Experimental Study Of The Starting Conditions Of The Basic Characteristics Of The Typical Debris Flow In Guizhou Province

Guizhou Province is located in the east of the Yunnan-Guizhou Plateau,where is aslope zone, Guizhou Province is typical of the mountainous province,because of theterritory of complex terrain, undulating hills.The area of Guizhou ’s total land isapproximately176,000square kilometers, which accounted for87%of the total area ofmountainous area. Guizhou Province is a typical karst mountainous,whose karstlandforms accounted for73%of the province’s land area, when the storm season iscoming every year,the surface water is violently in stormrain,Which Will take away alot of loose soil,causing serious soil erosion. Especially in steep mountainous terrain, itis easy to induce landslides and debris flow. Also Guizhou is one of the debrisflow-prone areas.By understanding the geological environment background in Guizhou Province,firstly to fix108debris flows in Guizhou Province DEM map,which is from《2006-2008mountainous hilly county (city) Census of geological disasters inGuizhou Province》,then from the terrain, lithology, structure, climate, hydrology,vegetation and human production activities to analysis on the factors of the distributioncharacteristics of GuiZhou debris flow, secondly by the results of analysis,Guizhoudebris flow is mainly distributed in the Bijie-Anshun area, Zunyi-Tongren area, andSoutheast and South of Guizhou. And there is an investigation in the houchang town ofBijie-Anshun area,by the nine of debris flow gullies Surveyed,the author did theexploration survey work in the field and carried out a detailed survey of four typicaldebris flow, sampling for particle analysis in the channel forming region. In order toobtain the typical study of a typical debris flow channel material starting conditions of the physical simulation experiment, the relationship between flow and depth of thecoarse layer thickness on the slope of the gully bed, single-wide to analyze the studyarea, typical debris flow starting conditions of the gully. The conclusions following:(1) There is the survey that9debris flow gully of hongchang town in the studyarea, the loose material of gully bed is more abundant, the main source for the upstreamerosion and channel cross-strait collapse. After measurement, the regional debris flowgully bed slope range is concentrated between12°~24°, the gully bed material particlemedian diameter D of about10mm, the coefficient of uniformity Cu values is morethan20,is a non-uniform sediment. Combined with the live survey, when it is1991and1996years due to heavy rainfall occurred in mudslides, the region has year-roundrainfall intensity, the channel surface clay was washed makes the surface mainly in thelarger size particles, and its rounded degrees in general.(2) After the formation condition in the study area are typical debris flow gulliesobtained:①the region for the distribution of karst areas, lava and non-lava and white,the formation of the the Zhongshan valley terrain. Mostly surrounded by mountains,multi-tributary confluence, the channel forming region longitudinal drop larger, easy toconfluence on the formation of the strong impact of the district;②The stormrain isfocus on a year, providing a good starting conditions to the outbreak in the debris flow;③the lithology of the study area is mainly Permian limestone and clastic rocks, andthe basalt-based is from rainfall-surface water along the limestone joints surface orfracture surface corrosion.(3) The gradient of debris flow channel to the physical simulation experimentswere conducted in12groups.respectively, from the slope of the gully bed, Debris Flowdepth, the coarse layer thickness and the single-wide-discharge analysis, the debris flowstarting depth and the single-wide-discharge obtained in the gully bed.Thesingle-wide-discharge and the starting depth are linear negative correlation with thethickness of the coarse layer in the different gradient of debris flow channel. In theapplication,by the method of finite difference,the related formula will be obtained in thegradient related,then,the thickness of the armoring layer is substituted in the relatedflrmula,the starting depth and the starting discharge,so in order to predict the DebrisFlow.