Numerical inversion and sensitivity analysis of deformation modulus for deep rock mass

Abstract

Rock deformation modulus is one of the key parameters for the design and construction of underground rock engineering. Obtaining accurate rock deformation modulus is crucial for a comprehensive analysis of the deformation behavior of the surrounding rock in deep rock engineering. To achieve this goal, the commonly used methods for calculating rock deformation modulus are systematically sorted out and summarized. Furthermore, the rock deformation modulus is inverse-calculated by simulating in-situ tests using the finite element method, and the results are verified and analyzed by comparing them with the in-situ test results. For the actual project of deep shaft, a numerical calculation model is established to conduct an inversion analysis of rock deformation modulus of different lithologies in the deep strata. Additionally, a sensitivity analysis is performed on different strength criteria, Poisson's ratio and rock cohesion on rock deformation modulus. Finally, the numerical simulation inversion results are compared and discussed with the empirical formula calculation results. The results show that the values of rock deformation modulus obtained from numerical inversion using finite element method are in good agreement with those calculated based on the experimental rigid plate load test; While Poisson's ratio does have some influence on rock deformation modulus, the sensitivity of rock deformation modulus to Poisson's ratio is generally low; When the cohesion of the rock mass is small, the choice of strength criterion has a significant influence on the inversion results of deformation modulus, and vice versa; the sensitivity of the rock deformation modulus to the changes of the rock cohesion varies depending on the depth and lithology of the strata; the deformation modulus of the rock mass obtained by numerical inversion has a good correlation with some empirical equations. Therefore, the numerical simulation and empirical formulae are useful during planning, design and development of deep rock projects to perform the inversion calculation of rock deformation modulus, thereby ensuring greater safety and economy.

Keywords

• rock mass mechanics
• deformation modulus
• inversion
• sensitivity analysis
• numerical simulation