基于Mindlin解的盾构隧道施工地表变形及参数敏感性分析

Analysis of surface deformation and parameter sensitivity of shield tunnel construction based on Mindlin

假设土体为弹塑性体,基于Mindlin解,引入摩擦角φ,推导了盾构施工纵向地表变形的弹塑性解析解,将理论计算结果与数值分析结果和现场监测数据进行对比分析,揭示了盾构施工纵向地表变形特征。研究结果表明:(1)盾构隧道中线上方纵向地表变形规律呈"S"型变化,掌子面前方地表隆起,掌子面后方地表下沉;(2)盾构开挖仓压力大小对掌子面前方的纵向地表变形影响较小;(3)盾构施工过程中盾壳与围岩之间的摩擦力、土体内摩擦角φ与纵向地表变形量呈正相关变化规律;(4)在相同土层中,随隧道埋深减小,纵向地表变形量增大;(5)土体的泊松比增大、变形模量减小,纵向地表变形量增大。

Assuming that the soil is an elastoplastic body, based on the Mindlin solution and introducing friction angle φ, the elastoplastic analytical solution of longitudinal surface deformation in shield tunneling is derived. The theoretical calculation results are compared with the numerical analysis results and the field monitoring data. The characteristics of longitudinal surface deformation in shield construction are revealed. The results show that:(1) the law of longitudinal surface deformation of shield tunnel is "S" type, the surface uplift in front of the face of the palm and the surface behind the surface of the face of the palm sink;(2) Shield excavation chamber pressure has little effect on longitudinal ground deformation in front of the palm face;(3) friction between shield shell and surrounding rock during shield construction, soil mass The internal friction angle φ is positively correlated with the longitudinal surface deformation;(4) in the same soil layer, the tunnel depth decreases and the longitudinal surface deformation increases;(5) with the Poisson′s ratio of soil increasing, the deformation modulus decreases, and the longitudinal surface deformation increases.