Abstract:

Case study is made on the construction of Baidian tunnel in Tertiary waterrich sand strata. First, the grouting technology is optimized on basis of the physical parameters of the sand strata and by theoretical and field tests; Then, study is made on the pattern of consolidation by means of advance grouting, water pressure reducing by water releasing through boreholes, supplementary grouting at local positions, and rapid excavation and rapid closing; Finally, key rapid construction technology, including advance periphery grouting, reinforced grouting at tunnel face, water pressure reducing by water releasing, supplementary grouting during excavation, and rapid excavation and rapid closing, is proposed. The technology proposed has been used in the construction of Baidian tunnel. Not only the water outburst, sand outburst and the tunnel face stability have been brought under effectively control, but also the comprehensive construction efficiency has been improved and the construction cost has been reduced. 

Key words: tunnel, Tertiary waterrich sand strata, advance grouting, borehole drilling, water pressure reducing