Influences of Roughness Sampling Interval and Anisotropy on Shear Failure Mechanism of Rock Joint Surface

Fan Chen,Hongming Yu,Daoyong Wu,Yilin Yang

doi:10.3390/en14216902

Abstract

Roughness is an important factor affecting the engineering stability of jointed rock masses. The existing roughness evaluation methods are all based on a uniform sampling interval, which changes the geometrical morphology of the original profile and inevitably ignores the influence of secondary fluctuations on the roughness. Based on the point cloud data obtained by 3D laser scanning, a non-equal interval sampling method and an equation for determining the sampling frequency on the roughness profile are proposed. The results show that the non-equal interval sampling method can successfully maintain the morphological characteristics of the original profile and reduce the data processing cost. Additionally, direct shear tests under constant normal load (CNL) conditions are carried out to study the influence of roughness anisotropy on the shear failure mechanism of joint surfaces. It is found that with the increase in shear displacement, the variations in the shear stress are related to the failure mechanisms of dilatancy and shear fracture of the joint. Finally, the distributions of shear stress, dilatancy and fracture areas on the rough joint in different shear directions are calculated theoretically. Results show that the anisotropy and failure mechanism of rough joint can be well characterized by the modified root mean square parameter Z2′.

Highlights

The safety and stability of jointed rock masses are mainly controlled by the mechanical behavior of the joints
Influences andthe thenon-stationary non-stationary nature of joints on roughness evaluation are discussed, and a method to remove the non-stationary feature of point evaluation are discussed, and a method to remove the non-stationary feature of point clouds is proposed
The reason the scale of jointmorphology surface roughness is that the regular sampling interval methodfor changes theeffect geometrical of the original profile, thereby ignoring the contribution of secondary fluctuations to roughness

Summary

Introduction

The safety and stability of jointed rock masses are mainly controlled by the mechanical behavior of the joints Many factors, such as the mineral composition, geometrical morphology, roughness and fillers, will significantly affect the mechanical characteristics of the jointed rock mass. Roughness will affect the apparent cohesion and friction angle, changing the dilatancy and the peak shear strength of rock joints [3]. This means that the roughness of the joint surface is a critical factor in determining the shear strength of rock joints [4]. Reasonable characterization of the joint surface roughness and establishment of the correlation between roughness parameters and shear strength are helpful to evaluate the mechanical behavior of rock joints

Methods

Results

Conclusion