Estimation of peak strength of jointed rock masses using GSI system

The Geological Strength Index (GSI) system is now widely used for the estimation of the rock mass strength and the rock mass deformation parameters. The GSI system concentrates on the description of two factors, rock structure and block surface conditions. First, A 3-D stochastic discontinuity network model was established by using the rock fracture data in Yuntaishan Road Tunnel in Lianyungang of Jiangsu, China. A determining method of the block volume WO was presented by using 3-D stochastic discontinuity network model, and a joint condition factor Ye) was acquired through field geological investigations. Then, the Hoek Brown strength parameters were determined by using the peak 051 value. Based on the stress condition analysing around tunnel excavation, the equivalent Mohr Coulomb strength parameters were calculated from the Hoek Brown strength parameters for a sigma(3) range of 0-sigma(3max).