【作者】 唐正光；

【导师】 徐则民；

【作者基本信息】 昆明理工大学 ， 工程力学， 2013， 博士

【摘要】 本论文“降雨入渗影响因素与滑坡的研究”依托国家自然科学基金与云南省联合基金项目“植被发育斜坡对强降雨过程的地下水响应机制及其灾害效应”(U1033601)开展降雨入渗影响因子与滑坡的研究工作,通过检索、分析国内外最新相关研究成果,将地形地貌、植被及岩土介质孔隙特性作为影响降雨入渗转化为地下水的关键因素进行了研究,分析了多因素影响下的降雨入渗及地下渗流状况,并结合滑坡案例研究。研究过程中,以呈贡大学城马卡山、昭通头寨滑坡区等玄武岩及石灰岩斜坡,进行地形地貌、植被、土壤裂隙、滑坡等现场综合调查分析。开展室内试验：斜坡表层持水度试验及相应的指标测试；现场试验：原位渗透试验、染色渗透示踪试验及自然降雨入渗观察等。基于上述相关试验分析成果,应用MIDAS/GTS模块进行斜坡降雨渗流二维数值模拟分析。取得的主要研究成果如下：1、植被促进降雨入渗主要分为两个层次,植被根系层有效提高岩土体中大空隙的数量和规模,植被叶冠层改善了岩土体的降雨入渗环境。植被与土体作用形成的根系通道、变形裂隙、干裂隙、动物通道及结构性孔隙等相对稳定的大空隙是降雨入渗的快速通道,提高了土体渗透能力,但主要集中于地表层一定深度范围内。2、斜坡表层土壤的结构性孔隙的决定性因素为母质因素及风化成土环境,土壤结构性孔隙对降雨入渗的影响显著,在降雨对斜坡的影响分析中,应作为关键因素。3、土体干缩裂隙发育分布特征：(1).影响岩土体干缩裂隙发育的主要因素：土体含水量、土壤粒径级配、土层干湿循环次数。(2).植被根系形成的土层团粒结构、根系在土中加筋的作用及植被叶冠层改散了表层土的小气候环境,影响了表层土干缩裂隙的发育。(3).根据断裂力学及土中应力的理论,土壤干缩裂隙呈垂直向下的、有一定深度范围的分布,深度取决于土壤干缩裂隙发育环境及土壤特性,土壤干缩裂隙为降雨入渗提供了优先流通道,但它提供的降雨入渗优先流影响范围是有限的。4、土体张拉裂隙的贯通性较好,且张拉裂隙的尺度较大,可直接深入到岩土体的内部,是降雨进入较深度岩土体内部的优先流通道,张拉裂隙对降雨入渗的影响是显著的。5、在有一定坡度的坡面降雨入渗过程中,存在下渗的水沿坡向的侧向渗流。侧向渗流的大小与坡度i、分层厚度h及各层的渗透系数k等有较大的关系。不同的地质剖面,有不同的渗透结构层组合,降雨入渗的效果也不同。对于整体斜坡而言,在有相同剖面的斜坡的不同位置(从坡上部到坡下部),由于侧向渗流的影响,其地表层土壤的含水量存在差异,导致地表层渗透系数及降雨入渗也有差异。6、降雨在斜坡表层的入渗深度及入渗量,一方面取决于降雨过程,另一方面则取决于地表渗透层的结构组合及渗透影响因子。渗透影响因子包括多方面的,而地形地貌、植被对入渗过程的影响较大。7、通过渗流计算验证：地形因素影响地下水流分布：岩土层渗透性能分层组合影响地下水流分布8、滑坡灾害的发生与其内因和外因有密切相关,往往是各种因素综合的结果。滑坡的发生需要一定的地形条件,在有一定坡度的斜坡上,除有特别的降雨入渗快速通道(如张拉裂隙)外,单次降雨过程的入渗量和入渗深度是有一定范围的,故降雨对斜坡的影响主要还是浅表层的地质灾害,如浅层滑坡、泥石流等。对于大型深层滑坡,滑坡的发生主要受控于其他原因的长期孕育过程,降雨只是滑坡孕育到一定时候的催化剂。研究成果不仅可以为斜坡灾害的预报-预警提供更为清晰的理论支撑,而且对于降雨诱发滑坡及其灾害防治也是重要的。更多还原

