Hazard Mechanism And Risk Assessment Of Debris Flow In Chezhou River In Shangri-La City

Shangri-La County,Yunnan Province has a unique geographical location,and the main terrain is the Hengduan Mountains.The geological structure of this area is complex and diverse,and there are large faults in the longitudinal direction.In addition,the freezing and thawing effect strongly promotes the weathering and fragmentation of rocks,and becomes a geological disaster in Yunnan Province,especially the debris flow.High incidence area.There were many debris flow in the Chezhou River in Shangri-La County from 1960 to 2015.In particular,debris flow occurred in 1998,causing one person to disappear,causing damage to farmland,villages and roads.The collapse of many shores endangered the safety of coastal residents.Therefore,the study of debris flow is very significant for hazard prevention and mitigation.In this paper,the debris flow of the Chezhou River is taken as the research object.Through the field investigation,the development characteristics,formation conditions,hazard mechanism and the stability of the debris flow are analyzed.On this basis,the debris flow control measures are proposed.The main work and research results of this paper are as follows:(1)According to the geological environment background of the Chezhou river,the three basic conditions of topography,provenance and precipitation formed by the debris flow of the Chezhou river are comprehensively analyzed,and the debris flow formation zone,circulation zone and accumulation zone are divided.The type of debris flow in the Chezhou River is medium-sized,low-frequency,gully-type,and dilute debris flow.The formation mechanism is that the loose deposits of the gully bed start to form a debris flow,the soil and stone mix with the water to form a debris flow,and the loose sediments and the water mix to form a debris flow.(2)According to the relevant norms and formulas,the dynamic characteristic parameters such as flow velocity,peak flow,impact force,climbing height,maximum flushing height and total amount of primary process are calculated for the debris flow risk assessment and prevention engineering design.Reference.(3)Using the comprehensive index method,the development stage of the debris flow,the degree of susceptibility,activity and hazard,and the risk of debris flow were predicted.The research results show that the Chezhou River is in the stage of debris flow,the debris flow are easy to develop,the damage is large,the risk level is medium,and the possibility of disasters is large.(4)According to the characteristics of the debris flow of the Chezhou river,corresponding prevention measures are proposed to provide reference for the prevention and control of debris flow.