Rock mass structural surface three-dimensional shape duplicating method

Abstract

The invention discloses a rock mass structural surface three-dimensional shape duplicating method which comprises the following steps: collecting rock samples of different types of structural surfaces, cleaning and cutting the structural surfaces of the rock samples into planes, and scanning to obtain a three-dimensional digital model of the structural surfaces; calculating a roughness parameter R lambda based on a Lyapunov index and a roughness parameter RD based on a fractal dimension according to an apparent dip angle of a data point on the three-dimensional digital model; selecting the roughness parameter R lambda and the three-dimensional digital model corresponding to the roughness parameter RD in the plurality of rock samples meeting preset conditions as a three-dimensional duplicated structural surface, and importing the three-dimensional duplicated structural surface into a carving machine; selecting a feeding mode of the structural surface, and inputting the feeding mode into a carving machine; the engraving machine generates a three-dimensional engraving path of the structural surface according to the input three-dimensional digital model and the feeding mode; according to the three-dimensional engraving path, the engraving machine is adopted to re-engrave the selected structural surface on the splicing surface of the two rock sample blocks, and then the rock sample blocks are spliced to form the test sample with the three-dimensional re-engraved structural surface.

Description

Technical Field

[0001] The invention relates to the technical field of rock mechanics experiments, and in particular to a method for replicating the three-dimensional morphology of a rock mass structural surface. Background Art

[0002] The engineering rock mass involved in geotechnical engineering is composed of complete rock blocks and structural surfaces. The influence of external factors such as the occurrence environment and excavation disturbance on the mechanical properties of the engineering rock mass is mainly reflected in the comprehensive influence on the fractured structural surface and the intact rock. The shear mechanical properties of the structural surface in a complex environment have gradually become the focus of scholars. However, affected by the three-dimensional morphology, filling and stress conditions of the structural surface, the mechanical properties of the structural surface are complex and changeable. It is crucial to replicate the structural surface with consistent three-dimensional morphology and conduct shear tests under different stresses and occurrence environments to accurately understand the shear mechanical properties of the structural surface in a complex environment.

[0003] Existing structural surface preparation methods can be simply divided into four methods: on-site collection, artificial splitting / shearing, artificial pouring, and 3D printing. Although the structural surfaces collected on-site can reflect the original three-dimensional morphological characteristics of the structural surfaces after geological action, it is difficult to collect structural surfaces with consistent morphological characteristics and mechanical properties in large batches. The structural surfaces obtained after artificial splitting / shearing can reflect the morphological characteristics of shear and tension-type structural surfaces, but the morphological characteristics of the structural surfaces obtained after artificial splitting / shearing with the same lithology and the same stress are not the same. Artificial pouring and 3D printing can effectively obtain large batches of structural surfaces with the same morphological characteristics, but because the mechanical properties of the materials used for pouring and 3D printing are somewhat different from those of natural rocks, the shear mechanical properties of the structural surfaces obtained from the test are significantly different from their own mechanical characteristics.

[0004] Therefore, it is urgent to propose a three-dimensional morphology replication technology for rock structural surfaces that is suitable for different testing conditions, to prepare large batches of rock structures with the same three-dimensional morphological characteristics, and to truly obtain the shear mechanical properties of natural structural surfaces. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the method for replicating the three-dimensional morphology of rock structure surfaces provided by the present invention solves the problem that the existing replication methods cannot obtain a large number of structural surfaces with consistent morphological characteristics and mechanical properties.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] A method for replicating the three-dimensional morphology of a rock mass structural surface is provided, which comprises the following steps:

[0008] S1. Collect rock samples of different types of structural surfaces at the construction site, clean and cut the structural surfaces of the rock samples into planes, and then scan to obtain a three-dimensional digital model of the structural surface;

[0009] S2. Calculate the roughness parameter R based on the Lyapunov index according to the chaotic bifurcation theory and the apparent inclination angle of the data points on the three-dimensional digital model. λ and the roughness parameter R based on fractal dimension D ;

[0010] S3. Select the roughness parameter R that meets the preset conditions from multiple rock samples λ and roughness parameter R D The corresponding three-dimensional digital model is used as the structural surface of the three-dimensional replica and is imported into the engraving machine;

[0011] S4. According to the test method of the structural surface, a cutting method of the structural surface is selected and input into the engraving machine; the engraving machine generates a three-dimensional engraving path of the structural surface according to the input three-dimensional digital model and the cutting method;

[0012] S5. According to the three-dimensional engraving path, an engraving machine is used to replicate the selected structural surface on the joint surface of the two rock sample blocks, and then the rock sample blocks are spliced ​​to form a test specimen with a three-dimensional replicated structural surface.

