A high-temperature cold-impact triaxial testing device and method

Abstract

The application provides a high-temperature cold impact triaxial test device and method, and relates to the technical field of rock mechanics test.The high-temperature cold impact triaxial test device comprises a loading unit, a heating unit, a liquid nitrogen cold impact unit and a sensor device.The high-temperature cold impact triaxial test device and method can accurately simulate the high-temperature cold impact process of a rock sample under triaxial loading conditions, are suitable for studying the influence of different confining pressures, high temperatures and cold impact coupling on the mechanical properties and failure modes of rocks, and provide more accurate data support and theoretical basis for the quantitative analysis of the mechanical response of rocks under complex environments in deep engineering.The rock sample is easy to install and operate, the processes of temperature rising, temperature keeping and cold impact are easy to control, the cold impact rate and amplitude can be accurately adjusted, and the test requirements can be effectively met.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, and more specifically to a high-temperature cold shock triaxial testing apparatus and method. Background Technology

[0002] In the exploration and development of deep energy resources such as deep oil and gas, geothermal energy, and coalbed methane, rocks often face complex environments including high ground stress and cold shocks from high-temperature surrounding rocks. Examples include the cold shock of drilling fluid on the high-temperature surrounding rocks during deep drilling, and the cold shock of water and liquid nitrogen on high-temperature reservoir rocks during fracturing for oil and gas reservoir enhancement. Cold shocks cause sudden temperature changes in the high-pressure, high-temperature surrounding rocks, leading to non-uniform deformation within the surrounding rocks, the expansion of existing fractures, or the initiation of new fractures, significantly impacting the strength of the surrounding rocks. Investigating the mechanical response and damage mechanisms of rocks under the coupled effects of high temperature, high pressure, and cold shocks is crucial for engineering design, stability assessment, and resource extraction efficiency.

[0003] Triaxial compression testing of rocks is an important tool in geotechnical engineering for studying the mechanical properties of rocks. However, existing triaxial testing equipment mostly focuses on determining the basic mechanical parameters of rocks under normal temperature or stable high temperature and high pressure conditions. Although some experimental equipment can achieve the rock cooling process through water cooling, water cooling heat exchange is time-consuming and the cooling rate is slow, making it difficult to achieve the effect of high temperature cold shock. Furthermore, water cooling has a certain time delay effect, making it impossible to accurately control the cooling rate and magnitude, and making it difficult to accurately simulate the damage and mechanical response of rocks under the coupled effects of high pressure, high temperature and cold shock.

[0004] Therefore, there is an urgent need for a new type of experimental device that can simulate the high-temperature cold shock of rock samples under triaxial loading conditions, study the effects of the coupling effect of confining pressure, high temperature and cold shock on the mechanical properties and failure modes of rocks, and provide more accurate data support and theoretical basis for the analysis of rock mechanical response in complex environments in deep engineering. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature cold shock triaxial testing device and method to accurately simulate the high-temperature cold shock of rock samples under triaxial loading conditions, and to solve the problems of slow cooling rate and difficult cooling control when existing triaxial testing devices are used for cold shock tests.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-temperature cold shock triaxial testing apparatus, comprising:

[0008] A loading unit is used to apply axial and confining pressures to the rock sample.

[0009] Heating unit, used to transfer heat to the rock sample;

[0010] The liquid nitrogen cold shock unit is used to transfer the cold energy generated by the vaporization of liquid nitrogen to the rock sample;

[0011] Sensors are used to monitor and collect data on the mechanical state of rock samples and the temperature changes of the environment in which the rock samples are located.

[0012] Preferably, the loading unit includes a loading frame, an axial pressure cylinder, a loading shaft, a loading head, a loading base, a confining pressure chamber, and a confining pressure pump;

[0013] The axial pressure cylinder is located at the upper end of the loading frame. The telescopic end of the axial pressure cylinder is connected to one end of the loading shaft, and the loading head is located at the other end of the loading shaft.

[0014] The loading base is located directly below the loading head, and a loading pad is provided on the loading base;

[0015] A rock sample is placed between the loading pad and the loading head, and an axial load is applied to the rock sample by the loading pad and the loading head.

[0016] The confining pressure chamber has an opening at the lower end, and the lower end of the confining pressure chamber can seal and connect to the edge of the loading base. The loading shaft passes through the upper end of the confining pressure chamber, and the loading shaft can dynamically seal and connect to the confining pressure chamber.

