Freeze-thaw rock mechanical local damage identification and evaluation method and system

Abstract

The invention provides a frozen-thawed rock mechanical local damage identification and evaluation method and system, and belongs to the field of rock damage evaluation, and the method comprises the steps: obtaining an apparent strain field cloud picture according to a speckle image of a frozen-thawed rock in a loading process; detecting the boundary of the local damage area of the frozen-thawed rock by using an improved Sobel operator in convolution operation to obtain a contour map, connecting inflection points in the contour map, and defining an area enclosed by the inflection points as the local damage area; and calculating a space localization parameter S, a numerical localization parameter N and a damage localization parameter Lf according to the space-time parameters of the local damage area identification result, quantitatively representing the local damage characteristics of the rock according to S, N and Lf to obtain a freeze-thaw rock mechanical local damage evaluation result, and realizing the evaluation of the freeze-thaw rock mechanical local damage by defining the three parameters.

Description

Technical Field

[0001] The invention belongs to the field of rock damage assessment, and specifically relates to a method and system for identifying and assessing local damage in freeze-thaw rock mechanics. Background Art

[0002] With the expansion of human engineering activities in alpine areas, the construction and operation of more and more rock engineering projects (such as slopes, tunnels, roadbeds, etc.) are facing severe climate problems. Affected by the temperature difference between day and night and the alternation of seasons, the freeze-thaw cycle has become the main weathering factor in alpine areas, leading to the deterioration of rock mechanical properties and changes in the damage and failure laws. This greatly increases the possibility and destructive power of rock instability, seriously threatening the safe operation and service life of rock engineering projects. When the temperature drops below the freezing point, the water in the rock pores migrates to the frozen zone and changes into ice, generating huge frost heave force. At this time, the rock is a multiphase damage medium of water, ice, and rock; in the subsequent thawing, the frost heave force is gradually released, but the water further migrates inward. Although the rock will not be damaged by a single freeze-thaw, the frequent freeze-thaw process leads to the development of rock pores, structural fragmentation, and severe mechanical damage, which in turn becomes a potential cause of geological disasters such as rockfalls and landslides in cold regions.

[0003] For the mechanical damage of rocks, existing technologies mostly use elastic parameters, ultrasonic velocity, etc. for quantitative analysis to characterize the "uniform damage, average damage" at the macro scale; or combine real-time scanning electron microscopy, micro-CT technology, etc. for observation to characterize the "pore damage" at the micro scale. However, frozen-thawed rocks are highly heterogeneous and highly deformed. Their deformation and destruction process is essentially a gradual damage evolution process from uniform deformation-local deformation-macroscopic fracture, which belongs to the "local damage" at the macro and micro scales and cannot be characterized by existing technologies. Summary of the invention

[0004] In order to solve the problem of identifying and evaluating local damage of frozen-thawed rocks, the present invention provides a method and system for identifying and evaluating local damage of frozen-thawed rock mechanics.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for identifying and evaluating local damage in freeze-thaw rock mechanics, comprising the following steps:

[0007] Obtain the apparent strain field cloud map of frozen-thawed rocks;

[0008] Using an improved Sobel operator to perform a convolution operation on the apparent strain field cloud map to obtain final gradient values ​​of multiple strain points, drawing a contour map according to the multiple final gradient values, connecting multiple inflection points in the contour map, and the area surrounded by the multiple inflection points is the local damage area;

[0009] The spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L are calculated according to the area of ​​the local damage zone, the strain value and the coordinates of the strain point. f , according to the S, N and L f The local damage characteristics of rock are quantitatively characterized, and the local damage evaluation results of freeze-thaw rock mechanics are obtained.

[0010] Preferably, the improved Sobel operator is specifically composed of four convolution kernels, including horizontal, vertical, 45° and -45° directions, and responds to the representation of edge information.

