System Research Of The Sourth And The North Slope In Foping Country In Shannxi Province

The new motion of the structure in Qinling Mountains is strong. The mountain slopes are all high and precipitations. In the other side, the rainfall is high in this area, therefore land sliding and collapsing are frequently happened. In June 8th or 9th, 2002, there was a short duration extraordinary storm in the Xixiang County, the Foping County, the Ningshan County and the Zhan'an County, which are in the south of Qingling Mountains. It leaded to the mountain torrents, landslide and debris flow in the area of the Jiaoxi River and the Puhe River in Foping and Ningshan at June 9th. If the sliding happens in this area, it will cause great losses to human lives and their properties. Therefore, it is utterly necessary to make a stability analysis and enforce or repair existing facilities.This article focuses on the north and south slope of the Guanshan Mountain in the Foping County. The influencing factor of the stability has been induced and summarized according to the data from the geological investigation and study. Then the in-depth research of the deformation and failure mechanism is made on this basis.Through elementary analysis, it is clear that the north slope is potentially in dangerous, and the south slope has been preliminary sided.The weak structural surface of this slope is the contact surface between the bedrock and the Quaternary Strata of the north slope of the Guanshan Mountain. The Structure of Strong Weathered Genisses is compact,and poor permeability.So it is easy to formed potential sliding surface.The sourth slope of the Guanshan Mountain is the quaternary ancient landslide, the sliding surface is between the bedrock and the Quaternary Strata. The soil sheer strength is be decreased by weathering and water.The slope slides because of slide force and anti-slide force on the slide surface.And the another important reason is the downward infiltration of surface water and the toe of slope erosion,besides its self-weight. Based on the experimental data and structure of the slope, we make a stability analysis to the slopes. Then we get the factor of safety (Fs) in different conditions by the slice method. The north slope remains stable, Fs﹥1.20(whether in natural state or in saturation state). However, the south slope is near equilibrium state limit. When it is in saturation state, Fs﹤1.20. So this slope may slide again. In the meanwhile, we make a sensitive factor analysis for the landslide. The prevention and control of landslide is based on the data and the theoretical basis above.We use the FLAC/SLOPE program which is the one of numerical simulation to study the factor of safety of two slopes. It researches the stability in natural state and in saturation state. It accords with the result which we had above.Because of the sliding evidence in the sourth slope of the Guanshan Mountain,and a tension crack appeared in the rainy season.It is dangous for the human lives and their properties who live in here.Last but not least, according to formation mechanics and influential factors, the corresponding feasible prevention and control measure of the landslide in researched area is put forward.