【作者】 李宏儒；

【导师】 胡再强； 郭增玉；

【作者基本信息】 西安理工大学 ， 岩土工程， 2009， 博士

【摘要】 在系统分析关于结构性、应变局部化、结构性土力学特性的基础上,选择了当前描述结构性土特性最具活力的破损力学理论作为本文研究的基本框架。针对杨凌地区黄土,通过室内试验、理论研究和数值模拟相结合的方法,对结构性岩土材料的破损机理、力学特性、二元介质模型破损率的演化方程、影响因素和局部化剪切带的启动发展进行了较为系统的研究,同时利用吸力的饱和度等效思想和二元介质模型,对黄土路基进行了增湿变形分析。本文主要取得了如下一些有益的成果：1)在系统阐述破损力学的理论基础之上,分析了二元介质模型荷载的分担规律、破损率演化方程及其确定办法,从原状黄土和重塑黄土的应力—应变关系出发,提出了一种针对单参数和双参数破损率确定的新办法,根据室内试验,求得其演化方程,并研究了围压和含水量对其的影响。2)基于二元介质模型概念,给出了一种模拟结构性岩土类材料破损过程的细观模拟方法,编制了既可用于轴对称、平面应变；也可以用于非饱和土、饱和土的有限元计算程序,模拟出不同侧向应力状态下结构性黄土在荷载作用下胶结元破损并逐步向摩擦元转化的过程,再现了土体破坏发展过程的规律。3)利用结构性土的二元介质本构模型、单参数和双参数破损率演化方程,对均匀三轴试样、内部不同位置设置薄弱单元、边界不同位置设置缺陷单元和饱和土样等不同计算方案下的局部化变形破坏规律进行了较为全面的数值试验模拟,并研究了单元尺寸大小对局部化剪切带的影响,得到了剪切带在初始发展阶段是分段不连通的破坏带,随着荷载的增加,逐渐连接贯通,形成连续的破坏带,证明了以往只有在实验室才可观察到的间断性现象。说明了二元介质模型用于局部化剪切带的分析有其优越性。4)利用二元介质模型和吸力饱和度等效的思想,结合非饱和土固结方程,建立了分析非饱和土增湿变形过程的方法,推导了有限元求解公式,编写了计算程序。针对陕西关中地区高速公路路侧由于雨水入渗造成路基下沉变形的情况,进行了有限元数值模拟,再现了降雨入渗造成高速公路路基变形的过程,为黄土的加载和增湿变形特性研究提供了一种新的途径和方法。更多还原

【Abstract】 Based on the systemical analysis of structral properties, strain localization, mechanical characteristics, choosed theory of breakage mechanism mechanics that can sufficiently describe structural soils as basic framework at present, systematical research on breakage mechanics, mechanical properties, numerical simulation, binary medium constitutive model breakage parameter, effect factors, shear hand startup and expand of structural geomaterials is carried out by laboratory tests, theoretical study for Yanglin region loess, taken means of saturation instead of suction and binary medium constitutive model into moistening deformation analysis of the loess road foundation.The main achievements obtained in the thesis are as follows:On basis of systematic research theory of breakage mechanics, analyse the load sharing ratio rule、breakage parameter evolvement equation and method of definition for binary medium constitutive model, analyzed data of tri-axial test, according as relation of stress-strain for undisturbed and disturbed loess, defined a sort of evolvement equation aim at simple parameter and double parameter model, and studied influence to it forσ3 and containing water.Based on the concept of the binary medium model for geomaterials, a mesoscopical numerical method which can simulate the breakage processes of geomaterials is proposed. The FEM program is coded and used to axis symmetry and plane strain model, also used to dissaturation and saturation soil, it can simulate the breakage process of structure loess under different lateral stresses. The numerical method can trace the processes of bonding elements breaking and transforming to frictional elements, reappearance process of failure rule of soils.Imposing binary medium constitutive model of structure soil, breakage ratio evolvement equation of simple and double parameter, progress rather general numerical simulate of strain localization destroy rule unde well-proportioned tri-axial test sample、setting differ position interior weakness element and limitation element on differ position boundary, and studied element size for strain localization influence, received some meaning conclusion such as shear band is aubsection, unattached damage area originaly, follow load increase,gradually connect, form continum failure band, proved the phenomenon of discontinity be observed in the laboratory. Explain the advantage of using binary medium constitutive model in strain localization analysis.Utilizing idea and method of binary medium constitutive model and saturation instead of suction, importing it into unsaturation soil concretion equation, imposed the compute method of instead pore water pressure, reduced finite element formula of structure loess moistening deformation, code the rain water infiltration finite element program, processed numerical simulate freeway roadbed side sinkage deformation due to rainwater infiltration combined Guanzhong area. Shaanxi province, reappearance process of defrmation form the rainfall infiltration, and to provide a new way and method to verify the researches of the load deformation characteristics, humidification characteristics.更多还原