Mechanism Of Hejiaqu Landslide In Yanchi City,Ningxia Hui Autonomous Region

As known, landslide which happens frequently is one of the most undesirablegeological phenomena; and it is one of the main ways for slope failure.Landslide often causes huge losses to the industry and agriculture production. What’sworse, some landslide is a disaster because it would wreck lives of people. Thus,landslide must be prevented and controlled. It is very important to make the formationmechanism of landslide clear because it has the intellectual value and realisticsignificance.In this study, Hejiaqu landslide was studied intensively. The Location of thelandslide was at the southwest of Hejiaqu, Mahuangshan village which was the sourceof Shezi River, Yanchi County, Ninxia autonomous regions. The landslide was atypical new landslide in loess layer. The overall slope of the landslide was like adustpan, and the morphology of section was like a ladder which was not clear. Theheight of the leading edge of the landslide was1362m; the trailing edge was next todrought-enduring plants which were at the edge of road, and the height was1455m;the relative height difference of the landslide reached93m; the length of landslidemainshaft was180m; the average width was287m; the average thickness was10m;the volume was520,000m3. The research of formation mechanism of Hejiaqulandslide was poor because little study was focus on the landslide. The formation andinstability mechanism of Hejiaqu landslide was studied in the paper based inqualitative analysis and numerical simulation by Geostudio software. In this study, thefactors which impacted the landslide were atmospheric rainfall, topography andgeomorphology, and formation lithology. The atmospheric rainfall was the main factor,and the rainfall was concentrated in the rainy season in Yanchi County. Rainfallinfiltration made the physical properties of rock descrease, and the infiltration alsocaused an uplift pressure. Then the landslide happened. The stability coefficient of thelandslide under nature condition was1.246which was calculated by limit equilibriummethod. The coefficient suggested that the slope was stable, and the landslide was caused by external factors. Atmospheric rainfall was considered to be the onlyexternal factor which could cause landslide. Thus the stability of the slope was studiedwith atmospheric rainfall factor and under the nature condition. The result of thenumerical simulation showed that the stability of slope became lowest, and it turnedinto landslide in144h after rainfall, which intensity reached65mm and last24h.