A method and system for quantitatively evaluating thermal damage at the scale of rock minerals

Abstract

The present invention discloses a method and system for quantitatively evaluating thermal damage at the scale of rock minerals, which relates to the field of high-temperature geotechnical engineering. The method includes obtaining the surface image of a rock sample, segmenting the surface of the rock sample through classification and regression algorithms to determine the contour images of each mineral component of the rock; establishing a rock numerical model based on the parallel bond model (PBM) and the smooth joint model (SJM) to determine the total number of inter-particle bonds; heating and cooling the rock numerical model to obtain the thermal crack distribution image of the rock after heating and cooling, and determining the number of microcracks in the rock sample; obtaining the new contours of each mineral after heating and cooling according to the thermal crack distribution image of the rock, and determining the crack area in each mineral and the crack area in the whole rock sample; and accurately evaluating the damage degree of the whole rock sample and each mineral according to the total number of inter-particle bonds, the number of microcracks in the rock sample, the crack area in each mineral and the crack area in the whole rock sample.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature geotechnical engineering, and particularly relates to a method and system for quantitatively evaluating thermal damage at the rock mineral scale. Background Art

[0002] In deep underground engineering such as mining, transportation, and water conservancy, rock masses often encounter high temperatures. High temperatures can cause uneven thermal expansion of minerals in the rock mass, resulting in cracks, which in turn affect the stability of rock engineering.

[0003] Currently, the damage evaluation of temperature-induced rock cracks often relies on microscopic observation methods to count information such as the length, width, and area of microcracks and compare them with the situation before high-temperature action to evaluate the degree of damage. Limited by the strict test conditions of in-situ high-temperature microscopy, different rock samples are often heated to a set temperature and then cooled for observation at present. However, this method is inevitably affected by the discreteness of the samples, and thus cannot accurately reflect the damage caused by temperature. Numerical simulation, due to its repeatability advantage, has become an effective means to explore rock temperature damage. The interior of a rock is composed of different minerals, and various minerals are affected by temperature to different degrees. Existing studies usually establish rock numerical models using the random distribution method of the grain-based model (GBM). However, this modeling method leads to a deviation between the simulation results and the actual situation because the real mechanical behavior of the rock is not considered, making it difficult to accurately reflect the real mineral crystal structure of the rock, such as the exact morphology and distribution characteristics of mineral crystals in the rock, and thus it is also difficult to accurately evaluate the degree of damage of various minerals. Summary of the Invention

[0004] The present invention provides a method and system for quantitatively evaluating thermal damage at the rock mineral scale to solve the above problems existing in the prior art, that is, the problem of how to accurately evaluate the degree of damage of various minerals in the prior art. The present invention provides a method for quantitatively evaluating thermal damage at the rock mineral scale, and the method includes:

[0005] Obtain the surface image of the rock sample, segment the surface of the rock sample through a classification and regression algorithm, and determine the contour images of each mineral component of the rock;

[0006] According to the obtained contour images of each mineral component of the rock, construct a numerical model of the rock mesoscopic structure, and use particles to fill the interior of the contour of the numerical model of the rock mesoscopic structure;

[0007] According to the numerical model of the rock mesoscopic structure after particle filling, select the parallel bond model (PBM) and the smooth joint model (SJM) to simulate the interaction between minerals inside and between minerals respectively, so as to construct a rock numerical model;

[0008] According to the constructed rock numerical model, meso-mechanical parameters and thermodynamic parameters are assigned to the particles filled in the mineral contour and the contacts between particles, and the total number of particle-to-particle bonds is determined;

[0009] The constructed rock numerical model is heated and then cooled to obtain the thermal crack distribution image of the rock after the heating-cooling action, and the number of microcracks in the rock sample is determined; according to the ratio of the number of microcracks in the rock sample to the total number of particle-to-particle bonds, the damage degree of the entire rock sample is obtained;

[0010] According to the thermal crack distribution image of the rock, the new contours of each mineral after the heating-cooling action are determined, and the crack area in each mineral and the crack area in the entire rock sample are obtained; according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral to the crack area in the entire rock sample, the damage degree of each mineral is obtained.

