深基坑格形地连墙支护结构变形与土压力研究

Study of Soil Stress and Deformation of Support Structure of Gridding Underground Diaphragm Wall of Deep Foundation Pits

为了对格形地连墙的受力和变形特征进行系统研究,针对南京某基坑工程的格形地连墙支护结构,建立有限元分析模型,其中岩土材料采用Mohr-Coulomb弹塑性本构模型;通过数值模拟研究分步开挖时此类基坑的变形和土压力分布规律,并与实测数据和朗肯土压力进行对比;最后分析后墙及隔墙深度、后墙宽度、前墙厚度和内坑加固等因素的影响。分析表明:格形地连墙的侧向变形类似于悬臂梁变形,最大侧向变形位于墙顶,这一变形形态与常见多道支撑支护结构的变形规律存在差异,且前墙厚度和内坑被动区加固对此类支护结构性状的影响比较显著。

The finite element model of support structure gridding underground diaphragm wall of a deep foundation pit in Nanjing is established; and Mohr-Coulomb elastoplastic constitutive model is adopted for rocks and soils. The finite element method is used to analyze the deformation of the deep foundation pit and the distribution rules of soil stress; and the results are compared with measured data and Rankine soil stress. The influencing factors,i. e. depth of backwall and separating wall, width of backwall, thickness of frontwall and foundation reinforcement, are analyzed. The analytical results show that： 1） The lateral deformation of gridding underground diaphragm wall is similar to that of cantilever beam. 2） The lateral deformation of wall roof is the largest,which shows that the deformation rules of the above-mentioned underground diaphragm wall are different from that of conventional multiple-supported structure. 3）The influencing factors of thickness of frontwall and reinforcement of foundation pit are obvious.