Brittleness evaluation method and device based on rock uniaxial compression damage evolution characteristics

Abstract

The invention discloses a brittleness evaluation method and device based on rock uniaxial compression damage evolution characteristics, and belongs to the technical field of rock mechanics. The method comprises the following steps: determining a rock damage evolution curve by using a deformation modulus attenuation method based on a stress-strain curve; determining a peak strain according to the peak stress of the stress-strain curve, and determining a pre-peak damage variable corresponding to the peak strain according to the rock damage evolution curve; fitting the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample; solving a first-order derivative of the theoretical damage evolution equation, and determining a maximum damage evolution rate and a corresponding strain value according to a peak point of the first-order derivative; and calculating the brittleness evaluation index of the rock sample by using a formula. According to the method, the rock brittleness evaluation index is established by comprehensively considering the rock pre-peak damage variable, the rock post-peak damage evolution rate and the peak strain from the angle of damage evolution characteristics of the whole rock compression damage process, and the method has reasonability and reliability and can be applied to engineering practice.

Description

Technical Field

[0001] The invention relates to the technical field of rock mechanics, and in particular to a brittleness evaluation method and device based on the uniaxial compression damage evolution characteristics of rock. Background Art

[0002] Brittleness is one of the important mechanical properties of rock. It refers to the property of suddenly destroying and losing bearing capacity after a small deformation under the action of external force. Quantitative evaluation of rock brittleness can provide an important reference for predicting the occurrence of rock bursts in deep buried high-stress tunnels and judging the tendency of rock bursts.

[0003] At present, rock brittleness evaluation indexes are mainly established based on rock strength parameters, deformation parameters, mineral composition, stress-strain curve morphology and energy evolution process. Among them, the rock brittleness evaluation index constructed based on the rock full stress-strain curve is the most extensive, intuitive and reliable. However, some brittleness evaluation methods based on the rock full stress-strain curve only consider the post-peak deformation mechanical properties and stress drop rate of the rock, or only consider the pre-peak deformation mechanical properties, which affects the accuracy of rock brittleness characterization; although some evaluation methods consider the influence of stress or deformation characteristics on the brittleness degree during the process from pre-peak crack initiation to peak value, there is still no standard method for determining crack initiation stress. The determination of initiation stress using crack volume strain curve is greatly affected by the properties of the rock itself; the integrity of the post-peak stress-strain curve is greatly affected by the test conditions, such as the stiffness of the testing machine, loading rate, and sample geometry. In addition, the selection of the starting point of residual strength will also affect the calculation results of the post-peak brittleness index. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides the following technical solutions.

[0005] The first aspect of the present invention provides a brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock, comprising:

[0006] Obtain the stress-strain curve of the uniaxial compression test of the rock specimen;

[0007] Based on the stress-strain curve, the rock damage evolution curve is determined using the deformation modulus decay method;

[0008] Determine the peak strain according to the peak stress of the stress-strain curve, and determine the damage variable value corresponding to the peak strain according to the rock damage evolution curve;

[0009] Fitting the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample;

[0010] The first-order derivative of the theoretical damage evolution equation is calculated, and the maximum damage evolution rate and its corresponding strain value are determined according to the peak point of the first-order derivative;

[0011] The brittleness evaluation index B of the rock sample is calculated using the following formula: DE :

[0012]

[0013] In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

[0014] Preferably, the method of determining the rock damage evolution curve based on the stress-strain curve by using the deformation modulus attenuation method comprises:

[0015] The damage variable is expressed as follows: in, is the slope of the line connecting any point on the stress-strain curve and the origin of the coordinate system, and E is the elastic modulus;

[0016] The rock damage evolution curve is established using damage variables and their corresponding strains.

[0017] Preferably, the rock damage evolution curve is fitted to obtain a theoretical damage evolution equation of the rock sample using the following formula:

[0018]

[0019] Where D is the damage variable; a and r are fitting parameters; and L is the strain.

