干湿循环下变坡比膨胀土边坡渗流及稳定性分析
发布时间：2019-05-18 10:40
【摘要】：膨胀土是一种吸水膨胀、失水收缩的高塑性粘土,具有超固结性、多裂隙性等不良工程特性。膨胀土边坡易受气候变化的影响,其降雨蒸发干湿循环效应显著,大量的膨胀土边坡失稳是发生在降雨期间或者降雨之后,其治理难度大。在降雨蒸发过程中,对于遇水极为敏感且渗透性极低的膨胀土边坡而言,膨胀土的密度和结构在局部范围内发生变化。而体积含水率的分布变化在降雨蒸发过程中能被最直接的反映出来,也是反映土体强度的最直接的物理量。本文通过室内试验、理论分析与数值模拟相结合的方法,建立了土柱模型、不同坡比的膨胀土边坡模型,旨在探讨降雨蒸发干湿循环对土柱和边坡土体内部体积含水率分布的影响。本文主要研究工作及成果概括如下:(1)在蒸发阶段,土柱表层土体水分消散的较快,随着土体埋深增大,水分消散的越慢,并且呈现一定的规律性。在降雨阶段,不同的降雨强度对土柱内部体积含水率分布的影响也不同,在一定范围内,降雨强度越大,其影响越明显;而超过一定范围,随着降雨强度增大,其影响是有限的。(2)蒸发效应的敏感性分析,主要考虑气候条件对蒸发的影响。结果表明,净辐射量、风速和最大相对温度对土体蒸发的影响较大,尤其以净辐射量和最大相对温度对蒸发的影响最为显著。(3)在降雨蒸发干湿循环条件下,膨胀土边坡的不同部位的干湿效果不同,坡顶的干湿循环效果最为明显,其次是坡中和坡脚。用nz wwwe????max0???曲线方程可以很好地描述膨胀土边坡的水分空间分布特性及变化规律,在此基础上提出了考虑降雨蒸发条件下以土体埋深为变量的膨胀土边坡土体强度关系式,即强度~体积含水量~埋深的关系式。(4)通过不同坡比的膨胀土边坡渗流分析,发现坡比不同,降雨对边坡整个渗流场的影响也不同。坡比的差异性在降雨初期和后期表现的较为明显,坡比越小,水分分布梯度越大,且具有显著的降雨滞后效应。(5)根据强度~体积含水率~埋深关系式,对膨胀土边坡进行了强度分层,强度分层的边坡稳定性要高于不分层的边坡稳定性。边坡稳定性受坡比的影响强烈,对于某特定的气候环境和土性参数,在一定范围内,存在一个最优坡比,边坡安全系数取极大值。
[Abstract]:Expansive soil is a kind of high plastic clay with water absorption and expansion and water loss and shrinkage, which has some bad engineering characteristics, such as overconsolidation, multiple cracks and so on. Expansive soil slope is easily affected by climate change, and its dry and wet cycle effect of rainfall evaporation is remarkable. A large number of expansive soil slope instability occurs during or after rainfall, so it is difficult to control it. In the process of rainfall evaporation, the density and structure of expansive soil change in local range for expansive soil slope, which is very sensitive to water and has low permeability. The distribution of volume moisture content can be reflected most directly in the process of rainfall evaporation, and it is also the most direct physical quantity reflecting the strength of soil. In this paper, the soil column model and expansive soil slope model with different slope ratios are established by means of laboratory test, theoretical analysis and numerical simulation. The purpose of this paper is to investigate the effect of rainfall evaporation dry and wet cycle on the distribution of volume moisture content in soil columns and slopes. The main research work and results of this paper are summarized as follows: (1) in the evaporation stage, the water dissipation of the surface soil of the soil column is faster, and with the increase of the buried depth of the soil, the slower the water dissipation, and presents a certain regularity. In the rainfall stage, the influence of different rainfall intensity on the distribution of volume moisture content in soil column is also different. In a certain range, the greater the rainfall intensity is, the more obvious the influence is. Over a certain range, with the increase of rainfall intensity, the influence is limited. (2) the sensitivity analysis of evaporation effect mainly considers the influence of climatic conditions on evaporation. The results show that the net radiation, wind speed and maximum relative temperature have great influence on soil evaporation, especially the net radiation and maximum relative temperature have the most significant effect on evaporation. (3) under the condition of dry and wet cycle of rainfall evaporation, The dry and wet effects of different parts of expansive soil slope are different, and the effect of dry and wet cycle on the top of the slope is the most obvious, followed by the neutralization of the slope and the foot of the slope. Using nz wwwe?max0? The curve equation can well describe the spatial distribution characteristics and variation law of water on expansive soil slope. On this basis, the relationship between soil strength of expansive soil slope considering rainfall evaporation and soil depth as variable is put forward. That is, the relationship between strength, volume water content and buried depth. (4) through the seepage analysis of expansive soil slope with different slope ratio, it is found that the influence of rainfall on the whole seepage field of slope is also different when the slope ratio is different. The difference of slope ratio is obvious in the early and late stages of rainfall. The smaller the slope ratio is, the greater the gradient of water distribution is, and has a significant rainfall lag effect. (5) according to the relationship between intensity, volume moisture content and buried depth, The strength stratification of expansive soil slope is carried out, and the slope stability of strength stratification is higher than that of unlayered slope. Slope stability is strongly affected by slope ratio. For a specific climate environment and soil parameters, there is an optimal slope ratio in a certain range, and the slope safety factor is maximized.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU443
