A method and system for predicting the peak shear strength of grouted structural planes

Abstract

The present application relates to the technical field of digital data processing, and provides a method and a system for predicting the peak shear strength of a grouted structural plane. The method includes: constructing a shear strength model of a non-filled structural plane according to the effective height and effective angle of the structural plane; based on the shear strength model of the non-filled structural plane, considering the influence of the contact mode, filling degree, and ratio of the filling material strength to the rock strength of the soft-filled structural plane on the shear strength of the soft-filled structural plane, constructing a peak shear strength model of the soft-filled structural plane; based on the peak shear strength model of the soft-filled structural plane, analyzing the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane, and constructing a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane. This method can accurately predict the peak shear strength of the grouted structural plane and provide theoretical explanations and supports for the grouting reinforcement mechanism.

Description

Technical Field

[0001] The present application relates to the technical field of digital data processing, and particularly relates to a method, a system, a computer-readable storage medium, and an electronic device for predicting the peak shear strength of a grouted structural plane. Background Art

[0002] The mechanical properties of rock masses are greatly affected by the mechanical properties of structural planes. In various rock mass engineering constructions, great importance needs to be attached to the mechanical properties of structural planes. Grouting, as an active support method for strengthening surrounding rocks, improving the stress state of surrounding rocks, giving full play to the self-bearing capacity of surrounding rocks, and controlling the deformation of surrounding rocks, is widely used in practical engineering.

[0003] However, the theoretical research on the grouting reinforcement mechanism lags behind the engineering application, and it is difficult to provide reasonable theoretical explanations and theoretical supports for problems such as whether the strength of the rock mass after grouting is improved, how much the improvement amplitude is, and what the reason for the improvement of the rock mass strength after grouting is.

[0004] Therefore, an improved technical solution is needed to address the deficiencies of the above-mentioned prior art. Summary of the Invention

[0005] The purpose of the present application is to provide a method, a system, a computer-readable storage medium, and an electronic device for predicting the peak shear strength of a grouted structural plane to solve or alleviate the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] The present application provides a method for predicting the peak shear strength of a grouted structural plane, including:

[0008] Step S101: Construct a shear strength model of a non-filled structural plane according to the effective height and effective angle of the structural plane;

[0009] Step S102: Based on the shear strength model of the non-filled structural plane, consider the influence of the contact mode, filling degree, and ratio of filling material to rock strength of the soft-filled structural plane on the shear strength of the soft-filled structural plane, and construct a peak shear strength model of the soft-filled structural plane;

[0010] Step S103: Based on the peak shear strength model of the soft-filled structural plane, analyze the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouted structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane;

[0011] Among them, the basic form of the shear strength model of the grouted structural plane is as follows:

[0012]

[0013] where τ p3 represents the peak shear strength of the grouting structural plane; C 0 represents the cohesion of the interface between sandstone and cement stone; ω′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; k represents the second fitting parameter; h′ represents the effective height; σ′ c represents the composite strength of rock and cement stone.

[0014] Preferably, in step S101, the expression of the shear strength model of the unfilled structural plane is as follows:

[0015]

[0016] where τ p1 represents the peak shear strength of the unfilled structural plane; σ n represents the normal stress; represents the basic friction angle; ω′ represents the effective angle; h′ represents the effective height; σ c represents the strength of the structural plane rock wall.

[0017] Preferably, in step S102, the expression of the filling degree is:

[0018]

[0019] where η represents the filling degree, t represents the filling thickness, and b represents the distance between the lowest point of the upper structural plane and the highest point of the lower structural plane.

[0020] Preferably, in step S102, the expression of the peak shear strength model of the soft filled structural plane is as follows:

[0021]

[0022]

[0023] τ p2 represents the peak shear strength of the soft filled structural plane; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; k and d are the second fitting parameter and the third fitting parameter respectively; ω′ represents the effective angle; h′ represents the effective height; σ′ c represents the composite strength of rock and cement stone; σ r and σ g represent the compressive strengths of rock and cement stone respectively.

[0024] Preferably, the first fitting parameter c takes a value of 4, the second fitting parameter k takes a value of 0.6, and the third fitting parameter d takes a value of 2. Then the specific expression form of the shear strength model of the grouting structural plane is as follows:

[0025]

[0026]

[0027] In the formula, τ p4 represents the peak shear strength of the grouting structural plane determined by the three fitting parameters c, a, and d; C 0 represents the cohesion of the interface between sandstone and cement stone; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; ω′ represents the effective angle; h′ represents the effective height; σ′ c represents the composite strength of the rock and cement stone; σ r and σ g respectively represent the compressive strengths of the rock and cement stone.

[0028] Preferably, in step S103, the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouting structural plane is analyzed through a shear test. The shear test includes the following steps:

[0029] Paste a buffer gasket with a specified thickness at the end of each grouting structural plane specimen;

[0030] Conduct a shear test on the grouting structural plane specimen under a vertical load to obtain the overall cohesion of the grouting structural plane. The overall cohesion of the grouting structural plane is used to characterize the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouting structural plane.

[0031] Preferably, the buffer gasket is a rubber gasket.