[0020] Preferably, the method further comprises the step of: using the following formula to obtain the first-order derivative of the theoretical damage evolution equation:

[0021]

[0022] The second aspect of the present invention provides a brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock, comprising:

[0023] Stress-strain curve acquisition module, used to obtain the stress-strain curve of the uniaxial compression test of rock samples;

[0024] A rock damage evolution curve determination module is used to determine the rock damage evolution curve based on the stress-strain curve using the deformation modulus attenuation method;

[0025] The first parameter determination module is used to determine the peak strain according to the peak stress point of the stress-strain curve, and determine the damage variable value corresponding to the peak strain according to the rock damage evolution curve;

[0026] A fitting module, used for fitting the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample;

[0027] The second parameter determination module is used to obtain the first-order derivative of the theoretical damage evolution equation and determine the maximum damage evolution rate and its corresponding strain value according to the peak point of the first-order derivative;

[0028] The brittleness evaluation index calculation module is used to calculate the brittleness evaluation index B of the rock sample using the following formula: DE :

[0029]

[0030] In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

[0031] Preferably, in the rock damage evolution curve determination module, the step of determining the rock damage evolution curve based on the stress-strain curve by using the deformation modulus attenuation method comprises:

[0032] The damage variable is expressed as follows: in, is the slope of the line connecting any point on the stress-strain curve and the origin of the coordinate system, and E is the elastic modulus;

[0033] The rock damage evolution curve is established using damage variables and their corresponding strains.

[0034] Preferably, in the fitting module, the rock damage evolution curve is fitted to obtain a theoretical damage evolution equation of the rock sample using the following formula:

[0035]

[0036] Where D is the damage variable; a and r are fitting parameters; and L is the strain.

[0037] Preferably, the fitting module is further used to calculate the first-order derivative of the theoretical damage evolution equation using the following formula:

[0038]

[0039] The present invention also provides a memory storing a plurality of instructions, wherein the instructions are used to implement the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in the first aspect.

[0040] The present invention also provides an electronic device, comprising a processor and a memory connected to the processor, wherein the memory stores a plurality of instructions, and the instructions can be loaded and executed by the processor so that the processor can execute the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in the first aspect.

[0041] The beneficial effects of the present invention are as follows: the brittleness evaluation method and device based on the uniaxial compression damage evolution characteristics of rock provided by the present invention establish a rock brittleness evaluation index from the perspective of the damage evolution characteristics of the entire rock compression failure process. The index comprehensively considers factors such as rock pre-peak damage variables, post-peak damage evolution rate and peak strain. After theoretical analysis and experimental verification, the results show that the brittleness evaluation index provided by the present invention has good rationality and reliability for rock brittleness evaluation and can be used in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the uniaxial compression stress-strain curve of rock;

[0043] Figure 2 It is a schematic flow chart of the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock according to the present invention;

[0044] Figure 3 Typical uniaxial compression stress-strain curve of rock and the corresponding rock damage evolution curve characterized by deformation modulus attenuation method;

[0045] Figure 4 The rock damage evolution curve and the corresponding rock damage evolution rate curve characterized by the Logistic growth model;

[0046] Figure 5(a) is a schematic diagram of the process of transforming the rock uniaxial compression stress-strain curve I considering the initial compression nonlinear deformation stage of the rock into the rock uniaxial compression stress-strain curve II not considering the initial compression nonlinear deformation stage of the rock, (b) is the rock uniaxial compression stress-strain curve not considering the initial compression nonlinear deformation stage of the rock;

[0047] Figure 6 is the uniaxial compression stress-strain curve of each sample;

[0048] Figure 7 Schematic diagram of the theoretical damage evolution curve and actual calculated damage results of each specimen;

[0049] Figure 8 This is a functional structural diagram of the brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock according to the present invention. DETAILED DESCRIPTION

[0050] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0051] The post-peak stress-strain curve of rock often has a stress sudden drop stage and a stress slow drop stage, such as Figure 1 As shown ( Figure 1 In the figure, the horizontal axis is strain and the vertical axis is stress), that is, the brittle drop stage and the strain softening stage. Figure 1 It can be seen that the stress sudden drop stage and stress slow drop stage of the stress-strain curve correspond to the damage acceleration stage and damage deceleration stage, respectively. That is, in the stress sudden drop stage, the microcracks inside the rock quickly converge and penetrate to form a macroscopic fracture surface. This fracture process is the manifestation of the rapid and concentrated release of energy accumulated before the rock peak, and the damage variable increases sharply. Therefore, it is reasonable to use the deformation mechanical properties of the stress sudden drop stage (damage acceleration stage) to characterize the degree of post-peak brittle fracture of the rock. In addition, the method of constructing brittle evaluation indexes from the perspective of rock damage evolution characteristics is relatively rare.

