Abstract:

Threebench sevenstep excavation method is adopted in the Anyuan tunnel, Fenghuangshan tunnel, Fandunping tunnel and Jiutaishan tunnel with shallow cover and asymmetricallyloaded soft and weak surrounding rocks, on basis of investigation and analysis on construction technologies of shallowcovered tunnel with asymmetricallyloaded soft and weak surrounding rocks in China. The construction difficulties, key construction technologies and countermeasures of threebench sevenstep excavation method are presented. The paper can provide references for similar projects in the future.

Key words: tunnel, shallowcovered and asymmetricallyloaded, soft and weak surrounding rock, threebench sevenstep excavation method, unloading reinforcement, backpressure and backfilling