关键词: TBM, 膨胀岩, 变形效应, 层间错动, 碎裂结构, 结构面组合, 应力重分布, 纵环向导洞, 化学材料, 灌浆固结

Abstract: Expansive shale rock masses have low strength, high weathering, and low resistance to the water and moisture. When the tunnel is excavated in this rock mass using a Tunnel Boring Machine (TBM), large deformations will occur in the tunnel cross sections. In addition, if the humidity in the excavation changes rapidly, expansion and contraction will occur in the expansive shale. Along the proposed tunnel excavation alignment, the rock mass is severely folded due to rapid change of dip directions. The broken zones along the daylighting joint direction are very well developed. The jointed rock mass is usually discontinuous. When a tunnel is excavated using TBM, various collapses might occur at the working surface due to stress relief and re-distribution. In order to reduce this disturbance to the rock mass, the excavation technique should be: "Three Lows and One Continuous": Low Thrust Force, Low Drill Bit Rotation; Low Penetration and Quick Continuous Forward. The side blade of the TBM should be adjusted so that a larger tunnel cross section can be created. The exposed rock mass needs to be quickly sealed off and the water consumption during the penetration should be strictly controlled. During construction, the TBM excavation guidance documents were improved and modified, i. e., longitudinal and radial pilot grouting holes were created at the proposed shielded zones so that the rock mass stability could be improved by chemical grouting. These techniques were successfully utilized in argillaceous soft rock masses with a total linear excavated length of 13,532 meters. This length consists of 67% of the total tunnel excavated in the project.

Key words: Boring Machine (TBM), Expansive Rock Mass, Deformation Effect, Folded Mass, Broken Zones, Tectonic Planes, Stress Redistributions, Longitudinal and Radial Pilot Holes, Chemical Grouting