[0011] Preferably, the convolution operation is performed on the apparent strain field cloud map using the improved Sobel operator to obtain the final gradient values ​​of multiple strain points, specifically by the following steps:

[0012] The convolution operation is performed in the improved Sobel operator, and the convolution kernel formula is as follows:

[0013]

[0014] If the strain field cloud diagram contains M×N strain points, and the strain value is expressed as F(m, n), then the gradient values ​​in the four directions are specifically:

[0015] G x =g x *F(m,n);

[0016] G y =g y *F(m,n);

[0017] G 45° =g 45° *F(m,n);

[0018] G -45° =g -45° *F(m,n);

[0019] Among them, G x , G y , G 45° and G -45° Respectively represent the gradient values ​​of the strain points in the horizontal, vertical, 45° and -45° directions; * represents the convolution operation;

[0020] The final gradient value at the strain point is calculated as follows:

[0021]

[0022] Where G is the final gradient value at the strain point.

[0023] Preferably, the spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L are calculated according to the area of ​​the local damage area, the strain value and the coordinates of the strain point. f , specifically through the following formula:

[0024] The calculation formulas of the spatial localization parameter and the numerical localization parameter N are specifically:

[0025]

[0026] Among them, S l is the area of ​​local damage; S t is the total area of ​​the observation area; is the average strain in the local damage area; ε t is the average strain in the observation area;

[0027] Damage localization parameter L f The specific calculation formula is:

[0028]

[0029] Among them, (x k ,y k ) is the coordinate of the strain point k in the local damage area; and are the average values ​​of {xk} and {yk} respectively.

[0030] Preferably, according to the S, N and L f The quantitative characterization of the local damage characteristics of rock is as follows: when S is 0, there is no local damage in the rock sample, and the corresponding N is 1; when S is greater than 0, it indicates that a local damage zone is formed in the sample, and the corresponding N is greater than 1; L f is the correlation coefficient of the spatial position of the strain points in the local damage area, reflecting the concentration of local damage, with a value range of 0-1. When the spatial positions of the strain points in the local damage area are concentrated on a straight line, L f is 0; when the spatial position becomes discrete, L f Gradually increase to 1.

[0031] Preferably, the obtaining of the apparent strain field cloud map of the frozen-thawed rock comprises first obtaining a speckle image of the frozen-thawed rock through a mechanical test loading process; importing the speckle image into the software of the Vic-3D system, and drawing the apparent strain field of the rock sample during the loading process through calculation and analysis to obtain the apparent strain field cloud map of the frozen-thawed rock.

[0032] Preferably, the freeze-thaw rock mechanics local damage evaluation results are specifically divided into a stable local damage development stage, an accelerated local damage development stage and a post-peak local damage development stage.

[0033] The present invention also provides a freeze-thaw rock mechanics local damage identification and evaluation system, which specifically includes:

[0034] The image acquisition module is used to obtain the apparent strain field cloud map of frozen-thawed rocks.

[0035] The damage identification module uses an improved Sobel operator to perform a convolution operation on the apparent strain field cloud map to obtain final gradient values ​​of multiple strain points, draws a contour map based on the multiple final gradient values, connects multiple inflection points in the contour map, and the area surrounded by the multiple inflection points is the local damage area.

[0036] A damage evaluation module is used to calculate the spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L according to the area of ​​the local damage area, the strain value and the coordinates of the strain point. f , according to the S, N and L f The local damage characteristics of rock are quantitatively characterized, and the local damage evaluation results of freeze-thaw rock mechanics are obtained.

[0037] The present invention also provides a computer device, including a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps described in the method for identifying and evaluating local damage in freeze-thaw rock mechanics.

[0038] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is loaded by a processor, the steps described in the method for identifying and evaluating local damage in freeze-thaw rock mechanics can be executed.

[0039] The method for identifying and evaluating local damage in freeze-thaw rock mechanics provided by the present invention has the following beneficial effects:

[0040] The present invention performs convolution processing on the apparent strain field cloud map of freeze-thaw rock through an improved Sobel operator, accurately identifies the edge information of local damage of freeze-thaw rock, and evaluates the local damage of freeze-thaw rock mechanics by using spatial localization parameters, numerical localization parameters and damage localization parameters according to the spatiotemporal evolution law of the local damage zone, quantitatively characterizes the local damage characteristics of rock, and achieves the purpose of identifying and evaluating the local damage of freeze-thaw rock mechanics. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1The present invention is a flowchart of a method for identifying and evaluating local damage in freeze-thaw rock mechanics according to an embodiment of the present invention.

[0043] Figure 2 is the evolution process of the strain field of the sample after 0 freeze-thaw cycles in the embodiment of the present invention. Figure 2 (A) is the stress-time relationship curve, Figure 2 (a)-(f) in (B) are the strain field cloud diagrams at different stress levels. Figure 2 (g) is a destroyed image.

