考虑土与结构非线性接触特性的格形地下连续墙围护结构力学性状研究  

Mechanical properties of cellular diaphragm wall in deep excavations considering nonlinear contact between wall and soil

作　　者：郭盼盼 龚晓南[1] 汪亦显[2] GUO Pan-pan;GONG Xiao-nan;WANG Yi-xian(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;School of Civil Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]合肥工业大学土木与水利工程学院,安徽合肥230009

出　　处：《岩土工程学报》2021年第7期1201-1209,I0004,I0005,共11页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51778575)。

摘　　要：格形地下连续墙(简称"格形墙")作为一种相对新型的无内支撑式基坑围护结构,其力学性状研究滞后于工程实践。基于将双曲线接触模型嵌入到商用软件中的二次开发,开展了砂土中格形墙围护结构的受力变形特性有限元分析。墙土间的接触采用线性和非线性两种本构模型,砂土的应力应变关系采用基于UMAT子程序自定义的亚塑性本构模型模拟。与已有离心模型试验结果的对比验证了本文有限元模型的有效性。研究结果表明,考虑墙土间非线性接触特性得到的格形墙围护结构的力学性状更为准确,其内在机理为双曲线接触模型能够反映出墙体底部与土体间接触面剪应力的非均匀分布特性以及关键节点的剪应力集中现象。作用于墙体上的土压力未达到极限状态,且具有明显的空间分布特性。墙体水平位移模式为悬臂式,墙顶竖向位移模式为前墙沉降后墙隆起的整体旋转式。前后墙两中隔墙中间位置的弯矩分布规律类似。研究成果对于格形墙围护结构的设计优化具有积极作用。Cellular diaphragm(CD)wall,as a new kind of excavation supporting structure without internal bracing system,has not been well studied,despite its successful applications in many engineering practices.By incorporating the hyperbolic contact model into a commercial finite element software through FRIC subroutine,the finite element analysis of the mechanical properties of CD wall in sand is performed.Two contact models,i.e.,the Mohr-Coulomb linear and hyperbolic nonlinear models,are adopted.The stress-strain behavior of sand is simulated using the user-defined hypoplastic model through UMAT subroutine.By comparing with that of the existing centrifuge test results,the performance of the proposed numerical model is validated.The results indicate that the nonlinear contact model adopted is superior to the linear contact model in capturing the performance of the CD wall during excavation.This is because that the nonlinear contact model has an ability to account for the nonuniform distribution of interfacial shear stress between the wall bottom and the surrounding soil as well as the stress concentration phenomenon in the critical part of the wall.The lateral earth pressure on the wall has not reached its ultimate state,and an obvious spatial distribution feature of the lateral earth pressure can be observed.The mode of the horizontal displacement of the wall is cantilever,while the mode of the vertical displacement at wall top can be regarded as integral rotation with the front-wall settling and the back-wall uplifting.The distributions of the bending moment in the middle of the backand front-walls are similar.The results obtained are helpful for the design optimization of CD wall for supporting excavation.

关 键 词：格形地下连续墙 基坑 非线性接触模型 数值模拟 力学特性 

分 类 号：TU43[建筑科学—岩土工程]