[0013] Furthermore, the step S2 further comprises:

[0014] S21, sort the obliquity angles of the data points according to their spatial positions to form a spatial sequence {θ1,θ2,...,θ N}, θ1, θ2 and θ N are the 1st, 2nd and Nth obliquity angles in the spatial sequence, and N is the total number of data points;

[0015] S22. According to the spatial sequence, the average mutual information method is used to determine the average mutual information corresponding to multiple different intervals τ, and the interval τ corresponding to the minimum average mutual information is selected; the expression of the average mutual information method is:

[0016]

[0017] Where I(τ) is the average mutual information; p i and p j is the probability density of two data points separated by τ in the spatial sequence; p ij (τ) is the joint probability density of two data points separated by τ in the spatial sequence;

[0018] S23. For each data point in the spatial sequence, the nearest neighbor method is used to determine the embedding dimension m of the spatial sequence. According to the embedding dimension and the selected interval τ, the reconstructed phase space vector is obtained:

[0019] X k =[θ k ,θ k+τ ,θ k+2τ,...,θ k+(m-1)τ ]

[0020] Among them, k = 1, 2, ..., N-(m-1)τ is a variable; θ k ,θ k+τ ,θ k+2τ and θ k+(m-1)τ The data points are numbered k, k+τ, k+2τ, and k+(m-1)τ respectively;

[0021] S24. For each phase space vector X k , find its nearest neighbor X k′ :

[0022]

[0023] Where ||·|| is the Euclidean distance; W is the exclusion window; k′ is the phase space vector X k The serial number of the nearest neighbor of ;

[0024] S25, according to the phase space vector X k and its nearest neighbor X k′ , calculate the initial distance d k (0) and track the evolution of distance d k (n):

[0025] d k (0) = || X k -X k′ ||, d k (n) = ||X k+n -X k′+n ||

[0026] Among them, X k+n and X k′+n The phase space vector X k and its nearest neighbor X k′ The space vector obtained at the discrete time step n;

[0027] S26. Calculate the maximum Lyapunov exponent λ based on the evolution of the initial distance and the tracking distance max :

[0028]

[0029] Wherein, Δt is the sampling time interval;

[0030] S27. Calculate the correlation dimension D2 based on the phase space vector:

[0031]

[0032] Where C(r) is the correlation score; r is the distance threshold; H(r-||X i -X j ||) is the Heaviside function, which takes 1 when the input is greater than zero, otherwise it takes 0; X i and X j are the i-th and j-th phase space vectors respectively;

[0033] S28, using the maximum Lyapunov exponent λ max As the roughness parameter R λ , using the correlation dimension D2 as the roughness parameter R D .

[0034] Furthermore, the test method includes a direct shear test and a triaxial test for a structural surface with an inclination angle; during the direct shear test, the tool moves in a manner of reciprocating engraving along the horizontal plane of the structural surface; during the triaxial test, the tool moves in a manner of reciprocating engraving along the oblique surface.

[0035] Furthermore, when replicating the rock sample blocks subjected to the direct shear test, after one of the rock sample blocks is engraved according to the generated engraving path, the engraving path is subjected to 3D mirroring and 2D mirroring operations to obtain a new path, and the new path is used to engrave another rock sample block;

[0036] When replicating the rock sample blocks undergoing triaxial tests, after one of the rock sample blocks is engraved according to the generated engraving path, the engraving path is 3D mirrored and 2D mirrored, and then the path is reversed to obtain a new path, and the new path is used to engrave another rock sample block.

