Crack propagation in jointed rock and its effect on rock macrofracture resistance: insights from discrete element analysis

The complicated fracturing process of jointed rock increases the difficulty of underground cavern support and deep earth resource exploitation. Herein, the crack propagation behavior and its effect on macrofracture resistance of jointed rock were evaluated through discrete element modeling (DEM). To quantify the joint distribution, strength ratio between joint and rock matrix on rock fracture toughness, a series of simplified rock structures were established in notched semi-circular bending tests. The results indicated that the apparent fracture toughness of jointed rock is governed by the cracking process and path in jointed rock mass. Cracking patterns could be classified into three types (deflection-dominant, pattern competition, and penetration-dominant) by strength ratio where high fracture toughness is found in the region of pattern competition. Thereafter, the influences of joint spacing on rock cracking and apparent fracture toughness were assessed by comparing our DEM results and previous laboratory tests. Finally, scale effects on fracture profile and toughness of jointed rock were elucidated along with the comparison of rock fracturing processes in homogeneous and jointed rock. The results clarify the correlation between cracking and rock fracture resistance, which helps us understand rock fracture and crack propagation in underground space for the extraction of geothermal energy and shale oil/gas resources.

Automated summary

This study evaluates the crack propagation behavior of jointed rock through discrete element modeling and identifies three types of cracking patterns. It also investigates the effects of joint spacing and scale on rock cracking and fracture toughness. The findings help us understand the correlation between cracking and rock fracture resistance.