[0032] The embodiment of the present application provides a prediction system for the peak shear strength of a grouting structural plane, including:

[0033] A first construction unit configured to construct a shear strength model of a non-filled structural plane according to the effective height and effective angle of the structural plane;

[0034] A second construction unit configured to construct a peak shear strength model of a weak filled structural plane based on the shear strength model of the non-filled structural plane, considering the influence of the contact mode, filling degree, and filling material to rock strength ratio of the weak filled structural plane on the shear strength of the weak filled structural plane;

[0035] The third construction unit is configured to analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane based on the peak shear strength model of the soft filling structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane;

[0036] Among them, the basic form of the shear strength model of the grouted structural plane is as follows:

[0037]

[0038] In the formula, τ p3 represents the peak shear strength of the grouted structural plane; C 0 represents the cohesion of the sandstone-cement interface; ω′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; k represents the second fitting parameter; h ′ represents the effective height; ρ c ′ represents the composite strength of the rock-cement.

[0039] The embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored, and the program is the method according to any one of the above embodiments.

[0040] The embodiment of the present application also provides an electronic device, including: a memory, a processor, and a program stored in the memory and executable on the processor, and when the processor executes the program, the method according to any one of the above embodiments is implemented.

[0041] The technical solution provided by the present application has the following beneficial effects:

[0042] This solution first constructs a shear strength model for a joint without filling based on the effective height and effective angle of the joint plane; then, based on the shear strength model of the joint without filling, considering the influence of the contact mode, filling degree, and strength ratio of the filling material to the rock on the shear strength of the soft filling joint plane, a peak shear strength model for the soft filling joint plane is constructed; finally, based on the peak shear strength model of the soft filling joint plane, the influence of the bonding effect at the rock-cement interface on the shear strength of the grouted joint plane is analyzed, and a shear strength model for the grouted joint plane is constructed to predict the peak shear strength of the grouted joint plane. The proposed shear strength model for the grouted joint plane can quantitatively predict the peak shear strength of the grouted joint plane, and its construction involves multiple influencing factors, comprehensively considering the influence of joint roughness, filling degree, strength ratio of rock to filling material, normal stress, and cohesion on the shear strength of the grouted joint plane, eliminating the difficult-to-determine critical filling degree, and maintaining a relatively simple expression form while ensuring the prediction accuracy. This model can be degenerated into the Mohr-Coulumb shear strength formula, reflecting the contribution of the friction and bonding force between the cement stone and the joint rock wall to the shear strength of the grouted joint plane, with a very clear physical meaning, and can provide a reasonable theoretical explanation and theoretical support for the shear strength of the joint plane. At the same time, this model is proposed based on the three-dimensional morphological characteristics of the joint plane, and the morphological parameters can be directly determined from the data of the three-dimensional laser scanning test, avoiding the error of manual judgment and being very convenient to operate. In addition, this model can also be degenerated into the peak shear strength model of the soft filling joint plane and the shear strength model of the joint without filling, and has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. Among them:

[0044] Figure 1 FIG. is a schematic flow chart of a method for predicting the peak shear strength of a grouted joint plane according to some embodiments of this application.

[0045] Figure 2 FIG. is a schematic structural diagram of a grouted joint plane according to some embodiments of this application.

[0046] Figure 3 FIG. is a schematic diagram of the relative relationship between the upper and lower joint planes according to some embodiments of this application.

[0047] Figure 4 FIG. is a schematic diagram of the grouting process according to some embodiments of this application.

[0048] Figure 5Schematic diagram of the grouting process provided according to some embodiments of the present application.

[0049] Figure 6 Schematic diagram of the shear test of a flat structural plane provided according to some embodiments of the present application.

[0050] Figure 7 Schematic diagram of the shear test of a rough structural plane provided according to some embodiments of the present application.

[0051] Figure 8 Provided according to some embodiments of the present application Figure 7 Partial enlarged schematic diagram at E in

[0052] Figure 9 Schematic diagram of the structure of a peak shear strength prediction system for a grouted structural plane provided according to some embodiments of the present application.

[0053] Figure 10 Schematic diagram of the structure of an electronic device provided according to an embodiment of the present application.

[0054] Figure 11 Hardware structure diagram of an electronic device provided according to an embodiment of the present application.

[0055] Description of reference numerals:

[0056] 1 - indenter, 2 - buffer gasket, 3 - specimen. Detailed implementation manners

[0057] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application rather than limitation of the present application. In fact, those skilled in the art will appreciate that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features shown or described as part of one embodiment can be used in another embodiment to yield yet another embodiment. Accordingly, it is intended that the present application cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0058] In the following description, the terms "first / second / third" involved are only used to distinguish similar objects and do not represent a specific order of the objects. It can be understood that "first / second / third" can be interchanged with a specific order or sequence when permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this disclosure belongs. The terms used herein are only for the purpose of describing the embodiments of this disclosure and are not intended to limit this disclosure.

[0060] Example 1:

[0061] An embodiment of the present application provides a method for predicting the peak shear strength of a grouted structural plane, as Figure 1 shown. This method includes:

[0062] Step S101: Construct a shear strength model of a non-filled structural plane according to the effective height and effective angle of the structural plane.

[0063] Figure 2 FIG. is a schematic structural diagram of a grouted structural plane provided according to some embodiments of the present application, as Figure 2 shown. The grouted structural plane mainly includes two parts: the structural plane rock wall and the hydrated cement. Among them, the structural plane rock wall refers to the rock surface or rock mass structure with obvious joints (fissures or cracks) in the rock or rock mass. If no material is filled in the structural plane, it is called a non-filled joint / non-filled structural plane. The hydrated cement includes: the hydrated cement body and the interfacial transition region between the hydrated cement and the structural plane rock wall. In this embodiment, by comparing the differences among the non-filled structural plane, the weak-filled structural plane, and the grouted structural plane, and based on the shear strength model of the non-filled structural plane, various influencing factors are fully considered to construct the shear strength model of the grouted structural plane.

