大气降水对黄土滑坡的影响和控制——以甘肃省陇西黄土高原为例

THE IMPACT AND CONTROL OF ATMOSPHERIC PRECIPITATION ON THE FORMATION OF LOESS LANDSLIDES——An example of Longxi Loess Plateau in Gansu Province

以野外实际调查资料为依据,总结分析甘肃陇西黄土高原滑坡类型及特征的基础上,从降水(主要指强降雨)改变地形地貌、改变滑坡土的成分构成、改变滑坡的土体结构、改变滑坡的力学强度4个方面阐述了大气降水对黄土滑坡形成的机理。大气降水对黄土滑坡的时空分布存在着较大影响和控制,年际上,同一区域滑坡发生的频次与多年降水的强弱过程呈现良好的相关性,存在丰水年滑坡次数多、规模大而枯水年滑坡次数少、规模小的规律;年内滑坡集中出现于3月份和6～9月份,前者是季节性冻结—融化作用所致,后者是降水在时间上的集中决定了滑坡发生时间的集中性;不同区域,在地形地貌、地层岩性基本相同和植被覆盖率相差不大的条件下,降水量越大,滑坡发生频率越高,反之,亦然。

This article based on field survey data and summary analysis the landslide type and characteristics of the Longxi Loess Plateau in Gansu Province, to elaborate the formation mechanism of loess landslides from four aspects which include precipitation （mainly referring to the heavy rain or overcast and rainy） change the topography, change the landslide composition,change the landslide soil structure,change the landslide mechanical strength. Precipitation has a greater influence and control on loess landslide in time and space distribution;In fact, there has a good correlation between the strength of landslide frequency and years of precipitation in the same area, in wet years ,the number of landslide is more and the scale is larger than dry years.In the same years, the landslide concentrated in March and June to September, the former case is due to seasonal freezing-melting role, while the latter case is the concentration of precipitation in a short time to determine the occurrence of landslide frequency is intensive. In different regions, If there has a similar condition of topography, stratigraphy of lithology and vegetation coverage, the more the rainfall,the higher the landslide frequency occurs, and vice versa.