Numerical Simulation of Mechanical Properties of Irregular Columnar Jointed Rock Mass

Long Yan,Zhipeng Xiang,Weiya Xu,Hua Ji,Rubin Wang

doi:10.3389/fphy.2022.836286

Abstract

Columnar jointed rock masses (CJRM) are characterized by significant anisotropy. The mechanical properties of CJRM are complicated by the presence of columnar joints. In this paper, based on the Voronoi random graph generation algorithm, the irregular CJRM numerical model is established, in which columns are simulated by solid elements while joints are simulated by contact surface elements. Uniaxial compression tests on irregular CJRM are then conducted by using FLAC3D to investigate the deformation and strength characteristics, and failure modes. Results indicate that irregular CJRM exhibit strong anisotropy under uniaxial compression, and the compressive strength varies with joint angle in a typical U-shape curve. Failure modes can be classified as three categories: splitting failure along loading direction, shear-sliding failure along columnar joint, and combined failure of column fracturing and joint splitting. The numerical results are then compared with the experimental results. It demonstrates the effectiveness and reliability of applying numerical simulation to investigations on mechanical properties and failure mechanism of irregular CJRM. The results of this study provide helpful information for the design and construction of the project involving CJRM.

Highlights

It can be found that the proportion of elastic deformation stage in the stress-strain curves increases with the increase of the joint angle
The main conclusions are as follows, 1) The curve of peak strength and deformation modulus of irregular columnar jointed rock mass versus joint angle has a U-shape, with the maximum occurring at joint angle of 90° and the minimum occurring at joint angle of 45° and 60°
2) The failure modes of irregular columnar jointed rock mass under uniaxial compression can be divided into three categories, which are tensile failure of the joint surface along the loading direction at joint angle of 0° and 15°, sliding failure along the inclined joint surface of the column at joint angle of 30°, 45° and 60° and combined fracture-tension failure at joint angle of 90°

Summary

INTRODUCTION

Columnar joint is a primary tensile-fracture structure with polygonal columnar shape, which is widely developed in basalt [1–3]. By using 3D printing technology, columnar jointed rock-like specimens with complex joint network fracture are prepared to the anisotropy of strength and deformation, stress structure effect and failure mechanism of CJRM [13–15]. These results provide a new way to intuitively understand the anisotropic mechanical properties and deformation and failure mechanism of CJRM. Based on the similarity theory, the similarity between the mechanical properties of model samples and in-situ columnar jointed rock mass is studied in the literature, in which high grade cement mortar is used to simulate basalt column, and appropriate proportion of white cement slurry is used as cementing material to simulate joints. The column and joint parameters of columnar jointed rock mass in numerical simulation refer to the parameters calibrated in previous model test [10]

EXPERIMENTAL RESULTS AND ANALYSIS

CONCLUSION

DATA AVAILABILITY STATEMENT