【作者】 余丽；

【导师】 扶名福；

【作者基本信息】 南昌大学 ， 工程力学， 2007， 硕士

【摘要】 非饱和土分布十分广泛，与工程实践密切联系的地表土几乎都是非饱和土，特别是干旱和半干旱地区，由于蒸发量大于降雨量，地下水位较深，这些地区的表层土是严格意义上的非饱和土，就连土坝、铁路、公路路基填土和一些压实填土也都是处于非饱和状态。因此非饱和土才是工程实践中经常遇到的土，饱和土是非饱和土的特例，真正意义上的饱和土在工程实践中很少见到。但是由于种种原因，现在好多非饱和土的理论都是借用了饱和土的理论，因此这不可避免的给工程应用带来了误差，所以如果能够以现有的比较成熟的土的本构模型作为基础，充分考虑饱和度的变化对土的工程性质的影响，建立真正意义上的非饱和土的本构模型，将会给工程带来较大经济效益，同时也丰富了现有的土力学理论，所以研究非饱和土的本构关系具有重要意义。本文首先回顾了前人的一些研究成果，总结了国内外非饱和土基本强度理论的发展现状。通过对强度理论的研究和总结，将缪林昌等人提出类似摩尔-库仑理论的强度公式应用于南昌地区粘性土的物理参数分析，得出了土体抗剪强度参数随含水量变化而变化的规律，拟合出了相关的近似公式。在此基础上运用缪林昌等人进一步在试验的基础上提出的非饱和膨胀土强度的指数函数公式，通过室内土工试验得到了南昌地区的试验系数。本文同时将得到的试验参数运用ANSYS软件分析了单桩承载力的影响。为了更加接近工程实际相符合，本文采用三维实体建模，几何尺寸与工程实际一样。对桩-土间的相互关系使用接触单元进行模拟，采用D-P弹塑性模型来反映土体的本构关系。通过对计算参数的选取和试算使其计算收敛，结果与理论值几乎一致。更多还原

【Abstract】 Unsaturated soil is widely dispersed all over the world.The soil on the earth’surface having a intimate relation with engineering practice is almost unsaturated soil,specially in dry and half dry area.Because evaporative spiration is bigger than rainfall,and the groundwater level is high, in strict sense,the surface soil of this area isunsaturated, While earth dam, railway, highway bed filled of soil and some dense soilare all in unsaturated state.So unsaturated soil is really often encountered soil in theengineering practice, saturated soil is unsaturated soil’ special case. But for a varietyof reasons, now a lot of unsaturated’ soil’ theory borrows saturated soil’ theory, thiscan not avoid errors to engineering application. So research unsaturated soil’sconstitutive relation has important sense. It is significantly meaningful to researchconstitutive relation of unsaturated soil.The text reviewed some research results of predecessor at first,summarizing thedevelopment present condition of unsaturated soil basic strength theories at home andabroad. Miaolinchang and others put forward a similar formula of Mohor-Coulomb’sstrength theory,which applied to analyse the physical parameter of clay in Nanchangand then got a disciplinarian between water content and shear strength.By a methodof fitting curve,the auther gained a similar formula. Miaolinchang with someothersfurther to put forward on the foundation for experimenting on this foundation ofinflation unsaturated soil strength of exponential function formula.By laboratory soiltest,the textgot the experiment parameter of Nanchang.Meantime, parameters are obtained in experiment. ANSYS software is used toanalyze its influence to a single pile’s bearing capacity, For more agreeing with tomatch physically with engineering, this literary sets up a mold with the 3D entity, itssizes are physically similar to engineering.The interrelation between pile and soil useosculating element to simulate and make use of Drucker-Prager elastoplastic model toreflect the constitutive relation of soil. Passes to select calculation parameter and triesto make its calculation convergen. The results found in finite element model are ingood agreement with those obtained in the theory, by optimizing parameters andmaking its calculation convergent.更多还原