平凉市区泾河北岸黄土斜坡演化规律研究

发布时间：2018-01-26 21:44

本文关键词： 黄土斜坡坡体结构地质灾害演化规律　出处：《兰州大学》2017年硕士论文　论文类型：学位论文

【摘要】：在黄土高原地区,由于黄土分布范围大,沉积厚度深,土体结构疏松等特征,在内、外地质作用的改造下,黄土塬不断遭到侵蚀,塬边斜坡及冲沟两侧斜坡逐渐形成,在黄土斜坡逐级演化的过程中,伴随产生大量的黄土滑坡、崩塌、泥石流和黄土裂缝等各种地质灾害,严重制约了社会经济的发展。为此,本文选取平凉市崆峒区泾河北岸黄土斜坡为研究对象,基于黄土斜坡坡体结构概念,结合地质灾害的分布发育特征,对比数值模拟计算结果,展开黄土斜坡演化规律的研究,为黄土地区地质灾害的预防和治理提供参考。本文主要研究成果如下:(1)将研究区坡体结构类型从岩性组合方面分为纯黄土斜坡和黄土-基岩斜坡两大类型。其中,纯黄土斜坡根据接触面和临空条件的交切关系分为4小类,且纯黄土斜坡的主要分布在塬顶及塬边斜坡中上部;黄土-基岩斜坡根据下部基岩岩性组合特征与接触面特征分为4小类,其主要分布于塬边斜坡坡脚一带和冲沟中前部两岸斜坡下部。(2)研究区滑坡主要包括黄土层内滑坡和黄土-基岩接触面滑坡;崩塌包括黄土窑洞崩塌和自然斜坡崩塌,其中自然斜坡崩塌根据其崩塌特征分为倾倒式崩塌、悬臂梁式崩塌和下挫式崩塌。黄土层内滑坡主要分布于斜坡中上部及坡顶,黄土-基岩接触面滑坡主要分布于泾河北岸一带斜坡,黄土崩塌集中分布于塬边斜坡顶部和冲沟及支沟沟脑处斜坡。(3)将研究区黄土斜坡演化根据黄土斜坡形成过程分为河谷型黄土斜坡和冲沟型黄土斜坡,两类黄土斜坡演化具有相似的特征(即对称性、相似性和灾害伴生性)。黄土斜坡的演化过程主要是以滑坡和崩塌的形式逐级向塬内侵蚀,导致黄土斜坡高度逐渐降低,坡度逐渐减缓,在局部山梁处可形成鞍部地形。与数值模拟计算结果所表现出的黄土斜坡演化规律相同。
[Abstract]:In the Loess Plateau, because of the characteristics of loess distribution, deep sediment thickness, loose soil structure and so on, the loess plateau has been continuously eroded due to the transformation of external geological action. The slope on the edge of the plateau and the slope on both sides of the gully are gradually formed. During the gradual evolution of the loess slope, a large number of geological disasters such as loess landslide, collapse, debris flow and loess crack are produced. Therefore, the loess slope on the north bank of Jinghe River in Kongtong District of Pingliang City is chosen as the research object, based on the concept of slope structure of loess slope, combined with the distribution and development characteristics of geological hazards. Comparing with the results of numerical simulation, the evolution law of loess slope is studied. This paper provides a reference for the prevention and management of geological hazards in loess region. The main research results of this paper are as follows: 1). The structural types of slope body in the study area are divided into two types: pure loess slope and loess-bedrock slope from the aspect of lithologic combination. The pure loess slope is divided into 4 subgroups according to the intersecting relation between the contact surface and the condition of the face of the sky, and the pure loess slope is mainly distributed in the middle and upper part of the slope on the top of the tableland and the edge of the plateau. Loess-bedrock slopes can be divided into 4 subgroups according to the lithologic assemblage and contact features of the lower bedrock. The landslide in the study area mainly includes loess layer landslide and loess-bedrock interface landslide. Collapse includes loess cave collapse and natural slope collapse, in which natural slope collapse can be divided into toppling type according to its collapse characteristics. The landslide in the loess layer is mainly distributed in the middle and upper part of the slope and the top of the slope, and the loess-bedrock interface landslide is mainly distributed in the north bank of the Jinghe River. Loess collapse is concentrated on the top of the slope and the slope of gully and branch trench brain.) the loess slope evolution in the study area is divided into valley loess slope and gully loess slope according to the forming process of loess slope. The evolution of the two types of loess slopes has similar characteristics (i.e. symmetry, similarity and disaster concomitant). The evolution process of loess slopes is mainly in the form of landslides and collapses in the form of gradual erosion to the tableland. As a result, the height of loess slope gradually decreases, and the slope decreases gradually, and the saddle topography can be formed at the part of the mountain beam, which is the same as the evolution law of loess slope shown by the numerical simulation results.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.2

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