Anisotropic characteristic of irregular columnar-jointed rock mass based on physical model test

Abstract

Columnar joint is a special geological structure with self-organized joint network which separates the rock into an assemblage of blocks. The mechanic characteristics of irregular columnar-jointed rock mass (ICJRM) are dependent not only on the intact rock material but also on unique types of columnar joints. In effort to understand the anisotropic mechanic characteristics of ICJRM by the inherent anisotropic nature of the jointed structure, we conducted a series of uniaxial compression tests. Experiments were performed on an artificial ICJRM of 50 mm in diameter and 100 mm high. The “intact material” consisted of cement mortar and the columnar joints of photosensitive resins. The columnar joint in the specimen was made into six different orientations: 0°, 30°, 45°, 60°, 75°, and 90°, respectively, so observe the deformation behavior and failure modes of ICJRM with different various angles between the loading orientation and columnar joint were observed. Based on the analysis of the test results, the uniaxial compression strength and elastic modulus of ICJRM showed strong anisotropic behavior along with a special “U” shape in response to the angle between the loading orientation and columnar joint. Furthermore, the failure modes of ICJRM was observed.