地震荷载下川西崩坡积混合土动变形特性的粗颗粒效应研究

发布时间：2018-12-07 12:53

【摘要】：川西山区滑坡区域多存在一种特有的崩坡积混合土,由其构成的天然边坡常因地震荷载导致变形或滑动,造成巨大损失。本文针对川西山区河谷及沟谷斜坡的典型崩坡积混合土,突出粗颗粒含量差异这一特征,通过大型动三轴等实验手段,研究在小应变范围内,循环荷载作用下,粗颗粒含量、固结围压对动变形特性(动剪切模量、阻尼比)影响规律。通过试验研究和理论分析,本文取得主要成果及结论如下:首先,对取自同一滑坡上三个不同坡高滑坡点的崩坡积混合土进行了物理性质试验,包括矿物成分鉴定、天然含水率、天然密度、土颗粒级配试验等。矿物成分鉴定显示三种土的原生矿物成分含量相似,都以亲水性较弱的石英和斜长石含量最高,而亲水性较强的黏土成分(蒙脱石等)占少数,因此可以认为是同一土类,具有相似性质。颗粒级配曲线显示三种土大于5mm的粗颗粒含量存在明显差异。其次,通过大型动三轴试验分析研究了粗颗粒含量和围压对川西崩坡积混合土动力特性的影响效应。运用Mathematica数据处理软件根据Hardin-Drnevich双曲线模型对试验数据进行拟合,得到G_d/G_(max)～γ_d和λ～γ_d等曲线。根据拟合曲线理论分析粗颗粒含量和围压对川西混合土的动剪切模量和阻尼比的影响,重点研究了粗颗粒含量这一影响因素。发现随着粗颗粒含量的增加和围压的升高,动剪模量和阻尼比都有一定程度的提高。另外,汇总试验数据绘制动剪切模量Gd和阻尼比λ随粗颗粒含量的变化关系图,发现川西崩坡积混合土在不同的粗颗粒含量区间下各土样的最大动剪模量和最大阻尼比增长趋势有所差异,总体上两者的增长趋势表现出现由低到高再降低的特点。最后,拟合川西崩坡积混合土的动三轴试验数据获得了各土样的动剪模量比函数G_d/G_(max)=G_d/G_(max)(γ_d)和阻尼比函数λ=λ(γ_d)中的各参数值。
[Abstract]:There is a special mixed soil in landslide area in western Sichuan mountainous area. The natural slope formed by it is often deformed or sliding due to earthquake load, resulting in huge losses. In view of the typical sloping mixed soil of valley and gully slope in western Sichuan mountain area, the difference of coarse particle content is highlighted in this paper. By means of large dynamic triaxial experiments, the coarse particle content in small strain range and under cyclic load is studied. The effect of consolidation confining pressure on dynamic deformation characteristics (dynamic shear modulus, damping ratio). Through experimental research and theoretical analysis, the main achievements and conclusions are as follows: firstly, the physical properties of sloping mixed soil from three different slope height landslide points on the same landslide are tested, including the identification of mineral composition. Natural moisture content, natural density, soil particle gradation test, etc. The mineral compositions of the three soils were similar, and the hydrophilic quartz and plagioclase had the highest content, while the hydrophilic clay (montmorillonite, etc.) was the minority, so they could be considered as the same soil. Have similar property. The particle gradation curve showed that the coarse particle content of the three soils was higher than that of 5mm. Secondly, the effect of coarse particle content and confining pressure on the dynamic characteristics of mixed soil in caving slope of western Sichuan was studied by large-scale dynamic triaxial test. Using Mathematica data processing software to fit the test data according to Hardin-Drnevich hyperbolic model, the Gd / G _ (max) ~ 纬 _ d and 位 ~ 纬 _ d curves are obtained. Based on the fitting curve theory, the effects of coarse particle content and confining pressure on the dynamic shear modulus and damping ratio of mixed soil in western Sichuan were analyzed. It is found that the dynamic shear modulus and damping ratio increase to some extent with the increase of coarse particle content and confining pressure. In addition, the dynamic shear modulus (Gd) and damping ratio (位) are plotted according to the experimental data. It is found that the increasing trend of the maximum dynamic shear modulus and the maximum damping ratio of each soil sample under different coarse particle content ranges of caving slope product mixed soil in western Sichuan are different, and the growth trend of the two soils shows the characteristics of decreasing from low to high on the whole. Finally, by fitting the dynamic triaxial test data of sloping mixed soil in western Sichuan, the parameters of the dynamic shear modulus ratio function Gd / G _ (max) = Gd / G _ (max) (纬 _ d and damping ratio function 位 = 位 (纬 _ d) of each soil sample are obtained.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.9;TU435

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