黄土的结构性力学特性及其变形与渐进破坏分析方法研究

Loess is characterized by the obviously structural behaviour and water sensitivety. Based on the point of equivalent consolidation theory of unsaturated soil，loess can be regarded as two-phase medium including of equivalent fabric phase and equivalent fluid phase. The structure of loess is also same as the equivalent fabric phase. On the basis of the comprehensive structural potential,the structural index and strength structural parameter of loess under loading and humudifying will be proposed by comparing the shear strength of intact loess, reconstituted loess and saturated loess, so as to discribe the initial strucutre and strctural changing perfectly with compression and shear strain. Further, the axial compression test, triaxial test, true triaxial test of loess, et al, are carried out in order to explore the structural parameters, deformation properties, strength law, consolidation deformation characteristics. Through analyzing the evolution of structural aprameters and the stress and strain relationship, strength law, consolidation characteristics and relationship between structural index and compression defornation property in the condition of the same structural parameter, the settlement calculation method of loess foundation based on structural chold modulus, non-linear constitutive model considering as structural parameter, structural elastic-plastic constitutive model and structural strength criterion can be established by appling the plastic mechanics, four-dimension space theory, space mobilized plane stength theory and loading test results. The new consolidatuon deformation analysis method and stress-strain field analysis method can be proposed respectively by replacing the physical equation in the equivalent consolidation theory and equilibrium eqution expressed by displacement variable by the structural constitutive. The limit analysis method can be improved by the structural strength criterion. The consolidation deformation, settlement and bear capacity of loess founadation can be calculated respectively by the equivalent consolidaton analysis method, stress-strain field analysis method, structural chord modulus method and modified limit analysis method. The progressive failure and slide of loess slope with the structural field evolvement can be discribed by the stress-strain field analysis method with the structural constitutive model and modified limit analysis method with structural strength criterion. The knowledge on structural mechanics characteristics of loess explored by this item will be the guide of loess engineering practice and geology disaster prevention and cure.

)：黄土具有显著的结构性和水敏性。基于土的等效固结理论观点，将黄土视为等效骨架相和等效流体相介质，黄土的结构实质上就是等效骨架相的结构；基于土的综合结构势思想，发展描述黄土初始结构及湿载作用下结构变化全过程的构度与压剪强度结构性参数体系。通过多种试验模拟不同应力条件和应力路径，开展不同黄土的结构性参数与变形强度特性、固结特性和压缩变形特性的试验研究，分析黄土结构性演变规律，结构性与应力应变关系、强度变化规律、固结变形特性的关系，以及构度与压缩变形特性的关系，建立结构性弦线模量分析方法、结构性参数非线性本构模型、结构性弹塑性模型、结构性强度准则。发展以等效固结理论为基础的黄土变形与稳定性分析方法原理。针对黄土地基和黄土边坡，开展加载增湿作用下考虑结构性演变的黄土地基固结、湿陷、沉降与承载特性分析，黄土边坡渐进破坏滑移变形与失稳变化过程分析，从而可以有效地指导黄土工程实践和地质灾害防治。

黄土具有显著的结构性及湿载作用下结构破坏的增湿和湿陷变形，造成了黄土体破坏，产生了滑坡、塌方和泥石流等灾害。从扰动灵敏度和浸水灵敏度反映加载、扰动、浸水作用下结构性演变及其对强度变形特性的影响出发，通过开展单轴抗压试验、三轴压缩试验、平面应变试验、真三轴剪切试验研究，分析了湿载作用下黄土的结构性演化特性，黄土的变形规律和强度变化规律，非饱和黄土力学特性，压板载荷试验的地基土压剪模量变化规律，地基自重湿陷变形评价方法，以及湿陷性黄土隧道地基的湿陷变形工程性状。建立了黄土初始结构性构度与其综合物理特征量和沉积年代之间的关系，结构性边界面模型，上下加载面模型，等向压缩损伤和剪切破坏损伤的弹塑性模型，新的动态空间滑动面强度准则，各向异性强度准则，地基黄土随构度、孔隙比和附加应力变化的模量表，隧道地基的湿陷变形评价方法，以及非饱和土等效固结分析方法。开展了地基的等效固结变形分析，结构性演变的地裂缝形成机制分析，黄土边坡的渐进破坏分析。研究成果对黄土地区地铁施工扰动变形问题，黄土隧道湿陷变形问题，黄土边坡稳定性问题具有重要的指导意义。