[0064] In this embodiment, asperities refer to the tiny structures or protrusions protruding on the surface of the structural plane or within the rock fissures. By respectively establishing the quantitative relationships between the inclination angle of the asperities and the potential damage area, and the height and the potential damage degree, and calculating the effective height h' and the effective angle ω' according to these quantitative relationships, the two independent topographic parameters of the effective height h' and the effective angle ω' are used to describe the roughness of the structural plane.

[0065] Considering the influence of the roughness of the upper and lower structural planes on the shear strength, based on the effective height h' and the effective angle ω', a shear strength model of the non-filled structural plane is proposed, and its expression is as follows:

[0066]

[0067] In the formula, τ p1 represents the peak shear strength of the non-filled structural plane; σ n represents the normal stress; represents the basic friction angle; ω' represents the effective angle; h' represents the effective height; σ c represents the strength of the structural plane rock wall.

[0068] Step S102: Based on the shear strength model of the non-filled structural plane, consider the influence of the contact mode, filling degree, and ratio of the filling material to the rock strength of the weak-filled structural plane on the shear strength of the weak-filled structural plane, and construct a peak shear strength model of the weak-filled structural plane.

[0069] If only considering the filling effect of the hardened cement paste on the rock wall of the structural plane and temporarily ignoring the influence of the cohesion at the interface between the hardened cement paste and the rock wall of the structural plane, the grouted structural plane can be regarded as a weak filling structural plane.

[0070] Compared with the shear strength model of the unfilled structural plane, the peak shear strength model of the weak filling structural plane mainly has the following differences:

[0071] ① In the unfilled structural plane, the contact mode between the upper and lower structural planes is rock wall of structural plane - rock wall of structural plane contact, while the contact mode of the weak filling structural plane is rock wall of structural plane - hardened cement paste contact. Therefore, the basic friction angle at the interface between the rock and the hardened cement paste should be adopted in the peak shear strength model of the weak filling structural plane to replace the basic friction angle of the rock.

[0072] ② The shear strength of the weak filling structural plane is significantly affected by the filling degree.

[0073] ③ The shear strength of the weak filling structural plane is also significantly affected by the composite strength σ′ of the rock - hardened cement paste c Although there is a significant strength difference between the hardened cement paste and the rock, in actual engineering, there are cases of strong grouting materials (i.e., the strength of the grouting material / filling material is large, such as ultra - fine cement, chemical grout) and weak rocks (i.e., the strength of the rock is small, such as mudstone). The strength of some grouting materials even exceeds the strength of the rock. Therefore, it is necessary to analyze the influence of the strength ratio of the filling material to the rock on the shear strength and the failure mode. When the strength of the filling material is similar to the strength of the rock wall of the structural plane, the composite strength of the rock wall of the structural plane and the filling material (such as rock - hardened cement paste) is basically equal to the strength of the rock wall of the structural plane; when the strength of the filling material is much lower than the strength of the rock wall of the structural plane, the composite strength is mainly determined by the filling material (such as the hardened cement paste); when the strength of the filling material is much higher than the strength of the rock wall of the structural plane (this situation is relatively rare), the composite strength is mainly determined by the rock wall of the structural plane.

[0074] Based on the above analysis, in this embodiment, the expression of the peak shear strength model of the weak filling structural plane is as follows:

[0075]

[0076]

[0077] τ p2 represents the peak shear strength of the weak filling structural plane; σ n represents the normal stress; represents the basic friction angle at the interface between the rock and the hardened cement paste; η represents the filling degree; k and d are the second fitting parameter and the third fitting parameter respectively; ω′ represents the effective angle; h′ represents the effective height; σ′c represents the composite strength of rock and hardened cement paste; σ r , σ g respectively represent the compressive strengths of rock and hardened cement paste.

[0078] To fully consider the influence of the filling degree on the shear strength of the weak filling structural plane, a new filling degree expression is adopted for the filling degree η in the peak shear strength model of the weak filling structural plane. The following details the expression of this filling degree η.

[0079] The three-dimensional topographic features of the grouted structural plane have a certain similarity to those of the ungrouted structural plane. For both, it is necessary to consider the influence of the roughness of the upper and lower structural planes on the mechanical properties of the grouted structural plane. In addition, although the cement slurry is a relatively thin filling, its thickness still has an important influence on the mechanical properties of the grouted structural plane. Therefore, when predicting the shear strength of the grouted structural plane, it is crucial to consider the influence of the filling thickness on the mechanical properties generated by the grouted structural plane.

[0080] Figure 3 is a schematic diagram of the relative relationship between the upper and lower structural planes provided according to some embodiments of the present application. Figure 3 Part (a) shows the relative relationship between the upper and lower structural planes in the general filling state. Arbitrarily select two mutually coupled microconvex bodies on the upper and lower structural planes. The lowest point of the upper structural plane is P 1 , and the highest point of the lower structural plane is P 2 . The distance from the bottom of the lower structural plane to the lowest point of the upper structural plane is P 1 is the filling thickness t, and the distance from the bottom of the lower structural plane to the highest point of the lower structural plane is P 2 is the height a of the microconvex body.

[0081] In previous studies on weak filling structural planes, generally the filling degree λ, that is, the ratio of the filling thickness t to the height a of the microconvex body, is used to replace the filling thickness. This expression of the filling degree λ is also called the traditional filling degree expression.

