天水市“7.25”群发性山洪地质灾害发育特征及成因分析

通过对天水市"7.25"群发性山洪地质灾害的现场调查,系统查明了此次地质灾害的灾情、致灾因素、灾害特征、致灾范围以及分布规律,分析了此次山洪地质灾害发育特征及成因。结果表明:本次由强降雨引发并加剧的地质灾害类型主要以黄土-泥岩及黄土滑坡为主,中小型沟谷泥石流、土质崩塌和土质不稳定斜坡次之。"7.25"山洪地质灾害具有普遍性、群发性、局地爆发性等特征,其隐蔽性强,潜在危害大,灾害链模式显著。灾害发生期间降雨具有强度大、范围广等特点,使区内山体岩土体饱和,显著降低了岩土体抗剪强度,加之与地震的叠加效应明显加剧了此次群发性山洪地质灾害。

Analysis on the Development Characteristics and Hydrodynamic Conditions for the Massive Debris Flow in Tianshui

Through a field investigation, the disastrous situation, causal factors, disaster characteristics, scope and distribution of massive mountain torrent geo--hazard on July 25 in Tianshui were systematically identified, and the development characteristics and causes were analyzed. The results show that the main types of geo hazard caused and exacerbated by the heavy rainfall are mud stone landslides and loess landslides, followed by small debris flow, soil collapse and soil slope instability. The geological hazards had the characteristics as follows： universality, obviously group-occurring, local outbreak, deeply concealed, potentially hazardous and of significant disaster chain mode. The rainfall during the geological hazard had such characteristics as highly intensive and wide in range, which leads to the saturation of rock and soil of the mountain, and reduces the shear strength of rock and soil significantly. The massive mountain torrent geological hazard is exacerbated with the superposition effect of the earthquake and rain.