Stability Analysis Of Landslide Along The Margins Of Heifangtai Loess Platform

Heifangtai as having perennial large areas of farmland irrigation and stratigraphic lithology and the special stratigraphic texture which make it become a typical landslide active zone has attracted many experts to study and investigate. The paper which is based on this research area analyzes the geological characteristics and the characteristics of the landslide disaster and the internal relations between them through consulting relevant materials, literature and field investigation. The seepage characteristics and stability of slope under different buried depth of groundwater level and different rainfall intensity are simulated and analyzed by numerical simulation technique. The conclusions of this paper are as follows:Firstly According to the investigation, there are 40 landslides, including 25 loess landslides and 15 loess bedrock landslides. Deep landslides are in the majority, accounting for 50% of the total number of landslides. Super-huge large landslides are in the majority, accounting for 40% of the total number of landslides.Secondly Through the numerical simulation of groundwater characteristics under steady state conditions we can know: some water go along the interface between loess layer and silty clay layer to the tableland edge slope by doing horizontal seepage movement, the other part of water in the course of horizontal movement do slow seepage to the bottom silty clay layer. With the rising of groundwater level, the range of saturated area is enlarged, the water content in unsaturated zone increasing, the scope of the water to soften the soil is enlarging, which cause the safety factor of the slope reducing.Thirdly Through the numerical simulation analyze, a certain thickness soil at the top of the slope affected obviously by rainfall; During the same rainfall time, The greater the rainfall intensity, the more rapid the pore water pressure and the water content of the slope increase, the equipotential lines of pore water pressure and volumetric water content will become more dense in the top of slope and ramp. under the condition of the same rainfall intensity, the safety factor of the slop decreases with the increase of the rainfall time.