[0011] Optionally, the step of heating and then cooling the constructed rock numerical model to obtain the thermal crack distribution image of the rock after the heating-cooling action and determining the number of microcracks in the rock sample specifically includes:

[0012] Particles at a preset width from the outer boundary of the rock numerical model are selected as the thermal boundary, the area to be measured is determined, and the temperature of the area to be measured is obtained using a thermal pointer;

[0013] By iteratively adjusting the temperature of the thermal boundary, when the preset temperature increase threshold is reached, the temperature is kept constant, and iterative mechanical calculations are performed to control the uniform distribution of the temperature field until no new thermal cracks are generated. By adjusting the cooling rate of the thermal pointer, the cooling process is simulated.

[0014] Optionally, the step of obtaining the damage degree of the entire rock sample according to the ratio of the number of microcracks in the rock sample to the total number of particle-to-particle bonds specifically includes:

[0015] The damage degree of the entire rock sample is obtained using the following formula:

[0016] ;

[0017] where, N 1 is the number of microcracks in the rock sample, N is the total number of particle-to-particle bonds in the rock sample before the heating-cooling treatment.

[0018] Optionally, the step of obtaining the damage degree of each mineral according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral to the crack area in the entire rock sample, specifically includes:

[0019] The damage degree of each mineral is obtained using the following formula:

[0020] ;

[0021] Among them, A 0 is the crack area within a certain mineral grain, A 1 is the total area of microcracks within the rock sample, N 1 is the number of microcracks within the rock sample, N is the total number of interparticle adhesions within the rock sample before the heating-cooling treatment.

[0022] Optionally, after obtaining the contour images of the respective mineral components of the rock, an RGB image of the entire rock sample is generated, and the RGB image of the entire rock sample is converted into a grayscale image, and then the contours of the respective mineral components of the rock are color-filled.

[0023] Optionally, the meso-mechanical parameters include the effective stiffness of the linear contact part, the normal-tangential stiffness ratio, the particle friction coefficient, the effective stiffness of the parallel bond part, the tensile strength, and the cohesion; the thermodynamic parameters include the linear expansion coefficient, the specific heat capacity, the thermal conductivity, and the thermal resistance.

[0024] Optionally, after obtaining the damage degrees of the entire rock sample and the respective minerals, markings are made within the contour images of the respective mineral components of the rock.

[0025] The present invention provides a system for quantitatively evaluating thermal damage at the rock mineral scale, including:

[0026] An acquisition module for acquiring the surface image of the rock sample, segmenting the surface of the rock sample through a classification and regression algorithm, and determining the contour images of the respective mineral components of the rock;

[0027] A rock meso-structure numerical model construction module for constructing a rock meso-structure numerical model according to the acquired contour images of the respective mineral components of the rock, and filling the interior of the contour of the rock meso-structure numerical model with particles;

[0028] A rock numerical model module for, according to the rock meso-structure numerical model after particle filling, respectively simulating the interactions within and between minerals by selecting the parallel bond model PBM and the smooth joint model SJM to construct a rock numerical model;

[0029] A total adhesion number determination module for, according to the constructed rock numerical model, assigning meso-mechanical parameters and thermodynamic parameters to the particles filled in the mineral contours and the particle-to-particle contacts, and determining the total number of interparticle adhesions;

[0030] The whole rock sample damage degree determination module is used to heat and cool the constructed rock numerical model, obtain the thermal crack distribution image of the rock after heating-cooling, and determine the number of microcracks in the rock sample; according to the ratio of the number of microcracks in the rock sample to the total number of inter-particle adhesions, obtain the damage degree of the whole rock sample;

