软土路基堆载下既有隧道变形特性分析

Deformation Characteristics Analysis for Existing Tunnel under Surcharge Preloading of Subgrade in Soft Soil Foundation

以福州地铁6号线区间隧道上方施工路基为工程背景,运用MidasNX有限元软件,建立在深厚软土地层中路基堆载对地铁盾构区间隧道变形影响的有限元模型,分析了考虑流固耦合作用下软土的变形特性及复合地基加固处理效果。结果表明:在未采取加固措施的情况下,堆载对隧道周边的影响较大;对深厚软土加固,采用CFG桩+水泥土搅拌桩方案,形成复合地基后可满足变形控制的标准。

The subgrade under construction above the interval tunnel of Fuzhou Metro Line 6 was depended on to establish the finite element model with Midas NX software for the influence of surcharge preloading in deep soft soil stratum on the deformation of this shield tunnel, and then to analyze the deformation characteristics of soft soil with fluid-solid coupling considered and the reinforcement effect of composite foundation. The result shows that, without reinforcement measures, surcharge has relatively large impact on the surroundings of tunnel;for the reinforcement of deep soft soil, CFG piles together with soil-cement mixing piles develops composite foundation, which may meet the deformation control criterion.