考虑水—土耦合的盾构隧道地表沉降试验研究

Experimental Study on the Shield Tunneling-Induced Surface Settlement Considering Water-Soil Coupling

考虑水—土耦合情况,进行不同隧道埋深、支护压力和掘进速度条件下盾构隧道施工致地表沉降的大型三维物理模型试验,总结不同条件下的地表沉降规律,分析孔隙水压力和围岩压力的变化特性,归纳不同条件下的地表沉降曲线;探讨隧道埋深、支护压力和掘进速度以及孔隙水压力对地表沉降值的影响,推导地表横断面沉降槽计算的经验公式,并将研究成果应用于北京地铁10号线部分区间的地表沉降预测。结果表明:随着隧道埋深增加,地表沉降值减小,地表横向沉降槽影响范围加宽;沉降值随支护超压比增加而增大;掘进速度变化对地表沉降的影响程度较小;施工扰动围岩及孔隙水压力消散对地表沉降值有较大影响;基于物理模型试验的经验公式预测值与FLAC3D数值模拟预测值、现场实测值均较为吻合。

The influence of cover height, face supporting pressure and penetration rate on shield tunneling- induced ground surface settlement was studied with physical model test under the water-soil coupling condition. The mechanism of the shield tunneling-induced ground surface settlement and the transformation of water-soil pressure were analyzed, the ground settlement curves in different parameters were obtained. The influence of cover depth, face supporting pressure and penetration rate of shield tunnel to the surface settlement were discussed. A newly-modified tunneling-induced ground settlement calculation method under water-soil coupling condition was presented and applied in the case of Beijing Metro Line 10. It is revealed that the maximum surface settlement is decreasing but the transverse settlement though is widening with the argument of cover height, the surface settlement is increasing with the increment of the face supporting pressure but little influenced by the shield penetration. It indicates that it is necessary considering the influence of the shield tunneling induced boundary soil disturbance, water-soil coupled induced-soil properties weakening and the excess pore water pressure dissipating induced soil consolidation to the surface settlement. The calculation result of the newly-modified surface settlement method agrees well with in-site observed data and the results of FLAC^3D numerical simulations.