Research purposes：As the span of continuous arch tunnel is big, in order to avoid the deep excavation and filling in the inclined area of the side slope at the tunnel opening and protect the natural environment, the subsurface excavation structure is adop ted on the deep buried side, the subgrade is built on the shallow buried side, and the ear wall is built on the middle part, which can stand the pushing force of the side slope, be as the side wall of tunnel and connected with the middle wall. Such structural type is part-tunnel and part-roadbed type. The part-tunnel and part-roadbed type tunnel is fresh in style, difficult in construction and comp licated in stressing, so it is necessary to do the research on the mechanics behavior in construction of this tunnel with numerical analysis and in-situ test.
Research conclusions：After excavation of the blind tunnel, large tensile stress happened to the surrounding rock on the right side of the foundation bottom of the ear wall to form a arc sliding zone. In construction, the foundation bottom of the ear wall was reinforced by anchor and grouting. Large tensile stress happened to the 8.5 m high area on the outside of the ear wall, but was smaller than the tensile design value of the concrete. The actual measurement showed the level disp lacement of the ear wall was small and the strength and stability of the ear wall were in the safe range. The stressing of the support structure for the blind tunnel was small and the stress of the secondary lining changed a little after completion of construction. All these showed the reinforcement of the side slope on left side before construction obtainedgood effect and verified the design and construction of this tunnel were reasonable and could be as the reference to the similar works.
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