黄土崩塌形成机理及其稳定性计算方法

发布时间：2018-05-11 06:50

本文选题：黄土崩塌 + 影响因素　；参考：《贵州大学》2017年硕士论文

【摘要】：黄土是干旱半干旱地区由风力搬运堆积的一种第四系沉积物,具有非饱和、多孔隙、弱胶结等特征。中国黄土分布面积广,厚度大,堪称世界之冠。山西省位于黄河中游的东岸,华北平原的西部,是黄土广泛覆盖的山地高原,地形高度变化大,地质构造条件复杂。随着山西省经济的快速发展,矿山开采、切坡建房、耕地开垦、公路及铁路建设等人类工程活动愈加频繁,致使黄土崩塌地质灾害频繁发生,不同程度威胁着人民的生命和财产安全。本文以山西省黄土崩塌地质灾害调查为依托,获取了194处崩塌的数据资料,基于对这些资料的统计分析,总结了山西省黄土崩塌的内因及外因,并重点讨论了黄土性质、黄土斜坡形态(坡型、坡度、坡高及坡向)、降雨、冻融及人类工程活动对崩塌的影响,揭示了黄土崩塌的发育规律。结合已有研究,并通过野外实地调查,将山西省的黄土崩塌破坏模式归纳为:剥落式、滑移式、坠落式、倾倒式、错落式及冒落式。本文分别总结了这六种黄土崩塌破坏模式的形成机理及发育特征,并找到与之相对应的崩塌实例,对其发育过程进行了分析。基于野外调查的数据,总结了黄土崩塌后壁的张裂隙及剪出口的宽度、深度、延伸方向等与崩塌类型、发育阶段及规模大小的关系,总结了相关规律,对黄土崩塌形貌特征有了更深刻的认识。针对山西省发生数量最多的倾倒式崩塌和滑移式崩塌,分别进行了稳定性计算公式的推导。对每种崩塌自身的破坏模式,考虑崩塌后壁垂直与倾斜两种情况,兼顾水压力对斜坡的影响,分别建立力矩平衡和受力平衡方程,求解对应的最小安全系数。运用ADINA软件,对最大剪应力、最小主应力及水平位移进行有限元分析,模拟了黄土斜坡从节理发育到崩塌发生的整个过程中应力及水平位移的变化,展示了黄土崩塌的形成机理。
[Abstract]:Loess is a kind of Quaternary sediment transported and accumulated by wind in arid and semi-arid area, which has the characteristics of unsaturated, porous and weak cementation. Loess in China is the largest in the world because of its wide distribution area and large thickness. Shanxi Province is located on the east bank of the middle reaches of the Yellow River and the west of the North China Plain. With the rapid economic development of Shanxi Province, human engineering activities such as mining, sloping construction, cultivated land reclamation, highway and railway construction and other human engineering activities have become more frequent, resulting in frequent geological disasters of loess collapse. To some extent, it threatens the life and property of the people. Based on the investigation of geological hazards of loess collapse in Shanxi Province, the data of 194 collapses are obtained in this paper. Based on the statistical analysis of these data, the internal and external causes of loess collapse in Shanxi Province are summarized, and the properties of loess are emphatically discussed. The shape of loess slope (slope type, slope degree, slope height and slope direction), rainfall, freeze-thaw and human engineering activities influence the collapse, which reveals the development law of loess collapse. Combined with the existing research and field investigation, the failure modes of loess collapse in Shanxi Province are summed up as spalling, sliding, falling, toppling, dislocation and falling. In this paper, the formation mechanism and development characteristics of the six kinds of loess collapse failure modes are summarized, and the corresponding collapse examples are found, and the development process is analyzed. Based on the data of field investigation, the relationship between the width, depth, extension direction and the type, development stage and size of the fracture and shear outlet of the loess collapse is summarized, and the relevant rules are summarized. A deeper understanding of the topographic features of loess collapses has been obtained. The formula of stability calculation is derived for the toppling collapse and slip collapse in Shanxi Province. For each failure mode, considering the vertical and inclined back wall of collapse, considering the influence of water pressure on slope, the equations of moment balance and force balance are established, and the corresponding minimum safety factor is solved. Using ADINA software, the finite element analysis of maximum shear stress, minimum principal stress and horizontal displacement is carried out, and the change of stress and horizontal displacement during the whole process of loess slope from joint development to collapse is simulated. The formation mechanism of loess collapse is demonstrated.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.21

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