基于Mindlin解的盾构隧道地表沉降黏弹性分析

Viscoelastic analysis of ground surface settlement of shield tunnel based on Mindlin solution

基于Mindlin解,采用三参数固体黏弹性模型,给出了盾构隧道黏弹性沉降的计算方法,通过退化验证,证明了所得出的黏弹性沉降计算方法的正确性。结合工程实例进行计算分析,分别得出了黏性系数、距开挖面距离以及开挖深度对刀盘正面摩擦、刀盘侧面摩擦、正面附加推力、盾壳与周围土体之间的摩擦力引起的地表变形的影响。计算表明:沉降稳定所需时间随黏性系数增大而延长,随开挖深度的不同而不同;不同的黏性系数,最终沉降值无明显差异;盾壳摩擦导致的沉降随距开挖面距离的增加而减小。

A method for calculating the viscoelastic ground surface settlement of shield tunnel is given by utilizing the three-parameter solid viscoelastic model based on the Mindlin solution.The validity of the proposed method is verified.An engineering example is introduced of which the influences of the viscosity coefficient,the distance to excavation face,and the depth of the excavation on surface deformation caused by the frontal friction of the cutter head,the side friction of the cutter head,the frontal additional thrust,and the frictional force between the shield and the surrounding soil are obtained respectively.The results show that some more time is required for the settlement to be stabilized for larger viscosity coefficient.The difference of the viscosity coefficients has little influence on the final settlement values.The ground surface deformation caused by the shield shell friction decreases with the increases of the distance to the excavation face.The time required for the settlement to be stabilized varies as for the different excavation depth.