Device for testing segregation ice growth and frost heaving force evolution process in low-temperature and low-saturation rock fracture and use method of device

Abstract

The invention belongs to the technical field of geotechnical engineering tests, and particularly relates to a device for testing the growth and frost heaving force evolution process of segregated ice in a low-temperature and low-saturation rock fracture and a use method of the device. According to the technical scheme, the system comprises a temperature gradient generation module, a load application module, a moisture supply module, a test module and a computer system, the temperature gradient generation module is used for controlling temperature change to simulate the temperature gradient of a slope site, and the load application module is used for controlling the loading condition of a preload to simulate the soil covering pressure of the slope site; the moisture supply module is used for supplying moisture, the test module is used for monitoring the surface temperature and frost heaving force of a rock test piece, and the computer system is used for analyzing data and implementing control. The device can refer to the actual environment where the low-saturation fractured rock mass of the cold region slope is located, the rock mechanical characteristics and the slope weakening problem under the conditions of the temperature gradient, different initial saturations and the preload action can be researched, and theoretical support can be provided for cold region mine slope prevention and control.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering tests, and particularly relates to a test device and a using method for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures. Background Art

[0002] In cold regions of our country (such as Inner Mongolia, Xinjiang, etc.), there are rich metal mineral resources. The reserves of lead, zinc, and silver in Inner Mongolia rank first in the country, and copper and molybdenum rank fourth; the reserves of copper, nickel, beryllium, etc. in Xinjiang are all among the top in the country, making it a key mineral base in the future. However, the extremely low winter temperatures in open-pit mines in cold regions (up to -50°C in Inner Mongolia and -51.5°C in Xinjiang) lead to significant freeze-thaw effects on rock masses. Moreover, due to the early mining sequence and the development of dipping structures (accounting for more than 40%) in the footwall slopes of the mines, there have been many studies on dipping hard rock slopes with saturated fractures. However, for dipping hard rock slopes with low-saturation fractures, why they will cause instability and landslides due to freeze-thaw effects has a huge impact on the safe and stable production of the mines. The moisture migration in fractures under freeze-thaw cycles induces non-uniform frost heaving forces, significantly weakening the rock mass structure. Currently, the research on the freeze-thaw instability mechanism of dipping hard rock slopes with low-saturation fractures is insufficient, restricting the safe and efficient mining of mines in cold regions. Summary of the Invention

[0003] The present invention provides a test device and a using method for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures, which can study the rock mechanical properties and slope weakening problems under temperature gradients, different initial saturations, and preloading conditions by referring to the actual environment of low-saturation fractured rock masses in cold-region slopes, and can provide theoretical support for the prevention and control of cold-region mine slopes.

[0004] The technical solution of the present invention is as follows:

[0005] A test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures includes a temperature gradient generation module, a load application module, a water supply module, a test module, and a computer system. The temperature gradient generation module is used to control temperature changes to simulate the temperature gradient at the slope site. The load application module is used to control the preloading situation to simulate the overburden pressure at the slope site. The water supply module is used to supply water. The test module is used to monitor the surface temperature of the rock specimen and the magnitude of the frost heaving force. The computer system is used to analyze data and implement control.

[0006] Furthermore, for the test device for the growth of segregated ice and the evolution of frost heaving force in low-temperature and low-saturation rock fractures, the temperature gradient generation module includes a heat preservation cavity, a water bath temperature control system, copper tubes, and aluminum beads. Five groups of copper tubes are embedded in the cavity wall of the heat preservation cavity and distributed from top to bottom. Five water bath temperature control systems are respectively connected to the five groups of copper tubes. The rock specimen is placed in the heat preservation cavity, and aluminum beads are placed between the rock specimen and the cavity wall of the heat preservation cavity.

