论文部分内容阅读
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。
2013-07-25 Tianshui City suffered a rare heavy rain, causing massive geological disasters (hereinafter referred to as “7.25” mass geological disasters), causing serious losses. Based on the actual survey data, the types, distribution and disaster characteristics of this geological disaster are discussed, and the causes are analyzed. Precipitation triggered 708 geological disasters, of which 415 landslides, 102 landslides, 86 unstable slopes, debris flow 100, ground fissures 3, the ground collapse 2. The distribution of geological disasters is characterized by spatial heterogeneity, basin concentration and mass mobilization, which are controlled by the rainfall range. Disaster characteristics are characterized by chain collapse-landslide-debris flow and landslide-dammed lake. The study shows that since 2013-06-20, the number of precipitation days is 24-26 days, and the number of precipitation days is 10-15 days more than in the same period of last year. Meanwhile, the precipitation in July is 2.2-3.4 times that of the same period of previous year. July 25 The maximum rainfall of 16 h observed on day is 152.2 mm. Precipitation showed the characteristics of earlier period richness and large decrease of current period, which were the main contributors to the mass disasters. The intensity of Wenchuan earthquake in the study area ranged from VI to VII, especially in the south Degree zone, to a certain extent, led to the loosening of the mountain and the crust. Therefore, a large number of landslides were caused under the conditions of superposition of precipitation. The combination of the landslide and its structure and the topographic conditions laid the material foundation for the formation of mass geological disasters.