盾构掘进引起土体扰动的数值模拟与现场验证

Numerical simulation and field verification of the soil disturbance caused by shield tunneling in structural soft soil

为了研究结构性软土中盾构掘进过程对土体扰动的影响,引入了修正结构性剑桥模型考虑土的结构性,在Abaqus中编写了该模型的子程序并建立了盾构掘进的三维有限元模型,以模型中结构强度参数为评价指标建立了盾构掘进引起土体扰动评价方法。以宁波地铁1号线二期工程邱隘东站到五乡站左线盾构隧道项目为例,分析了盾构推进过程中的土体变形、超孔压分布及土体扰动情况。结果表明,土体结构性变化对预测结果的准确性有较大影响,当考虑土体结构性的影响时,预测结果更接近实测值;数值模拟得到隧道底部土体扰动度大致呈三角形分布,最大值为31%,影响范围达3.0m,与采用静力触探锥尖阻力扰动评价结果基本一致。对盾构施工控制参数进行分析,开挖面的支护压力对土体扰动的影响较大,当增大0.5倍支护压力时,隧道底面扰动度从31%增加至40%,影响范围从3.0 m增大到4.0 m。

In order to study the influence of shield tunneling on soil disturbance, the Modified Structured Cam Clay Model(MSCC) subroutine is compiled to establish the analysis model of shield tunneling in structural soft soil established in Abaqus. A theoretical calculation method of soil disturbance degree is proposed based on structure strength in the constitutive model. Taking the excavation process of shield tunnel from Qiuai station to the Wuxiang station in the second stage of Ningbo Metro Line 1 as an example, the soil deformation, excess pore water pressure and soil disturbance degree are analyzed. The results show that the accuracy of the predicted results can be improved by considering the soil structure.Numerical results shows that the disturbance degree of the soil at the bottom of the tunnel has roughly triangular distribution,with a maximum value of 31% and an influence range of 3.0 m, which is basically consistent with the evaluation results of the static cone tip resistance disturbance. By analyzing the control parameters of shield construction, the support pressure has a greater influence on the soil disturbance degree. When the support pressure is increased by 0.5 times, the soil disturbance degree under the tunnel increases from 31% to 40% and the influence range increases from 3.0 m to 4.0 m.