[0052] Embodiment 1

[0053] like Figure 2As shown, the embodiment of the present invention provides a brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock, including: S101, obtaining the stress-strain curve of the uniaxial compression test of the rock sample; S102, based on the stress-strain curve, determining the rock damage evolution curve by using the deformation modulus attenuation method; S103, determining the peak strain according to the peak stress of the stress-strain curve, and determining the damage variable value corresponding to the peak strain according to the rock damage evolution curve; S104, fitting the rock damage evolution curve to obtain the theoretical damage evolution equation of the rock sample; S105, calculating the first-order derivative of the theoretical damage evolution equation, and determining the maximum damage evolution rate and its corresponding strain value according to the peak point of the first-order derivative; S106, calculating the brittleness evaluation index B of the rock sample by the following formula DE :

[0054]

[0055] In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

[0056] During the specific implementation process, rock samples of different lithologies can be first retrieved from the project site, and then processed into standard cylindrical specimens with a height of 100 mm and a diameter of 50 mm. Each specimen is subjected to a uniaxial compression test to obtain the stress-strain curve of the rock specimen.

[0057] like Figure 3 The typical uniaxial compression stress-strain curve of rock shown in the figure (the horizontal axis is strain L, the vertical axis is stress σ) generally includes four stages: elastic deformation, plastic deformation, post-peak stress brittle drop and strain softening process (I, II, III and IV are used to represent each stage in the figure). In order to describe the damage and degradation process of rock during compression deformation, the deformation modulus attenuation method can be used to characterize the damage variable D of the rock, that is: in, is the slope of the line connecting any point on the stress-strain curve and the origin of the coordinate system, and E is the elastic modulus. Therefore, the rock damage evolution curve in the typical rock compression process corresponding to the stress-strain curve is obtained (the horizontal axis is the strain L, and the vertical axis is the damage variable D). Figure 3 It can be seen from the figure that the rock damage evolution curve roughly presents an "S"-shaped development trend. The damage process can be roughly divided into four stages: initial no damage, damage onset, damage acceleration and damage deceleration (I, II, III and IV are used to represent each stage in the figure), which correspond to the four stages of elastic deformation, plastic deformation, post-peak stress brittle drop and strain softening in the rock compression deformation process.

[0058] The logistic growth model is a commonly used "S"-shaped curve in biology that is suitable for describing the process of population change from the beginning, rapid development, slow development and gradually becoming stable. Therefore, in the present invention, the rock damage evolution curve can be fitted with the help of the logistic growth model to obtain the theoretical damage evolution equation of the rock sample. The rock damage evolution model based on the logistic growth model is:

[0059]

[0060] Where: D is the damage variable; a and r are model parameters obtained by fitting; L is the strain.

[0061] By taking the first-order derivative of the obtained rock damage evolution equation, we can get the following expression of rock damage evolution rate:

[0062]

[0063] The rock damage evolution curve characterized by the Logistic growth model and the corresponding rock damage evolution rate curve can be shown as follows: Figure 4 As shown. Figure 4 It can be seen that the rock damage evolution process characterized by the Logistic growth model can be roughly divided into four stages: initial no damage, damage onset, damage acceleration and damage deceleration, which is consistent with the rock damage evolution process characterized by the elastic modulus attenuation method. The rock damage evolution rate increases first and then decreases with the increase of strain, showing a standard normal distribution law. The top of the rock damage evolution rate curve is the maximum rock damage evolution rate, which can be recorded as D m ′.

