinetic energy of the second conversion is a continuous application effect. This continuous application of dynamic load cannot be achieved through a single power conversion. The present invention applies a continuous dynamic load disturbance effect to the rock sample through two kinetic energy conversions.

[0027] The test method of this embodiment can test the relationship between stress and strain of rock samples under the separate or combined effects of different shock waves, different osmotic pressures, different temperatures, and different confining pressures after an explosion, and the load application in the test method is more accurate, which can solve the stability problem of rocks under the separate or combined effects of shock waves, rainfall, and freeze-thaw cycles after an explosion.

[0028] The device of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Embodiment 4, as shown in the attached drawings, the rock multi-field coupled rheological test equipment under dynamic load is specifically as follows: at least comprising a triaxial rheological test device, a load loading mechanism is connected to the top of the sample chamber of the triaxial rheological device, and the load loading mechanism comprises a power output unit, a hydraulic transmission unit, and a load output unit;

[0030] The power output unit at least includes an electric motor 41 and a crank connected to the electric motor, and the crank converts the rotational motion of the electric motor into a linear reciprocating motion; the load output unit at least includes a force transmission rod 49 and a loading plate 410 connected to the force transmission rod 49, and the loading plate 410 contacts the rigid pressure head 411 on the top of the sample chamber, and the force transmission rod 49 pushes the loading plate 410 to squeeze the rigid pressure head 411 on the top of the sample chamber to implement the load loading on the rock sample 2; the hydraulic transmission unit at least includes a cylinder body A and a power converter 48, and the liquid storage pressure chamber 44 below the piston A43 in the cylinder body A is filled with hydraulic oil, and the piston rod 42 fixed on the upper surface of the piston A43 is connected to the crank. After the electric motor 41 is started, the crank drives the piston rod 42 to perform reciprocating linear motion to push the piston A43, and a hydraulic valve 45 is provided on the oil supply pipe on the side of the liquid storage pressure chamber 44 The oil supply pipe connects the liquid storage pressure chamber 44 and the oil cylinder A46. The hydraulic valve 45 is a two-way valve, and the hydraulic valve 45 is used to control the inflow and outflow of the liquid in the liquid storage pressure chamber; the power converter 48 includes a cylinder body B and a piston B located in the cylinder body B, and the lower surface of the piston B is connected to the force transmission rod 49; the lower part of the liquid storage pressure chamber 44 and the upper part of the cylinder body B are connected through a hydraulic hose 47, and the crank drives the piston A43 to squeeze the hydraulic oil in the liquid storage pressure chamber 44. The hydraulic oil is transported to the upper part of the piston B in the cylinder body B through the hydraulic hose 47. The hydraulic oil squeezes the piston B so that the force transmission rod 49 fixed on the lower surface of the piston B pushes the loading plate 410. The loading plate squeezes the rigid pressure head above the rock sample to apply a dynamic load to the rock sample. During the implementation process, the loading plate 410 is always in contact with the rigid pressure head 411 to continuously apply a dynamic load to the rock sample.

[0031] Aluminum pans for adjusting the temperature in the sample chamber are connected to the top and bottom of the sample chamber of the triaxial rheological test device. The top aluminum pan A13 is connected to the temperature circulation box A11 through two temperature circulation liquid hoses A12. One temperature circulation liquid hose A12 transports the circulating liquid with adjusted temperature in the temperature circulation box A11 to the aluminum pan A13. The temperature in the sample chamber is controlled by absorbing heat through diffusion by the aluminum pan A. The temperature circulation liquid flowing through the aluminum pan A13 flows back to the temperature circulation box A11 through another temperature circulation liquid hose A12. The bottom aluminum pan B16 is connected to the temperature circulation box B14 through two temperature circulation liquid hoses B15. The working process is consistent with the upper temperature change unit, and they work together to adjust the temperature in the sample chamber. The temperature circulation box at least includes: a cylinder body, a heating rod and a condenser.

[0032] The top and bottom of the sample chamber of the triaxial rheological test device are connected with a ventilation pipe, the top ventilation pipe is connected with the cylinder A22, and the ventilation pipe is provided with an air pressure valve A21, and the bottom ventilation pipe is connected with the cylinder B24, and the ventilation pipe is provided with an air pressure valve B23; the cylinder A outputs gas, and the air pressure is controlled by the air pressure valve A21 to generate a constant air pressure at the top of the sample chamber to maintain the air pressure stable; the cylinder B24 outputs gas, and the air pressure is controlled by the air pressure valve B23 to maintain the air pressure stable, and the top air pressure is greater than the bottom air pressure. The constant air pressure difference generated is the osmotic pressure value of this embodiment. Replacing water with gas can overcome the problem that water freezing under low temperature conditions cannot meet the test conditions.