[0017] The confining pressure pump is connected to the confining pressure chamber via a hydraulic pipeline. The confining pressure pump is used to inject confining pressure fluid at a set pressure into the confining pressure chamber, and the confining pressure fluid applies confining pressure to the rock sample.

[0018] Preferably, the loading frame is provided with a lifting slide rail, which is arranged vertically;

[0019] The confining chamber is equipped with a lifting slider, which slides in conjunction with the lifting slide rail.

[0020] A lifting cylinder is installed on the loading frame. The lifting cylinder is arranged vertically, and the telescopic end of the lifting cylinder is connected to the confining pressure chamber.

[0021] Preferably, the outer wall of the confining chamber is provided with a thermal insulation layer.

[0022] Preferably, a groove is formed at the upper end of the loading base, and the loading pad is placed in the groove.

[0023] Preferably, the loading unit further includes a servo controller, which is signal-connected to the axial pressure cylinder and the confining pressure pump respectively.

[0024] Preferably, the heating unit includes a resistance wire, a power controller, and a power source. The resistance wire is connected to the power source via the power controller. The resistance wire is fixed to the top of the confining chamber and is arranged around the rock sample.

[0025] Preferably, the liquid nitrogen cold shock unit includes a liquid nitrogen storage tank, a multi-way valve, a cooling hollow column, and a vacuum pump;

[0026] The liquid nitrogen storage tank is filled with liquid nitrogen. The outlet of the liquid nitrogen storage tank is connected to the inlet of a multi-way valve via an inlet pipe. Several outlets of the multi-way valve are connected to cooling hollow columns via delivery pipes. The cooling hollow columns are located in the confining pressure chamber. Several cooling hollow columns are arranged around the rock sample. The cooling hollow columns are connected to the vacuum pump via an outlet pipe.

[0027] Preferably, the cooling hollow column is divided into a liquid storage chamber and a vaporization chamber;

[0028] The infusion pipeline is connected to the liquid storage chamber, and the gas outlet pipeline is connected to the vaporization chamber;

[0029] The liquid storage chamber and the vaporization chamber are connected by a transition pipeline;

[0030] The infusion pipeline is equipped with an inlet high-frequency solenoid valve, the transition pipeline is equipped with a vaporization high-frequency solenoid valve, and the outlet pipeline is equipped with an exhaust high-frequency solenoid valve.

[0031] By controlling the opening and closing frequency, number of times, and duration of the liquid inlet high-frequency solenoid valve, the vaporization high-frequency solenoid valve, and the exhaust high-frequency solenoid valve, liquid nitrogen first flows into the liquid storage chamber, and then flows through the liquid storage chamber into the vacuum vaporization chamber. The cooling hollow column achieves cold impact on the rock sample in the confining pressure chamber.

[0032] A high-temperature cold shock triaxial test method, using the above-mentioned high-temperature cold shock triaxial test apparatus, includes the following steps:

[0033] Step 1: Rock Sample Installation

[0034] After sealing and wrapping the rock sample with the loading pad, it is placed on the groove of the loading base. The lifting cylinder drives the confining pressure chamber to descend, so that the lower end of the confining pressure chamber is sealed and connected to the edge of the loading base.

[0035] Step 2: Apply axial compression and confining pressure

[0036] The axial pressure cylinder drives the loading head through the loading shaft to act on the upper end of the rock sample, applying initial axial pressure to the rock sample. The confining pressure pump injects the set confining pressure fluid into the confining pressure chamber to apply confining pressure to the rock sample.

[0037] Step 3: Heat and maintain the temperature

[0038] Turn on the power and control the resistance wire to heat the confining fluid through the power controller. The heat is then transferred to the rock sample through the confining fluid, raising both the confining fluid and the rock sample to the set temperature and maintaining it.

[0039] Step 4, Cooling shock

[0040] Liquid nitrogen from the liquid nitrogen storage tank is intermittently injected into the vaporization chamber of the cooling hollow column to vaporize and absorb heat, thereby reducing the temperature of the confining fluid and the rock sample and subjecting the rock sample to cold shock.

[0041] Step 5, Rock Sample Loading

[0042] After the rock sample has undergone the confining pressure, heating, and cold shock cooling set in the test, the rock sample is continuously loaded using a loading unit;

[0043] During steps 2 to 5, the sensor device monitors and collects the mechanical state data of the rock sample and the temperature change of the environment in which the rock sample is located in real time.

