The Tendency Of Tuzhai Landslide Accumulation To Transform Into Debris Flow

As a destructive geological phenomenon,debris flow not only severely restricts the development of the local economy,but also poses a huge threat to the lives and property of residents.For the prevention and control of debris flow,forecasting is the core content and the focus of people's attention.At present,domestic and foreign scholars mainly have started with the topography and rainfall conditions,and achieved good research reasults in the prediction of debris flow.However,it is controlled by the source area,the difficulty of identification and uncertainty of loose debris,which also leads to the difficulty of forecasting and predicting the occurrence of loose source-debris flow.Therefore,there is less research on this aspect,and further in-depth research is need..Based on the large-scale landslide event in Touzhaigou,Panhe Township,Zhaotong City,Yunnan Province on the afternoon of September 23,1991,this paper uses a combination of data retrieval,on-site investigations,and indoor tests.The tendency of the existing deposits in the ditch to transform into debris flow(that is,slurry)was studied to evaluate the tendency of the loose source to be further transformed into debris flow.The research results provide theoretical guidance and scientific basis for the prevention and control and forecasting of debris flows in areas with the same provenance conditions.The main research results obtained are summarized as follows:1.The average slope of the surface of the accumulation is 14°.Under the action of frequent floods caused by rainfall and surface runoff,the fine particles in the accumulation in the middle and upper reaches of the basin are taken away,leaving coarse particles to form an anti-scouring layer to inhibit debris flow The occurrence of this can make the loose material in the watershed accumulate all year round.When the rainfall in the watershed increases and causes rare floods,the coarse particles on the surface of the accumulation body can be washed away,causing strong underground erosion of the gully bed,and further formation of debris flow.In addition,the coarse particles in the accumulation have good roundness and are rich in clay minerals,which can promote the transformation of the accumulation into debris flow.2.Pore water escape test shows that Touzhai loose debris slurry has a wider range of slurry formation than Jiangjiagou original debris slurry,and increases with the increase of upper limit particle size,which makes Touzhai loose debris possible as debris flow source.3.The pore water escape test and the excess pore water pressure monitoring test jointly show that the Tuzhai loose debris slurry prepared in the laboratory is better than the original Jiangjiagou debris flow in terms of pore water retention and excess pore water pressure retention.Soil slurry,which allows the coarse particles in the slurry to be suspended in the slurry for a long time,even far beyond the incubation or migration time of the debris flow.4.In the dry soil saturation test,the excess pore water pressure in the saturated soil dissipates quickly.Therefore,compared with the excess pore water pressure monitoring test,this requires the formation of excess pore water pressure in the water-detritus mixture,and external load disturbances must occur.This has external environmental requirements for the formation of debris flow.5 The rheological parameters of Touzhai loose debris slurry and Jiangjiagou debris flow original sample soil slurry are obtained through rheological test.By analyzing the resistance characteristics and rheological characteristics of slurry,it is concluded that the resistance characteristics of Touzhai loose debris slurry are helpful to the migration of Touzhai loose debris slurry,and the rheological characteristics are helpful to the formation of high volume and heavy viscous debris flow in the region The process of debris flow is analyzed.