Study On Prediction Model Of Shallow Soil Slope Gully Debris Flow In The Formation Of The Collection

At present,the research of debris flow is mainly based on the geological conditions,terrain conditions and rainfall conditions,this paper studies the shallow soil landslide from the gully debris flow formed from the three aspects.The terrain conditions and rainfall conditions are in use of the previous research results P=RT^0.45?R is a comprehensive rainfall condition,T is a comprehensive terrain condition,P is a debris flow hazard determination index?.In this paper,we mainly study the quantitative analysis of the geological conditions and the establishment of the integrated forecasting model.There are two points need to be explained in the quantitative process of geological condition,first,this paper studies the shallow surface soil landslide is rainfall type soil landslide;second,this paper studies the slope of the slope soil and slope soil.The geological factors mainly refers to the hillside soil properties and effects of the nature of these environmental factors,including the soil microstructure,macrostructure,material composition,the relationship of the soil particle gradation,and its permeability,and environmental factors including regional climate,rainfall,earthquake intensity,tectonic geology.Through research and analysis of the mechanism of landslide,in this paper,the influence of geological factors such debris flow is simplified as coefficient of permeability,considering soil fissure effect on the permeability coefficient.The traditional methods of obtaining the permeability coefficient of soil include the experience value method,the formula calculation method,the experimental method and so on,but these methods need a lot of field work to carry on.,so we build the lithology quickly obtain the permeability coefficient method.In the permeability coefficient of the process,according to the rock is hard,the weathering eluvial slope plot of soil permeability coefficient is generally greater such mechanism,the use of eluvial and alluvial soil of original rock solid coefficient of permeability coefficient quantization,draw up a dimensional penetration index calculation formula is K=k/k₀=2.59F²-8.64F.Among them K is the dimensionless permeability index k is the soil permeability coefficient,K₀ is the standard minimal permeability coefficient,F is the original rock solid coefficient;In consideration of fracture to influence the permeability coefficient.In this paper,we first study the clay minerals influence on fracture development,which proves that the content of clay minerals on the permeability coefficient have greater impact,and in the quantization process introduction of clay mineral specific surface area,finally,a dimensionless clay index is obtained.,Considering the influence of soil cracks,the mineral composition and content of clay as quantitative criteria of the degree of fracture,N=n/n₀ calculation method and gives the clay index,where n is the total surface area values of rock residual soil,n₀ is the standard minimum clay surface area value of 10 m²/g.In n the calculation method is divided into 5 steps,first according to the weathering grade map of the study area to determine the degree of weathering,and specific surface area within the research area of rock minerals weathering secondary clay minerals are determined according to the comprehensive degree of weathering,and then determine the composition and the corresponding content within the research area of rock containing minerals,finally calculate the content of rock with each kind of mineral values and corresponding weathering clay particle surface area value of the product,all in the rock mineral product value added to obtain the total rock surface area value of n,if a stream In the presence of a variety of rocks,the weighted average value of each n value is calculated as the n value of the basin;After quantification of clear geological factors,combined with previous to the terrain and rainfall conditions quasi synthetic fruit P=RT^0.45,this paper in Taiwan Chen you lan xi step by step to develop the two indicators of the geological factors.First,the terrain and rainfall and infiltration index were fitted.Model P=RT^0.45K^0.15.On the basis of join clay modified index,obtained the preliminary prediction model P=RT^0.45K^0.15N^0.45.Although a preliminary prediction model can better division of occurrence of debris flow ditch and without the occurrence of debris flow ditch,but Chan Lanxi in Taiwan to establish the forecasting model does not consider the rainfall variation coefficient and the critical P values may not be applicable to other areas.In order to establish in the country has good compatibility prediction model,using Guizhou Wangmo 2011 6.6 debris flow data,and in the condition of rainfall added 1 hour rainfall variation coefficient Cv,rainfall conditionsR=(?B+?5.5I?/?R₀Cv??.Eventually obtain general prediction model P=RT^0.45K^0.15N^0.45.And the corresponding critical value P₁=1.19,P₂=1.41,P₃=1.63.In order to determine whether the prediction model is universal,this paper selects Liaoning Xiuyan 4 times the mass of the data of debris flows and Sichuan Nanjiang 2015 debris flow data for verification.The results show that the final prediction model and the corresponding critical value in the four regions have good applicability.