[0044] Step 6: Rock sample removal

[0045] The confining pressure pump discharges the confining pressure fluid from the confining pressure chamber, the lifting cylinder drives the confining pressure chamber to rise, the rock sample is removed, and the test ends.

[0046] The beneficial technical effects of this invention are:

[0047] The high-temperature cold shock triaxial testing apparatus and method of this invention places a cooling hollow column (vaporization chamber) in the confining pressure chamber. It utilizes the phase change of liquid nitrogen to absorb heat from the confining pressure liquid, thereby reducing the temperature of the confining pressure liquid and the rock sample within the confining pressure chamber. Furthermore, through the control of a high-frequency solenoid valve for liquid inlet, a high-frequency solenoid valve for vaporization, and a high-frequency solenoid valve for exhaust, the frequency and total amount of liquid nitrogen vaporization are precisely controlled, thus achieving precise control of the cooling rate and amplitude. Moreover, the liquid nitrogen vaporization rate is fast, and there is no delay in energy absorption during a single vaporization, effectively solving the problems of large delays in traditional water-cooled cooling and difficulty in accurately controlling the cooling rate and amplitude. This makes it better suited for studying the influence of the coupling effect of pressure and high-temperature cold shock on the mechanical properties and failure modes of rocks, providing more accurate data support and theoretical basis for the analysis of rock mechanical response in complex engineering environments. The installation of the rock sample and the operation of temperature rise, heat preservation, and cooling shock are simple, and the cooling rate and amplitude can be accurately controlled, easily and accurately achieving the experimental objectives. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the high-temperature cold shock triaxial testing device in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the loading unit portion in an embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram of the heating unit in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of the liquid nitrogen cold shock unit in an embodiment of the present invention;

[0052] Figure 5This is a flowchart of the high-temperature cold shock triaxial test method in an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Certain embodiments of the invention will be described more fully below with reference to the accompanying drawings, and some, but not all, of these embodiments will be shown. In fact, various embodiments of the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to enable the invention to meet applicable legal requirements.

[0054] In the description of this invention, it should be noted that the terms "inner," "outer," "upper," "lower," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In this embodiment of the invention, a high-temperature cold shock triaxial testing apparatus and method are provided. Please refer to [reference needed]. Figures 1 to 5 As shown.

[0056] A high-temperature cold shock triaxial testing device includes a loading unit, a heating unit, a liquid nitrogen cold shock unit, and sensor components.

[0057] Rock sample 4 is placed on the loading unit, which is used to apply axial pressure and confining pressure to rock sample 4.

[0058] The loading unit includes a loading frame 101, a axial pressure cylinder 102, a loading shaft 103, a loading head 104, a loading base 111, a confining pressure chamber 106, and a confining pressure pump 108.

[0059] A axial pressure cylinder 102 is located at the upper end of the loading frame 101. The telescopic end of the axial pressure cylinder 102 is connected to one end of the loading shaft 103, and the other end of the loading shaft 103 is provided with a spherical loading head 104. The loading base 111 is located directly below the loading head 104. A groove is formed at the upper end of the loading base 111, and a loading pad 105 is placed in the groove. A rock sample is placed between the loading pad 105 and the loading head 104, and the loading pad 105 and the loading head 104 apply an axial load to the rock sample 4. The lower end of the confining pressure chamber 106 is open, and the lower end of the confining pressure chamber 106 can seal and connect to the edge of the loading base 111. The loading shaft 103 passes through the upper end of the confining pressure chamber 106, and the loading shaft 103 can dynamically seal and connect to the confining pressure chamber 106. The confining pressure pump 108 is connected to the confining pressure chamber 106 via a hydraulic pipeline. The confining pressure pump 108 is used to inject confining pressure fluid at a set pressure into the confining pressure chamber 106, and the confining pressure fluid applies confining pressure to the rock sample 4.

[0060] A lifting slide rail 110 is provided on the loading frame 101, and the lifting slide rail 110 is arranged vertically. A lifting slider is provided on the outer wall of the confining pressure chamber 106, and the lifting slider slides in conjunction with the lifting slide rail 110. A lifting cylinder 109 is provided at the bottom of the loading frame 101, and the lifting cylinder 109 is arranged vertically. The telescopic end of the lifting cylinder 109 is connected to the outer wall of the confining pressure chamber 106.

