压实黄土增湿特性及数值模拟研究

发布时间：2018-06-15 10:36

本文选题：压实黄土 + 增湿　；参考：《兰州大学》2015年硕士论文

【摘要】：随着西部经济的快速发展,压实黄土广泛应用地基、路堤等工程中,由于管沟渗水、降雨入渗和地下水位的变化等原因,地基或路堤中压实黄土由于增湿,含水量常常会沿宽度和深度方向会发生一定的变化,造成地基或路堤过大的不均匀沉降,从而危害工程的安全。目前,大部分学者所研究的黄土湿陷问题,主要是关于原状黄土饱和浸水后的湿陷变形和强度问题,而对压实黄土增湿到某一含水量的情况研究相对较少,对青海地区压实黄土研究资料更少,基于此,本文以青海黄土为研究对象,采用固结压缩试验和直剪试验,设计五种干密度为分别1.4g/cm3、1.5g/cm3、1.6g/cm3、1.7g/cm3、1.8g/cm3,每种干密度分别设计10%、13%、15%、18%、20%的五种增湿含水量的压实黄土进行研究,获得了含水量w和干密度ρd对试样强度和变形特性的影响,结果表明：压实黄土含水量w一定,干密度ρd增大,试样的压缩模量Es增大；干密度ρd一定时,含水量w增加,试样的压缩模量Es呈指数函数Es=aebw形式减小。压实黄土干密度ρd相同,当含水量w增加,试样的粘聚力c呈指数函数c=aebw的形式减小,而内摩擦角φ呈一次函数φ=aw+b的形式而减小；压实黄土含水量w相同,当干密度岛增大时,试样的内摩擦角φ一直少量增加,而粘聚力c增大较快且幅度逐渐变大,可以用指数函数c=aebρd来表示变化规律。根据固结试验和直剪试验获得变形参数和强度参数,采用FLAC3D软件模拟管沟小量渗水,引起黄土地基的增湿变形,结果表明：对不同干密度的压实黄土地基,在渗水导致的增湿范围内,沉降值变化幅度较大,超增湿范围后,沉降值变化的幅度较小；当干密度小于1.60g/cm3时,提高干密度,可以显著消弱黄土地基由于渗水增湿产生的沉降值和沉降差,当干密度大于等于1.60g/cm3,提高干密度,消弱效果不明显。
[Abstract]:With the rapid development of western economy, compacted loess is widely used in foundation, embankment and other engineering, because of the seepage of pipe ditch, rainfall infiltration and the change of groundwater level, the compacted loess in foundation or embankment is due to humidification. The water content will often change along the width and depth of the embankment, resulting in uneven settlement of the foundation or embankment, thus endangering the safety of the project. At present, the problem of loess collapsibility studied by most scholars is mainly about the collapsing deformation and strength after saturated soaking of undisturbed loess, but the research on the situation of compacted loess humidifying to a certain water content is relatively few. The research data of compacted loess in Qinghai area are less. Based on this, the consolidation compression test and direct shear test are adopted in this paper, taking Qinghai loess as the research object. Five dry densities of 1.4 g / cm ~ 3 / 1.5 g / cm ~ 3 ~ 1.6 g / cm ~ (3) ~ 1.7 g / cm ~ (3) and 1.8 g / cm ~ (3) were designed respectively. The effects of water content w and dry density 蟻 _ d on the strength and deformation properties of specimens were obtained. The results show that when the moisture content of compacted loess is constant, the dry density 蟻 _ d increases, the compression modulus es increases, and when the dry density 蟻 _ d increases, the compression modulus es decreases in the form of exponential function Esaebw. The dry density 蟻 d of compacted loess is the same. When the water content w increases, the cohesive force c decreases in the form of exponential function c=aebw, while the internal friction angle 蠁 decreases in the form of primary function 蠁 aw b, and the moisture content of compacted loess is the same. When the dry density island increases, the internal friction angle 蠁 increases slightly, while the cohesive force c increases rapidly and the amplitude increases gradually, which can be expressed by the exponential function c=aeb 蟻 d. According to consolidation test and direct shear test, deformation parameters and strength parameters are obtained. FLAC3D software is used to simulate the small amount of water seepage in pipe trenches, which results in humidification deformation of loess foundation. The results show that: for different dry density compacted loess foundation, In the range of humidification caused by water infiltration, the variation of sedimentation value is larger than that of superhumidification range, and when dry density is less than 1.60g/cm3, the dry density is increased. The settlement value and settlement difference of loess foundation caused by water infiltration and humidification can be significantly reduced. When the dry density is greater than or equal to 1.60 g / cm ~ (3), the dry density can be increased, but the effect of weakening is not obvious.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.131

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