STRATUM DEFORMATION MONITORING AND MECHANISM ANALYSIS OF XIAMEN SUBSEA TUNNEL

Xiamen subsea tunnel is the first subsea tunnel in China. During its excavation process,engineers are faced with many technical difficulties,especially the large deformation of stratum,the controlling methods of sand layer and complete weathered granite. In addition,the issues that how to go through the weak structure interface, complete weathered deep valley or capsule during construction are specially considered;all these issues urgently need the understanding of the deformation law of tunnel for upper strata;and the controlling measures of the large deformation should be taken. Combining the three-dimensional numerical modeling of fluid-solid coupling,it is shown by the in-situ deformation monitoring that how the stratum subsidence is distributed and developed with time and space,and that how groundwater transports and works. Meanwhile,mutual influences and interaction of surrounding rock-lining-presupporting-pregrouting-water structure system can be well modeled and explained. The research results agree well with the results of field test of weak deep-sea valley. It is also further verified that surrounding rock,lining,as well as construction controlling techniques are the key factors in subsea tunneling.