[0007] Furthermore, for the test device for the growth of segregated ice and the evolution of frost heaving force in low-temperature and low-saturation rock fractures, the water bath temperature control system includes a refrigerant storage tank, a temperature controller, a temperature sensor, a compression refrigerator, and an electric heating heat exchanger. A liquid heat transfer medium is stored in the refrigerant storage tank. The compression refrigerator is used to lower the temperature of the liquid heat transfer medium, and the electric heating heat exchanger is used to increase the temperature of the liquid heat transfer medium. The temperature sensor is used to monitor the temperature of the liquid heat transfer medium and transmit it to the temperature controller, and the temperature controller is used to control the compression refrigerator and the electric heating heat exchanger to adjust the temperature of the liquid heat transfer medium.

[0008] Furthermore, for the test device for the growth of segregated ice and the evolution of frost heaving force in low-temperature and low-saturation rock fractures, the load application module includes a bracket, an air pump, a load sensor, a cushion block, an upper pressure plate, a lower pressure plate, and a positioning nut. The lower part of the bracket is fixedly connected to the outside of the heat preservation cavity. The upper pressure plate, the air pump, the lower pressure plate, the load sensor, and the cushion block are stacked together from top to bottom in sequence. The upper pressure plate and the lower pressure plate are provided with installation holes and sleeved on the upper rod of the bracket. The positioning nut is screwed on the upper rod of the bracket to position the upper pressure plate and the lower pressure plate. The cushion block is in contact with the rock specimen in the heat preservation cavity.

[0009] Furthermore, for the test device for the growth of segregated ice and the evolution of frost heaving force in low-temperature and low-saturation rock fractures, the water supply module includes a Mariotte bottle and a hose. The Mariotte bottle is connected to the water inlet at the bottom of the heat preservation cavity through the hose. The air inlet of the Mariotte bottle is used to stabilize the water level in the heat preservation cavity, and the scale on the bottle body of the Mariotte bottle is used to quantify the water replenishment amount of the heat preservation cavity.

[0010] Furthermore, for the test device for the growth of segregated ice and the evolution of frost heaving force in low-temperature and low-saturation rock fractures, the test module includes a strain gauge, a thermocouple thermometer, and a thin film pressure sensor. Multiple strain gauges of the strain gauge are pasted on the upper part of the fracture of the rock specimen to monitor the strain effect generated by the water-ice phase change of the rock specimen. The thin film pressure sensor is placed on the upper part of the fracture of the rock specimen to monitor the magnitude of the frost heaving force. Multiple temperature probes of the thermocouple thermometer are evenly pasted on the surface of the rock specimen from top to bottom to monitor the surface temperature of the rock specimen.

[0011] Further, for the test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures, the computer system includes a computer and an A / D. The computer is connected to a load sensor, a strain gauge, a thermocouple thermometer, and a thin-film pressure sensor through the A / D.

[0012] Further, for the test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures, the heat preservation cavity is made of stainless steel material.

[0013] The usage method of the above test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures includes the following steps:

[0014] S1. Take several large pieces from in-situ rock masses. Under laboratory conditions, cut the large pieces into cuboid rock specimens. Use the Brazilian splitting method to form irregular surface-through fractures at the center of the rock specimens to simulate the fractures of slope rock masses in the natural state.

[0015] S2. Carry out a small amount of water replenishment for the fractures by spraying to simulate the water content of low-saturation slope rock masses.

[0016] S3. Uniformly paste multiple temperature probes of the thermocouple thermometer on the surface of the rock specimen from top to bottom. Set the temperature above the fracture of the rock specimen to be lower than the freezing temperature. Paste multiple strain gauges of the strain gauge on the upper part of the fracture of the rock specimen. Place the thin-film pressure sensor on the upper part of the fracture of the rock specimen to monitor the surface temperature, frost heaving stress, and strain of the rock specimen.

[0017] S4. Put the rock specimen into the heat preservation cavity, cover the rock specimen completely with the aluminum beads. After the cushion block is in direct contact with the rock specimen, seal the heat preservation cavity to ensure the experimental sealing and reduce heat loss.

