【作者】 陈铁林；

【导师】 沈珠江；

【作者基本信息】 南京水利科学研究院 ， 岩土工程， 2001， 博士

【摘要】 “土体结构性数学模型——21世纪土力学的核心问题”，本文以此为对象进行研究。 为了建立本构模型而进行的微结构研究，目前存在几种不同的研究途径，分为理论派、计算派和实验派。本文以实验为基础，以理论为指导建立符合实际的本构模型，并通过简单、实用的方法将其推广应用。 从土的微结构出发，考虑土的真实变形机理，把结构性粘土的变形分为颗粒的滑移和结构的损伤。以颗粒材料力学特性和微结构模型进行理论分析，研究了滑移屈服函数和结构损伤函数的特征。引入速率过程理论和聚合物网络理论对结构性粘土的流变特性进行分析。力图建立微观与宏观的联系，为建立粘土结构性模型做理论准备。 把结构性粘土看成不同大小土块的集合体，以结构性粘土堆砌体模型为基础，充分利用其对损伤的引入和对损伤比概念的突破，把结构性粘土的流变分为滑移流变和损伤流变，建立结构性粘土速率相关本构模型。并证明堆砌体模型和传统的损伤力学并不矛盾，只是传统损伤力学的合理推广。 采用在天然料土中掺入微量水泥和冰粒的方法，人工制备结构性粘土。对结构性粘土和重塑粘土进行了等向压缩试验和不同应变速率下的三轴CU、三轴CD试验。研究了应变速率对结构性粘土和重塑粘土力学特性的影响，以及结构性粘土与重塑粘土力学特性的差别，提出了状态路径的概念。首次对人工制备结构性粘土进行了五种贯入速率下的室内孔压静力触探试验（CPTU）。 编制有限元程序，利用速率相关的堆砌体模型对三轴CD和三轴CU试验进行模拟，验证了模型的正确性。 编制大变形Condlcp程序模拟结构性粘土室内孔压静力触探试验，验证了程序和模型的正确性。利用该程序模拟不同门槛损伤力q_o下的孔压静力触探，反演出该参数的原位测试公式。更多还原

【Abstract】 The problem of constitutive model of structured soils is the focus problem of soil mechanics in the 2l century. This paper deals with the ccnstitutive model of structured clays. During the last three decades, many constitutive model for clay have been proposed and studied. The most important may be the Cam clay model which was originally developed for remould clay and based on experimental results for remould Weald ay. But natural soil usually have their pecuilar stucture and their behavior can not be properly modeled by traditional elasto-plastic theory. From an engineering point of view, the need for a natural clay model, which can accurately predict the behavior of soft clay deposited with the increased construction activity in recent years, has become more urgent. In this study, a structured clay is regarded as an assembly of lumps of different sizes, and it is assumed that the total deformation consists of three parts, i.e. elastic deformation of lumps, plastic deformation due to sliding between lumps and irrecoverable deformation due to crushing of lumps. Usually yield function is introduced to describe the plastic deformation, damage function is proposed to describe the deformation due to the damage of soil structure. In order to link the micromechanics to macroscopic behaviour of clays and to establish structured clay constitutive model, the plastic yield function and damage function have been researched by microstructural sliding model and microstructural crushing model. A study is made of rheology of clay which is assumed to obey the worknet theory of polymer and rate process theory. The theoretical predictions are found to agree with experimental results. The studies theoretically support the masonry model for structured clays proposed by Zhujiang Shen. Based on the masonry model, a viscous-elastic-plastic model for structured clays has been proposed, it is assumed that the total viscous deformation consists sliding viscous deformation and damage viscous deformation. It is shown by the simulation that the model can well duplicate the rheological properties of structured clays. By putting some amount of cement and ice particles in soil samples, structured clay with macropores is prepared. Then, on structured clays and the remoulded clays the virgin compression test, CD tests and CU tests with different strain-rate have been carried out to clarify the strength-deformation characteristics and to determine the strain-rate effect and yielding characteristics. In addition, CPTU test on structured soil with different installation rate have been carried out. On the basis of nonlinear continuum mechanics, the Total Lagrange method is used to develop an FEM consolidation analysis program for large-strain analysis. The effect of rigidity rotation constant is observed while the model presented in this paper is used in constitutive laws. The simulations of CPTU test have been successfully performed, and the parameter q0 has been derived from CPTU test by simulating inversion method.更多还原