Experimental Study And Numerical Analysis On Rainfall Infiltration And Drip Irrigation Of Fractured Loess Slope

Water is an important factor inducing loess landslides.Infiltration,deformation and failure characteristics of the loess slope and the evolution of the fissure over duration were examined in the laboratory.Changes in water content,pore-water pressure,and matrix suction in the soil were monitored.Deformation and failure process of the loess slope model was analyzed,and the experimental results were compared.The drip irrigation experiment of 60 ° and 45 ° loess slopes was carried out.The effect of irrigation on the loess slope stability was studied.The soil-water characteristic curves of the loess were obtained by the pressure plate experiment.Based on the seepage theory and elastic theory,the two-dimensional hydro-mechanical model in unsaturated soils was established.The equations of coupled seepage and deformation in unsaturated soils was computed using COMSOL Multiphysics.The evolution characteristics of seepage and displacement in unsaturated soils slope were examined.The numerical method was used to explore the rainfall infiltration problem of the loess slope.The experimental and calculated results were compared.The conclusions are drawn as follows:1.During the rainfall,tensile cracks were produced around the pre-crack,and the multi-stage evolution is presented.The crack provides a path for water infiltration,the abrupt changes in pore-water pressure are often accompanied with landslides or local deformation of the slope.The pore-water pressure increases over duration,and the fissure affects water movement within the slope.The change in pore-water is more marked at the foot and the shoulder of the slope.2.In the drip irrigation test,the slope failure can be summarized as the local slope at the foot-local sliding at the shoulder-the overall sliding,where deformation at the foot and shoulder occurs repeatedly.The variation in the pore-water pressure is a main factor causing the landslide.Most of the slope cracks are firstly generated in the shoulder of the slope.The 60° slope slides earlier than the 45 ° slope.The sliding distance is further for the 60 ° slope.3.In the numerical model,the horizontal displacement becomes gradually larger over duration,however,the change rate gradually becomes slower.The maximum horizontal displacement occurs at the foot of the slope.The deformation is greatly obvious at the foot and shoulder of the slope.The fissure provides a path for the migration of water and the pore-water pressure changes significantly around the fissure.