[0018] S5. Use the air pump to apply a quantitative preset load. The load sensor transmits data to the computer. After the computer analyzes that the preset stress is reached, use the positioning nut to fix the lower pressure plate and the load sensor to achieve the effect of maintaining the preset stress.

[0019] S6. The five-part water bath temperature control system is set with a temperature gradient from low to high from top to bottom respectively. Wrap the heat preservation cavity with a heat preservation blanket to reduce heat loss.

[0020] S7. After the temperature is stable, inject red ink into the Marriotte bottle cavity. Connect the Marriotte bottle to the water inlet at the bottom of the heat preservation cavity, stabilize the water replenishment interface, and observe the drop amount of the water level in the Marriotte bottle to quantify the water replenishment amount.

[0021] S8. After 72 hours, take out the rock specimen, suspend the acquisition of various data, take pictures to record the rising position of the red ink, so as to observe the migration of moisture under the action of temperature gradient and the segregated ice in the low-temperature area, and analyze the strain and temperature data;

[0022] S9. Select a new rock specimen, adjust the temperature gradient, the water supply condition on the rock surface and the preload value, repeat steps S1 to S8, and analyze the moisture migration amount in the cracks of low-saturation fractured rock under the coupled thermal-hydro-mechanical action according to the moisture migration amount and the crack frost heave strain value. Take out for naked-eye observation and photography, and quantify the distribution thickness of the segregated ice in the cracks and the variation law of the crack frost heave force.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1) The device of the present invention can control the temperature gradient and the preload, solving the problem of lacking experimental equipment for the generation of segregated ice in fractured rocks in the laboratory under the action of different temperature gradients and preloads.

[0025] 2) A mechanical test method for slope fractured rock mass considering the actual thermal-hydro-mechanical occurrence environment of the slope proposed by the present invention. Under the conditions of the mechanical properties of the rock specimen under the action of a stable temperature gradient, moisture migration and preload, and the weakening problem of the slope, the actual environment and stress conditions of the cold region slope are fully considered, and the stability problem of the cold region slope rock mass containing low-saturation fractures under the influence of ice segregation is studied more deeply and scientifically. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the test device for the growth of segregated ice and the evolution process of frost heave force in fractures of low-temperature and low-saturation rocks;

[0027] Figure 2 It is a schematic diagram of the combination of the load application module and the insulation cavity;

[0028] Figure 3 It is a structural diagram of the water bath temperature control system. Detailed Embodiment

[0029] As Figures 1-3 shown, the test device for the growth of segregated ice and the evolution process of frost heave force in fractures of low-temperature and low-saturation rocks includes a temperature gradient generation module, a load application module, a moisture supply module, a test module and a computer system. The temperature gradient generation module is used to control the temperature change to simulate the temperature gradient at the slope site. The load application module is used to control the preload loading situation to simulate the overburden pressure at the slope site. The moisture supply module is used to supply moisture. The test module is used to monitor the surface temperature of the rock specimen 3 and the magnitude of the frost heave force. The computer system is used to analyze data and implement control.

[0030] The temperature gradient generation module includes a heat preservation cavity 1, a water bath temperature control system 2, a copper pipe 12, and an aluminum bead 13. The heat preservation cavity 1 is made of stainless steel. Five groups of copper pipes 12 are embedded in the cavity wall of the heat preservation cavity 1 and distributed from top to bottom. Five water bath temperature control systems 2 are respectively connected to the five groups of copper pipes 12. A rock specimen 3 is placed in the heat preservation cavity 1. Aluminum beads 13 are placed between the rock specimen 3 and the cavity wall of the heat preservation cavity 1. The aluminum beads 13 are in close contact with the rock specimen 3, enabling more efficient heat conduction, transferring the temperature to the surface of the rock specimen 3, and reducing temperature loss.

