四川省北川县崩滑灾害孕灾地质条件分析

Analysis on the disaster-pregnancy geological conditions of collapse and landslide in Beichuan County,Sichuan Province

受龙门山断裂构造带及“5·12”特大地震震后效应影响,北川县地质环境表现出异常的复杂性及脆弱性,区内每逢汛期地质灾害频发。在野外孕灾地质条件调查的基础上,收集历年地质灾害资料,总结了区内地质灾害发育分布的总体特征。基于GIS平台,对崩塌和滑坡地质灾害进行了孕灾地质条件分析,研究了崩滑地质灾害与地形地貌条件(高程、高差、坡度、平剖面曲率、地势起伏度、沟壑密度、距水系距离)、地层岩性条件(工程地质岩组)、地质构造条件(断层)、地震后效应(地震烈度)、斜坡结构以及人类工程活动(距道路距离)等孕灾因子的相关关系。结果表明:地质构造、土地利用类型、斜坡结构、坡度及剖面曲率是孕育滑坡最主要的地质条件,给出了各孕灾条件中致使滑坡发育的优势区间;崩塌则受控于工程地质岩组,与距河流距离以及地震烈度也有一定关系。综合考虑北川县内主要孕灾条件,全县可分为5大孕灾地质条件区,并对每个区内的灾害孕灾特征及发育规律进行了详细阐述。进一步认识北川县崩滑灾害孕灾地质背景条件,能更好地助力于地方防灾减灾体系提升,也可为其他地质灾害风险调查评价项目提供一定的参考。

Affected by Longmenshan fault tectonic zone and the post-earthquake effect of“5.12”mega earthquake,the geological environment of Beichuan County is of unusual complexity and fragility,and the geological disasters occurred frequently in this area during the flood season.On the basis of the investigation of the disaster-pregnancy geological conditions in the wild,the authors collected geological disasters data and summarized the overall characteristics of the development and distribution of geological disasters in this region.Based on GIS,the authors analyzed disaster-pregnancy geological conditions of collapse and landslide,and studied the correlation between geological disasters and topographic conditions(elevation,height difference,slope,plane and profile curvature,relief,gully density,distance from water system),stratigraphic and lithological conditions(engineering geological rock group),geological structural conditions(fault),post-earthquake effects(seismic intensity),slope structure and human engineering activities(distance from road).The results show that geological structure,land use type,slope structure,slope and profile curvature are the most important geological conditions for landslide development,and the advantageous interval for the landslides development in each disaster-pregnancy condition is given.The collapse is controlled by the engineering geological rock group,distance from water system and seismic intensity.Considering the main disaster-pregnancy conditions in Beichuan County,the county can be divided into five major disaster-pregnancy geological conditions zones.And disaster-pregnancy characteristics and development laws of each area were described in detail.The further understanding of disaster-pregnancy geological conditions of collapse and landslide in Beichuan County can improve the local disaster prevention and mitigation system,and provide some references for other geological disaster risk investigation and evaluation projects.