A method for evaluating roughness of rock mass structural plane

Abstract

The present application provides a kind of roughness evaluation method of rock mass structural plane, belong to the field of tunnel construction.It solves the problem that the existing evaluation result has greater subjectivity and low accuracy.The roughness evaluation method of rock mass structural plane selects the rock mass structural plane required for analysis, obtains the three-dimensional point cloud data of rock mass structural plane by three-dimensional scanning of rock mass structural plane through three-dimensional laser scanning equipment, stores three-dimensional point cloud data as pts format, carries out denoising, cavity repair preprocessing to the obtained three-dimensional point cloud data, sets the interpolation grid size, carries out regular gridding processing to the irregularly distributed three-dimensional point cloud data obtained, and then forms regular three-dimensional point cloud data.The present application establishes a characterization method of rock mass structural plane roughness based on the relief degree of rock mass structural plane and the relief angle of rock mass structural plane, and gives the roughness characterization value change trend in each shear direction under different sampling intervals.

Description

Technical Field

[0001] This invention belongs to the field of rock mass structural surface technology, and in particular, a method for evaluating the roughness of rock mass structural surfaces. Background Technology

[0002] The well-developed joints and fissures in natural rock masses give them heterogeneity, anisotropy, and discontinuity. Rock mass instability and deformation are largely controlled by structural planes, making their physical and mechanical characteristics crucial for evaluating rock mass stability and safety. Studies show that the mechanical properties of structural planes are closely related to their surface roughness. Furthermore, surface roughness is a vital link between rock mass strength, deformation, and seepage characteristics. Therefore, accurate quantification of surface roughness is essential for studying the physical and mechanical properties of rock masses.

[0003] At present, scholars at home and abroad have proposed various methods for calculating the roughness of structural surfaces. Two-dimensional roughness quantification is mainly achieved through non-contact measurement methods such as single-row needle profile rulers and single-needle automatic profilers. However, a single profile curve is difficult to accurately and comprehensively reflect the overall characteristics of the roughness of the structural surface. Three-dimensional roughness quantification is mainly achieved through non-contact measurement methods such as photogrammetry and three-dimensional laser scanning. It can achieve accurate, comprehensive and refined acquisition of the morphological characteristics of the structural surface. The quantitative characterization method of three-dimensional roughness has become a research focus. Although the current three-dimensional roughness characterization methods are constantly being optimized and developed, there are still some problems, specifically: (1) Some three-dimensional roughness characterization methods average the calculation results of two-dimensional profile lines, ignoring the complexity of the three-dimensional morphology, resulting in a serious disconnect between two-dimensional and three-dimensional; (2) The data sampling interval of the structural surface will affect the evaluation of the roughness of the structural surface, and there is little research on the evaluation index of the data sampling interval; (3) The three-dimensional roughness quantification method that integrates undulation degree, undulation angle and considers the shear direction does not fully consider the discreteness of undulation degree and undulation angle. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a method for evaluating the roughness of rock mass structural surfaces. The technical problem to be solved by this invention is: how to select evaluation indicators to improve the accuracy of evaluating the roughness of rock mass structural surfaces.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for evaluating the roughness of rock mass structural surfaces, characterized by comprising the following steps:

[0007] A. Select the rock mass structure surface to be analyzed, perform a three-dimensional scan of the rock mass structure surface to obtain the three-dimensional point cloud data of the rock mass structure surface, and perform noise reduction and void repair preprocessing on the obtained three-dimensional point cloud data.

