Soft rock stratum crustal stress acquisition device based on inelastic strain recovery theory

Abstract

The utility model relates to the technical field of rock mechanics tests, and discloses a soft rock stratum crustal stress acquisition device based on a non-elastic strain recovery theory, which comprises a temperature adjusting mechanism used for respectively placing two groups of rock core samples in a constant-temperature environment and a variable-temperature environment; the strain acquisition mechanism is used for respectively measuring strain values of the two groups of rock core samples; and the control unit is electrically connected with the temperature adjusting mechanism and the strain acquisition mechanism and is used for respectively recording the temperature values and the strain values of the two groups of rock core samples. According to the utility model, the two groups of rock core samples can be respectively placed in a constant-temperature environment and a variable-temperature environment, and the strain values of the two groups of rock core samples are measured, so that the inelastic recovery strain value of the rock can be measured in the constant-temperature environment, and the thermal expansion coefficient of the rock can be measured in the variable-temperature environment; and the reliability of the crustal stress test method based on the rock inelastic strain recovery deformation is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of rock mechanics tests, in particular to a device for acquiring ground stress of soft rock formations based on the inelastic strain recovery theory. Background Art

[0002] Geostress is the natural stress in the earth's crust that is not disturbed by engineering. It is one of the important properties of the solid earth. As an important basic data for the study of the mechanism and prevention technology of deep tunnel engineering disasters, geostress is of great significance for understanding the mechanism of underground engineering disasters or damage, and effectively utilizing the distribution law of geostress to develop deep resources.

[0003] As for geostress measurement technology, hydraulic fracturing and stress relief are widely used geostress testing methods. However, all of the above methods are based on elastic theory and are therefore only suitable for geostress testing in hard rock formations. There are theoretical defects in their application to soft rock formations with strong rheological properties, and it is impossible to obtain a reliable three-dimensional geostress state of the soft rock formation. Therefore, it is necessary to use a geostress testing method based on inelastic recovery strain of drilled cores.

[0004] Temperature change and the thermal expansion coefficient of rock are one of the factors that affect the measurement accuracy of rock inelastic recovery strain stress, and to a certain extent affect the reliability of in-situ stress test results. The thermal expansion coefficient of rock refers to the change in the length of a solid material in a certain direction when the temperature changes by 1°C. Therefore, temperature changes have a significant effect on the thermal expansion coefficient of rock, which in turn affects the measurement accuracy of inelastic recovery strain. This is mainly because the inelastic recovery deformation of rock is relatively small, generally ranging from tens to hundreds of microstrains. A temperature change of 1°C will cause a measurement error of about 10% to 20%. Therefore, the temperature change range during the inelastic recovery strain measurement should be controlled within ±0.1°C to ensure that the impact of temperature on the test results is within 1 microstrain and the reliability of the test results is guaranteed.

[0005] In view of this, in the in-situ stress acquisition system based on rock inelastic recovery strain, how to eliminate the influence of temperature and how to accurately measure the thermal expansion coefficient of rock, so as to improve the reliability of the measurement results of the above method, have become technical problems that technical personnel in this field need to solve urgently. Utility Model Content

[0006] The utility model aims to provide a soft rock stratum ground stress acquisition device based on the inelastic strain recovery theory to overcome the above-mentioned shortcomings.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the utility model is: a device for acquiring ground stress of soft rock formation based on inelastic strain recovery theory, comprising:

[0008] The temperature regulating mechanism is used to place the two groups of core samples in a constant temperature environment and a variable temperature environment respectively;

[0009] A strain collection mechanism, used to measure the strain values ​​of two groups of core samples respectively; and

[0010] The control unit is electrically connected to the temperature regulating mechanism and the strain collecting mechanism to respectively record the temperature values ​​and strain values ​​of the two groups of core samples.

[0011] Preferably, the strain collection mechanism comprises:

[0012] Two sets of strain gauges, the two sets of strain gauges are pasted on the surfaces of the two sets of core samples in a one-to-one correspondence; and

[0013] A strain collector is electrically connected to the two sets of strain gauges, and the strain collector is electrically connected to the control unit.