[0044] Figure 3 The strain field evolution process of the sample after 60 freeze-thaw cycles in the embodiment of the present invention. Figure 3 (A) is the stress-time relationship curve, Figure 3 (a)-(f) in (B) are the strain field cloud diagrams at different stress levels. Figure 3 (g) is a destroyed image.

[0045] Figure 4 The damage parameter variation diagram of the sample under different freeze-thaw cycle times in the embodiment of the present invention is shown in FIG. Figure 4 (a)-(e) are the quantitative parameter curves at different stages of 0, 10, 20, 40, and 60 freeze-thaw cycles, respectively.

[0046] Figure 5 It is a schematic diagram of the image acquisition device during the freeze-thaw rock evolution process in an embodiment of the present invention.

[0047] Figure 6 FIG. 1 is a schematic diagram of determining the boundary of a damaged area using the convolution principle in an embodiment of the present invention, wherein: Figure 6 (a) is the contour map of the apparent strain field before and after convolution. Figure 6 (b) is the convolution operation process of the strain matrix DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0049] Example

[0050] Taking the gneiss widely distributed in open-pit mines as the object, the samples were collected and sealed and brought back to the room for sample preparation; the retrieved rock blocks were drilled and cut to make cylindrical samples with a height of 100mm and a diameter of 50mm, and the surface was carefully polished to ensure that the parallelism and surface smoothness of both ends met the specification requirements. After testing, the collected gneiss was mainly composed of albite, with a content of up to 47.2%, and the remaining mineral components were biotite, quartz and hornblende, with contents of 24.6%, 19.7% and 8.5% respectively, so the rock was named biotite hornblende gneiss.

[0051] The present invention provides a method for identifying and evaluating local damage in freeze-thaw rock mechanics. Figure 1 As shown, the specific steps include:

[0052] S1. The gneiss samples were subjected to saturation test, freeze-thaw test, mechanical test and other treatments to obtain the apparent strain field of the samples under axial load at different freeze-thaw cycles. The equipment is as follows: Figure 5 As shown. Taking the samples after 0 and 60 freeze-thaw cycles as examples, the evolution law of the apparent strain field is analyzed. Among them, AF is 6 typical points selected on the stress-time relationship curve to reflect the evolution process of the strain field; the strain field is the maximum principal strain field (e1), and its spatiotemporal evolution characteristics are more consistent with the expansion law and distribution of cracks on the sample surface during loading. Therefore, it can be seen that the evolution law of the apparent strain field of the sample has certain commonalities, and all experience the process from homogenization to localization and then to rupture: in the initial stage of loading for a long time, the strain field has no obvious change; only when the stress state reaches a higher level, a stable strain localization zone appears; as the stress level exceeds the peak stress, macro cracks are generated in the strain localization zone, and the sample ruptures.

[0053] like Figure 2 As shown in Figure 2, at point a (78% peak stress), the color of the cloud is relatively uniform, indicating that at this moment, the microcracks inside the sample have not yet begun to develop, and the deformation of the sample surface is relatively uniform. At this time, the maximum strain value is 1.22×10 -3 At point b (85% peak stress), a small number of large strain points appear at the bottom of the cloud, indicating that strain localization occurs in the sample. At this time, the maximum strain value is 1.37×10 -3 Points c and d are 91% and 96% of the peak stress, respectively. At this time, the strain localization area gradually increases with loading, and the maximum strain values ​​are 1.37×10 -3 and 2.74×10 -3 ; Point e corresponds to the peak stress, at which point the strain localization area reaches the maximum, and the maximum strain value is 2.96×10 -3After point e, the stress begins to drop rapidly and macro cracks begin to appear on the surface of the sample, indicating that the gneiss is about to be destroyed. Point f corresponds to 96% of the peak stress, at which time the sample is destroyed and the maximum strain value is 3.14×10 -2 .