[0064] During the compression process of brittle rock, the pre-peak plastic deformation is small, that is, the smaller the pre-peak damage variable is, the post-peak damage variable will experience a sudden increase, the more likely it is for cracks to extend and penetrate, the faster the damage evolution rate is, the greater its maximum damage evolution rate is; while the pre-peak plastic deformation of plastic rock is obvious, that is, the pre-peak damage evolution is obvious, and the overall damage is mainly progressive, the post-peak damage evolution rate is slow, and the maximum damage evolution rate is also smaller. When the external force on the rock exceeds the pre-peak cracking stress, the crack begins to initiate and expand steadily, and the damage variable gradually increases. The lower the pre-peak damage variable, the smaller the pre-peak plastic deformation of the rock, the lower the crack extension, the less dissipated energy, and the higher the pre-peak elastic strain energy storage rate, the more elastic energy released during post-peak failure, which improves the post-peak autonomous fracture capacity and crack expansion capacity, thereby showing a higher brittleness level; conversely, the higher the pre-peak damage variable, the stronger the pre-peak plastic deformation capacity of the rock, the more crack extension and more energy consumption, and the corresponding pre-peak elastic strain energy storage rate is lower, then the less elastic energy can be released during post-peak failure, thus showing a progressive low-brittle failure feature.

[0065] Based on the above analysis, the present invention establishes a rock brittleness evaluation index from the perspective of the damage evolution characteristics of the entire rock compression failure process. This index comprehensively considers the pre-peak damage variables, post-peak damage evolution rate and peak strain of the rock, and the expression is as follows:

[0066]

[0067] Where: ε cc is the crack closure strain, which can be determined according to the intersection of the reverse extension line of the linear elastic stage and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

[0068] The brittleness evaluation index of the rock sample can be used to evaluate the brittleness of the rock. The method provided by the present invention comprehensively considers the pre-peak damage variable, peak deformation and post-peak damage evolution rate of the rock. Analyzing the index, the damage variable at the peak is inversely proportional to the brittleness, that is, D p The larger the value, the lower the brittleness; D p The smaller it is, the stronger the brittleness. Since the maximum value of the rock damage variable is 1, 1-D pIt is directly proportional to brittleness. Peak strain is also inversely proportional to rock brittleness. It is generally believed that the smaller the peak strain when the rock is damaged, the stronger the brittleness. In engineering practice, the rock mass that has experienced various disturbances will contain more or less initial damage such as microcracks and microfissures, which will cause crack closure effect during the compression deformation of the rock, such as Figure 5 As shown in (a), the uniaxial compression stress-strain curve of rock is usually shown as curve I in (a), which includes the initial compaction nonlinear deformation stage, elastic deformation stage, plastic deformation stage and post-peak failure stage of rock. If the initial compaction nonlinear deformation stage of rock is not considered, that is, the rock directly enters the elastic deformation stage after being loaded, it is shown as curve II in (a), that is, the curve in (b). The brittleness of rock is related to its pre-peak elastic-plastic deformation, so the pre-peak deformation does not consider the crack closure strain, as shown in Figure 5 Based on the curve II shown in (b) in the figure, the damage variable is calculated by using the deformation modulus attenuation method. pre The calculation result is directly proportional to the brittleness, that is, B pre The larger the calculated result, the stronger the rock brittleness. Post-peak brittleness evaluation index B post Considering the maximum damage evolution rate and its corresponding strain ratio, it is obvious that B post The larger the calculated result, the stronger the post-peak brittleness. DE The larger the calculated result is, the more brittle the rock is. Specific embodiments

[0070] This embodiment provides a brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock, which is specifically implemented by the following steps:

[0071] Step 1: Process the rock samples of different lithologies retrieved from the project site into standard cylindrical specimens with a height of 100 mm and a diameter of 50 mm, and perform uniaxial compression tests on each specimen to obtain the stress-strain curve of the specimen.

[0072] Step 2: According to the test data of each sample, Figure 5 The crack closure strain of the rock sample can be obtained as shown in (a).

[0073] Step 3: Combine Figure 5 (b) Using the deformation modulus attenuation method Determine the rock damage evolution curve and determine the peak strain ε based on the peak stress point p The damage variable value D corresponding to the peak strain p .

[0074] Step 4: Use formula (1) to fit the damage evolution curve obtained in step 3 to obtain the theoretical damage evolution equation of the rock sample under uniaxial compression; then calculate the first-order derivative of the obtained theoretical damage evolution equation, and determine the maximum damage evolution rate D according to the peak point of the first-order derivative. m ′ and its corresponding strain value ε m .