[0082] A large number of existing studies have shown that when using the traditional filling degree λ to describe the influence on the mechanical properties of the grouted structural plane, there is a critical filling degree λ cri . When the filling degree λ is lower than the critical filling degree λ cri , the mechanical properties of the structural plane are significantly affected by the filling degree; when the filling degree λ is higher than this critical value λ cri , the mechanical properties of the structural plane basically remain stable and no longer change significantly with the filling degree. That is to say, the filling degree λ and the critical filling degree λ criThey are all key indicators affecting the mechanical properties of the filled structural plane, that is, the two indicators that need to be obtained in advance in the traditional peak shear strength prediction model. However, the applicant's research found that there are the following difficulties in this expression:

[0083] (1) The filling degree λ and the critical filling degree λ cri are two independent indicators. Only when the values of the filling degree λ and the critical filling degree λ cri are both determined can the influence law of the filling degree on the peak shear strength of the filled structural plane be obtained. However, the two indicators are too cumbersome, and their corresponding data are not easy to obtain.

[0084] (2) Regarding the value of the critical filling degree λ cri in the past, most studies used materials such as gypsum to make replicas of serrated structural planes, and then designed different thicknesses of filling materials. Through multiple groups of experiments, the critical filling degree λ cri was obtained. This process is complex and cumbersome, with low efficiency, and is prone to introducing errors.

[0085] (3) In fact, there are still many differences in the mechanical properties between materials such as gypsum and real rock materials. If model materials are used to simulate grouted structural planes, not only the mechanical properties of the structural plane replicas need to be comparable to those of real rocks, but also the mechanical properties of the interfaces between the structural plane replicas and the grout stones need to be consistent with those of the interfaces between rocks and grout stones. This increases the experimental difficulty and it is difficult to ensure the accuracy of mechanical property characterization.

[0086] (4) In addition, from the perspective of the filling material, high water-cement ratio cement slurry is a fluid. It is difficult to obtain any filling thickness value like a soft filled structural plane, and the critical filling degree cannot be determined through experimental means. 3D printing technology can solve this problem, but this method is costly and requires researching rock-like materials, slurry-like materials, and accurately simulating the mechanical properties of the rock-slurry interface, all of which are relatively difficult.

[0087] (5) The critical filling degree λ cri may vary with different rock types, the coupling degree of the upper and lower structural planes, the roughness of the structural plane, and the normal stress. The specific variation law is not clear in the industry at present and still needs further research. If the critical filling degree λ cri is significantly affected by these factors, only knowing the critical filling degree λ cri of a certain structural plane in a certain state will become meaningless, and it will also lead to a significant reduction in the accuracy of the constructed shear strength prediction model.

[0088] To address the above problems, this embodiment proposes a new expression for the filling degree.

[0089] Specifically,Figure 3 Part (b) shows the relative relationship between the upper and lower structural surfaces under the critical filling state. Figure 3 Part (c) shows the relative relationship between the upper and lower structural surfaces under the critical grouting state, referring to Figure 3 First, the upper structural surface is lifted so that the lowest point P 1 The highest point above the lower structural surface is P 2 , so that during the shear test, the upper and lower structural surfaces will be relatively offset and no longer in contact. Then, a soft filler is filled in the gap between the upper and lower structural surfaces, and it is assumed that the strength of the filler is significantly lower than the strength of the structural surface rock wall. In this way, during the shear test, shear failure occurs inside the filler and is not affected by the structural surface rock wall. Based on the above analysis, this embodiment compares the traditional filling degree λ and the critical filling degree λ cri The two indicators are integrated to propose a new expression of filling degree, which is as follows:

[0090]

[0091] In the formula, η represents the filling degree, t represents the filling thickness, and b represents the lowest point P of the upper structural surface. 1 To the highest point P of the lower structural surface 2 The distance between.

[0092] The difference from the traditional expression of filling degree λ is that the denominator of this formula is different. It is no longer calculated based on the height of the micro-convex body, but the lowest point P of the upper structural surface is used. 1 To the highest point P of the lower structural surface 2 The distance between them. For the grouting structural surface, when η=0, it corresponds to the unfilled structural surface. The contact state between the upper and lower structural surfaces during the shearing process is the structural surface rock wall-structural surface rock wall contact, and the shear strength is completely controlled by the structural surface rock wall; when 0<η<1, the contact state between the upper and lower structural surfaces during the shearing process is the structural surface rock wall-cement stone-structural surface rock wall contact, and the shear strength will be jointly controlled by the structural surface rock wall and cement stone, and the influence of the filler (cement stone) gradually increases with the increase of the filling degree; when η≥1, the contact state between the upper and lower structural surfaces during the shearing process is rock-cement stone contact, and the shear strength is completely controlled by the filler. In the calculation process, the filling degree η should be taken as 1, which is the critical filling degree. Therefore, the proposed filling degree η can accurately reflect the influence of the filling degree on the mechanical properties of the grouting structural surface.

[0093] It should be pointed out that this inference is only applicable to the case where the mechanical properties of the filling material are significantly weaker than those of the structural surface rock wall (such as cement slurry with a high water-cement ratio). If the filling material has a higher strength, when η = 1, shear failure may occur simultaneously in the filling material and the structural surface rock wall, and the critical filling degree is no longer equal to 1.

[0094] It should also be understood that although only cement grouting tests have been carried out in this application, this method is also applicable to other filling structural planes, chemical grouting, and other solid-liquid and solid-solid contact problems. This solution does not limit the contact method between structural planes and the filling material.

[0095] When the filling material is high water-cement ratio cement slurry, the filling thickness t (also known as the grouting volume) consists of two parts: (1) the fracture aperture r before grouting; (2) the height difference Δh of the specimen before and after grouting.

[0096] Among them, the fracture aperture r is a parameter used to measure the size of the fracture space, which exists abundantly in natural rock masses and is generated due to poor matching between the upper and lower structural planes.

