Abstract: This paper presents a case history of a larger diameter tunnel excavation of South extension of Heping Boulevard (Zhongshan Road to Zhang Zhidong Road) in Wuhan. The stress-strain characteristics of tunnel and its surrounding karstic cavity rock mass are analyzed by the finite element analysis software. The impact of the soil strata loss on the stability of the karstic rock cavity and the surround rock mass are evaluated, The results indicate that, when the size of the rock cavity is relatively large, the deformation of the tunnel is towards to the cavity and the stress in the tunnel structure is larger than that of in other locations. The rock cavity above the tunnel will induce a larger ground subsidence and even induce the sinkhole collapse on the ground surface. In the tunnel excavation, preventive measures should be applied to minimize the soil strata loss since the larger soil loss will induced the excessive ground subsidence.

Key words: Tunnel, Cavity Rock Mass, Deformation, Stresses, Loss of Soil Strata