土体杨氏模量对开挖卸荷引起隧道变形影响

Effect of Soil Young's Modulus on Tunnel Deformation due to Stress Relief

采用基于摩尔库伦准则的理性弹塑性模型开展有限元分析,研究土体的杨氏模量对基坑开挖卸荷引起隧道变形影响,分析隧道纵向隆起、衬砌直径变形以及弯曲应变的变化规律和趋势。研究表明,基坑开挖卸荷引起坑底下方的隧道隆起,隧道衬砌横截面竖向压缩、水平拉伸,隧道横向和纵向弯曲应变分别沿隧道横截面和纵轴线呈对称分布。随着土体杨氏模量增大,隧道顶部最大隆起,隧道衬砌直径以及隧道横向和纵向弯曲应变都呈对数减少,并给出了拟合方程,便于应用。

An elastic-perfectly plastic model based on Mohr-Coulomb criterion was used to conduct finite element analysis to study the effect of soil Young's modulus on tunnel deformation caused by stress relief. Tunnel deformation law and trend including tunnel longitudinal heave, tunnel diameter change and bending strain are analyzed. The results show that stress relief leads to the heave of the tunnel below the bottom of the foundation pit. Tunnel diameter is compressed vertically and stretched horizontally. The transverse and longitudinal bending strains of the tunnel are distributed symmetrically along the cross-section and longitudinal axis of the tunnel, respectively. With the increase of soil Young's modulus, the maximum tunnel heave, the diameter of tunnel lining and the transverse and longitudinal bending strain of tunnel decrease logarithmically, and the fitting equation is given, which is convenient for application.