| The southwest region of our country is located near the intersection of Eurasian plate and India Ocean plate.Most of it is mountainous and its geological conditions are very complex.In these regions,fault zone and broken zone are widely distributed and the earthquake disasters occur frequently.In addition,the climate is humid and the precipitation is abundant,so there is a lot of landslide disaster.And recently,the development of road,railway,water conservancy,hydropower and other infrastructure construction in the southwestern region is in full swing.The problem of landslide caused by the construction of the project is also more and more.A kind of these landslides,which is developed on the slope of the accumulation layer,is called the long strip accumulation landslide by this thesis due to the large longitudinal length.This kind of landslide in the southwest of China has a large scale and complex sliding surface morphology.Because of the limitation of survey condition,it is difficult to accurately determine the shape of sliding surface.The analysis model of landslide stability and sliding thrust can only be established by the broken lines between the two drill holes.The analysis result is not in conformity with the present situation of landslide,which seriously affects the rationality of management engineering design.This thesis analyzes the development characteristics of long strip accumulation landslide,the origin of accumulation body,the formation mechanism of the landslide and the main controlling factors of landslide thrust.It focuses on the analysis of the influence of different sliding surface morphology between the two drill holes on the sliding thrust,which aims to provide reference for the optimization of engineering design and cost saving.1.On the basis of summarizing the existing research results of accumulation landslides,the thesis analysis and discusses the development characteristics(including distribution characteristics,morphological characteristics,material composition),genetic mechanism(including a trench formed,the origin of accumulation body,landslide formation)and influence factors of stability of long strip accumulation landslide.2.It analyzes the reasonable value method and influence factors of the shear strength indexes of the landslide,then inverse calculates shear strength indexes of the long strip accumulation landslide of Wei Jia Wan by transfer coefficient method as the theoretical basis.3.The sliding thrust is analyzed and studied from the calculation method of landslide thrust,the distribution form of landslide thrust,the potential sliding surface morphology of landslide,the safety factor and other aspects.In this thesis,the influence of the different ways of connecting the broken lines between the two drill holes on the sliding thrust,that is,the influence of the different forms of the sliding surface on the sliding thrust is analyzed by using the transfer coefficient method.According to the analysis,it suggests that under the premise of satisfying that the angle of surface is slow and the changes of the angle are small,when the slip line combination between two drill holes turns into a straight line,landslide residual downslide thrust is the biggest.4.Taking the long strip accumulation landslide of Wei Jia Wan in Pingwu County as an example,it introduces the basic situation of landslide(including regional geological background,landslide development characteristics,material composition)and analyzes the stability influence factors and formation mechanism of Wei Jia Wan landslide.Then the mechanical analysis and verification of failure modes and stability of landslide in the natural condition and in heavy rain are carried out by means of the transfer coefficient method and the finite difference software of FLAC3D.Finally,by the transfer coefficient method this thesis verifys the conclusion that when the slip line combination between two drill holes turns into a straight line,landslide residual downslide thrust is the biggest. |
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