[0097] The following refers to Figure 4 、 Figure 5 to illustrate the method for obtaining and calculating the parameter filling thickness t.

[0098] Figure 4 、 Figure 5 is a schematic diagram of the grouting process provided according to some embodiments of the present application. Figure 4 Part (a) of Figure 4 is intact rock, and part (b) of Figure 5 is a structural plane without filling. Before grouting, the distance between the upper and lower structural planes is the fracture aperture r. During the grouting process, due to the good fluidity of the high water-cement ratio cement slurry, the slurry enters the fracture space and expels water and air. The slurry (cement stone) fills the fracture space, as shown in part (c) of Figure 5 . Under the extrusion of an external pressure source, the slurry gradually fills the entire fracture space and drives the fracture to further expand, forming an extrusion effect. The gap between the upper and lower structural planes further increases, resulting in a height difference Δh between the height of the specimen after grouting and the height of the specimen before grouting, as shown in part (d) of

[0099] Therefore, the filling thickness t can be obtained by calculating the sum of the fracture aperture r and the height difference Δh. cri It should be noted that both the fracture aperture r and the height difference Δh can be obtained through the production of grouting structural plane specimens and three-dimensional laser scanning tests. On this basis, the filling thickness t can be obtained, avoiding various problems brought by the need to obtain the critical filling degree λ through multiple groups of tests in the traditional expression of the filling degree λ

[0100] Exemplarily, high-strength sandstone from a certain coal mine is taken, and a series of sandstone structural plane specimens are obtained through splitting tests. Subsequently, these sandstone structural plane specimens are grouted to form grouting structural plane specimens.

[0101] Specifically, the three-dimensional laser scanning test may include the following steps:

[0102] ① Establish a coordinate system: Since the two side surfaces and the bottom surface of the structural plane are hardly affected during the shear test and can be almost ignored, they can be used as reference planes. Define any vertex on the bottom surface of the structural plane as the origin O of the coordinate system. With O as the vertex, two mutually perpendicular sides are respectively the X-axis and the Y-axis, forming the XOY plane. Then the two side surfaces are the XOZ and YOZ planes, thus establishing a three-dimensional coordinate system.

[0103] ② Obtain three-dimensional point cloud data: Stick multiple marker points on the side of the sandstone structural plane specimen, and scan the upper and lower structural planes and the assembled whole specimen respectively. Through the splicing of the marker points, a three-dimensional data point cloud including the upper and lower structural planes, the XOY plane, the XOZ plane, and the YOZ plane is obtained.

[0104] ③ Coordinate reconstruction: Import the three-dimensional data point cloud into MATLAB (Matrix Laboratory), calculate the distances from each point on the upper and lower structural planes to the YOZ plane, the XOZ plane, and the XOY plane, and define them as the x, y, and z coordinates of the point respectively, so as to realize the coordinate reconstruction of the surface of the structural plane and use it as the initial file for further calculation.

[0105] ④ Use MATLAB to realize the image reconstruction of the structural plane in the form of triangular elements and calculate the relevant topographic parameters.

[0106] ⑤ Use MATLAB to discretize the structural plane in the X and Y directions into rectangular grids with a specified spacing (such as 0.25 mm), calculate the z values of each point on the upper and lower structural planes at the grid nodes through interpolation method, and the average value of the differences in the z values at each node is the fracture aperture r.

[0107] ⑥ Obtain the fitting plane of each point on the bottom surface through least squares fitting, and the average value of the distances from each point on the upper surface to this fitting plane is the height of the specimen before grouting.

[0108] ⑦ After grouting, place the upper bottom surface of the grouted structural plane facing the scanner as the initial position, automatically rotate 360°, and record the topographic features of the upper and lower bottom surfaces and the two side surfaces of the grouted structural plane. Import the scanned data into MATLAB, obtain the fitting plane of each point on the bottom surface through least squares fitting, and the average value of the distances from each point on the upper surface to this fitting plane is the height of the specimen after grouting. Furthermore, the height difference Δh of the specimen before and after grouting can be obtained.

[0109] Step S103: Based on the peak shear strength model of the weak filling structural plane, analyze the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouted structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane.

[0110] It should be noted that, compared with the weak filling structural plane, the shear strength of the grouted structural plane is also significantly affected by the cohesion of the rock-cement stone interface. To analyze the contribution of the bonding effect to the shear strength, a new shear test method for the grouted structural plane is adopted in this embodiment. That is, in step S103, to analyze the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouted structural plane, the following steps can be specifically adopted: fabricate a grouted structural plane specimen, and paste a buffer gasket with a specified thickness at the end of each grouted structural plane specimen; conduct a shear test on the grouted structural plane specimen under a vertical load to obtain the overall cohesion of the grouted structural plane, and the overall cohesion of the grouted structural plane is used to characterize the influence of the bonding effect of the rock-cement stone interface on the shear strength of the grouted structural plane.