【Abstract】 The dissertation "Research into factors affecting rainfall infiltration and landslide", based on the project of "The effect of groundwater from strong rainfall on slope with vegetation and corresponding response mechanism"(U1033601) sponsored by YunNan-NSFC is intended to look into the factors to affect rainfall infiltration and landslide cases. Focusing on the primary factors such as vegetations and holes in soil and rock that affect rainfall infiltration, It analyzed a host of ingredients that have effect on rainfall infiltration and groundwater seepage in combination with up to date researches done at home and abroad.Taking the following slopes for field study:the basalt slopes of the Maqia-hill in Chenggong college town and Touzhai village in the city Zhaotong, the author has conducted a series of surveys and experiments, such as carrying out field studies on landform, vegetations, holes in soil and rock and slope locale, conducting indoor tests; test of water keeping for the surface of the slopes; locale tests:locale infiltration test, infiltration-trace test, rainfall infiltration observation. Based on the proceeding surveys and experiments, a two-dimensional numerical analysis can be made on slope seepage in terms of MIDAS/GTS.The mainly findings obtained are as follows:l.The contributions of vegetation to rainfall infiltration can be seen on two levels, on the one hand the roots of vegetation greatly increased the number and space of holes in soil and rock located at top layer of the earth’s surface; on the other hand leaves and crown of trees reform also facilitate rainfall infiltration. The channels from root, crannies from the transfiguration and shrinkage of soil and rock, the channel for insects, structural holes in soil and rock...etc. constitute channel of rainfall infiltration and enhance ability of soil and rock to suck in rainfall. But they are located in top layer of the earth’s surface.2.Rock and it’s rotten condition are decisive factors to form structural holes in soil and rock, Structural holes in soil and rock make a great difference to rainfall infiltration, and should be, therefore regarded as key factors in the analysis of the impact of rainfall lead on slopes.3. The characteristics of crannies from shrinkage in soil:(1). The key factors working on crannies from shrinkage in soil are the amount of water in soil、size of soil granules、cycling times from being dry to wet of the soil.(2).A11the chunks of soil formed at the roots、reinforcing effect of roots on soil, together with leaves and crowns help to develop a favorable microclimate to maintain dewiness in vegetation to inhibit the growth of crannies from shrinkage in soil.(3). According to rupture mechanics and stress in soil, the crannies from shrinkage in soil spread downwards and their depth depends on the environment and characteristics of soil. The crannies from shrinkage in soil offer preferential channel for rainfall to infiltrate, but the amount of water infiltrated is limited.4. The crannies from tensile force in soil and rock are large in diameter and go deep down into the interior of soil and rock, which serve as the preferential effective channel for rainfall to in filtrate.5. Some of the may sink along the gradient cover of slope in the process of rainfall infiltration, the amount of which depends on gradient、thickness of seep-layer, modulus of seepage...etc, The diverse geologic sections have different compages of seep-layer with divergent effect on rainfall infiltration. As a result, there are different in the amount of water in soil、modulus of seepage and rainfall infiltration at different positions across the slope(from top to bottom).6. The depth and amount of rainfall to penetrate the cover of the slope have to do with the process of rainfall, the compages of seep-layer and the factors working on infiltration which is omnifarious with hypsography and vegetation as the primary elements.7. As a result of planar numerical calculate simulated seepage of slope, the hypsography and compages of seep-layer can affect the flow of ground-water from rainfall.8. Landslide is a function of a multitude of factors such as interior factors and exterior factors, It has much to with hypsography. At certain level of the slope, unless there are channel for swift rainfall infiltration, the depth and amount of infiltration in a single rainfall is limited, with the result that the effect of rainfall on slope is mainly confined to geological hazards to surface of the slope of the surface of the slope, debris flows. The large-scale landslide at deeper levels is a consequence of long-term gestation of other factors, with the rainfall as activator.These findings can offer academic support for forecast of landslide, and is significant for the prevention and treatment of landslide induced by rainfall.更多还原