Study On The Stability Of Laolongwan Landslide In Yi-gong Road

Landslide is the most common geological disasters in the world. Laolongwan Landslide in Yigong highway is located in Yuejiang town, Gong county, Yibin city, which is a medium traction landslide induced by slope excavation. The existence of the landslide directly affect the Yigong highway opening to traffic, if no measurement, long-term deformation will naturally cause road damage or endanger highway driving pedestrian safety, and will lead to great harmfulness. Therefore, it is very important to find out the cause of the landslide, to evaluate its stability, to predict its development trend and its dangers.This paper is focus on the stability of Laolongwan Landslide in Yigong highway, and find out the conditions of landform, stratigraphic lithology conditions, the hydrological, geological conditions of the geological structure conditions and earthquakes and slope instability of the relationship through the study of the existing data and the geology survey in this area.Through the investigation on slope surface, exploration test results to determine landslide composition, structure characteristics, slide soil and sliding bed features, deformation damage characteristics. Based on the geological mechanics model of the landslide, and the cause of formation mechanism of landslide is analyzed.The stability coefficient of the landslide in various working conditions is calculated by using transfer coefficient method. And the numerical model is put forward with FLAC-3D. The stress characteristics of landslide, the deformation characteristics, deformation development trend are analyzed. The development of the landslide is forecasted. And the engineering suggestion is put forward.Through setting displacement monitoring stations in the field, the displacement of the landslide before and after the measurement is monitored, and long-term stability of landslide is monitored too. The further stability of landslide is evaluated.Finally in this paper, the vulnerability assessment to harmness of the landslide and the necessity of prevention and the control suggestions are put forward. The management plan of Retaining engineering combines with drainage works is recommended.Research shows that the landslide is naturally in a critical stable state, and is not stable in heavy rains. Landslide without improvement will cause a large displacement, the maximal displacement is located in central landslide, and in a convergence shape, the displacement and the groove are in the same direction. The field monitoring shows the landslide without improvement is in a deformation form, its deformation is more visible in central than front and back of the landslide, which is consistent with the numerical analysis. But field monitoring displacement is obviously less than that of numerical analysis, the result shows that retaining measures of a landslide is effective. The deformation is reduced after improvement and the landslide becomes more stable.