[0061] The outer wall of the pressure chamber 106 is provided with an insulation layer 107 to maintain the temperature inside the pressure chamber 106 and prevent experimental personnel from being burned and heat loss.

[0062] The servo controller 112 is connected to the axial pressure cylinder 102 and the confining pressure pump 108 via signal cables. It is used to control the axial pressure cylinder 102 to apply axial load to the rock sample 4 and the confining pressure pump 108 to apply confining pressure to the rock sample 4, thereby reducing the fluctuation of axial load and confining pressure caused by temperature changes in the confining pressure fluid and the rock sample 4.

[0063] A heating unit is used to transfer heat to rock sample 4.

[0064] The heating unit includes a resistance wire 201, a power controller 202, and a power supply 203. The resistance wire 201 is connected to the power supply 203 via the power controller 202. The resistance wire 201 is fixed to the top of the confining chamber 106 and is arranged around the rock sample 4. The power of the resistance wire 201 is controlled by the power controller 202 to adjust the heating rate and amplitude. Several support rods are arranged circumferentially at the top of the confining chamber 106, and the resistance wire 201 is wound around these support rods.

[0065] Resistance wires 201 are arranged around rock sample 4 and work with confining fluid in confining chamber 106. The resistance wires 201 around rock sample 4 heat the confining fluid in confining chamber 106, and the confining fluid then conducts heat to rock sample 4. The confining fluid surrounds rock sample 4, which can make the confining fluid and rock sample 4 heat up quickly and evenly to the set temperature value.

[0066] The liquid nitrogen cold shock unit is used to transfer the cold energy generated by the vaporization of liquid nitrogen to rock sample 4.

[0067] The liquid nitrogen cold shock unit includes a liquid nitrogen storage tank 301, a multi-way valve 302, a cooling hollow column, and a vacuum pump 304.

[0068] Liquid nitrogen storage tank 301 is filled with liquid nitrogen. The outlet of liquid nitrogen storage tank 301 is connected to the inlet of multi-way valve 302 via an inlet pipe. Several outlets of multi-way valve 302 are connected to cooling hollow columns via delivery pipes. The cooling hollow columns are located in confining pressure chamber 106. Several cooling hollow columns are arranged around rock sample 4. The cooling hollow columns are connected to vacuum pump 304 via an outlet pipe.

[0069] The cooling hollow columns are arranged around the rock sample 4 and work in conjunction with the confining fluid in the confining pressure chamber 106. The cooling hollow columns around the rock sample 4 cool the confining fluid in the confining pressure chamber 106, and the confining fluid in the confining pressure chamber 106 then conducts the cooling energy to the rock sample 4. The confining fluid surrounds the rock sample 4, which enables the confining fluid and the rock sample 4 to be rapidly and uniformly reduced to the set temperature value.

[0070] The cooling hollow column is divided into a liquid storage chamber 3032 and a vaporization chamber 3034. A liquid inlet pipeline connects to the liquid storage chamber 3032, and a vapor outlet pipeline connects to the vaporization chamber 3034. The liquid storage chamber 3032 and the vaporization chamber 3034 are connected by a transition pipeline. A liquid inlet high-frequency solenoid valve 3031 is installed on the liquid inlet pipeline, a vaporization high-frequency solenoid valve 3033 is installed on the transition pipeline, and an exhaust high-frequency solenoid valve 3035 is installed on the exhaust pipeline. The sidewalls of the vaporization chamber 3034 are made of a highly thermally conductive material to efficiently absorb external energy.

[0071] Before injecting liquid nitrogen into the vaporization chamber 3034, the vaporization chamber 3034 is first evacuated by the vacuum pump 304.

[0072] By controlling the opening and closing frequency, number of times, and duration of the liquid inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035, the liquid inlet frequency, vaporization frequency, and exhaust frequency are controlled and cyclically operated. By controlling the cyclic speed and the number of cycles, the heat absorption rate and heat absorption energy of the vaporization chamber 3034 are controlled.

[0073] The solenoid valve controller 305 is connected to the liquid inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035 via signal cables to control the opening and closing frequency, number of times, and duration of each high-frequency solenoid valve.

[0074] Liquid nitrogen first flows into the storage chamber 3032, and then flows into the vacuum vaporization chamber 3034. In the vaporization chamber 3034, the liquid nitrogen changes from liquid to gas. The phase change of nitrogen absorbs heat in the confining pressure chamber 106, thereby reducing the temperature in the confining pressure chamber 106. Then, it is discharged through the exhaust high-frequency solenoid valve 3035 and the vacuum pump 304. The vaporization chamber 3034, which cools the hollow column, achieves cold impact on the rock sample 4 in the confining pressure chamber 106.