[0111] According to the characteristics of the structural plane, the structural plane can be divided into a smooth structural plane and a rough structural plane, and the smooth structural plane is also called a flat structural plane. Figure 6 FIG. is a schematic diagram of a shear test of a flat structural plane provided by some embodiments of the present application. Figure 7 FIG. is a schematic diagram of a shear test of a rough structural plane provided by some embodiments of the present application. Figure 8 For some embodiments provided by the present application Figure 7 The partial enlarged schematic diagram at E in Figures 6 - 8 As shown, the sandstone structural plane specimen is divided into left and right parts. Whether it is a flat structural plane or a rough structural plane, before conducting the shear test, it is necessary to paste buffer gaskets with a specified thickness at the upper and lower ends of each sandstone structural plane specimen. For example, the buffer gasket can be a rubber pad. Further, the thickness of the rubber pad is preferably 5 mm. Place the sandstone structural plane specimen between the buffer gaskets for grouting, and after curing for 28 days, a grouted structural plane specimen is formed. Outside the buffer gasket is the indenter, and a vertical load F is applied to the grouted structural plane at the indenter. Since the elastic modulus of the buffer gasket is much smaller than that of the specimen, for example, the elastic modulus of the rubber pad does not exceed 10 MPa, while the elastic modulus of the sandstone is 30 GPa, therefore, the vertical load F almost entirely acts on the sandstone. Compared with the traditional direct shear test, the normal stress of the shear test method provided in this embodiment is 0. Therefore, the test result is equal to the overall cohesion of the grouted structural plane:

[0112]

[0113] In the formula, τ p represents the peak shear strength of the grouted structural plane in the shear test, C represents the overall cohesion of the grouted structural plane, σ n represents the normal stress, represents the friction angle of the grouted structural plane.

[0114] Next, refer to Figures 6 - 8Elaborate on the relationship between the test results of the above shear test and the overall cohesion of the grouted structural plane to prove that its test results are equal to the overall cohesion of the grouted structural plane.

[0115] Since the structural plane is divided into a smooth structural plane and a rough structural plane, if the structural plane is smooth, as Figure 6 shown, the test result will be determined by the cohesion C 0 of the sandstone-cement stone interface; if the structural plane is rough, as Figure 7 shown, the test result will be jointly determined by the structural plane roughness and the cohesion C 0 of the sandstone-cement stone interface.

[0116] Due to the very low tensile strength of the high water-cement ratio cement stone, in the rough structural plane, the load F mainly acts on the rock wall of the structural plane on the shear-opposing side, while the rock wall of the structural plane on the shear-back side is directly pulled and damaged. Combining Figure 8 , taking any rock wall of the structural plane on the shear-opposing side for force analysis, its force balance condition can be known. According to the force balance condition of the rock wall of the structural plane on the shear-opposing side, we can get:

[0117] F = (C 0 ·A) / cos(θ),

[0118] C = F / A = C 0 / cos(θ) (5)

[0119] In the formula, θ represents the geometric dip angle of the structural plane, F represents the load (applied by the testing machine), and A represents the area of the structural plane on the shear-opposing side.

[0120] Through formula (5), the following conclusions can be obtained: ① The overall cohesion C of the grouted structural plane is positively correlated with the structural plane roughness; ② When the structural plane is relatively smooth (for example, θ = 0°), the overall cohesion C of the grouted structural plane is equal to the cohesion C 0 of the sandstone-cement stone interface, that is, C = C 0 .

[0121] Based on the above analysis, the basic form of the shear strength model of the grouted structural plane can be obtained. In this application, the basic form of the shear strength model of the grouted structural plane is as follows:

[0122]

[0123] In the formula, τ p3 represents the peak shear strength of the grouted structural plane; C 0 represents the cohesion of the sandstone-cement stone interface; ω′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; k represents the second fitting parameter; h′ represents the effective height; σ′ c represents the composite strength of the rock and the cement stone.

[0124] In a specific example, three-dimensional laser scanning tests and shear tests were carried out on specimens numbered Z1 to Z10, and the test results are shown in Table 1 as follows:

[0125] Table 1 Three-dimensional laser scanning test, shear test and model prediction results

[0126]

[0127]

[0128] Combining the basic form of the shear strength model of the grouting structural plane with the results of the three-dimensional laser scanning test and the shear test shown in Table 1, that is, using the data in Table 1 to determine the values of the first fitting parameter c, the second fitting parameter k, and the third fitting parameter d, the specific expression form of the shear strength model of the grouting structural plane can be obtained. Among them, the value of the first fitting parameter c is 4, the value of the second fitting parameter k is 0.6, and the value of the third fitting parameter d is 2. The specific expression form is:

[0129]

[0130]

[0131] In the formula, τ p4 represents the peak shear strength of the grouting structural plane; C 0 represents the cohesion of the sandstone-cement interface; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; ω ′ represents the effective angle; h ′ represents the effective height; σ c ′ represents the composite strength of the rock and the cement stone; σ r and σ g respectively represent the compressive strengths of the rock and the cement stone.

[0132] Table 1 also includes the comparison data between the test results and the prediction results. Among them, the "test results" column lists the results of the shear tests of each specimen, and the "calculation results" column lists the corresponding prediction results of the shear strength model of the grouting structural plane. From the comparison data, it can be seen that the maximum error, minimum error, and average error between the test results and the model prediction results are: 0.2633, 0.0086, and 0.0879, respectively, indicating that the prediction results of the shear strength model of the grouting structural plane are in good agreement with the indoor test results.

[0133] In summary, the method for predicting the peak shear strength of the grouted structural plane provided by this application is based on the shear strength model of the unfilled structural plane, fully considers the morphological characteristics such as the effective height and effective angle of the structural plane, and comprehensively considers the influence of the filling degree, the strength ratio of the rock to the filling material, the normal stress, and the cohesion on the shear strength of the grouted structural plane. The proposed shear strength model of the grouted structural plane can accurately predict the peak shear strength of the grouted structural plane.

[0134] The proposed shear strength model of the grouted structural plane can be degenerated into the Mohr-Coulumb shear strength formula:

[0135]

[0136] Among them, τ is the shear strength,

[0137] Therefore, this model can reflect the contributions of the frictional force and adhesive force between the cement stone and the structural plane rock wall to the shear strength of the grouted structural plane, and its physical meaning is very clear.