[0008] B. Set the interpolation grid size according to d, d / 2, d / 4, d / 8, d / 16, d / 32 to perform regular gridding processing on the acquired irregularly distributed 3D point cloud data, thereby forming regularized 3D point cloud data;

[0009] C. Define three points and their coordinates on any triangular facet of the rock mass structure plane, respectively. , , The lengths of the three sides of the triangle are defined as follows: , , ,in

[0010] ,

[0011] ,

[0012] ,

[0013] Area of ​​the triangle ,in Rock mass structural surface area n is the total number of triangular faces;

[0014] , , The projection lengths on the xoy plane are respectively , , ,in

[0015] ,

[0016] ,

[0017] ,

[0018] Projected area on the xoy plane ,in Projected area of ​​rock mass structural plane ;

[0019] The volume of the oblique-cut triangular prism corresponding to the triangular facet rock mass structural surface volume ;

[0020] D. Calculate the equivalent height of rock mass structural planes. ;

[0021] E. The external normal vector of any triangular face is The undulation of the triangular face is taken as the average height of each corner point. The projected area of ​​the triangular face on the plane is The coefficient of variation for the undulation Hi of each triangular facet is: Outer normal vector The corresponding coefficients of variation are ,in , All are standard deviations. , All are mean values;

[0022] The correction factor for the triangular surface undulation is defined as follows:

[0023] ,

[0024] The angle between the outward normal of the triangle and the z-axis is defined with a correction factor as follows:

[0025] ;

[0026] The shear direction moves counterclockwise every 5° starting from the x-axis, and the angle between the outward normal of the triangle and the shear direction is defined as...

[0027]

[0028] Rock mass surface roughness parameters ,in .

[0029] Compared with existing technologies, the rock mass structural surface roughness evaluation method considering size effects of the present invention has the following advantages: First, the present invention determines the data sampling interval of the rock mass structural surface based on the volume and equivalent height of the rock mass structural surface, and then determines the size of the characterizing unit of the sampling interval; second, it establishes a characterization method of rock mass structural surface roughness based on the undulation degree and undulation angle of the rock mass structural surface, and gives the trend of roughness characterization values ​​under different shear directions at different sampling intervals. It shows that after the sampling interval is less than 0.125 mm, the volume and equivalent height values ​​of the rock mass structural surface gradually tend to stabilize. After the sampling interval is less than 0.125 mm, the data obtained under different shear directions are better. Furthermore, the roughness of the rock mass structural surface is larger when the shear direction is 250° to 300°, while the roughness of the rock mass structural surface is relatively smaller when the shear direction is 70° to 200°. Attached Figure Description

[0030] Figure 1 This is a graph showing the relationship between the volume of the rock mass structural surface and the sampling interval in this invention.

[0031] Figure 2This is a polar coordinate diagram of the surface roughness parameters of the rock mass structure obtained under different shear directions with a sampling interval of 2 mm according to the present invention.

[0032] Figure 3 This is a polar coordinate diagram of the surface roughness parameters of rock mass structure obtained under different shear directions with a sampling interval of 1 mm according to the present invention.

[0033] Figure 4 This is a polar coordinate diagram of the surface roughness parameters of the rock mass structure obtained under different shear directions at a sampling interval of 0.5 mm according to the present invention.

[0034] Figure 5 This is a polar coordinate diagram of the surface roughness parameters of the rock mass structure obtained under different shear directions at a sampling interval of 0.25 mm according to the present invention.

[0035] Figure 6 This is a polar coordinate diagram of the surface roughness parameters of the rock mass structure obtained under different shear directions at a sampling interval of 0.125 mm according to the present invention.

[0036] Figure 7 This is a polar coordinate diagram of the surface roughness parameters of the rock mass structure obtained under different shear directions at a sampling interval of 0.0625 mm according to the present invention. Detailed Implementation

[0037] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0038] The roughness evaluation method for the structural surface of this rock mass includes the following steps:

[0039] Step A: Select the rock mass structure surface to be analyzed, and perform a three-dimensional scan of the rock mass structure surface using a three-dimensional laser scanning device to obtain the three-dimensional point cloud data of the rock mass structure surface. The three-dimensional point cloud data is stored in pts format and converted to dat format to be saved in (x, y, z) coordinate form. The obtained three-dimensional point cloud data is then preprocessed by denoising and void repair based on the Visual Studio software platform.