[0031] The water bath temperature control system 2 includes a refrigerant storage tank 25, a temperature controller 21, a temperature sensor 22, a compression refrigeration machine 23, and an electric heating heat exchanger 24. A liquid heat transfer medium is stored in the refrigerant storage tank 25. The compression refrigeration machine 23 is used to lower the temperature of the liquid heat transfer medium, and the electric heating heat exchanger 24 is used to increase the temperature of the liquid heat transfer medium. The temperature sensor 22 is used to monitor the temperature of the liquid heat transfer medium and transmit it to the temperature controller 21. The temperature controller 21 is used to control the compression refrigeration machine 23 and the electric heating heat exchanger 24 to adjust the temperature of the liquid heat transfer medium.

[0032] The load application module includes a bracket 11, an air pump 4, a load sensor 5, a cushion block 6, an upper pressure plate 9, a lower pressure plate 10, and a positioning nut 17. The lower part of the bracket 11 is fixedly connected to the outside of the heat preservation cavity 1. The upper pressure plate 9, the air pump 4, the lower pressure plate 10, the load sensor 5, and the cushion block 6 are stacked on top of each other from top to bottom. The upper pressure plate 9 and the lower pressure plate 10 are provided with installation holes and sleeved on the upper rod of the bracket 11. The positioning nut 17 is screwed on the upper rod of the bracket 11 to position the upper pressure plate 9 and the lower pressure plate 10. The cushion block 6 is in contact with the rock specimen 3 in the heat preservation cavity 1.

[0033] The water supply module includes a Mariotte bottle 18 and a hose. The Mariotte bottle 18 is connected to the water inlet at the bottom of the heat preservation cavity 1 through the hose. The air inlet of the Mariotte bottle 18 is used to stabilize the water level in the heat preservation cavity 1. The scale on the body of the Mariotte bottle 18 is used to quantify the water replenishment amount of the heat preservation cavity 1.

[0034] The test module includes a strain gauge, a thermocouple thermometer, and a thin film pressure sensor 15. Multiple strain gauges 16 of the strain gauge are pasted on the upper part of the crack of the rock specimen 3 to monitor the strain effect generated by the water-ice phase change of the rock specimen 3. The thin film pressure sensor 15 is placed on the upper part of the crack of the rock specimen 3 to monitor the magnitude of the frost heaving force. Multiple temperature probes 14 of the thermocouple thermometer are evenly pasted on the surface of the rock specimen 3 from top to bottom to monitor the surface temperature of the rock specimen 3.

[0035] The computer system includes a computer 7 and an A / D 8. The computer 7 is connected to a load sensor 5, a strain gauge, a thermocouple thermometer, and a thin-film pressure sensor 15 through the A / D 8.

[0036] The usage method of the above test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures includes the following steps:

[0037] S1. Take several large pieces from in-situ rock masses. Under laboratory conditions, cut the large pieces into cuboid rock specimens 3, and use the Brazilian splitting method to form irregular surface-penetrating fractures at the center of the rock specimens to simulate the fractures of slope rock masses in the natural state.

[0038] S2. Carry out a small amount of water replenishment for the fractures by spraying to simulate the water content of low-saturation slope rock masses.

[0039] S3. Uniformly paste multiple temperature probes 14 of the thermocouple thermometer on the surface of the rock specimen 3 from top to bottom. Set the temperature above the fracture of the rock specimen 3 lower than the freezing temperature. Paste multiple strain gauges 16 of the strain gauge on the upper part of the fracture of the rock specimen 3, and place the thin-film pressure sensor 15 on the upper part of the fracture of the rock specimen 3 to monitor the surface temperature, frost heaving stress, and strain of the rock specimen 3.

[0040] S4. Place the rock specimen 3 into the heat preservation cavity 1, put the aluminum beads 13 to completely cover the rock specimen 3. After the spacer block 6 is in direct contact with the rock specimen 3, close the heat preservation cavity 1 to ensure the experimental seal and reduce heat loss.

