基于降雨响应的黄土丘陵区滑坡危险性预测研究--以宝鸡市麟游县为例

A Predictive Study of the Hazardousness of Landslides in Loess Hilly Region Based on Rainfall Response:A Case Study of Linyou County,Baoji City

极端降雨易造成群发滑坡灾害,难以作为单体预测。为预测评估黄土丘陵区不同降雨强度诱发滑坡灾害危险性,论文在区域滑坡灾害特征研究的基础上,分析降雨强度特征及滑坡分布特征。以岭南滑坡为代表分析降雨诱发黄土-丘陵区滑坡的形成机制,介绍了无限斜坡模型原理、参数选取,利用GIS空间建模与分析功能,定量完成了无降雨、25 mm、50 mm、75 mm四种情况下,滑坡灾害的危险性研究,并对误差进行了分析。结果表明:(1)黄土丘陵区滑坡灾害与地形地貌、岩土体力学性质相关,降雨、地表水的溯源侵蚀作用是滑坡灾害发育的宏观背景。(2)降雨在麟游县等黄土丘陵区易诱发浅表层黄土滑坡,形式上表现为黄土泥流、浅层滑坡。(3)降雨量相同时,区域斜坡单元的响应机制不相同,高危险区、中危险区与低危险区集中在不同区域产生,差异明显。在无降雨、25 mm、50 mm、75 mm四种不同降雨量下,中部分水岭地区、北部天堂镇、丈八乡是高危险区,极易形成降雨滑坡灾害。(4)降雨诱发灾害的高危险区,威胁附近村镇居民安全,需要采用监测预警和相应防治措施。中等危险区汛期需要采用群测群防预警措施。低危险面积汛期需提高警惕,防止突发事件发生。(5)无限模型适合计算降雨诱发的浅表层滑坡,能够很好反映降雨量诱发滑坡灾害响应,得出的危险性分布具有符合实际情况,危险性计算的误差与地理底图分辨率、计算参数有关。

Extreme rainfall may easily lead to mass landslide disasters, which, however, cannot be predicted as a monomer. To predict and evaluate the hazards of landslide disasters induced from different rainfall intensities in the loess hill regions, the authors analyzed the characteristics of rainfall intensity and landslide distribution on the basis of studying the characteristics of regional landslide disasters, introduced the principle of the infinite slope model and parameter selection by analyzing formation mechanism of landslides in loess-hilly areas induced by rainfall with Lingnan landslide as an example, completed quantitative studies of hazards of landslide disasters under four different rainfall conditions, i.e., no rainfall, 25 mm, 50 mm and 75 mm respectively using GIS spatialmodeling and analysis and analyzed their errors. The results show that： （1） landslide disasters in loess hilly areas are related to topography, mechanical properties of rock bodies and earth. Headward erosion of rainfall and surface water is macro background of developing landslide disasters. （2） Rainfalls in loess hilly areas such as Linyou County are prone to inducing shallow strata loess landslide, represented by loess mudflow and shallow landslides. （3） For the same amount of rainfall, different units in slope areas have different response mechanisms, and high risk zones, middle risk zones and low risk zones are generated in areas with significant differences. Under the four different rainfall conditions of no rainfall, 25 mm, 50 mm and 75 mm, watershed area in the middle, Tiantang Town in the north, and Zhangba Township are high risk zones which are prone to generating rainfall landslide disasters. （4） In high risk zones with rainfall induced disasters, the situation threatens safety of residents of nearby villages and small towns, and hence monitoring, warning and corresponding preventive measures should be taken. In middle risk zones, mass monitoring, preventing and warning measures should be taken in flood seasons. In low risk zones, people should be vigilant in preventing unexpected incidents in flood seasons. （5） The infinite model is fit for calculating shallow slides induced by rainfall, reflecting response to rainfall induced landslide disasters soundly. The derived hazard distribution meets actual conditions. The errors of calculating hazards are related to resolution of geographic base maps and selection of calculating parameters.