天水市“7·25”群发性地质灾害特征及成因  

Characteristics and Causes of Assembled Geo-hazards Induced by the Rainstorm on 25th July 2013 in Tianshui City,Gansu,China

作　　者：郭富赟 孟兴民[1] 黎志恒 谢正团[1] 陈冠[1] 何云峰 

机构地区：[1]兰州大学西部环境教育部重点实验室,甘肃兰州730000 [2]甘肃省地质环境监测院,甘肃兰州730050

出　　处：《山地学报》2015年第1期100-107,共8页Mountain Research

基　　金：国家重点基础研究发展计划项目;编号:2014CB744703;科技部支撑计划项目;编号:2011BAK12B06;甘肃省科技重大专项项目;编号:1102FKDA007~~

摘　　要：2013-07-25天水市遭遇罕见暴雨,引发群发性地质灾害(简称"7·25"群发性地质灾害),造成严重损失。基于实际调查数据,论述了本次地质灾害的类型、分布和成灾特征,并对成因进了分析。降水引发地质灾害708处,其中滑坡415处,崩塌102处,不稳定斜坡86处,泥石流100处,地裂缝3处,地面塌陷2处。地质灾害分布,在空间上具有不均性、流域集中性、群发性等特征,并受降雨范围控制;成灾特点表现为崩塌-滑坡-泥石流、滑坡-堰塞湖链式特征。研究表明,自2013-06-20以来,降水日数为24~26 d,降水日数较往年同期偏多10~15 d;同时,7月以来降水量是常年同期的2.2~3.4倍;7月25日观测到的16 h最大降水量达152.2 mm。降水表现出前期丰富、当期降强度大的特点,是此次群发性灾害的主要促发因素;"5·12"汶川地震在研究区的烈度为VI^VII度,特别是南部属于VII度区,一定程度上导致山体松动,岩层破碎,因此在降水叠加条件下引发大量的滑坡;易滑岩土及其结构组合、地形条件奠定了群发性地质灾害形成的物质基础。In July 25 th,2013,the Tianshui city has encountered a heavy rainstorm,which rainstrom triggered cluster geo-hazards,and caused serious casualties and economic losses. Based on field survey,the type,distribution,characterisic and formation of the geo-hazards were analyzed. The rainstorm induced 708 potential geo-hazards,including 415 landslides,102 collapse,86 unstable slopes,100 debris flow,three ground fissures,and two surface subsidence. The spatial distribution of geo-hazards,controlled by the rainfall,showed uneven,watershed-concentrated and clustering characteristics. The disaster exhibited chain characteristic,for example,collapse-landslide-debris flow and landslide—barrier lake,Results show that there were 24 ~ 26 days with rainfall since 20 th June,which was more than 10 ~ 15 days higher compared with the same period in last year. Meanwhile,the rainfall was over 2. 2 ~3. 4 times heavier than the perennial rainfall at the same period since July. The maximum amount of 16 hours precipitation observed on 25 th July was 152. 2 mm. The rainfall exhibited characteristics of abundant antecedent rainfall and high-intensity current rainfall,which were considered as the main triggering factors of this clusters of geohazards. Apart from that,the seismic intensity of ＂5·12＂Wenchuan earthquake in the study area was around 6 ~8 degree,and 8 degrees in particular in the southern area causing the mountain loose,rock crushing,and therefore,in combination with the rainfall,it is inclined to trigger large amounts of landslides,in addition,the sliding prone rock-soil with its structure composition,and high-relief topography could lay the material foundation for this clusters geo-hazards.

关 键 词：天水市 暴雨 群发性地质灾害 链式 促发因素 

分 类 号：P642[天文地球—工程地质学] P694[天文地球—地质矿产勘探]