Study On Formation Mechanism And Movement Process Of Landslide Debris Flow

With the intensification of global climate change,natural disasters occur frequently,among which landslide debris flow is a common natural disaster.Landslide debris flow is caused by natural factors such as landslides and debris flows.It is characterized by high speed,large scale and strong destructive power,which poses a great threat to human beings and the natural environment.Aiming at landslide debris flow disasters,based on the case of Huangyangkougou,Laomaoshan,the definition and formation conditions of landslide debris flow were analyzed,soil mechanics tests were carried out to obtain soil mechanical property parameters,and laboratory model tests were further established to simulate the influence of different conditions on the formation process and movement of debris flow.The movement process of landslide debris flow was divided into four stages.The discrete element software is used to carry out numerical simulation calculation to understand the trajectory and harm range of landslide debris flow deeply.The main research contents and achievements of this paper are as follows:(1)Study the geological environmental conditions of the study area,including the topography,meteorology,hydrology,stratigraphic lithology,etc.,determine the definition and classification of landslide debris flow,analyze the characteristic conditions of the landslide induced debris flow movement process,and provide a basis for systematically summarizing the movement law of landslide debris flow and scientific research and exploration.(2)Sample typical accumulated materials for soil mass in the study area for particle analysis test,direct shear test,permeability test,etc.,to explore the strength,deformation,permeability,stability and other characteristics of soil mass,so as to provide parameter basis for subsequent physical model tests,promote the exploration of the formation mechanism and movement law of debris flow,and improve the early-warning ability of debris flow.(3)The indoor flume experiment was conducted to simulate the movement process of debris flow,to study the influence of different gully slope and provenance composition on the initiation of landslide into debris flow after the formation of surface flow under the action of continuous rainfall,and to analyze the development laws of erosion failure pattern,gully development pattern,solid material accumulation morphology and particle size distribution characteristics in the provenance area.It provides the basis and support for the formation mechanism of landslide debris flow.(4)Through field investigation and data collection,combined with relevant mechanics theories,analyze the stress failure process of landslide transformation into debris flow,summarize the influence of various factors on landslide instability from the test phenomenon,discuss the movement track and the change law of harm range after transforming debris flow,refine the movement process of mud-landslide type debris flow,and conclude the movement law of slope transformation into debris flow.To provide scientific basis for emergency rescue work.(5)Combined with the engineering geological environment of the study area,the formation mechanism of landslide debris flow was verified by numerical simulation.Discrete element software was used to analyze the movement process of landslide debris flow under the influence of different gully slope and coarse particle accumulation with different content.The mesoscopic parameters were set to simulate the dynamic behavior of the particle system.The systematic evolution law of debris flow soil particles was predicted by monitoring the displacement field,velocity field,pore structure changes between particles and the change trend of contact force.It provides theoretical basis and technical support for engineering practice.In summary,taking the transformation of typical landslide into debris flow as the research object,combined with field geological exploration,data analysis and investigation,the whole process evolution of landslide transformation into debris flow under the influence of different gully slope and different particle content accumulation source area under the action of runoff was studied by using indoor flume experiment and numerical simulation.To predict the movement track and damage range of landslide debris flow,provide reference for the protection and treatment of landslide induced debris flow,and provide scientific basis for emergency rescue work.This paper has 72 figures,8 tables and 102 references.