Study On Risk Assessment Of Guoquanyan Debris Flow

In recent years, for debris flow disasters we need launch Debris Flow hazardassessment and prevention in railways, highways, and other large-scale hydropowerand resource development, integrated watershed development. By using geologicalexploration data, first research the background of debris flows, development status ofdebris flows, distribution of debris flows, then use GIS technology which can rapidlyand scientifically assess the debris flow hazard so that we can reduce the loss of life andproperty of local residents at the maximum extent. GIS-based landslides investigationwill bring great convenience and improve the accuracy and efficiency of the workgreatly. We can find calibration, hydrodynamic conditions by studying topographicmaps and satellite photos. By using GIS, we can get the meteorological, hydrologicaldata and compute the catchment area more accurately. Through field surveys andinterviews, combined with satellite image analysis, mudslides solids formed mainly inthe source region, a small amount distributed in circulation in the region, there are threemain provenance: Slump provenance, provenance and channel slope provenance. Forexample mudslides treated pot ring rock solid source side is calculated totaled200,000m3, dynamic reserves of about69,400m3and there are about2.17×104m3provenanceinvolved in debris flow activity directly. With the GIS technology and field surveys, wecan get that the length of pot ring rock valley debris flow is about1.56km, the width ofit is about4-20m.The midstream and downstream of pot ring rock valley debris flow isnarrow, but the upstream of it is relatively wide. The ramp slope of pot ring rock valleydebris flow is generally20°～40°,but for the erosion and cutting of water, the Toeof it forms cliffs partially and the slope greater than30°generally. At the height of1380m and1480m, there are two larges lumped mass.Through sampling test, we can confirm that Guoquanyan Debris flow is thickslurry debris flow with the bulk density of1.47t/m3. According to the mostdisadvantageous situation combined with field investigation, we take the rate of valleydebris flow by QC=69.731m3/s. Through calculating the summation of the debris flow process and total solids contents, in accordance with debris flow activity lasted1hours in rainstorm, considering the most disadvantageous situation, the summationof the debris flow gully’s total solids contents is652.90m3one time. Whencalculating, take the most disadvantaged situation. Thus, building’s forming Stresssurface and debris flow’s stamping direction are perpendicular to each other. Whenconsidering the round building, taking the overall impact force of debris flow by2.21×103Pa.When considering the round building, taking the overall impact force ofdebris flow by2.94×103Pa.When considering the rectangular building, taking theoverall impact force of debris flow by3.25×103Pa.The risk assessment resultsindicated that, the Guoquanyan debris flow belong to moderately susceptible degree.On the basis, individually using the method of risk index and single debris flow riskassessment to assess the dangerous degree of debris flow, it turns out that the risk ismoderate risk, and it should cause enough attention. Finally, according to the assessresults and geological conditions of landform, it suggested us to take―Soldier piles+anti scour wall+Sediment Storage dam+mud avalanche ditch+silting dam‖governance measures. This research has a good application prospect in urbanconstruction of mountain area, Major state construction project, Comprehensivedevelopment and programming of drainage basin of risk assessment of debris flow,Disaster prevention and mitigation.