Analysis of empirical estimation of rock mass modulus and its application

The deformation modulus is an important parameter in stability theory analysis and engineering design. Based on data from a large number of in situ measurements in mainland and Taiwan of China, Hoek and Diederichs proposed a new function on the method of modulus empirical estimation. This paper introduces the new relationship and how to determine Geological Strength Index (GSI) and Disturbance (D) factor. Then, the proposed method is applied to the practical project on deformation calculation of tunnel surrounding rocks. In order to prove the advantage of the new method, rock mass modulus is calculated by different empirical calculation methods, whose results are then used in numerical simulation in MIDAS/GTS. The rationality of Hoek-Diederichs method is further verified by comparing with field monitoring results. The new empirical estimation method of rock mass modulus is not popular at present in China, so the application is analyzed for the spreading in similar projects.