Comparison of crack processes in single-flawed rock-like material using two bonded–particle models under compression

Abstract

The parallel bond model (PBM), one type of basic bonded particle model (BPM), has been diffusely studied in natural rock and rock-like material. It is well-known that BPMs yield unrealistically low ratios of compressive to tensile strength (UCS/TS), friction angles and linear strength envelopes. The flat-joint model (FJM) overcomes those intrinsic deficiencies with a special structure. Thus, FJM can provide satisfactory replication of the mechanical behavior of rock-like materials. In this paper, rock-like material samples containing a single flaw were constructed with flaw angles of 0°, 30°, 45°, 60°, and 90° measured from the horizontal. The PBM and FJM were used to simulate this rock-like material. The results of the numerical simulations were compared with observations from physical tests, including strength, main types of microcracks, macroscopic fracture zones, and location and sequence of the first and secondary cracks. The results demonstrate that (1) the flaw inclination angle had a significant effect on strength; (2) the FJM results showed better agreement with respect to the main types of microcracks and macroscopic fracture zones, reproducing vertical tension failure dominance over shear failure in the rock-like material, contrary to the PBM results; and (3) using the FJM to capture the initiation location, direction, and sequence of the first and secondary cracks is recommended.