[0075] Step 5: Substitute the parameter values ​​obtained in steps 1 to 4 into formula (3) to calculate the rock sample brittleness evaluation index B: DE The value of is calculated and compared with the existing rock brittleness evaluation index to verify the rationality and reliability of the brittleness evaluation index proposed in the embodiment of the present invention.

[0076] Granite and three different sandstone samples taken from the site were processed into standard cylindrical specimens with a height of 100 mm and a diameter of 50 mm. Then, uniaxial compression tests were performed indoors to obtain the uniaxial compression stress-strain curves of each specimen (e.g. Figure 6 shown).

[0077] According to the above steps 2 to 4, the theoretical damage evolution equation of each rock sample can be obtained as follows:

[0078] granite:

[0079] Sandstone 1:

[0080] Sandstone 2:

[0081] Sandstone 3:

[0082] Figure 7 The theoretical damage evolution curve of each sample and the actual calculated damage result (according to the damage variable calculation formula By comparing the theoretical damage model of rock based on the Logistic growth model with the theoretical damage evolution model, it can be seen that the theoretical damage evolution model based on the Logistic growth model can better describe and predict the whole process of rock damage evolution. Further, by taking the first-order derivative of the theoretical damage evolution equation, the damage evolution rate curve, the maximum damage evolution rate and its corresponding strain value can be obtained.

[0083] According to the uniaxial compression stress-strain curves of each rock sample and the theoretical damage evolution curve, the parameter values ​​in the brittleness evaluation index can be obtained, as shown in Table 1. In order to verify the rationality and reliability of the brittleness evaluation index proposed in the present invention, it is compared with the following brittleness evaluation index proposed by Xia Yingjie et al. in the paper (Xia Yingjie, Li Lianchong, Tang Chunan, etc. Evaluation method of rock brittleness characteristics based on post-peak stress drop rate and energy ratio [J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 35(06): 1141-1154.):

[0084]

[0085] Where: p , ε p are the peak stress and peak strain, σ r , ε r are the residual stress and residual strain, B i This is the brittleness evaluation index proposed by Xia Yingjie.

[0086] Combined with the calculated value of the brittleness evaluation index, it can be found that the brittleness evaluation index B proposed in the present invention is DE Compared with the brittleness evaluation index B proposed by Xia Yingjie i The evaluation is consistent, and the brittleness relationship of different rock samples is: granite>sandstone 2>sandstone 3>sandstone 1. This shows that the rock brittleness evaluation index proposed in the present invention has certain rationality and reliability, can be used to judge the rock brittleness under conventional conditions, and obtain a quantitative evaluation value, and the index is simple in form, has fewer parameters, and has strong applicability.

[0087] Table 1 Parameter values ​​of rock brittleness evaluation indexes

[0088]

[0089] Embodiment 2

[0090] like Figure 8 As shown, another aspect of the present invention also includes a functional module architecture that is completely consistent with the aforementioned method flow, that is, the embodiment of the present invention also provides a brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock, including:

[0091] A stress-strain curve acquisition module 801 is used to acquire a stress-strain curve of a uniaxial compression test of a rock sample;

[0092] The rock damage evolution curve determination module 802 is used to determine the rock damage evolution curve based on the stress-strain curve using the deformation modulus decay method;

[0093] The first parameter determination module 803 is used to determine the peak strain according to the peak stress point of the stress-strain curve, and determine the damage variable value corresponding to the peak strain according to the rock damage evolution curve;

[0094] A fitting module 804 is used to fit the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample;

[0095] The second parameter determination module 805 is used to obtain the first-order derivative of the theoretical damage evolution equation, and determine the maximum damage evolution rate and its corresponding strain value according to the peak point of the first-order derivative;

[0096] The brittleness evaluation index calculation module 806 is used to calculate the brittleness evaluation index B of the rock sample using the following formula: DE :

[0097]

[0098] In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

[0099] The device can be implemented by the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock provided in the above-mentioned embodiment 1. The specific implementation method can be found in the description of embodiment 1 and will not be repeated here.

[0100] The present invention also provides a memory storing a plurality of instructions, wherein the instructions are used to implement the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in the first embodiment.

