The Failure Mechanism Of Irrigation-induced Slide-flow On Heifangtai Loess Platform

For the continuous expansion of economic development and population, water foragriculture is increasing. A large number of irrigation projects change the natural geologicalconditions of the irrigation district, causing ecological destruction, which triggered a seriesof geological disasters. The frequent geological disasters not only affect the sustainabledevelopment of agricultural production, but also bring great losses to people’s lives andproperties, where landslides is one of the most serious disasters.According to the characteristics of loess landslides kinematics, loess landslides aredivided into four styles: quick collapse landslides, rapid slide-flow, rapid long run-outlandslides and slow transitional landslides. The research chose the typical rapid slide-flow asthe research object, collecting the related hydrological and weather station data, usinggeological survey and mapping method and other means to identify the engineeringgeological conditions of the study area, and then proceed to indoor tests, studying thesaturated permeability coefficient, permeability coefficient under different pressures and thestrength parameters. After that, we make the parameters into SEEP/W、SIG,MA/W、SLPOE/W of GEO-Studio software, to analysis the seepage, stress and stability. The resultshows that with the rising of groundwater levels, soil pore water pressure is changing,resulting in redistribution of stress. When the water level rising to a certain extent, thepotential sliding surface soil is close to saturation, the landslide occurred.Based on the theory of fluid mechanics and three-dimensional landslide motion model,K.Sassa developed LS-RAPID which is appropriate for the simulation of the landslide, rapidslide-flow and debris flow. By ring shear test on soil sample points, we get the residualfriction angle, saturated undrained shear strength τss,estimating degree of pore waterpressure Bss,then simulate the movement process. From the result, we can get theinstantaneous velocity and scope of accumulation that is close to the actual situation. So thesimulation provides a basis for the prediction of the damage ability and disaster scopes.