| By collecting meteorological,geological,mountain hazards and socio-economic data in and around the study area,the background of the study area is known.Field investigation of the use of GPS precise positioning,determine the quantity and distribution characteristics of basin source later through the application of ArcGIS software,geographic parameters in the study area to be obtained,and in the valley of DEM figure,deposit type and distribution of land use on landslide development characteristics in the study area the intuitive and detailed analysis.Comprehensive analysis of Nangouzhang valley topography condition,material sources and hydrodynamic conditions,determine the research area of the basin area of 2.13 km2,main channel is 1353 m long,relative height of 218 m,average longitudinal grade 161.1 ‰.Research area has five branch lander,large difference between each branch lander source conditions,including 2 branch lander has obvious characteristics of debris flow development within the remaining three branch lander good vegetation development,slope stability,solid source rarely dynamic reserves.Research focus in the study area in the main channel and the 2 branch lander,solid source of dynamic reserves of 47200 m3,about 19300 m3,the slope source channel source is about 27900 m3,content rich source distribution,and under certain conditions to inspire potential hydrodynamic conditions of debris flow.The fluidity of debris flow is judged and the kinematic parameters of debris flow are calculated by formula method.According to the content of mucous particles,the volumetric weight of the mudslide in Nangouzhang valley is 1.55g/cm3,which is a rare debris flow.The dynamic parameters of debris flow during 20,50 and 100 years of recurrence were obtained by rain-flood correction method.According to the results,in 20 years,the flow rate of the first mudslide was 33.54m3/s,the total amount of the first mudslide was 295,100 m3,and the total amount of the material from the first mudslide was 0.95,500 m3.In 50 years,the total amount of solids discharged from a mudslide once was 15,600 m3.A reference form to determine the potential mudslide in Nangouzhang valley is a mountainous,low-frequency,low-rainfall-medium-size mudslide.Nangouzhang valley development by the interference of human activities destroy,engineering control and management for the train of thought,research to engineering measures and biological measures and management measures are put forward with the combination of prevention and cure measure system is designed,the debris flow disaster prevention in Beijing mountain area and the practice of small watershed comprehensive control research has important significance.The grade of design and prevention of engineering measures was determined to be level 3.The design standard was once every 20 years and once every 50 years.Three gravity sand bar DAMS and one drainage channel were built in the basin.The total interception amount of the three sand bar DAMS is 19,900 m3,which is greater than the total amount of primary solid under the design standard and the checking standard,and conforms to the design standard of prevention and control.The biological measures include the closure of mountain forests and the rehabilitation of terraces.It has been estimated that the total investment of the mud-rock flow prevention and control measures of nangou zhaigou is RMB 753,600 yuan,and the project construction period is planned to be from March 2019 to November 2019,for a total of 9 months. |
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