[0037] Furthermore, when the selected structural surface is reproduced on the rock sample block, a fixing fixture is used to clamp the rock sample block so that the joint surface of the rock sample block faces the engraving machine cutter; the fixing fixture for fixing the rock sample block for triaxial testing includes:

[0038] A base, on which a support plate is fixed, wherein a mounting hole is formed on the support plate, and an annular limit platform surrounding the mounting hole is provided at the edge of the mounting hole;

[0039] The rock sample block clamping part comprises a main clamping block and a secondary clamping block which are detachably connected by fastening bolts, and the main clamping block and the secondary clamping block are both provided with receiving grooves which cooperate with each other to clamp the rock sample block; the end of the main clamping block is provided with a circular rotating part which passes through the mounting hole;

[0040] The limiting part includes a limiting hole arranged on the annular limiting platform and the circular rotating part and a limiting piece inserted into the limiting hole to limit the rotation of the main clamping block relative to the supporting plate.

[0041] Furthermore, the circular rotating part includes a circular boss passing through the mounting hole, an annular knob is fixed to the end of the circular boss and reversely surrounds the annular limit platform, the limiting hole of the circular rotating part is opened on the annular knob, and an angle marking line is provided on the annular knob.

[0042] Furthermore, the method for replicating the three-dimensional morphology of a rock mass structural surface also includes a support block disposed on the main clamping block and / or the auxiliary clamping block for supporting the rock sample block at the end where the splicing surface is located.

[0043] Furthermore, the cross section of the limiting hole is semicircular or triangular.

[0044] Compared with the existing structural surface preparation method, this scheme proposes a three-dimensional morphology reproduction method of rock structural surface, which has the following beneficial effects:

[0045] This scheme collects various types of structural surfaces on site, obtains the three-dimensional digital model of the structural surface through three-dimensional laser scanning technology, and then calculates the roughness parameter R λ and roughness parameter R D Select the structural surface to be replicated, the roughness parameter R λ and roughness parameter R D It can capture complex nonlinear features that cannot be described by traditional methods, and can describe the self-similarity and complexity of structural surfaces at different scales.

[0046] By adopting the method provided in this scheme to select the structural surface, the obtained structural surface has relatively small anisotropy and the roughness is not too large or too small. When conducting the test, the result will not be too discrete. In this way, when studying the influence of environment on shear strength, the influence of environment on rock can be better highlighted.

[0047] This solution provides a fixing fixture for the rock sample block for triaxial testing. The angle of the rock sample block can be adjusted through the clamping part of the rock sample block so that the joint surface of the rock sample block faces the tool of the engraving machine, converting the inclined surface engraving into a flat surface engraving, simplifying the difficulty of engraving, and reducing tool breakage.

[0048] Compared with the existing structural surface preparation method, the present invention, in combination with the proposed relevant rock fixture, can realize three-dimensional replication of structural surfaces suitable for different experimental methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of the method for reproducing the three-dimensional morphology of rock mass structural surfaces.

[0050] Figure 2 It is a schematic diagram of a rock structure collected from a construction site according to an embodiment of the present invention.

[0051] Figure 3 for Figure 2 Schematic diagram of the three-dimensional digital model after scanning the rock structure surface.

[0052] Figure 4 Schematic diagrams of the tool path for structural surfaces suitable for different test methods are given; (a) is a schematic diagram of the engraving path for the direct shear test; (b) is a schematic diagram of the engraving path for the triaxial test.

[0053] Figure 5 Front view of the fixture for fixing the rock sample block for triaxial testing without the base and support blocks.

[0054] Figure 6 Left side view of the fixture used to secure the rock sample for triaxial testing.

[0055] Figure 7 Right side view of the fixture used to secure the rock sample for triaxial testing.

[0056] Figure 8 Schematic diagram of the cutting method suitable for elliptical bevel cuts.

[0057] Fig. 9 A schematic diagram of a test specimen applicable to a direct shear test on a structural surface according to an embodiment of the present invention is shown.

[0058] Fig.10 A schematic diagram of a test specimen applicable to a triaxial test on a structural surface with an inclination angle according to an embodiment of the present invention is shown.

[0059] Fig.11 A comparison diagram of a real structure surface and a replica structure surface according to an embodiment of the present invention is shown; (a) is a schematic diagram of the real structure surface; (b) is a schematic diagram of the replica structure surface.

[0060] Fig.12 A comparison diagram of a real structure surface trace and a replica structure surface trace according to an embodiment of the present invention is shown.

