陕北黄土高原不同地貌类型区黄土滑坡频率分布

Size-Frequency Distribution of Landslides in Different Landforms on the Loess Plateau of Northern Shaanxi

黄土滑坡是西北地区最为严重的地质灾害.频率分布对于区域滑坡风险评估具有重要的意义,借鉴粒度分析方法研究黄土滑坡分布情况,提出滑坡规模径概念,并通过Gamma分布函数对滑坡规模频率曲线进行了拟合.结果表明:(1)在区域尺度上,可以借鉴粒度分析的理论和方法分析区域滑坡规模百分含量;(2)在双对数坐标下,频率曲线具有"偏转效应",而Gamma分布函数在描述滑坡规模径频率分布方面具有广泛的适应性,能够很好地拟合黄土滑坡规模频率;(3)无论是黄土滑坡的数量还是规模,以墚为主的黄土丘陵区宝塔区都是受滑坡灾害威胁最为严重的区域;但黄土地貌在由塬向峁区的演变过程中,黄土滑坡规模变异或离散程度逐渐减小.

Loess landslide is the most catastrophic geohazard in the northwest area of China.Frequency distribution plays an important role in prediction and risk assessment of landslides since it can be used to find out certain distribution laws in different landslides.In this paper,the loess landslide distribution is studied by using method of grain size analysis theory,and the authors put forward the concept of landslide size diameter and use the Gamma distribution curve to fit size-frequency of landslides in different landforms of the loess plateau.The results show that：（1）At the regional scale,landslides can be viewed as＂particles＂widely distributed in the area,regional landslide scale percentage and its distribution can be obtained by application of grain size analysis theories and methods;（2）At log-log coordinates,frequency curve has a＂rollover effect＂,and the Gamma distribution function describes well the size frequency distribution of landslides;（3）The loess landslide scale variation or discrete degree decreases from loess tableland to loess hill in Baota district which is mainly covered by loess ridge suffering most serious threat of the landslide disasters both in number and size.