考虑蠕变三维效应和交通荷载的超固结软土沉降模型

项目名称： 考虑蠕变三维效应和交通荷载的超固结软土沉降模型

项目编号： No.41272327

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 李国维

作者单位： 河海大学

项目金额： 85万元

中文摘要： 我国东南沿海地区软土地层广泛分布。深厚软土路基工后长期沉降可导致安全事故和重大损失。超载预压法处理的深厚软基工程的工后沉降问题具有普遍性，主要原因是超载卸荷后形成的超固结软土的蠕变变形，软基低路堤还应考虑交通荷载的影响。本项研究基于Bjerrum时间平行线理论，建立超固结软土次固结系数的理论模型和一维蠕变沉降模型；根据超固结软土侧压力系数与应力历史的关系，建立一维蠕变理论拓展模型；结合超固结软土的三维蠕变性状，建立三维蠕变体变模型；根据流动法则建立体变和轴向应变的关系，构成三维蠕变沉降统一模型。基于"等效时间"的思想，建立现场软土蠕变过程时间状态的确定方法，形成考虑三维效应的蠕变沉降算法。依据蠕变模型，以分时段不同恒载蠕变过程迭加逼近低频小幅循环荷载过程，建立循环荷载累计应变迭加模型，最终形成考虑蠕变三维效应和交通荷载的超固结软土沉降模型。研究成果对土力学沉降计算理论也有重要价值。

中文关键词： 超固结软土；蠕变；超固结剪应力比；三维效应；循环荷载

英文摘要： Soft clay deposit is widely distributed in the coastal areas of South Eastern China. Long-term settlement of embankments constructed on deep and thick deposits of this soft clay can lead to unsafe incidents during service and heavy economic losses. The post construction settlement of embankment on the deep and thick soft clay foundation treated with drainage and surcharge preloading is prevalent in these coastal areas. The main reason of these phenomena is the creep deformation of overconsolidated clay formed by unloading of the surcharge loading, and also, the impact of cyclic traffic loading on low embankment constructed on the soft clay foundation. In this research, a theoretical model of secondary consolidation coefficient of over-consolidated soft clay and a 1D creep model of it will be elaborated based on the theory of parallel time lines proposed by Bjerrum. According to the relationship between the lateral pressure coefficient and stress history of over-consolidated soft clay, an expanded theoretical 1D creep model will be derived. From this model and combing the 3D creep behavior of over-consolidated soft clay, a volumetric strain model will be created. The relationship between the volumetric strain and axial strain of clay will be deduced from the associated flow rule of plastic theory. The relationsh

英文关键词： over-consolidated soft clay；creep；over-consolidated shear stress ratio；3D effect；cyclic loading