[0054] like Figure 3 As shown in Figure 2, at point a (46% peak stress), large strain points appear in many places on the cloud map, but the overall color is relatively uniform, the sample surface is uniformly deformed, and the maximum strain value is 8×10 -4 At point b (60% peak stress), an obvious strain localization area appears at the top of the cloud map, and the maximum strain value is 1.98×10 -3 ; With the increase of axial stress, the localized strain on the surface of the specimen expands slowly but the strain value continues to increase. The maximum strain values ​​at points c and d reach 3.04×10 -3 and 4.16×10 -3 Point e corresponds to the peak stress, the strain localization further expands, and the strain value also increases. At this time, the maximum strain value reaches 5.6×10 -3 ; Point f corresponds to 93% of the peak stress. At this time, it can be clearly seen from the cloud map that the sample has shear cracks along the strain localization direction and is damaged. The maximum strain value is 1.17×10 -2 .

[0055] As the axial loading progresses, the frozen-thaw gneiss transitions from uniform deformation to strain localization and then to macroscopic fracture, which is a typical progressive destruction process. This process is not only the result of local strain accumulation, but also the result of local damage to the rock material. Even if some strain localization zones do not form macroscopic cracks due to "competition failure", the excessive strain in the zone causes the material stiffness to deteriorate, causing mechanical damage to the rock material in the zone; while the rock material outside the zone remains basically intact due to the smaller cumulative deformation, and no mechanical damage occurs (or the damage is extremely small and can be ignored). The mechanical damage of the loaded rock is a local damage, not a uniform damage or an average damage. The strain field evolution process obtained by digital image correlation technology can be used to evaluate the mechanical local damage characteristics of frozen-thaw gneiss.

[0056] S2. Use the improved Sobel operator in the convolution operation to detect the boundary of the local damage area of ​​the frozen-thawed rock, obtain the contour map, connect the inflection points in the contour map, and the area surrounded by the inflection points is the local damage area. Use the improved Sobel operator in the convolution operation to detect the boundary of the local damage area of ​​the frozen-thawed rock, specifically through the following steps:

[0057] The maximum response to edge information is shown in the horizontal, vertical, 45° and -45° directions, where the convolution kernel formula of the Sobel operator is:

[0058]

[0059] If the strain field cloud diagram contains M×N strain points, and the strain value is expressed as F(m, n), then the gradient values ​​in the four directions are specifically:

[0060] G x =g x *F(m,n);

[0061] G y =g y *F(m,n);

[0062] G 45° =g 45° *F(m,n);

[0063] G -45° =g -45° *F(m,n);

[0064] Among them, Gx, Gy, G 45° and G -45° They represent the gradient values ​​in the horizontal, vertical, 45° and -45° directions respectively; * represents the convolution operation.

[0065] Furthermore, the final gradient value of the strain point can be calculated according to the following formula:

[0066]

[0067] Where G is the final gradient value of the strain point. Figure 6 As shown in the figure, taking a rock that has experienced 40 freeze-thaw cycles as an example, the convolution operation process of identifying the local damage zone at the peak stress is demonstrated. Before the convolution operation, the local damage zone has appeared, but the boundary of the local damage zone cannot be accurately determined due to the gradual change of the strain field. After the convolution operation, the strain gradient inside and outside the local damage zone tends to be flat, but the boundary is highlighted. According to the convolution principle, the boundary of the local damage zone is composed of strain points with large gradient values. The final gradient value is used to draw a contour map, and the inflection points in the contour map are connected. The enclosed area is the local damage zone, completing the purpose of local damage identification in freeze-thaw rock mechanics.

[0068] S3. Calculate the spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L according to the spatiotemporal parameters of the local damage area identification result. f , according to S, N and L f Quantitatively characterize the local damage characteristics of rock. Specifically through the following formula:

[0069] The calculation formulas of the spatial localization parameter and the numerical localization parameter N are as follows:

[0070]

[0071] Among them, S l is the area of ​​local damage; S t is the total area of ​​the observation area; is the average strain in the local damage area; t is the average strain in the observation area; when S is 0, it indicates that there is no local damage to the sample, and the corresponding N is 1; when S is greater than 0, it indicates that a local damage area is formed in the sample, and the corresponding N is greater than 1.

[0072] Damage localization parameter L f The specific calculation formula is:

[0073]

[0074] Among them, (x k ,y k ) is the coordinate of the strain point k in the local damage area; and are the average values ​​of {xk} and {yk} respectively. f L is the correlation coefficient of the spatial position of the strain points in the local damage area, which can reflect the concentration of local damage to a certain extent, and its value range is 0-1. Ideally, the spatial position of the strain points in the local damage area is concentrated on a straight line, L f is 0; as the spatial position becomes discrete, L f Gradually increase to 1.

