Abstract: Excavation in deep underground cavity results in numerous micro-cracks on the surface of surrounding rock. In the readjusting process of stress field, propagation and coalescence of these cracks will cause severe problems such as spalling, board split and collapse, which make it difficult to determine the elastic modulus in the damaged zones using drilling method. In this paper, based on the damage mechanics principle, the general range of the elastic modulus in the damaged zones is preliminary judged by in-situ sonic test combined with empirical formula, and then the distributing regularity of elastic modulus in damaged zones is obtained by accurate inversion using neutral network and RDM model. This approach is applied in the 27th stope of Hongtoushan Mine and it has been proved to be valid and feasible to determine both the elastic modulus of damaged rock mass and distribution regularity of rock mass integrity in deep underground projects.

Key words: deep rock mass, elastic modulus, wave sound test, parameter inversion