盾构隧道施工对西安钟楼影响的数值模拟预测

隧道施工导致古建筑及周围地表沉降的预测和控制是国内隧道工程领域遇到的研究课题之一．建立的三维有限元模型模拟了西安地铁2号线钟楼段的盾构施工过程，模拟了无隔离桩、无接触隔离桩及有接触隔离桩3种情况下盾构掘进过程中地面点沉降、钟楼周围地表和钟楼台四角点沉降的动态变化规律．结果表明，盾构施工有限元模型可以很好的模拟盾构通过的各个阶段，计算结果与盾构掘进规律一致；有接触隔离桩模型较好地反映了隔离桩的实际工程作用，有效的隔断了桩内外的地表沉降，隔离桩内外地表沉降差达到14．1mm；接触隔离桩减小了盾构施工引起的钟楼四角点的沉隆及差鼻沉降．对钟楼缸到了很好的保护作用．

Discussion on risk management in urban subway projects

Forecasting and controlling of the surface settlement close to the ancient buildings in the tunneling construction is one of the important research issues in the tunnel engineering in China. 3D finite element models are established to stimulate the process of shield tunneling of Xi＇an bell tower. Under three conditions of （1） without isolating piles, （2） isolating piles without contact, and （3） isolating piles with contact, this paper studied the dynamic discipline of ground settlement, settlement and dif- ference settlement of Xi＇an bell tower and the bell tower foursquare points, The results indicate that the finite element model could simulate each stages of shield tunneling, and the result is consistent with the discipline of measure data. The isolating piles model with contact reflects the practical function of project better, which can prevent the surface settlement effectively. The settlement difference between the interior and exterior part of the pile is 14.1 rnm. The isolating piles can reduce the foursquare point＇s settlement （caused by construction） of the bell tower and the bell tower can be well protected.