Study On Experiment Of Moraine-supply Debris Flow Initiation

The study which takes moraine-supply debris flow in Moxi basin on the east part of Mt.Gongga Gongga as the example,applys the related theories and methods of Geology and hydraulics and adopts means of field investigation,indoor simulation test,field test and mathematical statistical analysis,has completed the design of the test program and carried out a flume experiment about debris flow initiation exciting by moraine soil in State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource & Hydropower,Sichuan University and a field experiment in Moxi basin based on deeply investigation of topography and geological structure and hydrometeor and glacial activity.Through the combination of theoretical analysis and experiment,we preliminary identify source converge model of moraine-supply debris flow in alpine mountain and its influence on debris flow's action.By analyzing the different require of hydraulic parameter in the experiment about under different experimental conditions,we reveal the mechanism of moraine soil initiating the formation of debris flow under different runoff conditions and the affection about runoffs infiltrating to moraine soil and erosion and continuous process of debris flow's trigger.In addition,we preliminary established a mathematical model based on the time of debris flow initiation(y)and the armoring process of(x).Research results provide scientific basis for the formation mechanism and.forecast of moraine-supply debris flow in alpine mountain moraine.The main achievements of this research are as follows:1.The accumulation model of source about moraine-supply debris flow is a combination among gravity accumulation,collection in branch's debris flow,freezing and thawing,with the latter two as the main types.The Source Converge model of freezing and thawing includes 3 kinds of cyclic modes: cyclic freezing thawing combination,seasonal freezing thawing combination and slope direction freezing thawing combination.It maintains the characteristics of "non-thick layer" on moraine material source of in gully,that's why moraine-supply debris flow has different initiated mechanism from the general hydraulic debris flow.2.The initiation process of moraine-supply debris flow: coarsening process of source surface formation of channel runoff initiation process of coarse particles.The formation of channel runoff is the result of deep erosion and destruction of the surface of the source,which provides favorable conditions for the initiation of coarse particles.Coarse particle priming indicates the triggering of debris flow,and the flow of debris flow is continuously enhanced by means of lateral erosion and vertical erosion.3.The erosion of moraine-supply debris flow source is the result of basement's damage of coarse particles which consists of fine particles.The runoff erosion rate is greatly increased between the coarse particles,leading to the fine particles start-up and the coarse particles exposed.And stationary will start up because of the loss of the substrate support.4.The debris flow slurry and erosion surface always maintain a wavy morphology in longitudinal section during eroding process of debris flow to source,whose position of peaks and troughs is not fixed,but shows almost the same characteristics of coordinated changes.The erosion of gully bed is mainly concentrated in the wave trough with high permeability,and the whole process is characterized by "infiltration first and erosion first".With the increase of mud erosion intensity,the wave height and length of both water ebris flow slurry and erosion surface also increase.5.The relationship between the time of moraine-supply debris flow initiation(y)and the source coarsening process duration(x)model: y=3.5x.This shows that,although there is difference about the source's distribution of particles and the hydrodynamic conditions when debris flow initiation,the time of moraine-supply debris flow initiation always subjects to the time of the source coarsening process duration in specific priming conditions,and a certain functional relation exists between the them.