Debris Flow Characteristics And Control Measures System Of Taiyang Gully In Miyun Beijing

Debris flow is a kind of geological hazard which is a great threat to human economic activities.Taiyang gully is located in sanchakou 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,Taiyang gully is a debris flow prone areas.In this paper,we choose Taiyang 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 Taiyang gully,the result shows:Taiyang gully's area is 4.14km2,the total channel length is 0.392km,the average gradient is 159.7‰,the largest relative elevation is 98.5m.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:Taiyang 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.The average particle size of d50 is 83.4mm,and the effective particle size of d10 is 6.78mm.(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 Taiyang gully's debris flow density,peak flow,once out of total amount,impact force of debris flow in detail.The results show that the Taiyang gully's debris flow volume weight is 1.57g/cm3,20 year frequency for debris flow is 31.779m3/s,a total of once rush debris flow is 1.54x 104m3,a total amount of solid matter once time is 0.502x 104m3,the largest single stone impact force is 5.952×104N,analyzing as above,the debris flow type of Taiyang gully is diluted,the scale of the outbreak is small.(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.The entire program investment estimate is 38.616×104yuan,and the construction period is from March 2018 to October 2018.