Stress Analysis for Double Preliminary Support in Soft-rock Tunnel

Abstract:

The main lithology of the strata that Liangshui tunnel crossed is carbonaceous phyllite with poor geological conditions, the surrounding rocks are broken with high breaking degree and joint development. Since the construction of Liangshui tunnel in 2009, the problems of tunnel engineering have come out in an endless stream. The preliminary support cracking and failures happened, even serious tunnel structure failure such as cracking of the secondary lining, block falling and inveted arch uplift occurred, which led to slow construction progress. In the section of imported pile number of DK359+712～ DK359+742, good results have been received by double-layer preliminary support and single-layer secondary lining. The analysis on the stress situation provides a basis for the support mode selection of carbonaceous phyllite tunnel.