基于三维有限元模型的沉管隧道格形地墙护岸变形模式及方案比选分析

Deformation Pattern and Scheme Comparison of the I atticed Diaphragm Wallin the Revetment of an Immersed Tunnel via 3D Numerical Simulation

格形地墙作为一种新型支护结构形式,其受力变形性质相比传统支护结构存在明显的差异,相关理论研究滞后于工程实践.介绍了如意坊沉管隧道护岸工程中黄沙端格形地墙的设计方案,其依据基槽边坡开挖深度的差异,在不同区段采用了不同的格构形式和地墙长度.通过建立大型三维有限元模型,研究了护岸地墙变形的空间分布特征.计算结果表明,基槽边坡开挖引起的护岸地墙侧移模式具有刚性平移、整体转动和不同区段之间相对变形的特征.这种变形模式主要是由不均匀的土体开挖卸荷造成的,同时也受地墙格构形式分布特性的影响.最后,对既有设计方案中采用的格构形式和地墙长度进行了比选分析,论证了该方案是能同时兼顾安全性和经济性的优选方案.本文介绍的格形地墙护岸设计方案和得到的三维变形模式,对相关工程具有很好的参考借鉴价值.

The ltticed diaphragm wall has been wildly adopted in recent years.Compared with the traditional support,the mechanical property and deformation mode of latticed diaphragm wall are significant different.However,the relevant theoretical study lags far behind the booming engineering practice.Therefore,the design scheme of lat-ticed diaphragm wall in the Huangsha revetment of Ruyi immersed tunnel is intoduced in this paper.According to the change of the excavation depth of the trench,different lattice and length are adopted in different sections of the revetment.Then,a big 3D FEM model is established to study the defomation of ltticed diaphragm wall induced by the trench excavation.The simulation shows that the deformation pattem can be regarded as consisting of rigid translation,rotation,and relative deformation between different sections.This deformation characteristic is resulted from the uneven soil excavation and unloading.And the distri bution of stiffness of latticed diaphragm wall also contribute to it.Finally,the scheme comparison of different latice and the length of the ltticed diaphragm wall is carried out.The simulation results show that the original scheme is an optimization scheme.The design scheme and deformation behavior of ltticed diaphragm wall in this paper can provide a reference for related projects.