[0033] An oil pipe is connected to the side of the sample chamber, and the oil pipe is connected to the oil cylinder B31. A hydraulic valve 32 is provided on the oil pipe. The oil cylinder B31 inputs hydraulic oil into the sample chamber through the oil pipe. The hydraulic valve 32 on the oil pipe controls the inflow and outflow of the hydraulic oil. The pressure of the hydraulic oil on the rock sample is used to simulate the confining pressure of the soil and surrounding rock mass on the rock sample in actual working conditions.

Claims

1. A method for testing rock multi-field coupled rheological tests under dynamic loads, characterized in that: A rock sample is placed in a sample chamber of a triaxial rheological test device, the temperature of the sample chamber is controlled at -30°C to 50°C, the confining pressure of the sample chamber is controlled at no more than 30Mpa, the osmotic pressure of the sample chamber is controlled at no more than 1MPa, and a cyclic vibration dynamic load of no more than 100MPa in the axial direction and no more than 50Hz is applied to the top of the rock sample to carry out a triaxial rheological test; the dynamic stress strain and volume deformation of the rock sample under the dynamic load are measured over time; the cyclic vibration dynamic load is generated in the following manner: the rotational motion of the motor is converted into a linear reciprocating motion through a crank-connecting rod mechanism, the crank-connecting rod mechanism drives a piston A located in a cylinder body A to apply force to the liquid in the cylinder body A, and the cyclic vibration dynamic load is applied to the rock sample by utilizing hydraulic transmission, a cylinder body B, and a piston B located in the cylinder body B.

2. The method for testing rock multi-field coupled rheological tests under dynamic loads according to claim 1 is characterized in that: According to the measured values ​​of dynamic stress-strain and volume change of rock samples under dynamic load with time, the relationship function between dynamic stress-strain change, volume change and time is obtained.

3. The rock multi-field coupled rheological test method under dynamic load according to claim 1 is characterized in that The specific steps adopted are as follows: the temperature inside the sample chamber is adjusted by controlling the temperature at the top and bottom of the sample chamber, and the temperature inside the sample chamber is controlled at -30℃~50℃; hydraulic fluid is input into the sample chamber to create a confining pressure, and the confining pressure is controlled to be no more than 30Mpa; a constant air pressure is applied to the top and bottom of the sample chamber, and the air pressure at the top is greater than the air pressure at the bottom, so as to generate a constant air pressure difference to form an osmotic pressure, and the osmotic pressure is controlled to be no more than 1MPa; an axial dynamic load of no more than 100MPa and a cyclic vibration load of no more than 50Hz is applied to the rock sample; and the dynamic stress, strain and volume deformation of the rock sample under the dynamic load are measured over time.

4. A testing device for the multi-field coupled rheological test of rock under dynamic load as claimed in claim 1, comprising at least a triaxial rheological test device, characterized in that: A load loading mechanism is connected to the top of the sample chamber, and the load loading mechanism includes a power output unit, a hydraulic transmission unit, and a load output unit; The power output unit comprises at least an electric motor and a crank connected to the electric motor; The load output unit at least includes a force transmission rod and a loading plate connected to the force transmission rod, and the loading plate is in contact with the upper surface of the sample chamber; The hydraulic transmission unit at least includes a cylinder body A and a power converter. Hydraulic oil is filled in a liquid storage pressure chamber below the piston A in the cylinder body A. The piston rod fixed to the upper surface of the piston A is connected to the crank. A hydraulic valve is provided on the oil supply pipe on the side of the liquid storage pressure chamber. The oil supply pipe connects the liquid storage pressure chamber and the cylinder A. The power converter includes a cylinder body B and a piston B located in the cylinder body B. The lower surface of the piston B is connected to the force transmission rod. The lower part of the liquid storage pressure chamber and the upper part of the cylinder body B are connected through a hydraulic hose.

5. The rock multi-field coupling rheological test equipment under dynamic load according to claim 4 is characterized by: The top and bottom of the sample chamber of the triaxial rheological test device are connected with aluminum pans for adjusting the temperature in the sample chamber. The top aluminum pan A is connected to a temperature circulation box A through two temperature circulation liquid hoses A, and the bottom aluminum pan B is connected to a temperature circulation box B through two temperature circulation liquid hoses B. The temperature circulation box at least includes: a cylinder body, a heating rod and a condenser.

6. The rock multi-field coupling rheological test equipment under dynamic load according to claim 4 is characterized by: The top and bottom of the sample chamber of the triaxial rheological test device are connected with ventilation pipes. The top ventilation pipe is connected with cylinder A, and an air pressure valve A is provided on the ventilation pipe. The bottom ventilation pipe is connected with cylinder B, and an air pressure valve B is provided on the ventilation pipe.

7. The rock multi-field coupling rheological test equipment under dynamic load according to claim 4 is characterized by: The side of the sample chamber of the triaxial rheological test device is connected with an oil pipe, which is communicated with the oil cylinder B and has a hydraulic valve.

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