Dynamic cavity expansion in rock medium based on bounding surface plasticity damage model

Abstract

Dynamic cavity expansion model is an effective tool in many fields of rock mechanics and rock engineering, like pile installing, rock catering, etc. To provide more precise evaluation for engineering problems, this paper presents a semi-analytical solution on the dynamic spherical cavity expansion solution under different expanding velocities. The proposed solution is based on a bounding surface plasticity damage model, which has been proved as an appropriate tool to model rock behaviour under different strain rates. Self-similarity of the expansion process is exploited to simplify the controlling equations. During the self-similarity transformation, the constitutive relation and incompressible assumption is exploited to simplify controlling equations. The momentum conservation equation has been transformed to be an ordinary equation and solved by Runge-Kutta method. A damage-based standard is introduced to classify the response region around the cavity. Parametric analysis is conducted to investigate the influences of expanding velocity on the stress, and damage distributions around the cavity wall. Results show that the proposed solution is reliable and has potential applications on rock dynamics and rock engineering practice.