| In recent years, underwater tunnels have seen significant development in our country because of the advantages of short-distance traffic,strong bad-weather resistance and little impact on shipping. However, the construction of the underwater tunnels especially for the construction of underwater shallow tunnels with mining method in soft rock faces many complex engineering problems due to their special construction environment, One of the most prominent ones is stability during the excavation. This paper is to cover the research of Xiang jiang Road, Liu yang River Tunnel Project on the basis of the data from stress measurement, displacement measurement of on-site and laboratory test. FEM is adopted as the secondary research method,and analysis is focus on the impact of all pre-supporting on tunnel face Stability.(1)Four typical sections in the tunnel were selected for a long-term site monitoring. Based on the data, the thesis emphatically analyzes the variation of convergence of tunnel inner and vault settlement after the excavation of the tunnel face and the variation of contact pressure between surrounding rock and the first lining as well(2)as the variation with time of bolt stress and internal force of steel arch, etc.(3)Through a series of field and laboratory tests, incremental situation for the shear strength after grouting(c,φ),compressive strength and other parameters were got,and studies on grouting Parameters, grouting techniques, grouting quality testing method, grouting effect evaluation are carried out.(4)MIDAS-GTS software is adopted to build three-dimensional finite element model,soil displacement of tunnel face and force changes in the first lining (including pre-grouting) with pre-supporting are compared with that without pre-supporting.(5)The impact of pre-supporting (including pre-grouting) on the stability of tunnel face is analyzed and some suggestions are put forward on the design and construction of underwater tunnels in soft rock shallow. |
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