Research On Clay Particles Content For Initiation And Atastrophe Mechanism Of Debris-flows In Jiangjia Ravine

According to the grain size of debris-flow soil in Jiangjia Ravine, it's gravel soil with wide grain size, though clay particles content among it was not much, the initiation of debris-flow is obviously impacted by it because of its huge surface area and the hydrophilic. Graduation of soil for debris-flow initiation is very important for exploring the catastrophe mechanism of debris-flows. Debris-flow soil in Jiangjia Ravine is regarded as subject investigated in the paper, the factors impacting the initiation of debris-flow are studied by investigation, collection of information, physical and chemical experiment, indoor model experiment. the mechanical behavior of gravelly soil is studied by triaxial test, some experiment phenomena is explained, initiation model of debris-flow is established by mutation theory. Experimental results and on-site phenomena are combined, failure pattern and catastrophe mechanism of debris-flows are explored. The main research content is as follows:1. Topography, geology, geomorphology in Jiangjia Ravine is investigated and statistically analyzed, its special development environment and exceptional conditions for the formation of debris-flows are disclosed.2. the physical and chemical properties of soil in Jiangjia Ravine are studied by sophisticated equipment, clay mineral composition, chemical composition, grain size, ESP(Exchangeable Sodium Percentage), dispersion degree, seepage characteristic, the salinity and hardness of groundwater are included. The internal links between initiation of debris-flow and the properties mentioned above.3. Three type of samples were treated by equivalent substitution of grain diameter before triaxial test. Based on the result of different density, different graduation under undrained condition, the character of stress-strain, pore-water pressure and stress path are analyzed, index of shear strength and relational expression in different density, different graduation are obtained, they can be used for theoretical analysis and model experiment explaining.4. Susceptibility of debris-flows in different graduation, different density, different rainfall intensity, different slope angle are studied by self-designed model groove. meanwhile, the criticality of clay particles content and the impaction of grain migration for debris-flow initiation are studied. The "influent ratio" is introduced in model test and the relationship between "influent ratio" and susceptibility of debris-flows is studied.5. the formation process of debris-flow are divided into five stage by model test, physical and chemical test, triaxial test. The failure pattern and catastrophe mechanism of debris-flows are studied in condition of much clay particles, strong rain and few clay particles, weak rain.6.Combining the experiment results and the sudden breakout of debris-flow, the failure model are founded by mutation theory, the relational expression between shear strength and clay particles content, dry density and water content that obtained by experiment is embedded into the model, the applicability of it is improved. It provides theoretical support for debris-flow prediction...