【作者】 梁永恒；

【导师】 邵生俊；

【作者基本信息】 西安理工大学 ， 防灾减灾工程及防护工程， 2010， 硕士

【摘要】 非饱和土的固结变形特性及其分析理论一直是土力学的研究热点问题。非饱和土由于固、液、气三相之间的相互复杂作用,使得其固结过程中三相介质之间的传力机理和变化发展也难以认识清楚。鉴于问题的复杂性,人们业已提出了将复杂多变的非饱和土固、液、气三相及收缩膜和各相的物理化学表观作用简化为等效骨架相和等效流体相来认识其固结过程的分析方法,并通过压缩、固结试验揭示了非饱和土固结过程的等效骨架相应力和等效流体相压力的变化规律、瞬时压缩变形特性以及等效固结系数,将复杂的非饱和土固结问题简化为两相耦合作用问题,建立了一种简化的非饱和土一维等效固结分析方法。本文将这种方法进一步应用于结构性黄土的固结变形特性分析。首先对西安白鹿塬地区的Q2黄土和Q3黄土的等效固结变形特性进行分析。试验确定了不同固结应力和附加应力作用下结构性黄土的瞬时变形、瞬时压缩模量、等效流体压力系数,揭示了固结系数的变化规律、等效流体相渗透系数的变化规律,以及黄土的结构性和准先期固结压力对非饱和土固结特性的显著影响。其次,测试分析了基质吸力与固结特性和等效流体运动特性之间的关系；结合黄土的结构性与先期固结压力,通过基质吸力与固结系数的关系,提出了等效流体运动中“封气点”和“贯通点”影响固结的观点。最后,在真三轴试验条件下测试分析了结构性黄土的三维固结变形特性。不同应力路径等应力比分级加载时,剪应变在加载过程即可完成,体应变发展过程表明加载结束后才有明显的固结过程。初步证明了非饱和土剪缩变形存在固结过程。本文的研究成果对于进一步研究非饱和等效固结理论打下了理论基础。更多还原

【Abstract】 The consolidation deformation characteristics of unsaturated soil and its analysis methods are key issues in the field of soil mechanics. During the process of consolidation, due to the complex interaction among the solid phase, liquid phase and gaseous phase, the transmission mechanism and the develoment and change among three-phase porous medium are difficult to understant clearly. In view of the complexity of this problem, people have put forward a analytical method to make the process of consolidation clearly. In this analytical method, the interaction among the solid phase, liquid phase, gaseous phase, shrinkable film and physical and chemical effect is simplified to the interaction between equivalent fabric phase and equivalent fluid phase. Through consolidation test,the relationship of equivalent fabric phase, equivalent fluid phase and time, and, the changes of transient compression modulus and coefficient of consolidation are revealed during the process of consolidation. Then, the complex problem of consolidation is simplied to the problem of two-phase coupling effect, and one-dimensional equivalent consolidation analysis method is set up.This method will be used in the equivalent consolidation deformation characteristics analysis of structural loess further in this article. Firstly, the equivalent consolidation deformation characteristics analysis of Q2 and Q3 structural loess in the region of Xi’an Bailuyuan are tested by the consolidation apparatus. Testing to determine the structural loess changes of transient compression deformation, transient compression modulus and pressure coefficient of equivalent liquid under the condition of different consolidation stress and additional stress. Then, the changes of consolidation coefficient, permeability coefficient are revealed, as well as the significant impact on consolidation characteristics of unsaturated soil by structural loess and quasi-preconsolidation pressure. Secondly, the relationship between suction and consolidation characteristics and the motion characteristics is analysed by the test. According to the relationship of suction and consolidation characteristics, and the relationship of loess structure and quasi-preconsolidation pressure, the point of view that "seal gas point" and "linking point" impact of consolidation in the equivalent fluid movement is proposed. Finally, three-dimensional consolidation characteristics of structural loess is tested and analysed in the condition of true triaxial test. While loading score loads of the stress level in different stress paths, shear strain is completed in the loading process. But, the physical strain is developed significantly in the consolidation process after the end of loads. The point that unsaturated soil shear deformation exists in the consolidation process is certified initially.This paper expresses the results are the base for the further study equivalent consolidation theory.更多还原