[0014] Preferably, the core sample is cylindrical, and each set of strain gauges divides a circular end face of the cylinder into an x' axis and a y' axis, the x' axis and the y' axis are arranged perpendicular to each other, and the axial direction of the circle passing through the center of the circular end face is defined as a z' axis;

[0015] Each set of strain gauges contains 18 strain gauges, which are defined as c1, c2, ..., c18 respectively. The long axis direction of the strain gauge is defined as the axial direction of the strain gauge. There are 9 axial directions for the 18 strain gauges, which correspond to axis a1, axis a2, ..., axis a9 respectively. Axis a1 corresponds to c1 and c2, axis a2 corresponds to c3 and c4, ..., axis a9 corresponds to c17 and c18. The relationship between the 9 axial directions and the coordinate axes is as follows: axis a1 is parallel to the x′ axis, and perpendicular to the y′ axis and the z′ axis; axis a2 is parallel to the y′ axis, and perpendicular to the x′ axis and the z′ axis; axis a3 is parallel to the z′ axis, and perpendicular to the x′ axis and the y′ axis; axis a4 is oblique to the x′ axis and the y′ axis at a positive or negative 45°, and perpendicular to the z′ axis; axis a5 is parallel to the x′ axis and the y′ axis. Axis a6 and a7 are obliquely intersected with the x' and z' axes at a positive or negative 45° and are perpendicular to the z' axis; axes a8 and a9 are obliquely intersected with the y' and z' axes at a positive or negative 45° and are perpendicular to the y' axis; axes a8 and a9 are obliquely intersected with the y' and z' axes at a positive or negative 45° and are perpendicular to the x' axis, the x' axis is positioned as a baseline, and the strain gauges are pasted along the baseline and lines separated by 45°, 90° and -45° (negative in the clockwise direction) from the baseline, wherein c9 and c10 are located on a line separated by -45° from the baseline, c3, c4, c6, c15, c16, c17 and c18 are located on the baseline, c7 and c8 are located on a line separated by 45° from the baseline, and c1, c2, c5, c11, c12, c13 and c14 are located on a line separated by 90° from the baseline.

[0016] Preferably, the temperature regulating mechanism comprises a constant temperature water bath component and a variable temperature water bath component.

[0017] Preferably, the constant temperature water bath assembly comprises:

[0018] Constant temperature water bath, used to provide a constant temperature environment for core samples;

[0019] A waterproof component, used for being sleeved around the periphery of the core sample; and

[0020] A temperature sensor 1 is arranged in the constant temperature water tank, and a temperature data collector is electrically connected to the temperature sensor 1. The temperature data collector is electrically connected to the control unit.

[0021] Preferably, the constant temperature water bath assembly also includes a water bath circulation controller 1, which has a built-in heating and cooling device. The water bath circulation controller is provided with a circulating water outlet and a circulating water return port. A circulating water inlet and a circulating water outlet are provided on one side of the constant temperature water bath. The circulating water inlet and the circulating water outlet of the constant temperature water bath are connected to the circulating water outlet and the circulating water return port of the water bath circulation controller 1 in a one-to-one correspondence.

[0022] Preferably, the variable temperature water bath assembly comprises:

[0023] Variable temperature water bath, used to provide a variable temperature environment for core samples;

[0024] A waterproof component, used for being sleeved around the periphery of the core sample; and

[0025] A second temperature sensor is arranged in the constant temperature water tank, and a temperature data acquisition instrument is electrically connected to the second temperature sensor. The temperature data acquisition instrument is electrically connected to the control unit.

[0026] Preferably, the variable temperature water bath assembly also includes a second water bath circulation controller, which has a built-in heating and cooling device. The water bath circulation controller is provided with a circulating water outlet and a circulating water return port. A circulating water inlet and a circulating water outlet are provided on one side of the variable temperature water bath. The circulating water inlet and the circulating water outlet of the variable temperature water bath are connected to the circulating water outlet and the circulating water return port of the second water bath circulation controller in a one-to-one correspondence.

[0027] Preferably, the waterproof component is a plastic waterproof bag.