[0075] The sensor is used to monitor and collect the mechanical state data of rock sample 4 and the temperature change of the environment in which rock sample 4 is located.

[0076] The sensor components include temperature sensors, stress sensors, strain sensors, and acoustic emission sensors, and the sensor signals are connected to the data acquisition unit (computer).

[0077] A high-temperature cold shock triaxial test method, using the high-temperature cold shock triaxial test apparatus described in this embodiment, includes the following steps:

[0078] Step 1: Rock Sample Installation

[0079] After sealing and wrapping the rock sample 4 with the loading pad 105, it is placed on the groove of the loading base 111. The lifting cylinder 109 drives the confining pressure chamber 106 to descend, so that the lower end of the confining pressure chamber 106 is sealed to the edge of the loading base 111.

[0080] Step 2: Apply axial compression and confining pressure

[0081] The axial pressure cylinder 102 drives the loading head 104 through the loading shaft 103 to act on the upper end of the rock sample 4, applying initial axial pressure to the rock sample 4. The confining pressure pump 108 injects the set confining pressure liquid into the confining pressure chamber 106 to apply confining pressure to the rock sample 4.

[0082] Step 3: Heat and maintain the temperature

[0083] Turn on the power supply 203, and control the resistance wire 201 to heat the confining fluid through the power controller 202. The heat is transferred to the rock sample 4 through the confining fluid, so that the confining fluid and the rock sample 4 are heated to the set temperature value and maintained.

[0084] Step 4, Cooling shock

[0085] Liquid nitrogen from the liquid nitrogen storage tank 301 is intermittently injected into the vaporization chamber 3034 of the cooling hollow column to vaporize and absorb heat, thereby reducing the temperature of the confining liquid and rock sample 4 and subjecting rock sample 4 to cold shock.

[0086] Specifically, the solenoid valve controller 305 is connected to the liquid inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035 via signal cables to control the rapid opening and closing of the liquid inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035.

[0087] The liquid inlet high-frequency solenoid valve 3031 opens, and the vaporization high-frequency solenoid valve 3033 closes, allowing liquid nitrogen from the liquid nitrogen storage tank 301 to enter the storage chamber 3032. The storage chamber 3032 acts as a buffer and pressure stabilizer, completing the liquid inlet operation. The liquid inlet high-frequency solenoid valve 3031 closes, the vaporization high-frequency solenoid valve 3033 opens, and the exhaust high-frequency solenoid valve 3035 closes, allowing liquid nitrogen to enter the vaporization chamber 3034 from the storage chamber 3032. The liquid nitrogen vaporizes and absorbs heat, causing a rapid drop in temperature within the vaporization chamber 3034. The vaporization chamber 3034 absorbs heat from the confining fluid and rock sample 4 within the confining pressure chamber 106, rapidly reducing the temperature of the confining fluid and rock sample 4, thus completing the vaporization heat absorption operation and achieving a cold shock to the rock sample 4. The exhaust high-frequency solenoid valve 3035 is opened, the liquid inlet high-frequency solenoid valve 3031 is opened, and the vaporization high-frequency solenoid valve 3033 is closed. Under the action of the vacuum pump 304, nitrogen is discharged through the exhaust pipeline, and liquid nitrogen continues to enter the liquid storage chamber 3032 from the liquid nitrogen storage tank 301, completing the exhaust and liquid inlet operation.

[0088] The opening and closing frequency, number of times, and duration of the liquid inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035 are controlled by the solenoid valve controller 305, thereby controlling the frequency, number of times, and duration of heat absorption during vaporization of liquid nitrogen in the vaporization chamber 3034, and ultimately accurately controlling the cooling rate and amplitude.

[0089] Step 5, Rock Sample Loading

[0090] After rock sample 4 underwent the confining pressure, heating, and cold shock cooling set in the test, the loading unit continuously loaded rock sample 4.

[0091] During steps 2 to 5, the sensor device monitors and collects the mechanical state data of rock sample 4 and the temperature change of the environment in which rock sample 4 is located in real time.