[0075] Figure 4 The variation law of damage parameters of the specimens under different freeze-thaw cycles. Among them, the horizontal axis in the figure is the loading time, and the origin corresponds to the starting time of local damage of each specimen. Before the origin, the boundary of the local damage zone cannot be identified, indicating that there is no local damage to the specimen, and the corresponding three parameters are constants. With the formation of the local damage zone, the three parameters begin to change. According to the changes in each damage parameter, the development and evolution process of mechanical local damage can be divided into three stages: Stage I is the stable local damage development stage; Stage II is the accelerated local damage development stage; Stage III is the post-peak local damage development stage.

[0076] In stage I, S increases steadily from 0, with a small change range, and the maximum increase is only 0.23; N increases rapidly and remains relatively stable after a period of time, with a stable value between 3.53-8.02; L fIt shows irregular changes, generally showing a trend of first decreasing and then increasing. In stage I, local damage develops slowly and takes the longest time. In stage II, S increases rapidly and reaches a maximum value at the peak stress, while N decreases rapidly and reaches a minimum value at the peak stress. When the number of freeze-thaw cycles is 0, 10, 20, 40, and 60, respectively, the increase in S reaches 86.59%, 124.90%, 184.78%, 180.79%, and 100.84%, respectively; the decrease in N is 15.80%, 27.46%, 54.76%, 48.49%, and 35.61%, respectively. L f It shows a continuous downward trend, with a decrease of 22.62%-62.21%. Compared with stage I, the damage parameters in this stage change greatly in a short period of time. According to the mutation points of S and N, the boundary between stage I and stage II can be determined. After the peak stress, the specimen enters stage III. S begins to decrease rapidly from the peak, while N increases to varying degrees. f The decreasing trend continued, and the minimum value was only 0.27, indicating that a highly linear local damage zone was formed. Finally, the macro crack ran through the entire specimen along the local damage zone.

[0077] The spatial localization parameter S and the numerical localization parameter N are inversely related to each other to some extent, especially in stages II and III. The rapid expansion of the local damage zone not only increases the spatial proportion of the local damage zone in the strain field, but also affects the change of the average strain inside and outside the local damage zone. f There is no strong correlation with the other two parameters. f The continuous decrease of indicates that the local damage area of ​​the specimen has undergone a process from nonlinear to linear to macroscopic destruction. Overall, the freeze-thaw cycle has no obvious effect on the change trend of the damage parameters in the above three stages, but it changes the degree of change of the parameters to varying degrees. For example, for the specimen that has undergone 60 freeze-thaw cycles, S changes steadily and the corresponding value is small; N increases rapidly and maintains a large value for a long time.

[0078] According to the evaluation results, the evolution process of local damage in freeze-thaw rock mechanics can be divided into the stable local damage development stage, the accelerated local damage development stage and the post-peak local damage development stage. In the stable local damage development stage, the changes of the three damage parameters from the initial value to the relatively stable value characterize the stable development process of the local damage zone from nothing to something. In the accelerated local damage development stage, all factors show mutations, S increases significantly, N and L f This indicates that the local damage area develops from disorder to order at an accelerated rate. In this process, the spatial proportion and linearity of the local damage area increase rapidly. In the post-peak local damage development stage, S decreases rapidly from the peak value, while N increases and L fIt continues to maintain a downward trend. These changes characterize the post-peak development process of the local damage zone. The spatial proportion of the local damage zone decreases, while the average strain and linearity continue to increase, which is a precursor to macroscopic rupture. From a temporal perspective, the post-peak local damage development stage is closest to freeze-thaw rock failure, but the accelerated local damage development stage before peak stress is more suitable as a precursor to failure. In engineering practice, using the mutation points of various damage parameters as precursors can not only warn and predict freeze-thaw rock failure, but also make full use of rock strength to avoid waste. The technical solution of the present invention has been initially applied in Xingzhou Open-Pit Mine in Fushun City, Liaoning Province, providing certain technical support for disaster prevention and prediction of mine slopes in freeze-thaw environments.

