Abstract:

The influence of soft layer on TBM boring in deepburied soft and hard alternant strata and its characteristics are studied by taking a deepburied tunnel in Himalayas for example. Some effective construction countermeasures are put forward and put into practice successfully. The results show that: 1) The distribution of soft rock disasters is random in space due to that the hard and soft layers alternate frequently. 2) In deepburied tunnels with high ground stress, the TBM tunneling progress is restricted to the soft layer with the characteristics of water softening significantly, great deformation speed, serious mud muffled of cutters, expansion, hard be mucked and collapses frequently. The construction methods for TBM tunneling through soft and hard alternant strata are summarized; and sectioned dynamic construction countermeasures are adopted. The results can provide guidance for similar projects in China and abroad in the future.

Key words: deepburied water diversion tunnel, TBM, soft and hard alternant strata, soft rock large deformation