[0061] Among them, 1. fixing fixture; 11. base; 12. rock sample block clamping part; 121. main clamping block; 1211. receiving groove; 1212. circular rotating part; 12121. circular boss; 12122. annular knob; 122. auxiliary clamping block; 13. limiting hole; 14. supporting block; 15. supporting plate; 151. annular limiting platform; 2. engraving path; 3. rock sample block; 4. test specimen. DETAILED DESCRIPTION

[0062] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0063] refer to Figure 1 , Figure 1 A method for replicating the three-dimensional morphology of a rock mass structural surface is shown; the method S comprises steps S1 to S5.

[0064] In step S1, rock samples of different types of structural surfaces are collected at the construction site, the structural surfaces of the rock samples are cleaned and cut into planes, and then scanned to obtain a three-dimensional digital model of the structural surface; specifically:

[0065] Collect slightly weathered or unweathered rock structure surfaces of shear or tension type at the construction site, clean the surface of the rock structure surface appropriately with a soft brush, and cut the irregular structure surface samples into 100mm×100mm plane size (such as Figure 2 As shown in the figure, the 3D laser scanning requirements of the structural surface are met. The structural surface is scanned in detail with a high-precision 3D laser scanner to obtain a 3D digital model of the structural surface (as shown in the figure). Figure 3 shown).

[0066] The sizes of the scanned three-dimensional digital models are different. Before entering step S2, the three-dimensional digital model is appropriately cut using the Matlab algorithm based on the center point of the structural surface. Considering the error in the structural surface replication process and the test requirements, the three-dimensional digital model is cut into a plane size of 52mm×50mm.

[0067] In step S2, the roughness parameter R based on the Lyapunov index is calculated according to the chaotic bifurcation theory and the apparent inclination angle of the data points on the three-dimensional digital model. λ and the roughness parameter R based on fractal dimension D .

[0068] In one embodiment of the present invention, step S2 further comprises:

[0069] S21, sort the obliquity angles of the data points according to their spatial positions to form a spatial sequence {θ1,θ2,...,θ N}, θ1, θ2 and θ N are the 1st, 2nd and Nth obliquity angles in the spatial sequence, and N is the total number of data points;

[0070] S22. According to the spatial sequence, the average mutual information method is used to determine the average mutual information corresponding to multiple different intervals τ, and the interval τ corresponding to the minimum average mutual information is selected; the expression of the average mutual information method is:

[0071]

[0072] Where I(τ) is the average mutual information; p i and p j is the probability density of two data points separated by τ in the spatial sequence; p ij (τ) is the joint probability density of two data points separated by τ in the spatial sequence;

[0073] S23. For each data point in the spatial sequence, the nearest neighbor method is used to determine the embedding dimension m of the spatial sequence. According to the embedding dimension and the selected interval τ, the reconstructed phase space vector X is obtained. k :

[0074] X k =[θ k ,θ k+τ ,θ k+2τ ,...,θ k+(m-1)τ ]

[0075] Among them, k = 1, 2, ..., N-(m-1)τ is a variable; θ k ,θ k+τ ,θ k+2τ and θ k+(m-1)τ The data points are numbered k, k+τ, k+2τ, and k+(m-1)τ respectively;

[0076] S24. For each phase space vector X k , find its nearest neighbor X k′ :

[0077]

[0078] Where ||·|| is the Euclidean distance; W is the exclusion window; k′ is the phase space vector X k The serial number of the nearest neighbor of ;

[0079] S25, according to the phase space vector X k and its nearest neighbor X k′ , calculate the initial distance d k (0) and track the evolution of distance d k (n):

[0080] d k (0) = || X k -X k′ ||, d k (n) = ||Xk+n -X k′+n ||

[0081] Among them, X k+n and X k′+n The phase space vector X k and its nearest neighbor X k′ The space vector obtained at the discrete time step n;

[0082] S26. Calculate the maximum Lyapunov exponent λ based on the evolution of the initial distance and the tracking distance max :

[0083]

[0084] Wherein, Δt is the sampling time interval;

[0085] S27. Calculate the correlation dimension D2 based on the phase space vector:

[0086]

[0087] Where C(r) is the correlation score; r is the distance threshold; H(r-||X i -X j ||) is the Heaviside function, which takes 1 when the input is greater than zero, otherwise it takes 0; X i and X j are the i-th and j-th phase space vectors respectively;

[0088] S28, using the maximum Lyapunov exponent λ max As the roughness parameter R λ , using the correlation dimension D2 as the roughness parameter R D .