[0079] The present invention has the following beneficial effects: (1) Frozen-thawed rocks are highly heterogeneous and highly deformed, and conventional damage testing methods are difficult to apply. The obtained results are highly discrete, and the representativeness of the microscopic observation results is also poor, resulting in low accuracy in the mechanical damage assessment of frozen-thawed rocks, which may bring immeasurable losses. The use of the method of the present invention to identify and evaluate the local mechanical damage of frozen-thawed rocks not only overcomes the above-mentioned difficulties, but also conforms to the fact that "the instability and failure of frozen-thawed rocks is essentially the result of the initiation, development, and penetration of local damage on a macroscopic and microscopic scale." In addition, compared with scanning electron microscopy, micro-CT and other technical means, the present invention exhibits the effects of low cost, simple operation, and high reliability. It is not only suitable for indoor mechanical tests, but also can be used for in-situ testing.

[0080] (2) Combining digital image correlation technology with convolution theory to identify and evaluate local damage in freeze-thaw rock mechanics. Digital image correlation technology is used to obtain the evolution law of the apparent strain field of freeze-thaw rock under axial load. It has the advantages of full-field measurement, non-contact, strong applicability, and low cost, and can effectively overcome the problems of strong heterogeneity and large deformation of freeze-thaw rock. However, the spatiotemporal evolution process of the strain field is gradual, and it is difficult to judge the geometric characteristics, start-up timing, distribution range, etc. of the local damage zone with the naked eye. Therefore, the edge information of the local damage zone is detected by combining the convolution theory to accurately identify the local damage of freeze-thaw rock mechanics; according to the spatiotemporal evolution law of the local damage zone, three damage parameters (spatial localization parameter, numerical localization parameter, damage localization parameter) are proposed to quantitatively characterize the local damage characteristics of the rock, and establish its relationship with the number of freeze-thaw cycles; finally, the purpose of identifying and evaluating local damage in freeze-thaw rock mechanics is achieved.

[0081] The present invention also includes a freeze-thaw rock mechanics local damage identification and evaluation system, which specifically includes:

[0082] The image acquisition module is used to obtain the apparent strain field cloud map of frozen-thawed rocks.

[0083] The damage identification module uses the improved Sobel operator to perform convolution operation on the apparent strain field cloud map to obtain the final gradient values ​​of multiple strain points, draws a contour map based on the multiple final gradient values, connects the multiple inflection points in the contour map, and the area surrounded by the multiple inflection points is the local damage area.

[0084] The damage assessment module is used to calculate the spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L according to the area of ​​the local damage zone, the strain value and the coordinates of the strain point. f , according to S, N and L f The local damage characteristics of rock are quantitatively characterized, and the local damage evaluation results of freeze-thaw rock mechanics are obtained.

[0085] Each module in the above-mentioned freeze-thaw rock mechanics local damage identification and evaluation system can be implemented in whole or in part by software, hardware and their combination. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, 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 each of the above modules.

[0086] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps in an embodiment of a method for identifying and evaluating local damage in freeze-thaw rock mechanics. The specific implementation method can be found in the method embodiment, which will not be described in detail here.

[0087] Furthermore, the present invention also provides a non-temporary computer-readable storage medium containing instructions, and a computer program is stored on the storage medium. For example, a memory containing instructions, the above instructions can be executed by a processor of a computer device to complete the above method. For example, a non-temporary computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. When the computer program is executed by the processor, it can implement the steps in an embodiment of a method for identifying and evaluating local damage in freeze-thaw rock mechanics. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0088] It will be appreciated by those skilled in the art that embodiments of the present invention may provide methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0092] It should be pointed out that the specific implementation methods described above can enable those skilled in the art to understand the invention more comprehensively, but do not limit the invention in any way. Therefore, although the invention has been described in detail in this specification and embodiments, those skilled in the art should understand that the invention can still be modified or replaced by equivalents; and all technical solutions and improvements that do not deviate from the spirit and scope of the invention are included in the protection scope of the patent for the invention. Any figure mark in the claims should not be regarded as limiting the claims involved. Any simple change or equivalent replacement of the technical solution that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belongs to the protection scope of the present invention.