[0041] S5. Use the air pump 4 to apply a quantitative preset load. The load sensor 5 transmits data to the computer 7. After the computer 7 analyzes that the preset stress is reached, use the positioning nut 17 to fix the lower pressing plate 10 and the load sensor 5 to achieve the effect of maintaining the preset stress.

[0042] S6. The five-part water bath temperature control system 2 is set with a temperature gradient from low to high from top to bottom, and use a heat preservation blanket to wrap the heat preservation cavity 1 to reduce heat loss.

[0043] S7. After the temperature is stable, inject red ink into the cavity of the Mariotte bottle 18, connect the Mariotte bottle 18 to the water inlet at the bottom of the heat preservation cavity 1, stabilize the water replenishment interface, and observe the water level drop in the Mariotte bottle 18 to quantify the water replenishment amount.

[0044] S8. After 72 hours, take out the rock specimen 3, suspend the acquisition of various data, take pictures to record the rising position of the red ink to observe the migration of water under the action of the temperature gradient, as well as the segregated ice in the low-temperature area, and analyze the strain and temperature data.

[0045] S9. Select a new rock specimen 3, adjust the temperature gradient, the water replenishment condition on the rock surface and the preloading value, repeat steps S1 to S8, analyze the moisture migration amount in the cracks of low-saturation cracked rocks under the coupled thermal-hydro-mechanical action according to the moisture migration amount and the crack frost heave strain value, take out for macroscopic observation and photographing, and quantify the distribution thickness of segregated ice in the cracks and the variation law of crack frost heave force.

Claims

1. A test device for the growth of segregated ice and the evolution process of frost heaving force in rock fractures at low temperature and low saturation, characterized in that, It includes a temperature gradient generation module, a load application module, a moisture supply module, a test module and a computer system. The temperature gradient generation module is used to control the temperature change to simulate the temperature gradient at the slope site. The load application module is used to control the pre-load application situation to simulate the overburden pressure at the slope site. The moisture supply module is used to supply moisture. The test module is used to monitor the surface temperature of the rock specimen and the magnitude of the frost heaving force. The computer system is used to analyze data and implement control.

2. The test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures according to claim 1, wherein The temperature gradient generation module includes a heat preservation cavity, a water bath temperature control system, copper tubes and aluminum beads. Five groups of copper tubes are embedded in the cavity wall of the heat preservation cavity and distributed from top to bottom. Five water bath temperature control systems are respectively connected to the five groups of copper tubes. The rock specimen is placed in the heat preservation cavity, and aluminum beads are placed between the rock specimen and the cavity wall of the heat preservation cavity.

3. The test device for the segregation ice growth and frost heaving force evolution process in low-temperature and low-saturation rock fractures according to claim 2, wherein The water bath temperature control system includes a refrigerant storage tank, a temperature controller, a temperature sensor, a compression refrigerator and an electric heating heat exchanger. A liquid heat transfer medium is stored in the refrigerant storage tank. The compression refrigerator is used to lower the temperature of the liquid heat transfer medium. The electric heating heat exchanger is used to increase the temperature of the liquid heat transfer medium. The temperature sensor is used to monitor the temperature of the liquid heat transfer medium and transmit it to the temperature controller. The temperature controller is used to control the compression refrigerator and the electric heating heat exchanger to adjust the temperature of the liquid heat transfer medium.

4. The test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures according to claim 2, wherein The load application module includes a bracket, an air pump, a load sensor, a cushion block, an upper pressure plate, a lower pressure plate and a positioning nut. The lower part of the bracket is fixedly connected to the outside of the heat preservation cavity. The upper pressure plate, the air pump, the lower pressure plate, the load sensor and the cushion block are stacked together from top to bottom in sequence. The upper pressure plate and the lower pressure plate are provided with mounting holes and sleeved on the upper rod of the bracket. The positioning nut is screwed on the upper rod of the bracket to position the upper pressure plate and the lower pressure plate. The cushion block is in contact with the rock specimen in the heat preservation cavity.

