A coupled fluid FEM-DEM technique for predicting blasting operations in tunnels

Abstract

We present recent developments in the coupling of the finite element method (FEM) and the discrete element method (DEM) for the analysis of rock blasting operations in tunnels. The coupled FEM-DEM technique has been proven to be an efficient procedure for predicting the multiple fractures of rock induced by the loads generated in blasting. The coupled FEM-DEM procedure is applied in tunnel construction, as well as to gas pressure blasting pyrotechnics to break rocks for the excavation of the tunnel front. In the latter case, the effect of gas explosion is modeled by solving the equations of gas dynamics in the analysis domain using FEM. The effect of gas forces in the underlying rock mass is modeled via an embedded fluid-structure interaction method. The efficiency of the coupled FEM-DEM technique is demonstrated in several examples of fracture tests and rock blasting problems related to tunnel engineering. The examples presented indicate that the combination of the DEM with simple three-node linear triangular elements (for two-dimensional problems) captures the onset of fractures and their evolution accurately, accounting for the penetration of gas in the failure domain (Zárate & Oñate, 2015; Zárate, Cornejo, & Oñate, 2018). Keywords: Discrete elements, Finite elements, Fracture mechanics, FEM-DEM, Gas dynamics