Method of determining deformation modulus of rock mass based on three-dimensional discontinuity network simulation

As an important parameter to characterize the deformation characteristics of the rock mass, deformation modulus is one of the basic mechanical parameters in rock mass engineering design. Based on previous studies, a method in determining rock mass modulus of deformation is proposed on the basis of three-dimensional discontinuity network simulation method, and then a three-dimensional network simulation program and a RQD values calculation program were completed. Taking the rock mass in a hydropower station dam area located in the southwest of China as an example, a three-dimensional discontinuity network model was generated by using the Monte Carlo method, based on the distribution form of geometric elements of each preponderant discontinuities group from statistical analysis, and thereby obtained three-dimensional RQD values of rock mass. Deformation modulus and the quality of dam area rock mass were then evaluated and compared to drilling data statistics method and in-situ test. The results showed that the relative error between the estimation result based on drilling data statistics and the result of in-situ test is up to 31.62%; the relative error between the estimation result based on three-dimensional network simulation and the result of in-situ test is only 2.56%.This method takes into account of the spatial anisotropy of rock mass quality, which provides a more reasonable evaluation for the rock mass quality and parameter determination, and meanwhile provides reasonable mechanical parameters for optimization design of the project.