本文编号：2479927
[Abstract]:Expansive soil is a kind of high plastic clay with water absorption and expansion and water loss and shrinkage, which has some bad engineering characteristics, such as overconsolidation, multiple cracks and so on. Expansive soil slope is easily affected by climate change, and its dry and wet cycle effect of rainfall evaporation is remarkable. A large number of expansive soil slope instability occurs during or after rainfall, so it is difficult to control it. In the process of rainfall evaporation, the density and structure of expansive soil change in local range for expansive soil slope, which is very sensitive to water and has low permeability. The distribution of volume moisture content can be reflected most directly in the process of rainfall evaporation, and it is also the most direct physical quantity reflecting the strength of soil. In this paper, the soil column model and expansive soil slope model with different slope ratios are established by means of laboratory test, theoretical analysis and numerical simulation. The purpose of this paper is to investigate the effect of rainfall evaporation dry and wet cycle on the distribution of volume moisture content in soil columns and slopes. The main research work and results of this paper are summarized as follows: (1) in the evaporation stage, the water dissipation of the surface soil of the soil column is faster, and with the increase of the buried depth of the soil, the slower the water dissipation, and presents a certain regularity. In the rainfall stage, the influence of different rainfall intensity on the distribution of volume moisture content in soil column is also different. In a certain range, the greater the rainfall intensity is, the more obvious the influence is. Over a certain range, with the increase of rainfall intensity, the influence is limited. (2) the sensitivity analysis of evaporation effect mainly considers the influence of climatic conditions on evaporation. The results show that the net radiation, wind speed and maximum relative temperature have great influence on soil evaporation, especially the net radiation and maximum relative temperature have the most significant effect on evaporation. (3) under the condition of dry and wet cycle of rainfall evaporation, The dry and wet effects of different parts of expansive soil slope are different, and the effect of dry and wet cycle on the top of the slope is the most obvious, followed by the neutralization of the slope and the foot of the slope. Using nz wwwe?max0? The curve equation can well describe the spatial distribution characteristics and variation law of water on expansive soil slope. On this basis, the relationship between soil strength of expansive soil slope considering rainfall evaporation and soil depth as variable is put forward. That is, the relationship between strength, volume water content and buried depth. (4) through the seepage analysis of expansive soil slope with different slope ratio, it is found that the influence of rainfall on the whole seepage field of slope is also different when the slope ratio is different. The difference of slope ratio is obvious in the early and late stages of rainfall. The smaller the slope ratio is, the greater the gradient of water distribution is, and has a significant rainfall lag effect. (5) according to the relationship between intensity, volume moisture content and buried depth, The strength stratification of expansive soil slope is carried out, and the slope stability of strength stratification is higher than that of unlayered slope. Slope stability is strongly affected by slope ratio. For a specific climate environment and soil parameters, there is an optimal slope ratio in a certain range, and the slope safety factor is maximized.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU443
【参考文献】
相关期刊论文 前3条
1 包承纲;非饱和土的性状及膨胀土边坡稳定问题[J];岩土工程学报;2004年01期
2 陈建斌;孔令伟;赵艳林;吕海波;;非饱和土的蒸发效应与影响因素分析[J];岩土力学;2007年01期
3 杨洋;姚海林;卢正;;蒸发条件下路基对气候变化的响应模型及影响因素分析[J];岩土力学;2009年05期
，本文编号：2479927
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