A coupling method for simulating tunnel excavation with block, particle and bar elements

Excavation of tunnel in rock mass refers to complex continuum-discontinuous processes. For capturing the damages of side walls and the supports of bolts/cables, different types of elements shall be used in the same framework. In this work, a novel method is proposed which couples block, particle, and bar elements for simulating the intact rock mass, the broken rock mass, and the supporting system respectively during tunnel excavation. Brittle Mohr-Coulomb fracture constitutive law and tensile fracture constitutive law are introduced for describing the contact behavior between different parts. Penalty springs are adopted for accounting the pre-stresses effects. Moreover, for assuring the proper transitions of forces and displacements between different types of elements, an interpolation coupling approach is presented. Cases considering different tunnel sections and supporting strategies are numerically studied, indicating the reliability of the method.