[0031] The damage degree determination module for each mineral is used to determine the new contour of each mineral after heating-cooling according to the rock thermal crack distribution image, obtain the crack area in each mineral and the crack area in the whole rock sample; according to the damage degree of the whole rock sample, combined with the ratio of the crack area in each mineral to the crack area in the whole rock sample, obtain the damage degree of each mineral.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for quantitatively evaluating the thermal damage at the rock mineral scale. This method segments the obtained rock sample surface image through classification and regression algorithms, and can accurately obtain the contours of each mineral component of the rock; then, according to the contour images of each mineral component of the rock, a mesoscopic structure numerical model of the rock is constructed, and particles are used to fill the interior of the contour of the mesoscopic structure numerical model of the rock, and a preliminary model construction result can be obtained; according to the filled mesoscopic structure numerical model of the rock, by selecting the parallel bond model PBM and the smooth joint model SJM to simulate the interactions inside and between minerals respectively, the true mineral crystal structure of the rock can be accurately reflected, and thus the true mineral crystal structure of the rock can be accurately reflected, such as the shape, size, distribution of crystal grains and the interactions between crystal grains; at the same time, by applying different temperatures to the rock numerical model, the influence degree of high-temperature action can be evaluated at the same mineral position, avoiding the influence of the discreteness of real rocks; at the same time, the present invention obtains the damage degree of the whole rock sample according to the ratio of the number of microcracks in the rock sample to the total number of inter-particle adhesions, and then obtains the damage degree of each mineral through the damage degree of the whole rock sample and the extraction of thermal cracks inside each mineral, and can accurately evaluate the difficulty of crack initiation and damage of various minerals under high-temperature action, realize the quantitative evaluation of thermal damage at the rock mineral scale, and improve the accuracy of the damage degree evaluation of various minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments in line with the present invention, and are used together with the specification to explain the principles of the present invention.

[0034] Figure 1 It is a flowchart of a method for quantitatively evaluating the thermal damage at the rock mineral scale provided by an embodiment of the present invention;

[0035] Figure 2 It is a schematic diagram of the extraction of the rock mineral contour and the construction of the numerical model provided by an embodiment of the present invention;

[0036] Figure 3 The rock thermal crack distribution diagram after the action of different temperatures provided by the embodiments of the present invention;

[0037] Figure 4 The schematic diagram for extracting the mineral contours of the rock containing thermal cracks after the action of different temperatures provided by the embodiments of the present invention;

[0038] Figure 5 The rock mineral damage degree distribution diagram after the action of different temperatures provided by the embodiments of the present invention;

[0039] Figure 6 The change trend diagram of the damage degree of the whole rock and various minerals with the increase of temperature provided by the embodiments of the present invention. Detailed implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] The technical solutions of the present invention and how the technical solutions of the present invention solve the above technical problems will be described in detail below with specific embodiments. These specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0042] Figure 1 It is a flowchart of a method for quantitatively evaluating the thermal damage of rock minerals at the scale of the present invention. As Figure 1 shown, a method for quantitatively evaluating the thermal damage of rock minerals at the scale shown in this embodiment includes:

[0043] S1: Obtain the surface image of the rock sample, segment the surface of the rock sample through a classification and regression algorithm, and determine the contour images of each mineral component of the rock.

[0044] Exemplarily, crop the surface photo of the rock sample and cut off the non-rock sample part to facilitate the subsequent extraction of the rock mineral contours. After cropping the surface photo of the rock sample, as Figure 2As shown in (a) of the present embodiment, taking potassium feldspar as an example, after selecting and delineating the potassium feldspar minerals in the cut picture, the contour of the potassium feldspar minerals is extracted, and an RGB image of the contour map is generated. By converting the RGB image into an 8-bit grayscale image, the potassium feldspar contour is filled with color, thus avoiding the influence of the potassium feldspar mineral boundary on the extraction of the remaining minerals. Finally, the potassium feldspar contour is extracted and color-filled, as Figure 2 shown in (b).

[0045] Repeat the above operations to sequentially complete the extraction and color filling of the plagioclase, quartz, and mica mineral contours, and obtain all mineral contours within the rock sample, as Figure 2 shown in (c). Vectorize the RGB image of the rock mineral contour and save it as a DXF file.

[0046] S2: According to the obtained contour images of each mineral component of the rock, construct a numerical model of the rock mesostructure, and use particles to fill the interior of the contour of the numerical model of the rock mesostructure.

[0047] Exemplarily, it can be grouped according to the mineral components in step S1. Taking potassium feldspar as an example, according to the DXF file of the potassium feldspar mineral contour, use small particles to fill the contour and complete the grouping; repeat the above operations to sequentially complete the contour particle filling and grouping of plagioclase, quartz, and mica minerals.

[0048] S3: According to the numerical model of the rock mesostructure after particle filling, select the parallel bond model (PBM) and the smooth joint model (SJM) to simulate the interaction inside and between minerals respectively, so as to construct a rock numerical model.

