基于图幅调查的六盘山镇滑坡易发性分析

Analyses on Landslide Susceptibility of Liupan Shan Town Based on Map Sheet Survey

调查研究区域孕灾地质环境背景,是分析地质灾害时空分布规律与成灾模式,完成地质灾害易发性区划评价,提出地质灾害综合防治对策建议的重要依据。基于实地调查和GIS技术,分析了六盘山镇幅内工程地质岩组、坡度、坡向、地形起伏度、断裂构造、河流与公路7个因素与滑坡分布的关系,应用滑坡点分布频数这一指标来衡量每个因素中各个级别对滑坡的影响程度;然后运用层次分析法来确定触发滑坡控制参数的权重大小。在GIS环境下对这些参数进行综合分析,通过分析结果将研究区按易发程度分为高易发区,占12.43%;中易发区,占20.14%;低易发区,占42.98%;非易发区,占24.46%。此外,结果还表明:(1)大的地貌单元和格局较明显地控制着滑坡的分布,不同地貌单元内的滑坡类型、发育程度和分布特征等都有差异性,滑坡一般沿地貌边界带密集分布发育,尤其是沿断裂呈线状展布;(2)工程地质岩组对滑坡的影响作用最大,尤其在软弱的泥岩岩组易滑地层区域内,在不同工程地质岩组区间内滑坡面积的多寡与滑坡分布密度相关性不大;(3)区域地质构造不仅控制着区域地层的展布,也控制着区域滑坡的发育,不同断裂也凸显出一定的差异性。

The investigation of regional geological disaster environmental background is an important basis for analysis of temporal and spatial distribution of geological hazards and disaster mode.It is also an important basis for completing geological hazard assessment and proposing comprehensive geological disaster prevention countermeasures.Based on field investigation and GIS technology,analyzing the relationship between7factors of rock group of engineering geology,slope,slope aspect,terrain,faults,river,highway and the distribution of landslide in Liupan Shan Town sheet,landslide distribution frequency index was used to measure the influence of each level on landslide.Then AHP was used to determine the weight of controlling parameters for landslide.These parameters were analyzed comprehensively in the GIS environment.According to the susceptible degree,the results of the study area were divided into high easy happening area,accounting for12.43%;medium-easy happening area,accounting for20.14%;low easy-happening area,accounting for42.98%;not happening area,accounting for24.46%.In addition,the results also show as follows.①Big geomorphic units and pattern obviously control landslide distribution,landslide types,development degree and distribution characteristics are different in each geomorphic unit.The landslides were densely developed along the geomorphological boundary zone,especially along the fault is linear distribution.②The engineering geological rock group is the highest influencing factor on the landslide,especially easy to slide in shale rock group soft strata area.Landslide number density is of little relevance with landslide distribution area in different engineering geological rock group.③The regional geological structures not only control the regional stratigraphic distribution,but also control the regional development of landslide,and different fracture also highlights some differences.