Claims

1. A method for identifying and evaluating local damage in freeze-thaw rock mechanics, characterized in that: The following steps are involved: Obtain the apparent strain field cloud map of frozen-thawed rocks; Using an improved Sobel operator to perform a convolution operation on the apparent strain field cloud map to obtain final gradient values ​​of multiple strain points, drawing a contour map according to the multiple final gradient values, connecting multiple inflection points in the contour map, and the area surrounded by the multiple inflection points is the local damage area; The spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L are calculated according to the area of ​​the local damage zone, the strain value and the coordinates of the strain point. f , according to the S, N and L f The local damage characteristics of rock are quantitatively characterized, and the local damage evaluation results of freeze-thaw rock mechanics are obtained.

2. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 1, characterized in that: The improved Sobel operator is specifically composed of four convolution kernels, including horizontal, vertical, 45° and -45° directions, and responds to the representation of edge information.

3. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 2, characterized in that: The improved Sobel operator is used to perform a convolution operation on the apparent strain field cloud map to obtain the final gradient values ​​of multiple strain points, specifically through the following steps: The convolution operation is performed in the improved Sobel operator, and the convolution kernel formula is as follows: If the strain field cloud diagram contains M×N strain points, and the strain value is expressed as F(m, n), then the gradient values ​​in the four directions are specifically: G x =g x *F(m,n); G y =g y *F(m,n); G 45° =g 45° *F(m,n); G -45° =g -45° *F(m,n); Among them, G x , G y , G 45° and G -45° Respectively represent the gradient values ​​of the strain points in the horizontal, vertical, 45° and -45° directions; * represents the convolution operation; The final gradient value at the strain point is calculated as follows: Where G is the final gradient value at the strain point.

4. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 1, characterized in that: The spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L are calculated according to the area of ​​the local damage zone, the strain value and the coordinates of the strain point. f , specifically through the following formula: The calculation formulas of the spatial localization parameter and the numerical localization parameter N are specifically: Among them, S l is the area of ​​local damage; S t is the total area of ​​the observation area; is the average strain in the local damage area; is the average strain in the observation area; Damage localization parameter L f The specific calculation formula is: Among them, (x k ,y k ) is the coordinate of the strain point k in the local damage area; and are the average values ​​of {xk} and {yk} respectively.

5. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 4, characterized in that: According to the S, N and L f Quantitatively characterize the local damage characteristics of rock, specifically: when S is 0, there is no local damage in the rock sample, and the corresponding N is 1; when S is greater than 0, it indicates that a local damage zone is formed in the sample, and the corresponding N is greater than 1; L f is the correlation coefficient of the spatial position of the strain points in the local damage area, reflecting the concentration of local damage, with a value range of 0-1. When the spatial positions of the strain points in the local damage area are concentrated on a straight line, L f is 0; when the spatial position becomes discrete, L f Gradually increase to 1.

6. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 1, characterized in that: The method of obtaining the apparent strain field cloud map of the frozen-thaw rock specifically comprises first obtaining a speckle image of the frozen-thaw rock through a mechanical test loading process; importing the speckle image into the software of the Vic-3D system, and drawing the apparent strain field of the rock sample during the loading process through calculation and analysis to obtain the apparent strain field cloud map of the frozen-thaw rock.

7. A freeze-thaw rock mechanics local damage identification and evaluation method according to claim 1, characterized in that: The freeze-thaw rock mechanics local damage evaluation results are specifically divided into a stable local damage development stage, an accelerated local damage development stage and a post-peak local damage development stage.

8. A freeze-thaw rock mechanics local damage identification and evaluation system, characterized in that: include: Image acquisition module, used to obtain the apparent strain field cloud map of frozen-thawed rocks; A damage identification module, using an improved Sobel operator to perform a convolution operation on the apparent strain field cloud map to obtain final gradient values ​​of multiple strain points, drawing a contour map according to the multiple final gradient values, connecting multiple inflection points in the contour map, and the area surrounded by the multiple inflection points is the local damage area; A damage evaluation module is used to calculate the spatial localization parameter S, the numerical localization parameter N and the damage localization parameter L according to the area of ​​the local damage area, the strain value and the coordinates of the strain point. f , according to the S, N and L f The local damage characteristics of rock are quantitatively characterized, and the local damage evaluation results of freeze-thaw rock mechanics are obtained.

9. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is loaded into a processor, the computer program can execute the steps of the method according to any one of claims 1 to 7.

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