Estimation of regional stress state and Young's modulus by analyzing mining induced deformation

A method to evaluate regional stress state and Young's modulus by analyzing mining induced deformation of ground is proposed. Mining induced deformation is interpreted as the deformation due to the geometrical change of ground surface caused by mine activity and it is classified into two types, i.e., the displacement increment induced by the gravity and that by the horizontal regional strain. It is pointed out that both regional strain and Young's modulus can be estimated by analyzing the mining induced deformation, because the displacement induced by the regional strain is independent of the Young's modulus and the displacement induced by the gravity is in inversely proportional to the Young's modulus. The relative displacement arising from mine excavation in Torigatayama limestone mine, Japan have been measured by GPS. Both the stress state and Young's modulus of the regional field including the limestone mine were estimated by back-analysis using three dimensional finite element method. It is shown that the maximum principal direction of the regional stress is almost NE-SW and Young's modulus of the ground is between 3 and 6 GPa.