平凉市区泾河北岸崩塌特征与分布规律研究

发布时间：2018-04-26 23:34

本文选题：黄土 + 崩塌　；参考：《兰州大学》2017年硕士论文

【摘要】：崩塌是我国中西部常见的地质灾害之一。黄土崩塌主要分布于黄土高原地区,由于其单体规模相对较小,其危害往往被人们所忽视,但黄土崩塌在黄土高原地区广泛发育,且对黄土斜坡的稳定和演化有着不可忽略的作用。为此,本文以平凉市区泾河北岸为研究区,研究该区域崩塌灾害的分布发育特征及演化过程,并对拉裂-坠落式崩塌临界破坏条件加以研究。首先,通过调查平凉市区泾河北岸崩塌灾害,根据其物质组成和破坏模式对崩塌进行分类。崩塌的分布特征受到了地形地貌和地层岩性的控制,黄土崩塌较规模相对较小,广泛分布于调查区黄土塬边、冲沟两侧岸坡高陡之处;相较于黄土崩塌,黄土-基岩崩塌规模相对较大,分布在调查区冲沟沟口基岩出露的地方。其次,对崩塌的影响因素进行分析。崩塌的影响因素主要有:地形地貌、地层岩性、结构面、水的作用、风化作用、人类工程活动、根劈作用及楔劈作用。分析各个影响因素对崩塌的影响,并对崩塌的演化过程进行研究。最后,对拉裂-坠落式崩塌的临界破坏条件进行研究。黄土-基岩崩塌的破坏模式为拉裂-坠落式破坏,是由于底部泥岩遭受风化剥蚀形成空腔,空腔上部形成悬臂,随着底部泥岩进一步风化剥蚀,悬臂长度不断增加,当悬臂增加到一定长度时,基岩和上覆物质的重力在悬臂根部产生的拉应力将大于基岩的抗拉强度,此时基岩就会产生拉裂缝,随着拉裂缝不断发展,最终基岩和黄土将一起产生崩塌破坏。本文根据材料力学和弹塑性力学,归纳其力学模型,推导了悬臂临界长度的理论计算公式,并对理论公式的计算结果进行分析对比,结合崩塌实例对理论公式进行校验。
[Abstract]:Collapse is one of the common geological hazards in the Midwest of China. The collapse of loess is mainly distributed in the Loess Plateau area. Because of its relatively small size, its harm is often neglected by people, but the collapse of the loess is widely developed in the Loess Plateau area and has an unnegligible effect on the stability and evolution of the loess slope. The North Bank of the Jinghe River in cold urban area is the research area, studying the distribution development characteristics and evolution process of the collapse disaster in this area, and studying the critical failure conditions of the collapse and falling type collapse. First, by investigating the collapse of the northern shore of the Jinghe River in Pingliang, the collapse is classified according to its material composition and failure mode. The distribution characteristics of the collapse are subjected to the distribution characteristics of the collapse. The landform and formation lithology control, the loess collapse is relatively small, widely distributed in the Loess Tableland of the investigation area, the slope of the gully slope is high and steep, compared with the loess collapse, the Loess bedrock collapse scale is relatively large, distributed in the area of the gully gully base rock in the investigation area. Secondly, the influence factors of the collapse are analyzed. The main factors affecting the collapse are: topography, lithology, structure surface, water effect, weathering, human engineering activities, root splitting and wedge splitting. The impact of various factors on the collapse is analyzed and the evolution process of the collapse is studied. Finally, the critical conditions for the collapse and fall type collapse are studied. The failure mode of rock collapse is cracked and falling, because the bottom mudstone is weathered and denuded to form the cavity, and the cantilever is formed on the upper part of the cavity. With the further weathering and erosion of the bottom mudstone, the length of the cantilever increases continuously. When the cantilever is increased to a certain length, the tensile stress produced by the gravity of bedrock and overlying material at the root of the cantilever will be greater than that of the cantilever. The tensile strength of the bedrock will produce tensile cracks at this time. With the continuous development of the tensile cracks, the bedrock and the loess will eventually produce collapse and destruction together. In this paper, the mechanical model is summed up based on the mechanics of material and elastoplastic mechanics, the theoretical calculation of the critical length of the cantilever is derived, and the calculation results of the theoretical formula are analyzed and compared. The theoretical formula is checked with the case of collapse.

【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】：P642.21

【参考文献】