地下水渗流对崩坡积滑坡稳定性和变形的影响——以湖南安化春风滑坡群为例

Influence of groundwater seepage on stability and deformation of colluvial deposit landslide:taking Chunfeng Landslide group in Anhua County of Hunan Province as an example

为了研究地下水渗流对崩坡积滑坡变形的影响,通过分析现场调查勘察资料,在研究该滑坡所处的地质环境条件、滑坡的形态特征和变形特征的基础上,探讨了该滑坡的形成机制,对比了地下水渗流对崩坡积滑坡和老滑坡的影响,并开展了数值模拟。取得的认识有:(1)地形地貌、地层岩性、大气降水、人类工程活动是该滑坡形成的主要原因。在这些因素共同作用下,滑坡最终失稳变形,过程中可能发生多次滑动,形成现今的堆积形态。(2)降雨引起的地下水渗流对该崩坡积滑坡稳定性和变形的影响是十分显著的。对于局部架空现象较严重的崩坡积组成的Ⅲ号滑坡体,雨水更易入渗进入坡体,地下水渗流对其稳定性和变形的作用十分明显;而对于优势通道较少的Ⅰ号和Ⅱ号老滑坡体,局部架空现象相对较差,地下水渗流对其稳定性和变形的作用不显著。(3)降雨时间和降雨强度与滑坡稳定性负相关。降雨强度较小时、一定时间内降水对滑坡稳定性影响不大,但降雨较大时,滑坡稳定性将快速降低。

In order to analyze the influence of groundwater seepage on the deformation of colluvial deposit landslide,the formation mechanism of Chunfeng Landslide was discussed,and the influence of groundwater seepage on the stability and deformation of colluvial deposit landslide and old landslide was compared on the base of analyzing geological environmental conditions,morphological characteristics and deformation characteristics of the landslide after field investigation,and numerical simulation was carried out.Some conclusions can be gotten.Firstly,topography,formation lithology,atmospheric precipitation and human engineering activities are the main reasons of Chunfeng Landslide formation.Under the common action of the four factors,the slopes became instable and the deformation or sliding happened in the end.Multiple sliding might happen,and the current accumulation form was formed.Secondly,the influence of groundwater seepage produced by rainfall on stability and deformation of colluvial deposit landslide was very significant.As for theⅢlandslide body constituted by colluvial deposit where local overhead was more common,it is easier for the rain to penetrate into the slope,and it is very obvious that groundwater seepage affects the landslide stability and deformation.As for theⅠandⅡold lanslide where local overhead was not common,it is not obvious that groundwater seepage affects landslide stability and deformation.Thirdly,the time and intensity of rainfall were negatively correlated with the landslide stability.When the rainfall intensity is small,the precipitation has little influence on the stability of landslide within a certain period of time,but when the rainfall intensity is large,the stability of landslide will decrease rapidly.