超浅层顶管施工引起路基地层移动数值模拟

覆盖土层薄的超浅层顶管穿越路基施工引起管道周围土体移动会对路面结构造成破坏。结合实际工程,运用有限元模拟超浅层顶管穿越路基引起的地层移动和现场地表变形监测,研究了管道摩擦力、注浆率、顶推力、路面交通荷载等因素对覆盖土层变形的影响。研究表明:地层移动是先隆起后沉降,覆盖土层下部的移动速度比表层的大;地表变形的有限元计算结果和现场实测数据基本吻合;超浅层顶管施工对浅埋覆盖路基土层移动,横断面地表沉降变形在工具管纵向通过2倍顶管外径后基本趋于稳定,横向地表沉降沿侧向分布近似为正态分布,主要影响范围在顶管轴线左右两侧各1.5倍顶管外径的范围内;变形要求严格的地面下进行超浅层顶管施工,可以通过有限元分析对周围环境影响程度的评价。

3D FEM Analysis of Subgrade Soil Movement and Deformation Caused by Extra Shallow Underground Pipe Jacking

Pavement structures will be damaged by subgrade soil movement around the pipes introduced by extra-shallow-underground-pipe jacking.Soil layer deformation with shallow deposits on pipes during extra-shallow-underground-pipe jacking is analyzed using 3D FEM.The effects on pavement deformation created by the friction between shield and soil,injection slurry,jacking forces and the vehicle loads are studied with a practical project.The analytical results show that the ground surface deformation is an uplift first followed by settling with the lower part of the cover moving faster than the upper layers.It is demonstrated by comparing computational results of FEM simulation and the observed data from the in-situ test that these FEM models can be applied to real-world engineering.Subgrade soil settling on extra-shallow-underground-pipe jacking in a cross-section will be stable when the shield has passed through a section with a length twice the diameter of the pipe.Horizontal surface subsidence along the lateral distribution is similar to a normal distribution curve,with the primary affected areas on both sides of the axis approximately 1.5 times the diameter of the pipe.