[0049] Exemplarily, the parallel bond model (Parallel bond model, PBM) is used inside the minerals, and the smooth joint model (Smooth joint model, SJM) is used between the minerals to complete the modeling, as Figure 2 shown in (d).

[0050] S4: According to the constructed rock numerical model, assign meso-mechanical parameters and thermo-dynamic parameters to the particles filled in the mineral contour and the contacts between the particles, and determine the total number of inter-particle bonds.

[0051] Exemplarily, meso-mechanical parameters and thermo-dynamic parameters can be assigned to the particles filled in the mineral contour and the contacts between the particles; the meso-mechanical parameters can include, for example, the effective stiffness of the linear contact part, the ratio of normal to tangential stiffness, the particle friction coefficient, the effective stiffness of the parallel bond part, the tensile strength, and the cohesion, etc.; the thermo-dynamic parameters can include, for example, the linear expansion coefficient, the specific heat capacity, the thermal conductivity, and the thermal resistance, etc.; then, obtain the total number of inter-particle bonds before the heating-cooling treatment; in this embodiment, the total number of bonds is 20576.

[0052] S5: Heat and then cool the constructed numerical rock model to obtain the image of the thermal crack distribution of the rock after the heating-cooling action, and determine the number of microcracks in the rock sample. Obtain the damage degree of the entire rock sample according to the ratio of the number of microcracks in the rock sample to the total number of particle-particle bonds.

[0053] Exemplarily, select the particles at a preset width away from the outer boundary of the numerical rock model as the thermal boundary. For example, the particles 1 mm away from the outer boundary can be taken as the thermal boundary, and use a thermal pointer to monitor the temperature in these areas. By iteratively adjusting the temperature of the thermal boundary, the heat conduction from the outside to the inside is achieved. Once the predetermined temperature rise threshold is reached, the temperature is kept constant, and iterative mechanical calculations are performed to control the uniform distribution of the temperature field until no new thermal cracks are generated. Adjust the temperature drop amplitude of the thermal pointer, set the internal high-temperature particles as the heat source for heat transfer, and then perform mechanical equilibrium calculations to simulate the cooling process.

[0054] The internal thermal crack distributions of the numerical specimens after being heated to 200 °C, 400 °C, 600 °C and 800 °C and then cooled to room temperature are as Figure 3 shown.

[0055] Read the number of thermal cracks in the rock sample after the high-temperature-cooling ends. In this embodiment, the numbers of thermal cracks after high-temperature-cooling at 200 °C, 400 °C, 600 °C and 800 °C are 8, 96, 719 and 2805 respectively.

[0056] Optionally, the damage degree of the entire rock sample is obtained by using the following formula:

[0057] ;

[0058] where N 1 is the number of microcracks in the rock sample, and N is the total number of particle-particle bonds in the rock sample before the heating-cooling treatment.

[0059] S6: According to the image of the rock thermal crack distribution, determine the new contours of each mineral after the heating-cooling action, and obtain the crack area in each mineral and the crack area in the entire rock sample. Obtain the damage degree of each mineral according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral to the crack area in the entire rock sample.

[0060] Exemplarily, since each mineral expands or is extruded and deformed under the action of the high-temperature-cooling cycle, it is necessary to re-extract the contour of the mineral after high-temperature-cooling to obtain the new contours of each mineral after deformation. Based on the crack distribution image after high temperature, combined with step S2, the new contours of each mineral after the heating-cooling treatment can be obtained. The results of the extraction of the mineral contours in the rock sample after high-temperature-cooling at 200 °C, 400 °C, 600 °C and 800 °C are asFigure 4 As shown. Then, the internal microcrack area of each mineral is obtained.

[0061] Optionally, according to the damage degree of the whole rock sample, combined with the ratio of the crack area in each mineral to the crack area in the whole rock sample, the damage degree of each mineral is obtained by using the following formula:

[0062] ;

[0063] Wherein, A 0 is the crack area within a certain mineral grain, A 1 is the total microcrack area within the rock sample, N 1 is the number of microcracks within the rock sample, N is the total number of intergranular adhesions within the rock sample before the heating-cooling treatment.

