| The structure of a rock mass directly controls its mechanical and hydraulic properties,and determines the deformation and failure mode of rock mass.Joints,as the fourth-level structural surface,have a significant controlling effect on rock mass structures.The distribution of rock mass volume directly reflects the development of joints and is one of the important indicators for evaluating rock mass structures.The current reconstruction of three-dimensional joint networks often ignores the influence of joint geometric shapes by simplifying them into smooth planes.However,roughness controls the joint geometry and has an important influence on the distribution of rock mass volume.Simplifying joints into smooth planes will result in an inaccurate joint model and reduce the accuracy of research results.This text uses Hurst exponent(H)and root-mean-square height(R_q)to characterize joint roughness and establishes non-planar orthogonal joint models and joint disc models based on non-planar joint network reconstruction technology to study the law of the influence of joint roughness on the distribution of rock mass volume and number.The text collects joint development information on a slope of a highway in Dalian through close-range photogrammetry and validates the accuracy of the research conclusions with the corresponding model.The main research contents are as follows:(1)This article uses close-range photogrammetry to establish a textured 3D point cloud model of an actual rock slope.The accuracy of the point cloud model is verified from the two aspects of length and angle through feature point measurement,coordinate transformation,orientation calculation,and outdoor experiments,showing that its accuracy meets the extraction requirements.The coordinates of the turning points of the joint traces are manually extracted from the 3D point cloud model,and the joints orientation is calculated.The roughness of the joints is quantified using the Hurst exponent H and the root-mean-square height R_q.(2)The roughness of the joints is reconstructed using H and R_q,and a non-planar disc joint model reconstruction method is proposed.The relationship between R_q and the joint spacing is analyzed when parallel joints are cut.An equidistant orthogonal joint model is established,and the model is cut and calculated.It is shown that H and R_q control the roughness and undulations of the joints,and the roughness increases as R_q increases and H decreases,while the mean volume and median volume decrease.The quantity of rock blocks is generally positively correlated with the joint roughness,and its variation with roughness can be divided into three stages,with H and R_q jointly controlling the relative distribution range of each interval.H and R_q mainly affect the volume distribution of rock blocks by changing the proportion of small-volume blocks.(3)Based on the non-planar disc joint model reconstruction method,different disc joint models are established,and the impact of joint morphology parameters(Hurst exponent H,root-mean-square R_q)and joint distribution parameters(joint volume density,joint disc diameter)on rock mass structural evaluation indicators in joint 3D network reconstruction is analyzed.As R_q decreases and H increases,the joint surfaces tend to be planar,and the corresponding indicators tend to be similar to those of planar models.Joint volume density and joint diameter affect the evaluation indicators by changing the number and size of joints in the model,and the two parameters have the same impact pattern on planar and non-planar models.(4)Based on the joint data of an actual slope rock obtained by close-range photogrammetry,the specific generation parameters of the non-planar disc joint model for the actual slope rock are obtained by joint sets division,mean trace length and joint trace midpoint density estimation,disc diameter and volume density derivation,and roughness parameter range statistics.At the same time,three types of joint morphology disc joint models,namely planar,mean,and extreme,are established using different parameter combinations of H and R_q to verify the relevant impact patterns of roughness parameters. |
