饱和砂土地震液化及治理措施

我国是多地震国家，地震区分布广，地震灾害严重，许多重要设施处于地震液化敏感区内。本文从饱和砂土振动液化的机理、影响因素、液化效应及治理措施等几个方面进行了分析和介绍。     

振冲加密技术在曹娥江大闸基础处理中的应用

采用振冲挤密法处理曹娥江大闸粉质砂土地基,对振冲剂密法的原理、施工工艺、施工参数和质量控制、质量检测、振冲效果作了介绍.     

海成砂土的动力稳定性研究

本文引用了在动荷载和静荷载作用下，浅海滩涂地段海成砂土的试验研究成果，阐明了松散砂土的体质特征，确定了其动力稳定性。     

辽西地区风积土的强度、冻融特性及其分形性质的研究

博士学位论文摘要 冻土在我国分布面积很广，其研究一直是学术界的一个热点问题，关于冻土的研究，多数是涉及黄土、砂土和粘土，而对风积土的研究目前开展的还不多。针对辽西地区广泛存在的风积土的特殊性进行了大量系统的研究，主要研究工作体现在以下几个方面：     

碎石类人工地基的动力触探评价

成都地区高强度的卵石土地基，多埋深3～6米左右，为城市建设提供了得天独厚的优越的地基基础条件，但基上广泛地分布有松散饱和液化粉土，粉、细砂土，市区内堆积有较厚的人工填土，它们均不能满足建（构）筑的的地基需要，由于未很好开发挖掘天然地基的潜力，大量采用桩基础，从而在地基基础方面增加了较大的投入。     

砂土边坡对泄露重油截留行为试验研究

针对道路运输事故次生突发水环境事件重油泄露入河行为,通过模拟试验,研究罐车以小裂开面积(0～9×10-4 m2)的泄露速度(0.1、0.4、0.6、1.1 L/s)泄露后自然砂土边坡(5、10、15°)对重油的截留影响。试验结果表明:(1)单位长度截留时间与坡度、泄漏速度分别有线性关系;(2)泄漏速度不是单位面积截留量的影响因子,建立单位面积截留量与坡度回归方程I=-0.101S+4.850;(3)初步拟定小裂开面积下,重油单位长度截留时间为4～8 min,单位面积截留量3～6 L,大裂开面积可以此为参考,以期为泄露重油入河时间、入河量提供参考。     

砂土各向异性和不排水剪切特性研究

在不同应力路径下,进行三轴和扭剪不排水剪切试验,揭示砂土力学行为与应力路径和各向异性的关系,并对砂土的细观结构和各向异性进行量化.研究结果表明,砂土的力学特性受材料各向异性和应力各向异性耦合影响.砂土各向异性的量化研究和力学试验结果为后续本构模型发展提供了依据.     

考虑中主应力效应Gudehus-Bauer亚塑性模型的改进

针对Gudehus-Bauer亚塑性模型不能考虑中主应力影响,在Gudehus提出的响应包络线理论基础上,提出了在模型的非线性项乘以一个考虑中主应力的因子进行改进.这种改进增加了土体剪切时的强度,改变了土体受压时的变形.新模型对中主应力的变化在中主应力参数影响程度能够有一定反映.同时将改进后的模型与中主应力参数为常量的真三轴实验进行了比较.结果表明改进后的模型可以模拟中主应力对砂土强度和变形特性的影响,能够定量预测由于中主应力影响产生的体积应变.     

Constitutive equations and finite element implementation of strain localization in sand deformation

A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity tensor was naturally treated as a function of the spatial discretization matrix about the displacement and the stress field, allowing a more realistic representation of the physical phenomenon. The fully Lagrangian form of the Darcy law was resolved by Piola algorithm, and then the flow law was gained, leading to the implementation of a modified model of the saturated sand. Then the criterion for the onset of localization was derived and utilized to detect instability. The constitutive model was implemented in a finite element program coded by FORTRAN, which was used to predict the formation and development of shear bands in plane strain compression of saturated sand. At last, the formation mechanism of the shear band was discussed. It is shown that the model works well, and the simulation sample bifurcates at 1.18% axial strain, which is in a good qualitative agreement with the experiment. The pore pressure greatly affects the onset and development of the deformation band, and it obviously increases around the localization-prone regions with the direction toward the outer side of the normal of the shear band, while the pore stress flows nearly horizontally and is distributed equally far away the shear band region. Foundation item: Project(2006G007-C) supported by the Foundation of the Science and Technology Section of Ministry of Railway of China; Project(77206) supported by the Excellent PhD Thesis Innovation Foundation of Central South University, China