Research On The Disaster Chain Modes Of Avalanche And Landslide And The River Blocking Dam Risk Assessment

This paper is the basic research on the type of disaster chain and the disaster pattern of landslide blocking and river valley in the mountainous area.The results can provide scientific and technical support for the major engineering projects in China,such as disaster prevention and disaster reduction,and ensure the smooth implementation of the project.Reduce the economic losses and casualties caused by geological disasters such as landslides and avalanches,and enrich and develop the theories and methods of study on the avalanche and landslide disaster chain.Layue landslide is the main support of the project.Through typical disaster research and data collection,it reveals that the mechanism of river blocking by avalanche and landslide disaster,proposes the disaster chain type and model of landslide damming.The whole avalanche and landslide disaster chain process is simulated by using the discrete element numerical simulation technology based on the field survey.The mode of Layue avalanche and landslide disaster chain are comprehensively analyzed under chain structure theory and source failure mechanism.The key problems of avalanche and landslide disaster chain are discussed in this paper based on disaster chain theory:(1)General rules and characteristics of the avalanche and landslide disaster chain has been summarized and The chain relation of landslide,debris flow,avalanche and complex geological disasters is briefly analyzed.The source of the avalanche and landslide disaster chain is classified into 4 groups.(1)It can be divided into completely river-blocking and uncompletely river-blocking according to the degree of blocking(long-time blocking is more than 1 year,and short-time blocking is less than 1 year).(2)It can be divided into landslide river-blocking disaster,avalanche river-blocking disaster,landslide ? debris flow river-blocking disaster,avalanche and landslide ? debris flow river-blocking disaster according to the cause of the disaster.(3)It can be divided into earthquake-induce,rainfall-induce,snow melting-induce and human activity-induce river-blocking disaster chain according to the inducing factors.(4)It can be divided into rock-landslide and soil-landslide river-blocking disaster chain.(2)The avalanche and landslide river-blocking disaster chain mode is summarized based on the disaster chain structure.They are:(1)“Avalanche ? Landslide ? Debris Flow ? River-Blocking” Mode;(2)“Landslide ? Debris Flow ? River-Blocking” Mode;(3)“Landslide ? River-Blocking” Mode;(4)“Avalanche ? River-Blocking”Mode;(5)“Landslide ? Debris Flow? Mudslides ? River-Blocking”Mode;(6)“Avalanches? Landslides? River-Blocking”mode.The theoretical analysis of disaster chain modes has been carried from forming condition,forming process,forming mechanism and dam failure analysis,etc.(3)The avalanche and landslide river-blocking disaster chain mode is summarized based on damage of disasters source mechanism.They are:(1)Outburst destruction disaster chain mode,(2)Toppling disaster chain mode,(3)Slip destruction disaster chain mode,(4)Horizontal push destruction disaster chain mode.The theoretical analysis of disaster chain modes has also been carried from forming condition,forming process,forming mechanism and dam failure analysis,etc.(4)The paper discusses the destruction influence factors of avalanche and landslide river-blocking dams.Three kinds of natural failure modes of avalanche and landslide river-blocking dam(the unstability of the dam crest overflow mode,piping,dam crest)and three ways of dam destruction(instant totally collapse,instant partial collapse and gradually collapse)are concluded.Propose the risk assessment methods of avalanche and landslide river-blocking dam destruction from risk assessment and vulnerability assessment.(5)The whole process of Layue avalanche and landslide river-blocking disaster chain is simulated by The discrete element numerical simulation technology(UDEC)based on the above analysis and field investigation.The disaster chain mode of Layue Disaster is analyzed through the principle of the chain structure and source failure mechanism.The risk assessment of Layue Disaster is also calculated from two aspects: risk assessment and vulnerability assessment.