[0089] Chaos bifurcation theory can reveal the nonlinear dynamic behavior of the system. Applying it to the evaluation of structural surface roughness can capture complex nonlinear characteristics that cannot be described by traditional methods. At the same time, chaotic characteristic parameters (such as fractal dimension) can describe the self-similarity and complexity of structural surfaces at different scales. This is particularly important for rock structural surfaces with multi-scale roughness characteristics.

[0090] In step S3, a plurality of rock samples are selected whose roughness parameters R meet the preset conditions. λ and roughness parameter R D The corresponding three-dimensional digital model is used as the structural surface of the three-dimensional replica and is imported into the engraving machine;

[0091] In step S4, according to the test method of the structural surface, the cutting method of the structural surface is selected and input into the engraving machine; the engraving machine generates a three-dimensional engraving path 2 of the structural surface according to the input three-dimensional digital model and the cutting method, specifically using the JD Paint software in the engraving machine.

[0092] During implementation, the preferred test methods of this scheme include direct shear test and triaxial test for structural surfaces with inclination angles; during the direct shear test, the tool movement mode is to carve reciprocatingly along the horizontal plane of the structural surface; during the triaxial test, the tool movement mode is to carve reciprocatingly along the oblique surface.

[0093] According to different test methods, the engraving method of the structural surface is different, and the method of generating the three-dimensional engraving path 2 of the structural surface is also different. In order to facilitate the understanding of the three-dimensional engraving path 2, this scheme gives a schematic diagram of the engraving path 2 of the direct shear test and the triaxial test. For details, please refer to Figure 4 (a) and (b) in .

[0094] In step S5, according to the three-dimensional engraving path 2, an engraving machine is used to replicate the selected structural surface on the joint surface of the two rock sample blocks 3, and then the rock sample blocks 3 are spliced ​​to form a test sample 4 with a three-dimensional replicated structural surface.

[0095] During implementation, this scheme preferably replicates the rock sample block 3 for the direct shear test, and after one of the rock sample blocks 3 is engraved according to the generated engraving path 2, the engraving path 2 is subjected to 3D mirroring and 2D mirroring operations to obtain a new path, and the new path is used to engrave another rock sample block 3;

[0096] When replicating the rock sample block 3 undergoing the triaxial test, after one of the rock sample blocks 3 is engraved according to the generated engraving path 2, the engraving path 2 is subjected to 3D mirroring and 2D mirroring operations, and then the path is reversed to obtain a new path, and the new path is used to engrave another rock sample block 3.

[0097] This solution uses the above method to carve two matching rock sample blocks 3, which can ensure that the structural surface of the joint surface is completely in line with each other, which is closer to the real structural surface in nature. After the two rock sample blocks 3 are carved, they are spliced ​​together to obtain a test sample 4 that can be used for direct shear test of the structural surface. Fig. 9 , which can be applied to the test specimens with inclined structural surface triaxial test 4 such as Fig.10 shown.

[0098] like Figure 5-Figure 7 As shown, when the selected structural surface is reproduced on the rock sample block 3, the rock sample block 3 is clamped by a fixing fixture 1 so that the joint surface of the rock sample block 3 faces the engraving machine cutter; the fixing fixture 1 for fixing the rock sample block 3 for triaxial testing includes a base 11, a rock sample block clamping portion 12 and a limiting portion;

[0099] A support plate 15 is fixed on the base 11, and a mounting hole is formed on the support plate. An annular stopper 151 surrounding the mounting hole is provided at the edge of the mounting hole.

[0100] The rock sample block clamping part 12 comprises a main clamping block 121 and a secondary clamping block 122 which are detachably connected by fastening bolts, and the main clamping block 121 and the secondary clamping block 122 are both provided with receiving grooves 1211 which cooperate with each other to clamp the rock sample block 3; the end of the main clamping block 121 is provided with a circular rotating part 1212 which passes through the mounting hole;

[0101] The limiting portion includes a limiting hole 13 provided on the annular limiting platform 151 and the circular rotating portion 1212 and a limiting member inserted into the limiting hole 13 to limit the rotation of the main clamping block 121 relative to the supporting plate 15 , and the limiting member is not shown in the figure.

