滨海超深软土刚性桩复合地基工作性能研究

Study on Working Characteristics of Rigid Pile Composite Foundation in Coastal Super-deep Soft Soil Area

滨海地区深厚软土地基沉降控制是工程建设的关键。本文以珠海航空新城某近海市政道路工程为依托,对超深软土刚性桩复合地基工作性能进行了研究,研究结果表明:(1)采用等效桩墙简化的平面应变模型可以有效模拟刚性桩复合地基的受力及变形;(2)持力层沉降占地基总沉降比例超80%,当边桩桩间距较大时,最大沉降及最大桩-土差异沉降均发生在路堤边缘区域,最外侧桩体处于最不利状态;(3)施工过程中超静孔隙水压力集中于桩端持力层,桩端超静孔压持续消散,而加固区超静孔隙水压力呈先增加后减小规律,超静孔隙水压力与有效应力之间呈此消彼长的关系;(4)采取缩小边桩间距、加大桩体直径、加深桩端进入持力层深度和加大桩帽尺寸等优化设计措施能有效控制超深厚软土地层沉降,促进桩土间的协调变形,减少道路病害。

Settlement control of the deep soft in the coastal area is the key to the construction. Based on an offshore municipal road project in Zhuhai Aviation New City,the working performance of rigid pile composite foundation in super-deep soft soil area is analyzed. The results show that:( 1) The plane strain model simplified by equivalent pile wall can effectively simulate the stress and deformation of rigid pile composite foundation.( 2) The settlement of bearing stratum accounts for more than 80% of the total foundation settlement. When side pile spacing is large,the maximum settlement and pile-soil differential settlement occur at the edge of the embankment,and the outermost pile is in the most unfavorable state.( 3) During the construction process,the excess pore pressure is concentrated in bearing stratum under pile tip,and the excess pore pressure at the pile end continues to dissipate,while the excess pore pressure in the reinforcement area increases first and then decreases,and effective stress increase at the expense of the excess pore pressure.( 4) The optimal design measures,such as reducing the distance between side piles,increasing the diameter of piles,deepening the depth of pile tip into bearing stratum and increasing the size of pile cap,can effectively control the settlement of super deep soft soil layer and promote the coordinated deformation of pile-soil,and reduce road diseases.