[0040] Step B: Set the interpolation grid size according to d, d / 2, d / 4, d / 8, d / 16, d / 32 to perform regular gridding processing on the acquired irregularly distributed 3D point cloud data, thereby forming regularized 3D point cloud data;

[0041] Define three points and their coordinates on any triangular facet of the rock mass structural plane, respectively. , , The lengths of the three sides of the triangle are defined as follows: , , ,in

[0042] ,

[0043] ,

[0044] ,

[0045] Area of ​​the triangle ,in Rock mass structural surface area n is the total number of triangular faces;

[0046] , , The projection lengths on the xoy plane are respectively , , ,in

[0047] ,

[0048] ,

[0049] ,

[0050] Projected area on the xoy plane ,in Projected area of ​​rock mass structural plane ;

[0051] The volume of the oblique-cut triangular prism corresponding to the triangular facet rock mass structural surface volume ;

[0052] D. Calculate the equivalent height of rock mass structural planes. ;

[0053] In this embodiment, the sampling intervals for the rock mass structural planes are 2mm, 1mm, 0.5mm, 0.25, 0.125mm, 0.0625mm, and 0.03125mm, respectively, which correspond to grid sizes of 2mm, 1mm, 0.5mm, 0.25, 0.125mm, 0.0625mm, and 0.03125mm. The characteristic parameters under different grid sizes are statistically analyzed in Table 1 below.

[0054] Table 1

[0055] Grid size d Rock mass structural surface area S <![CDATA[Projected area S0 of rock mass structural plane]]> Rock mass structural surface volume V equivalent height h of rock mass structural surface 2 4525.8699 4363.7807 14283.2455067266 3.2731355292 1 4552.8358 4363.7807 14283.6960269222 3.2732387700 0.5 4571.3093 4363.7807 14285.9302891861 3.2737507715 0.25 4599.1921 4363.7807 14285.0665095526 3.2735528286 0.125 4621.2049 4363.7807 14285.1061707243 3.2735619402 0.0625 4633.5853 4363.7807 14285.0582298977 3.2735509312 0.03125 4646.9577 4363.7807 14285.0791025524 3.2735557144 0.015625 4646.9577 4363.7807 14285.0878972814 3.2735577298

[0056] According to Table 1 and Figure 1Analysis shows that when the sampling interval of the rock mass structural surface is less than 0.125 mm, the volume and equivalent height of the rock mass structural surface gradually stabilize. Therefore, during the sampling process of the rock mass structural surface, the sampling interval should be controlled below 0.125 mm, which can be used as a characterizing unit for selecting the interval size of the rock mass structural surface to improve the accuracy of the quantitative characterization of the roughness of the rock mass structural surface.

[0057] Step E: The external normal vector of any triangle face is The undulation of the triangular face is taken as the average height of each corner point. The projected area of ​​the triangular face on the plane is The coefficient of variation for the undulation Hi of each triangular facet is: Outer normal vector The corresponding coefficients of variation are ,in , All are standard deviations. , All are mean values;

[0058] The triangular surface undulation degree and the defined correction factor are:

[0059] ,

[0060] The angle between the out-of-plane normal and the z-axis is defined by a correction factor.

[0061] ;

[0062] The shear direction moves counterclockwise every 5° starting from the x-axis, and the angle between the outward normal of the triangle and the shear direction is defined as...

[0063]

[0064] Rock mass surface roughness parameters ,in .

[0065] Figures 2-7 The closed irregular shape in the figure represents the rock mass structural surface roughness data obtained under different shear directions at corresponding sampling intervals. The right side of the figure is a polar coordinate plot, and the left side is the roughness parameter. Figures 2-3 Analysis shows that the closed irregular shapes obtained under different shearing directions with sampling intervals of 2mm and 1mm have many jagged edges, the lines of the shapes are not smooth enough, and the obtained data is of poor quality; according to Figures 4-7 Analysis shows that after the sampling interval is less than 0.125 mm, the lines in the closed irregular shapes obtained under different shearing directions are smoother, and the obtained data effect is better; in addition, according to Figures 2-7The data show roughness data obtained from shear directions ranging from 0° to 360°. Based on the roughness characterization parameters obtained from different shear directions, it can be seen that the rock mass surface roughness is larger when the shear direction is between 250° and 300°, while it is relatively smaller when the shear direction is between 70° and 200°. Therefore, when calculating and evaluating the roughness of rock mass surfaces, the sampling interval and shear direction should be fully considered. While satisfying the size effect, roughness calculation, evaluation, and related research need to be conducted based on anisotropic characteristics.

