Debris Flow Characteristics And Control Engineering Plan Of Mengsenglang Gully In Miyun Beijing

Debris flow is a kind of geological hazard which is a great threat to human economic activities.Mengsenglang gully is located in Fengjia village of Miyun district,Beijing.It's located in the windward slope of rainy area,affected by Miyun reservoir,the local climate rainfall concentrates;at the same time,there are lots of deposit in the gully,with rich water and source conditions,Mengsenglang gully is a debris flow prone areas.In this paper,we choose Mengsenglang gully's debris flow as the research object,through field investigation and consulting related disasters based on the study on the history,doing depth analysis of the characteristics of debris flow development,aims to put forward a set of scientific and effective prevention of debris flow engineering design system.The main work and conclusions are as follows:(1)Using debris flow scene survey,the construction of digital elevation model and other methods to obtain the basic parameters of Mengsenglang gully.Effected by the comprehensive geological structure and various forces,the slope is steep,gully is U,and the source material is rich,prone to debris flow.(2)In the study area,we collected the accumulation of particles obtained and after the analysis of experiment,we know that:Mengsenglang gully's debris flow accumulation boulders,gravel and boulders,gravel soil with different particle size components were 9.09%,27.21%,45.5%,18.2%,particle composition discrimination,which accounted for most gravel.(3)Using the relationship of clay and bulk density of solid particles in debris flow,rain and flood correction,statistical model and other methods to calculate Mengsenglang gully's debris flow density,peak flow,once out of total amount,impact force of debris flow in detail.The results show that the Mengsenglang gully's debris flow volume weight is 1.57g/cm3,20 year frequency for debris flow is 51.45m3/s,,the largest single stone impact force is 5.952×104N,analyzing as above,the debris flow type of Mengsenglang gully is diluted.(4)Using the method which combines civil engineering and biological engineering measures to design and control the debris flow prevention project.Using a 20 years' return design standard,50 years'return check standard,we propose to build a total of 3 dams in the whole watershed,the total storage capacity of the dams is 2.19×104m3,meeting the use requirements;building drainage groove 50m to smooth the excretion of debris flow;at the same time,implement biological engineering measures,such as afforestation and terrace repairs.