Abstract:

Accident often happens due to the serious ground surface settlement caused by shield launching. 3D shield-launching model is established by means of FLAC3D program. The full course of shield launching in typical strata in Beijing, Hangzhou, Nanjing and Shanghai is simulated, the rules of the influence of the shield launching in the above-mentioned typical strata on the ground surface settlement are summarized and countermeasures are proposed. The study result shows that under the same construction conditions: 1) the ground surface settlement induced by shield launching in different strata varies much, the scope of the influence of the settlement trough in cohesive soil is larger than that in sandy soil and the settlement at the central point in the case of cohesive soil is smaller than that in the case of sandy soil. 2) In the case of cohesive soil in the above-mentioned typical regions, the ground surface settlement is small; in the case of non-cohesive soil, the ground surface settlement is large and the differential ground surface settlement at the transverse boundary of the foundation pits is large. 3) The effect of the control of the ground surface settlement in Beijing is the best, that in Nanjing takes the second place, that in Hangzhou takes the third place and that in Shanghai is the worst.

Key words: shield launching, strata parameter, ground surface settlement, numerical simulation