Numerical prediction of thermal weakening effects on granite rock

Abstract

This paper presents a numerical method to predict the temperature weakening effects on granite rock. Thermally induced cracking is modelled in the continuum sense by using a damage-viscoplasticity model based on the rounded Rankine surface. The governing thermo-mechanical problem is solved with an explicit staggered method. Rock heterogeneity is described as random clusters of finite elements assigned with the constituent mineral, here Quartz, Feldspar, and Biotite, material properties. The temperature dependence of the minerals is accounted for up to 800 °C, i.e. well beyond the Curie point (573 °C) of Quartz. The simulations demonstrate that the present approach can accurately predict the experimental weakening effects on the rock strength and stiffness as well as the macroscopic failure modes in tension. Moreover, it does so in a noncircular way, i.e. not using the laboratory data on rock strength as an input data in the constitutive description.