[0138] During the model construction process of this application, the expression of the traditional filling degree was also optimized. By integrating the traditional filling degree and the critical filling degree, a new expression of the filling degree η was proposed, so that the filling degree η can be directly determined from the morphological data, eliminating the difficult-to-determine critical filling degree λ cri , avoiding various problems caused by the difficulty in obtaining the numerical value of the critical filling degree λ cri during the shear strength prediction process.

[0139] Example 2:

[0140] The embodiment of this application provides a system for predicting the peak shear strength of a grouted structural plane. As Figure 9 shown, this system includes:

[0141] The first construction unit 901 is configured to construct a shear strength model of the unfilled structural plane according to the effective height and effective angle of the structural plane;

[0142] The second construction unit 902 is configured to construct a peak shear strength model of the weak filling structural plane based on the shear strength model of the unfilled structural plane, considering the influence of the contact mode, filling degree, and strength ratio of the filling material to the rock of the weak filling structural plane on the shear strength of the weak filling structural plane;

[0143] The third construction unit 903 is configured to analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane based on the peak shear strength model of the soft filling structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane;

[0144] Among them, the basic form of the shear strength model of the grouted structural plane is as follows:

[0145]

[0146] In the formula, τ p3 represents the peak shear strength of the grouted structural plane; C 0 represents the cohesion of the sandstone-cement interface; ω ′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; k represents the second fitting parameter; h ′ represents the effective height; ρ c ′ represents the composite strength of the rock-cement.

[0147] The peak shear strength prediction system of the grouted structural plane provided by the embodiments of the present application can implement the steps and processes of the peak shear strength prediction method of the grouted structural plane provided by any of the above embodiments, and achieve the same technical effects, which will not be repeated here one by one.

[0148] Embodiment 3:

[0149] Figure 10 It is a schematic structural diagram of an electronic device provided according to some embodiments of the present application; as Figure 10 shown, the electronic device includes:

[0150] One or more processors 1001;

[0151] A computer-readable storage medium, which can be configured to store one or more programs 1002. When one or more processors 1001 execute one or more programs 1002, the following steps are implemented:

[0152] Step S101, construct a shear strength model of the unfilled structural plane according to the effective height and effective angle of the structural plane;

[0153] Step S102, based on the shear strength model of the unfilled structural plane, consider the influence of the contact mode, filling degree, and filling material-rock strength ratio of the soft filling structural plane on the shear strength of the soft filling structural plane, and construct a peak shear strength model of the soft filling structural plane;

[0154] Step S103: Based on the peak shear strength model of the weak filling structural plane, analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane.

[0155] Among them, the basic form of the shear strength model of the grouted structural plane is as follows:

[0156]

[0157] In the formula, τ p3 represents the peak shear strength of the grouted structural plane; C 0 represents the cohesion of the sandstone-cement interface; ω ′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; k represents the second fitting parameter; h ′ represents the effective height; σ c ′ represents the composite strength of the rock-cement.

[0158] Figure 11 The hardware structure of the electronic device provided by some embodiments of the present application is as follows; as Figure 11 shown, the hardware structure of the electronic device may include: a processor 1101, a communication interface 1102, a computer-readable storage medium (also referred to as a memory) 1103, and a communication bus 1104.

[0159] Among them, the processor 1101, the communication interface 1102, and the computer-readable storage medium 1103 complete communication with each other through the communication bus 1104.

[0160] The computer-readable storage medium 1103 can be configured to store one or more programs.

[0161] Optionally, the communication interface 1102 can be an interface of a communication module, such as an interface of a GSM module.

[0162] Among them, the processor 1101 executes one or more programs, and the program implements the following steps:

[0163] Step S101: Construct a shear strength model of the unfilled structural plane according to the effective height and effective angle of the structural plane;

[0164] Step S102: Based on the shear strength model of the unfilled structural plane, consider the influence of the contact mode, filling degree, and filling material-rock strength ratio of the weak filling structural plane on the shear strength of the weak filling structural plane, and construct a peak shear strength model of the weak filling structural plane;

[0165] Step S103: Based on the peak shear strength model of the weak filling structural plane, analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane;

[0166] Among them, the basic form of the shear strength model of the grouted structural plane is as follows:

[0167]

[0168] In the formula, τ p3 represents the peak shear strength of the grouted structural plane; C 0 represents the cohesion of the sandstone-cement interface; ω ′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the rock-cement interface; η represents the filling degree; k represents the second fitting parameter; h ′ represents the effective height; σ c ′ represents the composite strength of the rock-cement.

[0169] The processor 1101 can be a general-purpose processor, including a central processing unit (CPU for short), a network processor (NP for short), etc., and can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0170] The electronic devices in the embodiments of the present application exist in various forms, including but not limited to:

[0171] (1) Mobile communication devices: The characteristic of such devices is that they have mobile communication functions and mainly aim to provide voice and data communication. Such terminals include: smart phones (e.g., iPhone), multimedia phones, functional phones, and low-end phones, etc.

[0172] (2) Ultra-mobile personal computer devices: Such devices belong to the category of personal computers, have computing and processing functions, and generally also have the characteristic of mobile Internet access. Such terminals include: PDAs, MIDs, and UMPC devices, etc., such as iPad.

[0173] (3) Portable entertainment devices: Such devices can display and play multimedia content. This type of device includes: audio and video players (e.g., iPod), handheld game consoles, e-books, as well as smart toys and portable in-vehicle navigation devices.

