Visco-plastic behaviour during the excavation phase of a salt cavity

The stress field and flow characteristics are studied for a cavity with the shape of a prolate spheroid in dome salt with emphasis given to the excavation phase. A semi-empirical creep law is derived from thermodynamic principles and experimental results. In this paper, an elementary non-linear form is used in the kinetic relation. A finite element solution procedure is discussed which incorporates the creep law, excavation sequence, and arbitrary non-homogeneous initial stress field.