Numerical investigation on progressive fracture behaviours of macroscopic heterogeneous rock bridge

Abstract

Failure of jointed rocks is highly dependent on the presence of rock bridges that exist across joint surfaces. It has long been assumed that such bridges are homogeneous orders, but continued investigation has found that, more often than not, they are a heterogeneous order. In this paper, the failure processes of generalised rock bridges (including two barriers and one which contains an inclusion) under compression with confinement are investigated experimentally and numerically. The impact of macroscopic heterogeneity is discussed in terms of fracture patterns and acoustic emission (AE) data amongst models. The patterns of crack propagation and coalescence are strongly dependent on macroscopic heterogeneity, and characterised by spatial distribution of AE events especially those of high magnitude. Local accelerations observed from curves of AE data suggest that failures are of heterogeneous orders. The piecewise curves separated by transforms from accelerations to decelerations are in the same exponential expression form, implying that the orders of crack development are similar.

Keywords:

• Confining compression
• numerical simulation
• rock bridge
• macroscopic heterogeneity
• fracture pattern
• acoustic emission