[0102] Reference again Figure 6 The circular rotating part 1212 includes a circular boss 12121 passing through the mounting hole, and an annular knob 12122 is fixed to the end of the circular boss 12121 and reversely surrounds the annular limit platform 151. The limiting hole 13 of the circular rotating part 1212 is opened on the annular knob 12122, and the annular knob 12122 is provided with an angle mark.

[0103] like Figure 6 and Figure 7 As shown, the fixing fixture also includes a support block 14 provided on the main clamping block 121 and / or the auxiliary clamping block 122 for supporting the rock sample block 3 at the end where the splicing surface is located. The cross section of the limiting hole 13 is semicircular or triangular. When it is set to a triangle, the same specification of the fixture can be adapted to the clamping of rock sample blocks of different diameters, which is more practical.

[0104] Combination Figure 5-Figure 7 The fixed fixture shown rotates the bevel surface to keep it horizontal. The cutting method is the same as Figure 4 Considering that the beveled surface is elliptical, it is not convenient to locate the initial point of the engraving path 2, so the "circular equidistant" method can be used to generate the annular engraving path 2 (such as Figure 8 shown).

[0105] A rock sample was collected at the construction site. After cleaning and cutting its structural surface, a high-precision 3D laser scanner was used to perform a detailed scan of the structural surface. The scanning results are referenced to Fig.11 (a) in the following; Figure 4 The rock sample block 3 is engraved according to the engraving path shown in (a) of FIG. 1 , and the scanning result of the structure surface obtained by engraving is referred to as Fig.11 In (b), compare Fig.11 As can be seen from (a) and (b) in the figure, the replica structural surface basically simulates the rough features of the actual structural surface. It can be seen that the engraving method can be used to replicate structural surfaces with consistent morphological features and mechanical properties in large batches.

[0106] exist Fig.11 A trace is selected from the corresponding positions of the structural surfaces shown in (a) and (b) for comparison, as shown in FIG. Fig.12 As shown, it can be seen that the trace of the replica structural surface is relatively close to the trace of the real structural surface, and the difference in z value under the same y value condition is less than 0.2mm. It can be seen that the engraving method can basically restore the real structural surface, and the replica structural surface can basically reflect the original three-dimensional morphology characteristics of the structural surface after geological action.

Claims

1. A method for replicating the three-dimensional morphology of a rock mass structural surface, characterized in that: Includes steps: S1. Collect rock samples of different types of structural surfaces at the construction site, clean and cut the structural surfaces of the rock samples into planes, and then scan to obtain a three-dimensional digital model of the structural surface; S2. Calculate the roughness parameter R based on the Lyapunov index according to the chaotic bifurcation theory and the apparent inclination angle of the data points on the three-dimensional digital model. λ and the roughness parameter R based on fractal dimension D ; S3. Select the roughness parameter R that meets the preset conditions from multiple rock samples λ and roughness parameter R D The corresponding three-dimensional digital model is used as the structural surface of the three-dimensional replica and is imported into the engraving machine; S4. According to the test method of the structural surface, a cutting method of the structural surface is selected and input into the engraving machine; the engraving machine generates a three-dimensional engraving path of the structural surface according to the input three-dimensional digital model and the cutting method; S5. According to the three-dimensional engraving path, an engraving machine is used to replicate the selected structural surface on the joint surface of the two rock sample blocks, and then the rock sample blocks are spliced ​​to form a test specimen with a three-dimensional replicated structural surface.

