Study On The Origin And Stability Of Xuelongnang Landslide Dam In The Upper On Jinsha River Valley

Because China is a country with frequent geological disasters, and every year by the earthquake, tectonic of intense activity caused by the collapse, landslide, debris flow disaster phenomenon occurred frequently, which caused by them blocking river events are not uncommon. And these blocking river events caused by the lake or a weir dam for the research on the changes of the meaning of engineering construction and geological environment has important value. Therefore, it is an urgent problem to analyze the causes of the dam break and the stability of the residual accumulation after the dam break.The Jinsha River Xuelongnang ancient landslide lake dam break residual dam as the research object, based on the field geological survey, the basic characteristics of the remaining accumulation body of the landslide are analyzed and described in detail. The reasons and the failure mechanism of the dam are analyzed qualitatively, and then the stability of the remaining residual dam is analyzed and evaluated quantitatively:(1) The field geological investigation in Xuelongnang landslide as an ancient large-scale rock landslide, the huge landslide damming of the Jinsha river formed large area of lake, landslide volume about 4.0 x 10~7 m. After the dam out-break will be divided into two parts part residue, left and right bank part of residue residue.(2) In the whole research region, from the accumulation of material relationship of body and the dam of the lake view, gravel dam material, and fine source may in part from the dam, and partly from in former lake dam upstream of lake facies sedimentary layer.(3) The study found that there is a certain relationship between fractal dimension value and sorting coefficient, that there was a positive correlation between the separation coefficient and fractal dimension value. The grain size fractal dimension and coarse degree of relationship, provide a basis to explain the causes of the dam break from the micro perspective.(4) Based on FLAC3 D software to analysis of residue of Xuelongnang of dam break bulk, the results show that the stability coefficient of residual dam in natural state is 1.22, which is in stable condition after dam break. Under the action of earthquake the stability coefficient is 0.84, and is in an unstable state, should be prevented to prevent the occurrence of disasters.