[0064] Exemplarily, the damage degrees of each mineral inside the rock sample after high-temperature cooling at 200°C, 400°C, 600°C, and 800°C are as Figure 5 shown; the variation trends of the damage degrees of the whole rock sample and various minerals after high-temperature cooling with the increase in temperature are as Figure 6 shown.

[0065] The above is the method for quantitatively evaluating the thermal damage at the rock-mineral scale provided by one or more embodiments of this specification. Based on the same idea, this specification also provides a corresponding system for quantitatively evaluating the thermal damage at the rock-mineral scale, including:

[0066] An acquisition module, configured to acquire the surface image of the rock sample, segment the surface of the rock sample through classification and regression algorithms, and determine the contour images of each mineral component of the rock;

[0067] A numerical model construction module for mesoscopic rock structure, configured to construct a numerical model of the mesoscopic rock structure according to the acquired contour images of each mineral component of the rock, and use particles to fill the interior of the contour of the numerical model of the mesoscopic rock structure;

[0068] A rock numerical model module, configured to, according to the numerical model of the mesoscopic rock structure filled with particles, simulate the interactions inside and between minerals by selecting the parallel bond model PBM and the smooth joint model SJM respectively, so as to construct a rock numerical model;

[0069] A total adhesion number determination module, configured to, according to the constructed rock numerical model, assign mesoscopic mechanical parameters and thermodynamic parameters to the particles filled in the mineral contour and the contacts between the particles, and determine the total number of interparticle adhesions;

[0070] The whole rock sample damage degree determination module is used to heat and cool the constructed rock numerical model, obtain the thermal crack distribution image of the rock after heating-cooling, and determine the number of microcracks in the rock sample; according to the ratio of the number of microcracks in the rock sample to the total number of inter-particle adhesions, obtain the damage degree of the whole rock sample;

[0071] The damage degree determination module of each mineral is used to determine the new contour of each mineral after heating-cooling according to the rock thermal crack distribution image, obtain the crack area in each mineral and the crack area in the whole rock sample; according to the damage degree of the whole rock sample, combined with the ratio of the crack area in each mineral to the crack area in the whole rock sample, obtain the damage degree of each mineral.

[0072] For the specific limitations of the thermal damage quantification and evaluation system at the rock mineral scale, reference can be made to the limitations of the thermal damage quantification and evaluation method at the rock mineral scale in the above text, which will not be elaborated here. Each module in the above thermal damage quantification and evaluation system at the rock mineral scale can be implemented in whole or in part by software, hardware and their combination. The above modules can be embedded in the processor of the computer device in the form of hardware or be independent of it, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0073] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded by the present invention.

Claims

1. A method for quantitative evaluation of thermal damage at rock mineral scale, characterized in that: include: Obtain the surface image of the rock sample, segment the surface of the rock sample through classification and regression algorithms, and determine the contour image of each mineral component of the rock; According to the obtained contour images of each mineral component of the rock, a numerical model of the rock mesostructure is constructed, and particles are used to fill the inside of the contour of the numerical model of the rock mesostructure; According to the numerical model of the rock mesostructure after particle filling, the parallel bond model PBM and the smooth joint model SJM are selected to simulate the interaction within and between minerals respectively to construct a rock numerical model. According to the constructed rock numerical model, the microscopic mechanical parameters and thermodynamic parameters are assigned to the particles filled in the mineral contour and the contact between the particles to determine the total bonding amount between the particles; The constructed rock numerical model is heated and cooled to obtain the rock thermal crack distribution image after heating-cooling, and the number of microcracks in the rock sample is determined; the damage degree of the entire rock sample is obtained based on the ratio of the number of microcracks in the rock sample to the total number of bonds between particles; The damage degree of the entire rock sample is obtained according to the ratio of the number of microcracks in the rock sample to the total number of bonds between particles, specifically including: The damage degree of the entire rock sample is obtained using the following formula: ； in, N 1 is the number of microcracks in the rock sample, N is the total amount of bonding between particles in the rock sample before heating-cooling treatment; According to the rock thermal crack distribution image, the new contours of each mineral after heating-cooling are determined, and the crack area in each mineral and the crack area in the entire rock sample are obtained; according to the damage degree of the entire rock sample, the damage degree of each mineral is obtained by combining the ratio of the crack area in each mineral and the crack area in the entire rock sample; The damage degree of each mineral is obtained according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral and the crack area in the entire rock sample, specifically including: The damage degree of each mineral is obtained using the following formula: ； in, A 0 is the crack area within a mineral grain, A 1 is the total area of ​​microcracks in the rock sample, N 1 is the number of microcracks in the rock sample, N is the total amount of bonding between particles in the rock sample before heating-cooling treatment.