[0092] Specifically, the ambient temperature of rock sample 4 is monitored and collected in real time by a temperature sensor, and stress and strain data of rock sample 4 under stress and high temperature cold shock are collected by stress sensor and strain sensor. The minute stress changes and deformations of rock sample 4 are recorded in real time, and the acoustic emission parameters of rock sample 4 are recorded in real time by acoustic emission sensor, so as to provide accurate data for subsequent mechanical analysis.

[0093] Step 6: Rock sample removal

[0094] Confining pressure pump 108 discharges confining pressure fluid from confining pressure chamber 106, lifting cylinder 109 drives confining pressure chamber 106 to rise, rock sample 4 is removed, and the failure mode of rock sample 4 is observed. By analyzing the mechanical property data of rock sample 4 during the entire high-temperature cold shock and loading process, the influence law of the coupling effect of confining pressure and high-temperature cold shock on the mechanical properties and damage of rock is obtained, and the test ends.

[0095] This concludes the detailed description of this embodiment with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the high-temperature cold shock triaxial testing apparatus and method of the present invention. The high-temperature cold shock triaxial test apparatus and method of the present invention sets a cooling hollow column (vaporization chamber 3034) inside the confining pressure chamber 106. It utilizes the phase change of liquid nitrogen to absorb heat from the confining pressure liquid, thereby reducing the temperature of the confining pressure liquid and rock sample 4 within the confining pressure chamber 106. Furthermore, through the control of the inlet high-frequency solenoid valve 3031, the vaporization high-frequency solenoid valve 3033, and the exhaust high-frequency solenoid valve 3035, precise control of the liquid nitrogen vaporization frequency and total amount is achieved, thus enabling precise control of the cooling rate and amplitude. Moreover, the liquid nitrogen vaporization rate is fast, and there is no delay in energy absorption during a single vaporization, effectively solving the problems of large delays in traditional water-cooled cooling and difficulty in accurately controlling the cooling rate and amplitude. This makes it better suited for studying the influence of the coupling effect of pressure and high-temperature cold shock on the mechanical properties and failure modes of rocks, providing more accurate data support and theoretical basis for the analysis of rock mechanical response in complex engineering environments. The installation of the rock sample 4 and the operation of temperature rise, heat preservation, and cooling shock are simple, and the cooling rate and amplitude can be accurately controlled, easily and accurately achieving the test objectives.

[0096] Of course, the specific embodiments described above further illustrate the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high temperature cold shock triaxial testing apparatus, characterized by, The application relates to a high-temperature cold-impact triaxial test device. The device comprises a loading unit, a heating unit and a liquid nitrogen cold-impact unit. The loading unit is provided with a rock sample and is used for applying axial pressure and confining pressure to the rock sample. The loading unit comprises a loading frame, an axial pressure oil cylinder, a loading shaft, a loading pressure head, a loading base, a confining pressure chamber and a confining pressure pump. The axial pressure oil cylinder is arranged at the upper end of the loading frame, the telescopic end of the axial pressure oil cylinder is connected with one end of the loading shaft, and the other end of the loading shaft is provided with the loading pressure head. The loading base is located directly below the loading pressure head, and the loading base is provided with a loading pad. The rock sample is placed between the loading pad and the loading pressure head, and the loading pad and the loading pressure head apply axial load to the rock sample. The lower end of the confining pressure chamber is open, the lower end of the confining pressure chamber can be sealingly connected with the edge of the loading base, the loading shaft passes through the upper end of the confining pressure chamber, and the loading shaft can be dynamically sealingly connected with the confining pressure chamber. The confining pressure pump is connected with the confining pressure chamber through a hydraulic pipeline, the confining pressure pump is used for injecting confining pressure liquid with a set pressure into the confining pressure chamber, and the rock sample is applied with confining pressure by the confining pressure liquid. The heating unit is used for transferring heat to the rock sample. The liquid nitrogen cold-impact unit is used for transferring cold energy generated by gasification of liquid nitrogen to the rock sample. The liquid nitrogen cold-impact unit comprises a liquid nitrogen storage tank, a multi-way valve, a cooling hollow column and a vacuum pump. The liquid nitrogen storage tank is filled with liquid nitrogen, the liquid outlet of the liquid nitrogen storage tank is connected with the liquid inlet of the multi-way valve through a liquid inlet pipeline, a plurality of liquid outlets of the multi-way valve are connected with the cooling hollow column through liquid delivery pipelines, the cooling hollow column is located in the confining pressure chamber, the plurality of cooling hollow columns are arranged around the rock sample, and the cooling hollow column is connected with the vacuum pump through a gas outlet pipeline. The cooling hollow column is divided into a liquid storage chamber and a gasification chamber. The liquid delivery pipeline is connected with the liquid storage chamber, and the gas outlet pipeline is connected with the gasification chamber. The liquid storage chamber and the gasification chamber are communicated through a transition pipeline. The liquid inlet high-frequency electromagnetic valve is arranged on the liquid delivery pipeline, the gasification high-frequency electromagnetic valve is arranged on the transition pipeline, and the exhaust high-frequency electromagnetic valve is arranged on the gas outlet pipeline. By controlling the opening and closing frequency, times and duration of the liquid inlet high-frequency electromagnetic valve, the gasification high-frequency electromagnetic valve and the exhaust high-frequency electromagnetic valve, the liquid nitrogen first flows into the liquid storage chamber, then flows into the gasification chamber in a vacuum state through the liquid storage chamber, and the cooling hollow column realizes cold impact on the rock sample in the confining pressure chamber. The electromagnetic valve controller is connected with the liquid inlet high-frequency electromagnetic valve, the gasification high-frequency electromagnetic valve and the exhaust high-frequency electromagnetic valve through signal cables respectively, so as to control the opening and closing frequency, times and duration of the high-frequency electromagnetic valves. The sensor device is used for monitoring and collecting the mechanical state data of the rock sample and the environmental temperature change of the rock sample.

