Risk Assessment Of Debris Flow And Its Countermeasure In Lianhexi Gully,Yueyang County,Hunan Province

Debris flow is a kind of sudden geological disaster.Its occurrence and development are closely related to the topography and geomorphology of the disaster area.It is the product of the deterioration of the mountain envir onment and the imbalance of ecological balance.Debris flow is extremely harmful,and flows rapidly.At the same time,it carries large amounts of sand and rock.It seriously threatens the local ecological environment and people's lives and property.The two periods of large debris flows in the Dayunshan area of Yueyang County,Hunan Province,have caused a large amount of property loss and casualties to the local residents,and the direct economic losses are hundreds of millions yuan in 2011 and 2012.On the basis of the field investigation of the terrain conditions and the source conditions of the debris flow in the Lian he xi gully,Yueyang County,Hunan,this paper simulates and analyzes the movement characteristics of the debris flow.And the risk asses sment of it.The main research contents and results are as follows:(1)Through field investigation,the regional geological background of the Lian hexi gully debris flow is analyzed.It is concluded that the tectonic zone in this area is the second grade Alpine uplift zone of the Xinhua xia system,and the rock environment of the debris flow is the granite area under strong weathering.T he hydrological condition is poor in this area,and heavy rainfall is the main disaster inducing factor(2)The formation conditions of debris flow in the Lianhexigou gully are analyzed in detail.The forming area,circulation area,channel accumulation condition and water source condition of debris flow are summarized respectively.It can be seen from the analysis that there is no obvious boundary between the forming area and the circulation a rea in this area.In the event of debris flow,these substances are easily washed down downstream with water,causing harm to downstream residents(3)The dynamic characteristics of debris flow in this area are analyzed and calculated.It mainly includes bulk density,flow rate of debris flow,flow velocity of debris flow,total amount of debris flow and total discharge pressure of debris flow.(4)The RAMMS software is used to simulate the movement characteristics of the debris flow source in this area,and the movement parameters of the debris flow source are obtained,it is flow depth and flow velocity.and the simulation results are used to evaluate the hazard of the debris flow.(5)Effective control measures are put forward for debris flow hazard areas in this area.It mainly includes grid dam,block rock(mud sand)block dam,drainage ditch and other projects.