Development of Equivalent Stress- and Strain- Dependent Model for Jointed Rock Mass and Its Application to Underground Structure

초록

Current design methods for underground structures surrounded by jointed rock masses fail to account for the deformational characteristics of these surrounding rock masses, employing only input parameters that are defined prior to construction. Thus, there is the need to investigate the effects on underground structures that result from the deformational characteristics of jointed rocks that undergo stress relaxation during their excavation. Comprehensive research is conducted in this study. First, we propose an equivalent stress- and strain-dependent model incorporating equivalent stiffness at small strains into a hyperbolic model from intermediate to large strains. Then, experimental tests are conducted to characterize the deformational characteristics of jointed rock masses and extract requisite model parameters such as joint properties and nonlinearity. Finally, two numerical simulations are conducted using the proposed model to determine its field applicability to an unlined circular tunnel. The nonlinear simulation results are compared with the conventional analysis method that uses a constant stiffness value. Our results show that the proposed equivalent jointed rock mass model, which considers stress-and strain-dependency, can be utilized for deformational analysis of underground structures involving excavations in jointed rocks.

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