2. The method for quantitatively evaluating thermal damage at the rock mineral scale according to claim 1, characterized in that: The step of heating and cooling the constructed rock numerical model, obtaining a rock thermal crack distribution image after heating-cooling, and determining the number of microcracks in the rock sample specifically includes: Selecting particles with a preset width from the outer boundary of the rock numerical model as thermal boundaries, determining the area to be tested, and using thermal pointers to obtain the temperature of the area to be tested; By iteratively adjusting the temperature of the thermal boundary, when the preset temperature rise threshold is reached, the temperature is kept constant, and iterative mechanical calculations are performed to control the uniform distribution of the temperature field until no new thermal cracks are generated. The cooling process is simulated by adjusting the temperature drop amplitude of the thermal pointer.

3. The method for quantitatively evaluating thermal damage at rock mineral scale according to claim 1, characterized in that: After obtaining the contour images of each mineral component of the rock, an RGB image of the entire rock sample is generated, and the RGB image of the entire rock sample is converted into a grayscale image, and then the contours of each mineral component of the rock are filled with colors.

4. The method for quantitatively evaluating thermal damage at rock mineral scale according to claim 1, characterized in that: The microscopic mechanical parameters include the effective stiffness of the linear contact part, the normal-to-tangential stiffness ratio, the particle friction coefficient, the effective stiffness of the parallel bonding part, the tensile strength and the cohesion; the thermodynamic parameters include the linear expansion coefficient, the specific heat capacity, the thermal conductivity and the thermal resistance.

5. The method for quantitatively evaluating thermal damage at rock mineral scale according to claim 1, characterized in that: After obtaining the damage degree of the entire rock sample and each mineral, marking is performed in the contour image of each mineral component of the rock.

6. A rock mineral scale thermal damage quantitative evaluation system, characterized in that: include: The acquisition module is used to acquire the surface image of the rock sample, segment the surface of the rock sample through classification and regression algorithms, and determine the contour image of each mineral component of the rock; A rock mesostructure numerical model construction module is used to construct a rock mesostructure numerical model based on the acquired contour images of each mineral component of the rock, and to fill the contour of the rock mesostructure numerical model with particles; The rock numerical model module is used to construct a rock numerical model by simulating the interaction between minerals and minerals by selecting the parallel bond model PBM and the smooth joint model SJM according to the numerical model of the rock mesostructure after particle filling; The total bonding number determination module is used to assign microscopic mechanical parameters and thermodynamic parameters to the particles filled in the mineral contour and the contact between the particles according to the constructed rock numerical model, and determine the total bonding number between the particles; The whole rock sample damage degree determination module is used to heat and cool the constructed rock numerical model, obtain the rock thermal crack distribution image after heating-cooling, and determine the number of microcracks in the rock sample; according to the ratio of the number of microcracks in the rock sample to the total bonding number between particles, the damage degree of the whole rock sample is obtained; The damage degree of the entire rock sample is obtained according to the ratio of the number of microcracks in the rock sample to the total number of bonds between particles, specifically including: The damage degree of the entire rock sample is obtained using the following formula: ； in, N 1 is the number of microcracks in the rock sample, N is the total amount of bonding between particles in the rock sample before heating-cooling treatment; The module for determining the damage degree of each mineral is used to determine the new contours of each mineral after heating-cooling according to the rock thermal crack distribution image, and obtain the crack area in each mineral and the crack area in the entire rock sample; according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral and the crack area in the entire rock sample, the damage degree of each mineral is obtained; The damage degree of each mineral is obtained according to the damage degree of the entire rock sample, combined with the ratio of the crack area in each mineral and the crack area in the entire rock sample, specifically including: The damage degree of each mineral is obtained using the following formula: ； in, A 0 is the crack area within a mineral grain, A 1 is the total area of ​​microcracks in the rock sample, N 1 is the number of microcracks in the rock sample, N is the total amount of bonding between particles in the rock sample before heating-cooling treatment.

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