[0028] Preferably, the control unit is a computer.

[0029] Compared with the prior art, the utility model has at least the following advantages:

[0030] The utility model can place two groups of core samples in a constant temperature environment and a variable temperature environment respectively, and by measuring the strain values ​​of the two groups of core samples, it can measure the inelastic recovery strain value of the rock in a constant temperature environment, and measure the thermal expansion coefficient of the rock in a variable temperature environment. On the basis of obtaining the inelastic strain tensor, by conducting an experiment on the inelastic strain recovery compliance of the rock, on the basis of determining the corresponding rock inelastic strain recovery compliance, the size of the ground stress can be relatively calculated, thereby improving the reliability of the ground stress test method based on the inelastic strain recovery deformation of the rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 This is a schematic diagram of the overall structure of the soft rock formation ground stress acquisition device based on the inelastic strain recovery theory of the utility model;

[0033] Figure 2 This is a schematic diagram of the distribution of strain gauges on the side wall of the core sample of the utility model.

[0034] Figure numerals: 1. core sample; 2. strain collector; 3. constant temperature water bath; 4. waterproof part; 5. temperature sensor 1; 6. temperature data collector; 7. control unit; 8. water bath circulation controller 1; 9. variable temperature water bath; 10. temperature sensor 2; 11. water bath circulation controller 2. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0037] Reference Figure 1The utility model provides a device for acquiring in-situ stress of soft rock formations based on the inelastic strain recovery theory, including a temperature regulating mechanism, a strain acquisition mechanism and a control unit 7. The temperature regulating mechanism can provide two different temperature environments for the experiment, namely a constant temperature environment and a variable temperature environment. During the experiment, the two groups of core samples 1 need to be placed in a constant temperature environment and a variable temperature environment respectively. The strain acquisition mechanism is used to be respectively arranged on the outer surfaces of the two groups of core samples 1, and is used to measure the strain values ​​on the surfaces of the core samples 1; the control unit 7 preferably uses a computer, and the control unit 7 is electrically connected to the temperature regulating mechanism and the strain acquisition mechanism, and respectively records the temperature values ​​and strain values ​​of the two groups of core samples 1, which is convenient for subsequent data analysis and processing.

[0038] The strain collection mechanism includes two groups of strain gauges and a strain collection instrument 2 electrically connected to the two groups of strain gauges. The two groups of strain gauges are pasted on the outer wall surfaces of the two groups of core samples 1 in a one-to-one manner. The strain collection instrument 2 is used to monitor the strain force of the core samples 1 in real time. The strain collection instrument 2 is electrically connected to the control unit 7, and the strain collection instrument 2 sends the collected strain force to the control unit 7.

[0039] In the present invention, the core sample 1 is cylindrical, and a cylindrical end face of the cylinder is divided into an x' axis and a y' axis, the x' axis and the y' axis are arranged perpendicular to each other, and the axial direction of the cylinder is defined as the z' axis through the center of the cylindrical end face.

[0040] Reference Figure 2A set of strain gauges is set on the surface of each core sample 1, and each set of strain gauges contains 18 strain gauges, namely c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15, c16, c17 and c18. The long axis direction of the strain gauge is defined as the axial direction of the strain gauge. There are 9 axial directions for the 18 strain gauges, and the 9 axial directions correspond to axis a1, axis a2, axis a3, axis a4, axis a5, axis a6, axis a7, axis a8, respectively. 7, axis a8 and axis a9, where axis a1 corresponds to c1 and c2, that is, c1 and c2 are attached to the surface of core sample 1 along the direction of axis a1. Similarly, axis a2 corresponds to c3 and c4, axis a3 corresponds to c5 and c6, axis a4 corresponds to c7 and c8, axis a5 corresponds to c9 and c10, axis a6 corresponds to c11 and c12, axis a7 corresponds to c13 and c14, axis a8 corresponds to c15 and c16, axis a9 corresponds to c17 and c18. The relationship between the 9 axial directions and the coordinate axes is: axis a Axis 1 is parallel to the x' axis and perpendicular to the y' and z' axes; axis a2 is parallel to the y' axis and perpendicular to the x' and z' axes; axis a3 is parallel to the z' axis and perpendicular to the x' and y' axes; axis a4 is obliquely intersected with the x' and y' axes at a positive or negative 45° and perpendicular to the z' axis; axis a5 is obliquely intersected with the x' and y' axes at a positive or negative 45° and perpendicular to the z' axis; axis a6 and axis a7 are obliquely intersected with the x' and z' axes at a positive or negative 45° and perpendicular to the y' axis; axis a8 and axis a9 are obliquely intersected with the y' and z' axes at a positive or negative 45° 5°, perpendicular to the x′ axis, position the x′ axis as the baseline, and paste strain gauges along the baseline and the lines 45°, 90° and -45° (negative clockwise) away from the baseline, among which c9 and c10 are located on the line -45° away from the baseline, c3, c4, c6, c15, c16, c17 and c18 are located on the baseline, c7 and c8 are located on the line 45° away from the baseline, and c1, c2, c5, c11, c12, c13 and c14 are located on the line 90° away from the baseline.