2. The high-temperature cold-impact triaxial test device according to claim 1, wherein the loading frame is provided with lifting sliding rails arranged along the vertical direction. The confining pressure chamber is provided with lifting sliding blocks which are slidingly matched with the lifting sliding rails. The loading frame is provided with lifting oil cylinders arranged along the vertical direction, and the telescopic end of the lifting oil cylinder is connected with the confining pressure chamber.

3. The high-temperature cold-impact triaxial test device according to claim 1, wherein the outer wall of the confining pressure chamber is provided with a heat preservation layer. ​ 4. The high-temperature cold-shock triaxial test device according to claim 1, characterized in that: the upper end of the loading base is provided with a groove, and the loading pad is placed in the groove.

5. The high-temperature cold-shock triaxial test device according to claim 1, characterized in that: the loading unit further comprises a servo controller, and the servo controller is signal connected to the shaft pressure oil cylinder and the confining pressure pump, respectively.

6. The high-temperature cold-shock triaxial test device according to claim 1, characterized in that: the heating unit comprises a resistance wire, a power controller and a power supply, the resistance wire is connected to the power supply through the power controller, the resistance wire is fixed to the top of the confining pressure chamber, and the resistance wire is arranged around the rock sample.

7. A high temperature cold shock triaxial test method using the high temperature cold shock triaxial test apparatus according to any one of claims 1 to 6, characterized by, comprising the following steps: Step 1, rock sample installation After the rock sample and the loading pad are sealed and wrapped, they are placed on the groove of the loading base, the lifting oil cylinder drives the confining pressure chamber to descend, and the lower end of the confining pressure chamber is sealingly connected to the edge of the loading base; Step 2, applying axial pressure and confining pressure The shaft pressure oil cylinder drives the loading ram to act on the upper end of the rock sample through the loading shaft to apply initial axial pressure to the rock sample, and the confining pressure pump injects the set confining pressure liquid into the confining pressure chamber to apply confining pressure to the rock sample; Step 3, warming and keeping warm Turn on the power supply, control the resistance wire to heat the confining pressure liquid through the power controller, and transfer the heat to the rock sample through the confining pressure liquid to heat the confining pressure liquid and the rock sample to the set temperature value and keep it; Step 4, cooling shock Intermittently inject liquid nitrogen in the liquid nitrogen storage tank into the gasification cavity of the cooling hollow column to absorb heat and reduce the temperature of the confining pressure liquid and the rock sample to cold shock the rock sample; Step 5, rock sample loading After the rock sample has experienced the set confining pressure, warming, and cold shock cooling, the loading unit is used to continuously load the rock sample; During steps 2 to 5, the sensor device monitors and collects the mechanical state data of the rock sample and the environmental temperature change of the rock sample in real time; Step 6, rock sample removal The confining pressure pump discharges the confining pressure liquid in the confining pressure chamber, the lifting oil cylinder drives the confining pressure chamber to rise, the rock sample is removed, and the test is completed.

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