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2013年7月,延安市发生了自1945年有气象记录以来,强度最大、持续时日最长且间隔时间最短的强降雨。在此过程中,区内沟壑斜坡发育大量的滑坡地质灾害。通过野外调查和典型重大滑坡地质灾害隐患点工程地质勘查,分析了滑坡体形成原因和影响因素。结果显示:坡度角大于28°、坡体形态为阶梯型和复合型、有第四系坡积黄土堆积的斜坡在持续强降雨作用下产生滑坡地质灾害的概率高,同时当降雨量大于100 mm、土体浸湿深度大于55 cm时,产生坡面泥流灾害的可能性大。因此,黄土地区(延安)新建工程应避免在坡度陡、坡形复杂、坡积黄土较厚的斜坡危害区内选址,在降雨期间应密切监测降雨量,及时撤离疏散易发区内群众。
In July 2013, a heavy rainfall occurred in Yan’an City with the highest intensity, the longest duration and the shortest interval since meteorological records began in 1945. In the process, a large number of landslide geological disasters develop in the gully slopes in the area. Through the field investigation and geological survey of typical landslide hazard geological hazards, the causes and influential factors of landslide formation are analyzed. The results show that the slope angle is greater than 28 ° and the shape of the slope is of a staircase type and a complex type. There is a high probability of slope landslides accumulated in the Quaternary slop loess area during the continuous heavy rainfall. When the rainfall is more than 100 mm , When soil wetting depth is more than 55 cm, there is a high possibility of slope mud flow disaster. Therefore, the new project in the loess area (Yan’an) should avoid the site selection in the slope hazardous areas with steep slope, complicated slope shape and thick slope loess area. During the rainfall, the rainfall should be closely monitored and the evacuation of the masses in the evacuation zone should be promptly carried out.