【作者】 李滨；

【导师】 殷跃平；

【作者基本信息】 长安大学 ， 地质工程， 2009， 博士

【摘要】 多级旋转型黄土滑坡因其特殊性、递进性和复杂性成为我国黄土高原地区典型的滑坡灾害类型，本文在概要论述多级旋转滑坡国内外进展的基础上，依托国家科技支撑项目课题“特大型滑坡早期识别及空间预测研究”和中国地质调查局项目“陕西宝鸡地区地质灾害详细调查”，以陕西省宝鸡金台区和甘肃永靖黑方台多级旋转型黄土滑坡为例，采用遥感解译、野外调查、现场勘查、室内试验、数值模拟等方法，重点研究多级旋转型黄土滑坡的形成条件、基本特征、分布规律、破坏模式、成灾机理和稳定性评价，进而探索多级旋转型黄土滑坡风险评估预测方法。主要研究成果包括：(1)多级旋转滑坡多分布于河流和沟谷侵蚀强烈的黄土塬边地带，其形成条件包括：新构造运动、河流侧蚀作用、高陡斜坡结构和岩土特性；主要诱发因素包括：降雨、灌溉、地震以及季节性冻融作用，其中地下水的作用是最主要的影响因素。(2)典型多级旋转型黄土滑坡特征表现为：规模大、滑带深、3-5级滑面分层叠置、单个滑面成后缘高陡-中部平缓-前缘微翘的“犁式”结构特征；其变形破坏方式表现为：蠕滑-滑移-拉裂-块体滑动-旋转-逐级扩展，其扩展方式主要包括：扩展式旋转滑动、渐灭式旋转滑动和复合式旋转滑动。(3)对多级旋转滑坡的滑带地层上新世硬粘土进行综合试验研究。上新世硬粘土粘粒含量高，粘土矿物以蒙脱石或伊利石/蒙脱石混层矿物为主，有效蒙脱石含量比较高，因而具有很高的物理化学活性，这些特性成为硬粘土不良工程特性的基础，而硬粘土的的裂隙性、超固结性和膨胀性，加之层间剪切带的发育，是灾害发生的主要原因；无侧限抗压试验、直剪试验、三轴试验和流变试验结果显示，上新世硬粘土是一种硬土-软岩的过渡类型，其应力应变曲线呈强软化-软化型，呈脆性破坏，含水量对硬粘土的强度影响十分明显，峰值、残余强度间存在明显的差值，由加速蠕变到破坏蠕变时间短暂，因此滑坡发生时，突然损失的峰残差值形成下滑推力，导致滑体沿着滑床面瞬间剧烈滑动。(4)提出了多级旋转滑坡“最小滑坡稳定系数”和“分级叠加”的稳定性评价方法，利用Fellennius法、Bishop法和Sarma法，从滑坡前缘滑体开始依次向后进行叠加，进行块体组合分析，确定最危险滑动块体组合，同时根据稳定性的计算结果可以判断滑坡的运动形式。计算结果显示，Bishop法和Sarma法计算结果相对接近。(4)利用有限元强度折减法对多级旋转滑坡各个阶段的破坏演化过程进行数值计算分析，得到滑坡失稳及塑性区的发展过程，同时与“分级叠加”极限平衡法的计算结果对比耦合，认为实际工程中可以采用有限元强度折减法对多级旋转滑坡进行叠加计算。更多还原

【Abstract】 Multiple rotational landslide is the typical disaster type of landslide with its particularity, progressive and the complexity in loess plateau region. On the base of discoursing the progress of multiple rotational landslide in and abroad, relying on the national scientific supporting problem " Study on early identification and dimensional forecast of oversize landslide" and the China Geological Survey item "Geological disaster detailed survey of Baoji area in Shaanxi province", taking the example of the two multiple rotational loess landslide in Jintai district in Baoji City in Shaanxi province and in Heifangtai in Gansu province, by the research methodology of field survey, remote sense interpretation, scene investigation, laboratory test, numerical simulation, the paper studies formation condition, landslide feature, distribution regulation, failure modes, formative mechanism and stability analysis of multiple rotational loess landslides, and then researches the risk evaluation methods of multiple rotational loess landslides. The main results of research as follows:(1) Multiple rotational landslides distribute in river and valley where erosion strongly in loess plateau region zones. The formation factors including: Neotectonics, river lateral erosion, structure and geotechnical Characteristics of high sheer slope. The mainly inducing factors including: rainfall, irrigation, earthquake and freezing-thawing. The most important influent factor is the function of ground water.(2) The feature of typical multiple rotational loess landslides is: large scale, deep sliding face, three-five sliding face cascades, single landslide with the "plough" structural character of behind high and sheer-middle subdued-front tilt. The main formation mode of landslide is creeping-sliding-tensile fracturing. The failure modes contain extensive rotation sliding, digressive rotation sliding and compound rotation sliding.(3) Take the comprehensive test research on Pliocene hard clay of the multiple rotational landslides. As to Pliocene hard clays, the clay particle content is high, and montmorillonite or illite/montmorillonite turbostratic mineral is the dominating clay mineral. The content of effective montmorillonte is very high, which is the basis for the undesirable engineering properties of Pliocene hard clays, and main factors of disaster are obvious properties such as fissured, overconsolidated and expansive and seam-sheared zone; the result of unconfined compression test, direct shear test, triaxial test and rheological test shows that Pliocene hard clays is an intermediate type of the material between the hard soil and the soft rock, the stress-strain curve is strong-softening-softening type, brittle failure. The influence of water content is clearly to hard clay. There is an obvious difference between peak value and residual strength. There is a short space of time from accelerated creep to destroyed creep. Therefore, for landslide happens, the strength loss will generate the thrust, leading landslide sliding accelerated along the slide base.(4) Put forward the stability evaluation method of "least landslide stability coefficient" and "classification superposition" of multiple rotational landslides. By using the method of Fellennius, Bishop and Sarma, doing the superimposition from front landslide to back, analyzing block combination to make sure the most dangerous sliding block combination. At the same time, the landslide movement formation can be judged by the calculation result of stability. The result shows the calculation results of the method of Bishop and Sarma are relatively closed.(5) Using the finite element shear strength reduction method to analyze the calculation results of mass failure evolution during every phrase, to get the development process of slope instability and plastic zone. Meanwhile, contrasting the results with that of "classification superposition" limit equilibrium to make sure that we can superposition calculate the multiple rotational landslide by finite element by strength reduction in real project.更多还原