[0174] (4) Servers: Devices that provide computing services. The composition of a server includes a processor, hard disk, memory, system bus, etc. Servers are similar to general computer architectures, but due to the need to provide highly reliable services, they have higher requirements in terms of processing power, stability, reliability, security, scalability, manageability, etc.

[0175] (5) Other electronic devices with data interaction functions.

[0176] It should be noted that according to the needs of implementation, each component / step described in the embodiments of the present application can be split into more components / steps, or two or more components / steps or partial operations of components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present application.

[0177] The methods according to the embodiments of the present application can be implemented in hardware, firmware, or be implemented as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk, or magneto-optical disk), or be implemented as computer code originally stored in a remote recording medium or a non-transitory machine storage medium and downloaded through a network and to be stored in a local recording medium, so that the methods described herein can be processed by such software stored on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the peak shear strength prediction method of the grouting structural plane described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein.

[0178] Those of ordinary skill in the art can realize that the units and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application of the technical solution and the involved constraints. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the embodiments of the present application.

[0179] It should be noted that the various embodiments in this specification are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for the device and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiments.

[0180] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for predicting the peak shear strength of a grouted structural plane, characterized in that, it includes: Step S101: Construct a shear strength model of the unfilled structural plane according to the effective height and effective angle of the structural plane; Step S102: Based on the shear strength model of the unfilled structural plane, considering the influence of the contact mode, filling degree, and ratio of filling material to rock strength of the soft-filled structural plane on the shear strength of the soft-filled structural plane, construct a peak shear strength model of the soft-filled structural plane; Step S103: Based on the peak shear strength model of the soft-filled structural plane, analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane; wherein, the basic form of the shear strength model of the grouted structural plane is as follows: In the formula, τ p3 represents the peak shear strength of the grouting structural plane; C 0 represents the cohesion of the interface between sandstone and cement stone; ω′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; k represents the second fitting parameter; h′ represents the effective height; σ c ′ represents the composite strength of rock and cement stone.

2. The method according to claim 1, characterized in that, in Step S101, the expression of the shear strength model of the unfilled structural plane is as follows: where τ p1 represents the peak shear strength of the unfilled structural plane; σ n represents the normal stress; represents the basic friction angle; ω′ represents the effective angle; h′ represents the effective height; σ c represents the rock wall strength of the structural plane.

3. The method according to claim 1, characterized in that, in Step S102, the expression of the filling degree is: In the formula, η represents the filling degree, t represents the filling thickness, and b represents the distance between the lowest point of the upper structural plane and the highest point of the lower structural plane.

4. The method according to claim 1, characterized in that, in Step S102, the expression of the peak shear strength model of the soft-filled structural plane is as follows: τ p2 represents the peak shear strength of the weak filling structural plane; σ n represents the normal stress; represents the basic friction angle of the interface between the rock and the cement stone; η represents the filling degree; k and d are the second fitting parameter and the third fitting parameter respectively; ω′ represents the effective angle; h′ represents the effective height; σ c ′ represents the composite strength of the rock and the cement stone; σ r and σ g represent the compressive strengths of the rock and the cement stone respectively.

5. The method according to claim 4, characterized in that, when the first fitting parameter c takes the value of 4, the second fitting parameter k takes the value of 0.6, and the third fitting parameter d takes the value of 2, the specific expression form of the shear strength model of the grouted structural plane is: where τ p4 represents the peak shear strength of the grouting structural plane determined by the three fitting parameters c, a, and d; C 0 represents the cohesion of the interface between sandstone and cement stone; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; ω′ represents the effective angle; h′ represents the effective height; σ c ′ represents the composite strength of rock and cement stone; σ r , σ g respectively represent the compressive strengths of rock and cement stone.

6. The method according to claim 1, characterized in that, in Step S103, analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane through a shear test, and the shear test includes the following steps: Paste a buffer gasket with a specified thickness at the end of each grouted structural plane specimen; Conduct a shear test on the grouted structural plane specimen under a vertical load to obtain the overall cohesion of the grouted structural plane, and the overall cohesion of the grouted structural plane is used to characterize the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane.

7. The method according to claim 6, characterized in that, the buffer gasket is a rubber gasket.

8. A system for predicting the peak shear strength of a grouted structural plane, characterized in that, it includes: A first construction unit configured to construct a shear strength model of the unfilled structural plane according to the effective height and effective angle of the structural plane; A second construction unit configured to construct a peak shear strength model of the soft-filled structural plane based on the shear strength model of the unfilled structural plane, considering the influence of the contact mode, filling degree, and ratio of filling material to rock strength of the soft-filled structural plane on the shear strength of the soft-filled structural plane; The third construction unit is configured to analyze the influence of the bonding effect of the rock-cement interface on the shear strength of the grouted structural plane based on the peak shear strength model of the soft filling structural plane, and construct a shear strength model of the grouted structural plane to predict the peak shear strength of the grouted structural plane; Among them, the basic form of the shear strength model of the grouted structural plane is as follows: where τ p3 represents the peak shear strength of the grouting structural plane; C 0 represents the cohesion of the interface between sandstone and cement stone; ω′ represents the effective angle; c represents the first fitting parameter; σ n represents the normal stress; represents the basic friction angle of the interface between rock and cement stone; η represents the filling degree; k represents the second fitting parameter; h′ represents the effective height; σ c ′ represents the composite strength of rock and cement stone.

9. A computer-readable storage medium, on which a computer program is stored, Characterized in that, When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. An electronic device, Characterized in that, Comprising: A memory, a processor, and a program stored in the memory and executable on the processor, and when the processor executes the program, the steps of the method according to any one of claims 1 to 7 are implemented.

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