[0041] Refer again Figure 1 The temperature regulating mechanism includes a constant temperature water bath component and a variable temperature water bath component.

[0042] The constant temperature water bath assembly includes a constant temperature water bath 3, a waterproof component 4, a temperature sensor 5 and a temperature data acquisition instrument 6. The constant temperature water bath 3 is used to provide a constant temperature environment for the core sample 1, and the waterproof component 4 is preferably a sealed plastic bag, which is used to be sleeved on the periphery of the core sample 1 to ensure that the humidity of the core sample 1 remains unchanged during the test; the temperature sensor 5 is arranged in the constant temperature water bath 3, and the temperature data acquisition instrument 6 is electrically connected to the temperature sensor 5 and is used to read the water bath temperature measured by the temperature sensor 5. The temperature data acquisition instrument 6 is electrically connected to the control unit 7, and the temperature data acquisition instrument 6 is used to send the read water bath temperature to the control unit 7.

[0043] The constant temperature water bath assembly also includes a water bath circulation controller 8, which has a built-in heating and cooling device, and the heating and cooling device is preferably a heating and cooling pump. The water bath circulation controller 8 is provided with a circulating water outlet and a circulating water return port. A circulating water inlet and a circulating water outlet are provided on one side of the constant temperature water bath 3. The circulating water inlet and the circulating water outlet of the constant temperature water bath 3 are connected to the circulating water outlet and the circulating water return port of the water bath circulation controller 8 in a one-to-one correspondence.

[0044] In addition, the variable temperature water bath assembly includes a variable temperature water bath 9, a waterproof component 4, a temperature sensor 10 and a temperature data acquisition instrument 6. The variable temperature water bath 9 is used to provide a variable temperature environment for the core sample 1; the waterproof component 4 is preferably a sealed plastic bag, and the waterproof component 4 is used to be sleeved on the peripheral side of the core sample 1 to ensure that the humidity of the core sample remains unchanged during the test; the temperature sensor 10 is arranged in the variable temperature water bath 9, and the temperature data acquisition instrument 6 is electrically connected to the temperature sensor 10, and is used to read the water bath temperature measured by the temperature sensor 10, and the temperature data acquisition instrument 6 is electrically connected to the control unit 7, and the temperature data acquisition instrument 6 is used to send the read water bath temperature to the control unit 7.

[0045] The variable temperature water bath assembly also includes a water bath circulation controller 11, which has a built-in heating and cooling device, and the heating and cooling device is preferably a heating and cooling pump. The water bath circulation controller 11 is provided with a circulating water outlet and a circulating water return port. A circulating water inlet and a circulating water outlet are provided on one side of the variable temperature water bath 9. The circulating water inlet and the circulating water outlet of the variable temperature water bath 9 are connected to the circulating water outlet and the circulating water return port of the water bath circulation controller 11 in a one-to-one correspondence.

[0046] The following specific examples are used to illustrate the calculation method for determining the thermal expansion coefficient of rocks:

[0047] The cylindrical core samples 1 and 2 taken from the same borehole were tested according to the inelastic strain recovery method for geostress. Figure 2 The strain gauge is glued to the surface of the core.

