Rate-dependent behaviour of fracture propagation in salt rock

Abstract

This paper describes an on-going experimental and numerical modelling research project on salt rock specimens. The experimental part of the study consists of a number of Mode I fracture tests with the WST (Wedge-Splitting Test) configuration, which are performed at different loading rates and complemented by a series of standard uniaxial creep tests. The preliminary WST results show a greater mechanical fracture work accompanied with lower force peaks, for the slower tests. As a first attempt to represent the experimental results, an in-house Finite Element model has been used, which combines an inviscid discrete fracture approach with a Maxwell chain model for the continuum material. The simulations show a decrease of the mechanical work needed for opening the fracture and higher peak force, as foreseen by the ongoing experimental results, but not with the same intensity, which seems to indicate that work dissipation may not be caused eclusively by the bulk viscosity.