Strain energy dependent numerical simulation of rock fracture initiation and propagation using soundless cracking demolition agents (SCDA): Effects of SCDA-filled rock joints

Abstract

Soundless Cracking Demolition Agents (SCDA) are gaining traction as an innovative technique for controlled rock fracturing in applications such as underground energy, mineral extraction, and excavation. This paper presents a novel numerical approach to simulate SCDA-charged rock fracture initiation using the strain energy density of SCDA. This approach eliminates the need for prior knowledge of the peak expansive pressure developed in a rock, a common requirement in conventional SCDA modelling. An empirically derived model is presented which captures the rate of energy release in SCDA as a function of applied strain to the surrounding material. The model was implemented in the 3-dimensional Distinct Element Code by applying an exponential strain-rate decay function. The proposed fracture stimulation method accurately mimics the expansion behaviour and finite strain energy release from SCDA expansion. The method was extended to simulate SCDA expansion in rock joints. The SCDA expansion method was assessed by creating a numerical model in which a central injection well was intersected by a horizontal joint and SCDA expansion was simulated in the injection well and the joint. The simulations were verified against laboratory fracture experiments. The model was extended to evaluate the fracturing performance of SCDA under varying joint roughness and confining pressures. SCDA expansion in rock joints introduces an additional compressive stress field that inhibits fracture initiation and propagation near the joint. Increasing fracture roughness suppressed fracture growth, but led to more fracture nucleation points around the injection well and shear damage at the joint interface. The simulation method employed shows sensitivity to confining pressures and simulates the fracturing potential of SCDA in different rocks subjected to confining pressures without requiring further calibration of the SCDA expansion parameters. The proposed numerical simulation method improves the accuracy in investigating the fracturing potential of expansive agents over existing simulation methods for SCDA.