[0048] The strain gauge on the core sample 1 with the strain gauge attached is connected to the strain acquisition instrument 2, and then placed in a constant temperature water bath. The temperature sensor 5 is connected to the temperature data acquisition instrument 6. The temperature of the constant temperature water bath is set to 20°C, and the inelastic recovery strain of the core sample 1 is continuously collected when the temperature is kept constant.

[0049] The strain gauge on the core sample 2 with the strain gauge attached is connected to the strain acquisition instrument 2, and then placed in a variable temperature water tank. The temperature sensor 2 10 is connected to the temperature data acquisition instrument 6. The water bath circulation controller of the variable temperature water tank is adjusted to increase the temperature of the variable temperature water tank by 4°C per stage. Each stage is maintained for 2 hours. The temperature heating rate is about 1°C / min. The thermal expansion coefficient of the sample can be calculated based on the curve of the thermal expansion deformation of the core sample 2 as a function of temperature and time.

[0050] Then, the inelastic recovery strain of core sample 1 and the thermal expansion coefficient of core sample 2 are obtained through the above measurement.

[0051] The thermal expansion coefficient of core sample 2 is calculated as follows:

[0052]

[0053] Where △L is the change in sample length from temperature t1 to t2; L0 is the sample length at standard temperature t0, t0 is usually 20℃; △T is the temperature change during the measurement, △T=t2-t1.

[0054] Unit: ×10 -6 / ℃

[0055] The magnitude of the ground stress is calculated using the following formula.

[0056] The relationship between the inelastic strain of the core sample and the variable stress tensor component is as follows:

[0057]

[0058] where ε a (t) is the inelastic strain, l, m, n are the direction cosines with respect to the x', y' and z' axes respectively, σ x , σ y , σ z , τ xy , τ yz , τ zx is the stress tensor component, p0 is the pore pressure, σ m is the average normal stress, ▽t(t) is the temperature change during the measurement, at is the linear thermal expansion coefficient, jas(t) and jav(t) are the inelastic strain recovery compliances in shear and volume deformation modes, respectively.

[0059] The direction cosines of l, m, n with respect to the x' axis, y' axis and z' axis are shown in the following table:

[0060]

[0061] The inelastic strain is obtained through actual measurement. From the above formula, we can see that we can get the relationship between the inelastic strain and the six stress tensor components, and then we can calculate the six stress tensor components. The geostress is mathematically composed of six stress tensor components. Obtaining the six stress components is equivalent to obtaining the magnitude of the geostress.

[0062] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0063] The embodiments described above are only descriptions of the preferred methods of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A device for acquiring ground stress in soft rock formations based on inelastic strain recovery theory, characterized in that: include: The temperature regulating mechanism can provide a constant temperature environment and a variable temperature environment respectively, and is used to place two groups of core samples (1) in the constant temperature environment and the variable temperature environment respectively; A strain collection mechanism, used to measure the strain values ​​of the two groups of core samples (1) respectively; and a control unit (7) which is electrically connected to the temperature regulating mechanism and the strain collecting mechanism and records the temperature values ​​and strain values ​​of the two groups of core samples (1) respectively.

2. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 1, characterized in that: The strain collection mechanism comprises: Two sets of strain gauges, the two sets of strain gauges are pasted one by one on the surfaces of the two sets of core samples (1); and a strain collector (2) electrically connected to the two groups of strain gauges, wherein the strain collector (2) is electrically connected to a control unit (7).

3. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 2 is characterized in that: The core sample (1) is cylindrical, and a circular end face of the cylinder is divided into an x' axis and a y' axis, the x' axis and the y' axis are arranged perpendicular to each other, and the axial direction of the cylinder is defined as a z' axis passing through the center of the circular end face; Each set of strain gauges contains 18 strain gauges, which are defined as c1, c2, ..., c18. The long axis direction of the strain gauge is defined as the axial direction of the strain gauge. There are 9 axial directions for the 18 strain gauges, which correspond to axis a1, axis a2, ..., axis a9, respectively. Axis a1 corresponds to c1 and c2, axis a2 corresponds to c3 and c4, ..., axis a9 corresponds to c17 and c18. The relationship between the 9 axial directions and the coordinate axes is as follows: axis a1 is parallel to the x′ axis, and perpendicular to the y′ and z′ axes; axis a2 is parallel to the y′ axis, and perpendicular to the x′ and z′ axes; axis a3 is parallel to the z′ axis, and perpendicular to the x′ and y′ axes; axis a4 is oblique to the x′ and y′ axes at a positive or negative 45°, and perpendicular to the z′ axis; axis a5 is parallel to the x′ and y′ axes, and perpendicular to the z′ axis. The ' axis is obliquely intersected at plus or minus 45° and is perpendicular to the z' axis; the axis a6 and the axis a7 are obliquely intersected at 45° with the x' axis and the z' axis and are perpendicular to the y' axis; the axis a8 and the axis a9 are obliquely intersected at 45° with the y' axis and the z' axis and are perpendicular to the x' axis, the x' axis is positioned as the baseline, and the strain gauges are pasted along the baseline and the lines separated by 45°, 90° and -45° from the baseline, wherein the clockwise direction is the negative direction, wherein c9 and c10 are located at the line separated by -45° from the baseline, c3, c4, c6, c15, c16, c17 and c18 are located on the baseline, c7 and c8 are located at the line separated by 45° from the baseline, and c1, c2, c5, c11, c12, c13 and c14 are located at the line separated by 90° from the baseline.

4. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 1, characterized in that: The temperature regulating mechanism comprises a constant temperature water bath component and a variable temperature water bath component.

5. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 4 is characterized in that: The constant temperature water bath assembly comprises: A constant temperature water bath (3) for providing a constant temperature environment for the core sample (1); A waterproof member (4) is used to be sleeved around the periphery of the core sample (1); and A temperature sensor (5) is arranged in the constant temperature water bath (3), and a temperature data acquisition device (6) is electrically connected to the temperature sensor (5), and the temperature data acquisition device (6) is electrically connected to a control unit (7).

6. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 5, characterized in that: The constant temperature water bath component also includes a water bath circulation controller (8), the water bath circulation controller (8) has a built-in heating and cooling device, the water bath circulation controller (8) is provided with a circulating water outlet and a circulating water return port, one side of the constant temperature water bath (3) is provided with a circulating water inlet and a circulating water outlet, the circulating water inlet and the circulating water outlet of the constant temperature water bath (3) are connected to the circulating water outlet and the circulating water return port of the water bath circulation controller (8) in a one-to-one correspondence.

7. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 4, characterized in that: The variable temperature water bath assembly comprises: A variable temperature water bath (9) for providing a variable temperature environment for the core sample (1); A waterproof member (4) is used to be sleeved around the periphery of the core sample (1); and A second temperature sensor (10) is arranged in the variable temperature water bath (9), and a temperature data acquisition device (6) is electrically connected to the second temperature sensor (10), and the temperature data acquisition device (6) is electrically connected to the control unit (7).

8. The device for acquiring in-situ stress of soft rock formations based on the inelastic strain recovery theory according to claim 7, characterized in that: The variable temperature water bath component also includes a water bath circulation controller 2 (11), which has a built-in heating and cooling device. The water bath circulation controller 2 (11) is provided with a circulating water outlet and a circulating water return port. A circulating water inlet and a circulating water outlet are provided on one side of the variable temperature water bath tank (9). The circulating water inlet and the circulating water outlet of the variable temperature water bath tank (9) are connected to the circulating water outlet and the circulating water return port of the water bath circulation controller 2 (11) in a one-to-one correspondence.

9. The device for acquiring in-situ stress of soft rock formations based on the inelastic strain recovery theory according to any one of claims 5 to 8, characterized in that: The waterproof component (4) is a plastic waterproof bag.

10. The device for acquiring in-situ stress of soft rock formations based on inelastic strain recovery theory according to claim 1, characterized in that: The control unit (7) is a computer.

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