Identification of damage tensor for jointed rock mass and deformation prediction during excavation of underground cavern

This paper describes the behavior of jointed rock mass about an underground opening during excavation, calculated by employing a damage analysis together with the characterized values of damage tensors of the jointed rock mass estimated from the inverse analysis obtained by using observed displacements of the mass during the excavation of arch section of the cavern. This inverse analysis method is newly developed by using the Newton's iteration scheme, least square method and linear searching method. By using this inverse analysis method, the mechanical properties of the jointed rock mass can be easily estimated with the use of those of the intact rock and the observed displacement data at the initial excavation stage of the underground cavern or at an associated tunnel excavation. The predicted response of the surrounding rock mass about the cavern using this procedure is in good agreement with the observations made at later stages of the excavation. This confirms that the method proposed and used in this article is an effective and reliable method for assessing the stability of the cavern and predicting the mechanical response of the surrounding rock mass.