Research purposes: The segment of shield tunnel is the key factor that affect engineering safety，engineering cost and construction speed．Wuhan Yangtze river tunnel exists some engineering difficulties， such as excavation surface with large diameter，high water pressure，long distance，stratum with strong water permeability，big variations of river bed，complex geological condition， and so on． On condition that there is no more similar experiences at home， it should conduct a study on key technologies of segment of shield tunnel to ensure the security and reliable of the structure， and the obtained conclusions can offer a guideline for the similar underground projects．
Research conclusions: First proposed a new type of the large diameter shield tunnel structure，which is“general －purpose and wedge － shaped，2 －meter width， nine uniform blocks ”， and by comparing with the different thickness of the segments under stress，recommends adoption of 0． 5 －meter thickness of the segment． This structure is safe and reliable，economic and effective，more adaptive to the construction of the project． This paper studied on the distribution of internal force of the structure by using the 3D shell － spring model， reveals the feature of the large － width segment that the bending moment at both sides are bigger than that in the middle． So it can draw a conclusion that different parts of the segment use the different reinforcement along the width of the segment to cut down engineering cost．
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