【摘要】 依托穿越工程实例,从扰动机理、沉降变形及计算方法等角度,通过采用两阶段法与有限元数值模拟对盾构隧道开挖引起CFG桩复合地基的沉降变形进行研究。在盾构开挖时隧道土体对CFG桩复合地基内力影响较小,且桩体、桩周土体应力都有减小趋势,变化率为3%;隧道衬砌时周围土体应力较大。并有增大趋势,变化率为16%;复合地基桩周土体变形过程分为桩土的瞬时相对运动阶段和复合地基再次固结沉降阶段,桩土相对位移为1.5 mm;隧道开挖后褥垫层散体材料补充到桩周土体中,且褥垫层应力变化较大,褥垫层在盾构隧道土体开挖过程中起到有利的调节作用;桩顶、桩端应力和剪力相对较大,最大剪力值为139 kN,设计与施工时应加以重视。更多还原

【Abstract】 Based on the example of a crossing project,the two-stage method and the finite element numerical simulation are adopted to study the settlement deformation of CFG pile composite foundation caused by shield tunnel excavation from the perspectives of disturbance mechanism,settlement deformation and calculation method. The research results show that,the influence of soil body during shield tunneling on the internal force of composite foundation of CFG pile is small,and the stress of pile and the surrounding soil decrease with a change rate of 3%;the stress of surrounding soil around tunnel lining increases with a change rate of 16%;the deformation process of surrounding soil of composite foundation pile is divided into the instantaneous relative movement stage of pile and soil and the stage of re-consolidation and settlement of composite foundation, the relative displacement of pile and soil is 1.5 mm;after tunnel excavation,the cushion material is added to the soil around the pile,and the cushion stress varies greatly. The cushion layer plays an advantageous regulating role in the process of soil excavation of shield tunnel;the stress and shear of pile top and pile end are relatively large,and the biggest shear value is 139 kN,which should be paid attention to in design and construction.更多还原