[0066] This invention first determines the data sampling interval of rock mass structural surfaces based on the volume and equivalent height of the surface, thereby determining the size of the characterizing unit for the sampling interval. Secondly, it establishes a method for characterizing the roughness of rock mass structural surfaces based on their undulation and undulation angle, and presents the trend of roughness characterization values ​​under different shear directions at different sampling intervals. The results show that when the sampling interval is less than 0.125 mm, the volume and equivalent height values ​​of the rock mass structural surfaces gradually stabilize. The data obtained under different shear directions are better when the sampling interval is less than 0.125 mm, and the roughness of the rock mass structural surfaces is larger when the shear direction is 250°–300°, while it is relatively smaller when the shear direction is 70°–200°.

[0067] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for evaluating roughness of a rock mass structural plane, characterized by, Comprising the following steps: A. Selecting the rock mass structure surface to be analyzed, performing three-dimensional scanning on the rock mass structure surface, obtaining three-dimensional point cloud data of the rock mass structure surface, and performing denoising and hole repairing preprocessing on the obtained three-dimensional point cloud data; B. Setting the interpolation grid size according to d, d / 2, d / 4, d / 8, d / 16, d / 32, performing regular grid processing on the obtained irregularly distributed three-dimensional point cloud data, and then forming regularized three-dimensional point cloud data; C. Define three points and their coordinates on any one triangular face in the rock mass structural plane, respectively A i (x i1 , y i1 , z i1 ), B i (x i2 , y i2 , z i2 ), C i (x i3 , y i3 , z i3 ), define the lengths of the three edges of the triangular face as a i , b i , c i , respectively, where a i = ((x i1 - x i2 ) 2 + (y i1 - y i2 ) 2 + (z i1 - z i2 ) 2 ) 0.5 , b i = ((x i2 - x i3 ) 2 + (y i2 - y i3 ) 2 + (z i2 - z i3 ) 2 ) 0.5 , c i = ((x i1 - x i3 ) 2 + (y i1 - y i3 ) 2 + (z i1 - z i3 ) 2 ) 0.5 , The triangular face area S i = p i i -a i i -b i i -c i , wherein p i = 0.5(a i +b i +c i ), the rock mass structure surface area n is the total number of triangular faces;​​​ a i , b i , c i The projection lengths on the xoy plane are a' i , b' i , c' i , respectively, where a′ i = ((x i1 - x i2 ) 2 + (y i1 - y i2 ) 2 ) 0.5 , b′ i = ((x i2 - x i3 ) 2 + (y i2 - y i3 ) 2 ) 0.5 , c′ i = ((x i1 - x i3 ) 2 + (y i1 - y i3 ) 2 ) 0.5 , S i projected area S' on the xoy plane i = p' i (p' i -a' i )(p' i -b' i )(p' i -c' i ), where p' i = 0.5(a' i +b' i +c' i ), the projected area of the rock mass structure surface the triangular face corresponding to the volume of the truncated triangular prism volume of the rock mass structure plane D. Calculate the equivalent height of rock mass structure surface E、the outer normal vector of any one triangular face is defined as n i , the fluctuation of the triangular face is the average height H of the vertexes i , the projected area of the triangular face on the plane is S' i , the fluctuation H of each triangular face i , the corresponding discrete coefficient is the outer normal vector n i , the corresponding discrete coefficient is wherein σ1, σ2 are standard deviations, and μ1, μ2 are mean values; The fluctuation degree of the triangular surface defines the correction coefficient as: The angle between the outer normal of the triangular surface and the z-axis defines the correction coefficient as: The shear direction starts from the x-axis and moves every 5° in the counterclockwise direction, and the angle between the outer normal of the triangular surface and the shear direction is defined as Rock mass discontinuity roughness parameter where V i = H i S i '.

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