[0101] The present invention also provides an electronic device, comprising a processor and a memory connected to the processor, wherein the memory stores a plurality of instructions, and the instructions can be loaded and executed by the processor so that the processor can execute the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in Example 1.

[0102] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock, characterized in that: include: Obtain the stress-strain curve of the uniaxial compression test of the rock specimen; Based on the stress-strain curve, the rock damage evolution curve is determined using the deformation modulus decay method; Determine the peak strain according to the peak stress of the stress-strain curve, and determine the damage variable value corresponding to the peak strain according to the rock damage evolution curve; Fitting the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample; The first-order derivative of the theoretical damage evolution equation is calculated, and the maximum damage evolution rate and its corresponding strain value are determined according to the peak point of the first-order derivative; The brittleness evaluation index B of the rock sample is calculated using the following formula: DE : In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

2. The brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock according to claim 1 is characterized in that: The method of determining the rock damage evolution curve based on the stress-strain curve by using the deformation modulus attenuation method includes: Using the formula represents the damage variable D; where, is the slope of the line connecting any point on the stress-strain curve and the origin of the coordinate system, and E is the elastic modulus; The rock damage evolution curve is established using damage variables and their corresponding strains.

3. The brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock according to claim 1 is characterized in that: The rock damage evolution curve is fitted to obtain the theoretical damage evolution equation of the rock sample, using the following formula: Where D is the damage variable; a and r are fitting parameters; and L is the strain.

4. The brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock according to claim 3 is characterized in that: The step also includes: using the following formula to obtain the first-order derivative of the theoretical damage evolution equation:

5. A brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock, characterized in that: include: A stress-strain curve acquisition module is used to obtain the stress-strain curve of a uniaxial compression test of a rock sample; A rock damage evolution curve determination module is used to determine the rock damage evolution curve based on the stress-strain curve using the deformation modulus attenuation method; The first parameter determination module is used to determine the peak strain according to the peak stress point of the stress-strain curve, and determine the damage variable value corresponding to the peak strain according to the rock damage evolution curve; A fitting module, used for fitting the rock damage evolution curve to obtain a theoretical damage evolution equation of the rock sample; The second parameter determination module is used to obtain the first-order derivative of the theoretical damage evolution equation and determine the maximum damage evolution rate and its corresponding strain value according to the peak point of the first-order derivative; The brittleness evaluation index calculation module is used to calculate the brittleness evaluation index B of the rock sample using the following formula: DE : In the formula, ε cc is the crack closure strain, which is determined by the intersection of the reverse extension line of the elastic stage of the stress-strain curve and the horizontal axis; ε p is the peak strain; D p is the damage variable value corresponding to the peak strain; D m ′ is the maximum damage evolution rate; ε m is the strain value corresponding to the maximum damage evolution rate; B DE B is the brittleness evaluation index of rock samples; pre B is the pre-peak brittleness evaluation index of rock samples; post It is an evaluation index of post-peak brittleness of rock samples.

6. The brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock according to claim 5, characterized in that: In the rock damage evolution curve determination module, the rock damage evolution curve is determined based on the stress-strain curve by using the deformation modulus attenuation method, including: The damage variable is expressed as follows: in, is the slope of the line connecting any point on the stress-strain curve and the origin of the coordinate system, and E is the elastic modulus; The rock damage evolution curve is established using damage variables and their corresponding strains.

7. The brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock according to claim 5, characterized in that: In the fitting module, the rock damage evolution curve is fitted to obtain the theoretical damage evolution equation of the rock sample, using the following formula: Where D is the damage variable; a and r are fitting parameters; and L is the strain.

8. The brittleness evaluation device based on the uniaxial compression damage evolution characteristics of rock according to claim 7 is characterized in that: The fitting module is also used to calculate the first-order derivative of the theoretical damage evolution equation using the following formula:

9. A memory, characterized in that: A plurality of instructions are stored, and the instructions are used to implement the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in any one of claims 1 to 4.

10. An electronic device, characterized in that: It comprises a processor and a memory connected to the processor, wherein the memory stores a plurality of instructions, and the instructions can be loaded and executed by the processor, so that the processor can execute the brittleness evaluation method based on the uniaxial compression damage evolution characteristics of rock as described in any one of claims 1 to 4.

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