The rapid development of underground constructions in China has raised many new issues for the research works on rock mechanics and engineering. Some of them are very significant for the recent engineering practices. This paper mainly presents the research works carried out on two issues, i.e., 1) stability analysis of the surrounding rock of large span underground structures built in complex geological condition, 2) deformation behavior and support mechanism of deep-buried long and large rock tunnel. The stability analysis is applied to the huge caverns at the Longtan Hydroelectric Power Station. Numerical simulations on the behavior of the layered rock mass with steep dip angle are presented. A back analysis method to obtain the initial rock stress and material parameters and to predict the deformation of the surrounding rock mass is established, in which the geological statistics method is employed to estimate the variation range of the Young's modulus and the u-t curves measured in situ are used to determine the time-dependant parameters of the surrounding rock mass. The back analysis can be conducted efficiently and the fitness function converges quickly. The main aspects related to the second topic are discussed. Laboratory tests to reveal the effect of rock bolts are also presented. Furthermore, the importance of the research works is emphasized, at the end of the paper.
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