【作者】 刘平；

【导师】 郑健龙；

【作者基本信息】 长沙理工大学 ， 道路与铁道工程， 2007， 硕士

【摘要】 膨胀土是一种具有胀缩性、裂隙性和超固结性的特殊粘土,随着高等级公路的大量修建,膨胀土对公路的危害和破坏日渐增多。在公路工程中,降雨引起的膨胀土边坡滑坡是最常见和破坏最严重的工程问题。了解降雨入渗引起膨胀土边坡内部渗流场的变化规律,以及裂隙对膨胀土边坡渗流场的影响,为研究膨胀土边坡浅层滑动的内在机制、提高边坡设计水平,以及预防和治理滑坡灾害提供理论依据。本文结合南友路一典型膨胀土路堑边坡,通过室内试验了解膨胀土的渗透特性,采用ANSYS分析软件对考虑的膨胀土土体进行降雨条件下渗流分析,了解两种情况下边坡内部渗流场分布的变化规律,研究主要内容如下:1)对全国典型膨胀土地区的膨胀土试样在室内进行土水特征曲线、收缩试验和饱和渗透试验,对膨胀土土水特征曲线的特征和影响因素进行归纳总结。采用土水特征曲线间接预测渗透系数的方法,获得了灰白色、灰黑色膨胀土和河南邓县膨胀土不同体积含水量下的渗透系数,并对两者关系曲线进行对数模型拟合,拟合效果很好。2)采用ANSYS分析软件,模拟降雨条件下,考虑裂隙与不考虑裂隙的膨胀土土体内部渗流场的分布情况,对两种情况下渗流结果进行对比分析,分析结果表明,对于渗透性极差的膨胀土而言,在进行渗流分析时,必须考虑裂隙对渗流场的影响。3)结合实际工程中的膨胀土边坡,在边坡的不同位置设置主裂隙,模拟降雨条件下,存在裂隙的膨胀土边坡内部渗流场分布情况,通过对不同降雨持时边坡内压力水头分布进行分析,分析结果表明:裂隙的存在是诱发膨胀土边坡浅层滑动的关键因素。更多还原

【Abstract】 Expansive soil is a kind of special clays featured with the Swell-Shrinking characteristic, fissure character and over-consolidation. With the constructions of a great number of high-grade expressways, the hazards and damages of expansive soils to highways become more and more. Especially in highway engineering, rainfall causes expansion soil slope’s landslide, which is the most common and most serious engineering problem. Comprehending rainfall infiltration causes variation law of seepage flow fields in expansive soils’slopes, and the influence of fissures to seepage flow fields in expansive soils’slopes, provide theoretical foundation for researching the inherent mechanism of shallow sliding of expansive soil slopes, improving slope design level, and preventing and treating lanslides’hazards.Combined with a expansive soil slope in Nanyou Expressway, understand permeability of expansive soils through laboratory tests, carry out seepage analysis of expansive soils featured with fissures on the condition of rainfall using ANSYS analysis software, comprehend change law of seepage flow fields’distribution in slopes’inner, the main research contents are as follows:1)Through laboratory soil - water characteristic curve (SWCC) test,shrinkage test and saturated permeating test for expansive soil samples from typical expansive soil districts all over China, and summarize SWCC for expansive soil character and influencing factors. By adopting soil-water characteristic curve to predict coefficient of permeability indirectly, get osmotic coefficient in different water content of hoar, grey dark expansive soil and expansive soil in Deng Town of Henan. Then adopt logarithmic model to fit the relation of their SWCC, and the fitting effect is rather good.2)Using ANSYS software,simulate rainfall condition, research seepage flow fields’distribution in slopes’inner with fissures and without fissures, by comparative analysis about seepage results of two conditions,analytical results indicate that the influence of fissures to seepage flow fields must be considered for expansive soil with very small penetrability when carrying out seepage analysis.3)Combined with expansive soil slopes in practical engineering, set master fractures at different positions,simulate rainfall condition, research seepage flow fields’distributing situation in slopes’inner with fissures. The analytical results of total pressure water head’s distribution in slope through different rainfall time show that the existence of fissures and cracks is the main factor that causes expansive soil shallow landslides.更多还原