Estimation on scale effect of strength of jointed rock

For analyzing the soft rock masses, it is necessary to model the discontinuous and inhomogeneous rock masses. In homogeneous model, the scale effect attributed to the discontinuous nature must be evaluated. A stochastic method based on minimum link model is presented to estimate the equivalent strength of soft rock mass in this paper. Scale effect is evaluated by the mixture strength model using the result of laboratory tests. Strength of soft rock mass(mixture strength model) with cracking is described by the summing the both strength of intact part and cracking part. The proposed equivalent strength model considering scale of rock mass is verified by comparing with results computed using 3D FEM and exiting loading test in situ.