5. The test device for the segregation ice growth and frost heaving force evolution process in low-temperature and low-saturation rock fractures according to claim 2, wherein, The moisture supply module includes a Mariotte bottle and a hose. The Mariotte bottle is connected to the water inlet at the bottom of the heat preservation cavity through the hose. The air inlet of the Mariotte bottle is used to stabilize the water level in the heat preservation cavity. The scale on the bottle body of the Mariotte bottle is used to quantify the water replenishment amount of the heat preservation cavity.

6. The test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures according to claim 4, wherein The test module includes a strain gauge, a thermocouple thermometer and a thin film pressure sensor. Multiple strain gauges of the strain gauge are pasted on the upper part of the crack of the rock specimen to monitor the strain effect generated by the water-ice phase change of the rock specimen. The thin film pressure sensor is placed on the upper part of the crack of the rock specimen to monitor the magnitude of the frost heaving force. Multiple temperature probes of the thermocouple thermometer are evenly pasted on the surface of the rock specimen from top to bottom to monitor the surface temperature of the rock specimen.

7. The test device for the segregation ice growth and frost heaving force evolution process in low-temperature and low-saturation rock fractures according to claim 6, wherein The computer system includes a computer and an A / D. The computer is connected to the load sensor, the strain gauge, the thermocouple thermometer and the thin film pressure sensor through the A / D.

8. The test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures according to claim 2, wherein The heat preservation cavity is made of stainless steel material.

9. The method for using the test device for the growth of segregated ice and the evolution process of frost heaving force in low-temperature and low-saturation rock fractures as described in claim 7, characterized in that, It includes the following steps: S1. Take several large pieces from the in-situ rock mass. Under laboratory conditions, cut the large pieces into cuboid rock specimens, and use the Brazilian splitting method to form irregular surface-penetrating cracks at the center position of the rock specimens to simulate the cracks in the slope rock mass in the natural state. S2. Supplement a small amount of water to the crack by spraying to simulate the water content of the low-saturation slope rock mass. S3. Uniformly paste multiple temperature probes of the thermocouple thermometer on the surface of the rock specimen from top to bottom. Set the temperature above the crack of the rock specimen to be lower than the freezing temperature. Paste multiple strain gauges of the strain gauge on the upper part of the crack of the rock specimen, and place the thin-film pressure sensor on the upper part of the crack of the rock specimen to monitor the surface temperature, frost heaving stress and strain of the rock specimen; S4. Place the rock specimen into the insulation cavity, put the aluminum beads to completely cover the rock specimen. After the spacer block is in direct contact with the rock specimen, seal the insulation cavity to ensure the experimental sealing and reduce heat loss; S5. Use the air pump to apply a quantitative preset load under pressure. The load sensor transmits data to the computer. After the computer analyzes that the preset stress is reached, use the positioning nut to fix the lower pressure plate and the load sensor to achieve the effect of maintaining the preset stress; S6. The five-part water bath temperature control system is set with temperature gradients from low to high from top to bottom respectively. Wrap the insulation cavity with a heat preservation blanket to reduce heat loss; S7. After the temperature is stable, inject red ink into the Marriotte bottle cavity, connect the Marriotte bottle to the water inlet at the bottom of the insulation cavity, stabilize the water replenishment interface, and observe the water level drop in the Marriotte bottle to quantify the water replenishment amount; S8. After 72 hours, take out the rock specimen, pause the collection of all data, take pictures to record the rising position of the red ink to observe the migration of water under the action of the temperature gradient and the segregated ice in the low-temperature area, and analyze the strain and temperature data; S9. Select a new rock specimen, adjust the temperature gradient, the water replenishment condition on the rock surface and the pre-load value, repeat steps S1 to S8. According to the water migration amount and the crack frost heaving strain value, analyze the water migration amount in the crack under the thermo-hydro-mechanical coupling action of the low-saturation cracked rock. Take out for visual observation and photography to quantify the distribution thickness of the segregated ice in the crack and the change law of the crack frost heaving force.

Images