【作者】 李兵；

【导师】 刘高；

【作者基本信息】 兰州大学 ， 地质工程， 2018， 硕士

【摘要】 黄土台塬斜坡段地质灾害的发育,严重威胁当地的公路、工厂等公共设施及居民人身安全;由于研究的不足以及治理难度较大,黑方台地区地质灾害一直是当地亟待解决的大事。据此,本文以野狐沟两岸斜坡为研究对象,充分利用研究区区域地质资料,运用地质演化过程分析、数值计算分析、多期地球影像分析和室内实验等多种分析方法结合,对野狐沟两岸斜坡的变形破坏方式、机理及野狐沟的整体演化方式进行研究,取得了初步的成果,对黄土沟谷演化及其过程中伴生的地质灾害的防治具有重要的参考意义。主要结论如下:(1)通过分析发现野狐沟两岸斜坡地层接触面对斜坡变形的影响可以忽略,而基岩的产状更为重要。通过基岩的产状与临空面的交切关系,将野狐沟两岸斜坡坡体结构类型分为两大类四小类;左岸为顺向型,右岸为反向型。(2)两岸斜坡变形特征呈现差异性的原因在于两岸坡体结构的不同,通过对比斜坡的坡体结构类型和斜坡的变形破坏特征,发现二者存在联系;基岩的产状对于斜坡的稳定性影响很大,顺向坡较反向坡易发生变形破坏;左岸为顺向型,因此变形以滑坡为主,右岸为反向型,斜坡变形以崩塌为主。(3)野狐沟左岸斜坡变形特征在纵向上呈现出规律性,变形类型依次为黄土-基岩滑坡、黄土-粉质粘土滑坡、纯黄土滑坡。这种变化与基岩出露厚度有关。基岩未出露的纯黄土斜坡稳定性好,其变形破坏过程缓慢,基岩出露厚度较大时,斜坡稳定性很差,上部土体容易在基岩的带动下,被拉裂从而发生破坏。通过数值计算分析,发现基岩在水的作用下软化发生塑性流动加剧了野狐沟左岸斜坡变形破坏。(4)野狐沟的演化存在多种模式,其中两岸斜坡演化从而改变沟宽是最主要的演变方式;在沟宽的演化过中,滑坡是最显著和演化速度最快的一种方式。(5)野狐沟左右岸的演化存在差异性,左岸演化速度明显大于右岸;出现差异的原因在于坡体结构的不同。更多还原

【Abstract】 The development of geological disasters on the loess slope section of the loess platform severely threatens local roads,factories and other public facilities and residents’ personal safety.Due to the lack of research and the difficulty of control,geological disasters in the Hei Fangtai area have always been a major issue to be resolved.Based on this,this paper takes the slopes of both sides of the Yehu valley as the research object,makes full use of the regional geological data,and uses geological analysis of the evolution process,numerical calculation and analysis,multi-period earth image analysis,indoor experiments and other analysis methods combined to make a study on deformation failure modes and mechanisms of the slopes on both sides and the overall evolution of Yehu valley.And preliminary results were obtained,which are of important reference significance for the prevention and control of the associated geological disasters in the evolution of the Loess Valley.The main conclusions are as follows:(1)Through the analysis,it is found that the impact of slope contact surfaces on the slopes of the two sides of the Yehu valley can be neglected,and the occurrence of bedrock is more important.Through the intersection relationship between the occurrence of bedrock and the free surface,there are two big types of slope structure types on both sides of the Yehu valley;the left bank is the bedding slope,and the right bank is the reversal type.(2)The reasons for the differences in slope deformation characteristics between the two banks are different at different sections in the two bank slopes.By comparing the types of slope structures and the deformation and destruction characteristics of the slopes,it is found that there is a connection between the two;the occurrence of bedrock has a great influence on the stability of slope,and the bedding slope is easier to deform and damage than the reverse slope.The left bank is a bedding slope,so the deformation is mainly landslide,the right bank is an inverted type,and the slope deformation is mainly collapse.(3)The characteristics of the slope deformation on the left bank of the Yehu valley are regular in the longitudinal direction.The types of deformation are from loess-basement landslides,loess-silt clay landslides to loess landslides.This change is related to the exposed thickness of bedrock.The pure loess slope with unexposed bedrock has good stability,and its deformation and destruction process is slow.When the exposed thickness of bedrock is large,the stability of the slope is very poor.The upper soil are easily driven by the bedrock and pulled and cracked to cause damage.(4)There are multiple models for the evolution of the Yehu valley,of which the evolution of the slopes on both banks to change the width of the ditch is the most important evolutionary method;in the evolution of the ditch width,the landslide is the most significant and the fastest.(5)There are differences in the evolution of the left and right banks of the Yehu valley,and the evolution speed of the left bank is significantly greater than that of the right bank;the reason for the difference is different from that of the slope structure,resulting in the difference in the evolution patterns and strengths of the slopes on both sides.更多还原