2. The method for replicating the three-dimensional morphology of a rock mass structural surface according to claim 1, characterized in that: The step S2 further comprises: S21, sort the obliquity angles of the data points according to their spatial positions to form a spatial sequence {θ1,θ2,...,θ N }, θ1, θ2 and θ N are the 1st, 2nd and Nth obliquity angles in the spatial sequence, and N is the total number of data points; S22. According to the spatial sequence, the average mutual information method is used to determine the average mutual information corresponding to multiple different intervals τ, and the interval τ corresponding to the minimum average mutual information is selected; the expression of the average mutual information method is: Where I(τ) is the average mutual information; p i and p j is the probability density of two data points separated by τ in the spatial sequence; p ij (τ) is the joint probability density of two data points separated by τ in the spatial sequence; S23. For each data point in the spatial sequence, the nearest neighbor method is used to determine the embedding dimension m of the spatial sequence. According to the embedding dimension and the selected interval τ, the reconstructed phase space vector X is obtained. k : X k =[θ k ,the k+τ ,the k+2τ ,...,θ k+(m-1)τ ] Among them, k = 1, 2, ..., N-(m-1)τ is a variable; θ k ,θ k+τ ,θ k+2τ and θ k+(m-1)τ The data points are numbered k, k+τ, k+2τ, and k+(m-1)τ respectively; S24. For each phase space vector X k , find its nearest neighbor X k′ : Where ||·|| is the Euclidean distance; W is the exclusion window; k′ is the phase space vector X k The serial number of the nearest neighbor of ; S25, according to the phase space vector X k and its nearest neighbor X k′ , calculate the initial distance d k (0) and track the evolution of distance d k (n): d k (0)=||X k -X k′ ||,d k (n)=||X k+n -X k′+n || Among them, X k+n and X k′+n The phase space vector X k and its nearest neighbor X k′ The space vector obtained at the discrete time step n; S26. Calculate the maximum Lyapunov exponent λ based on the evolution of the initial distance and the tracking distance max : Wherein, Δt is the sampling time interval; S27. Calculate the correlation dimension D2 based on the phase space vector: Where C(r) is the correlation score; r is the distance threshold; H(r-||X i -X j ||) is the Heaviside function, which takes 1 when the input is greater than zero, otherwise it takes 0; X i and X j are the i-th and j-th phase space vectors respectively; S28, using the maximum Lyapunov exponent λ max As the roughness parameter R λ , using the correlation dimension D2 as the roughness parameter R D .

3. The method for replicating the three-dimensional morphology of a rock structure surface according to claim 1 or 2, characterized in that: The test method includes a direct shear test and a triaxial test for a structural surface with an inclination angle; during the direct shear test, the tool moves in a manner of reciprocating engraving along the horizontal surface of the structural surface; during the triaxial test, the tool moves in a manner of reciprocating engraving along the oblique surface.

4. The method for replicating the three-dimensional morphology of a rock structure surface according to claim 3, characterized in that: When re-engraving the rock sample block for direct shear test, after one of the rock sample blocks is engraved according to the generated engraving path, the engraving path is subjected to 3D mirroring and 2D mirroring operations to obtain a new path, and the new path is used to engrave the other rock sample block; When replicating the rock sample blocks undergoing triaxial tests, after one of the rock sample blocks is engraved according to the generated engraving path, the engraving path is 3D mirrored and 2D mirrored, and then the path is reversed to obtain a new path, and the new path is used to engrave another rock sample block.

5. The method for replicating the three-dimensional morphology of a rock mass structural surface according to claim 3, characterized in that: When engraving the selected structural surface on the rock sample block, a fixing fixture is used to clamp the rock sample block so that the joint surface of the rock sample block faces the engraving machine cutter; the fixing fixture for fixing the rock sample block for triaxial testing includes: A base, on which a support plate is fixed, wherein a mounting hole is formed on the support plate, and an annular limit platform surrounding the mounting hole is provided at the edge of the mounting hole; The rock sample block clamping part comprises a main clamping block and a secondary clamping block which are detachably connected by fastening bolts, and the main clamping block and the secondary clamping block are both provided with receiving grooves which cooperate with each other to clamp the rock sample block; the end of the main clamping block is provided with a circular rotating part which passes through the mounting hole; The limiting part includes a limiting hole arranged on the annular limiting platform and the circular rotating part and a limiting piece inserted into the limiting hole to limit the rotation of the main clamping block relative to the supporting plate.

6. The method for replicating the three-dimensional topography of a rock mass structural surface according to claim 5, characterized in that: The circular rotating part includes a circular boss passing through the mounting hole, an annular knob which surrounds the annular limiting platform in reverse is fixed to the end of the circular boss, the limiting hole of the circular rotating part is opened on the annular knob, and an angle mark is arranged on the annular knob.

7. The method for replicating the three-dimensional topography of a rock mass structural surface according to claim 5 or 6, characterized in that: It also includes a support block which is arranged on the main clamping block and / or the auxiliary clamping block and is used to support the rock sample block at the end where the splicing surface is located.

8. The method for replicating the three-dimensional topography of a rock mass structural surface according to claim 5 or 6, characterized in that: The cross section of the limiting hole is semicircular or triangular.

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