Experimental Study On Influencing Factors Of Shear Strength Of Saturated Remolded Loess And Discrete Element Analysis

As a special kind of soil,loess is usually characterized by structural features such as macropores,weak cementation and the development of joints along the vertical direction.In view of its particularity,the decrease of strength and saturated failure result in the occurrence of loess landslide,bringing serious disasters to local people due to heavy rainfall and irrigation.Because many factors affect the shear strength of loess,and a lot of experimental studies on different factors such as the matric suction,water content,and shear rate are conducted and analyzed the influence of various factors on the shear strength parameters.Based on the existing research results,the back wall soil taken from Dangchuan landslide is taken as the subject.a series of saturated tests and consolidated undrained(CU)tests were conducted on remolded samples by modified.The shear rates set as 0.02mm/min,0.06mm/min,0.2mm/min and 0.4mm/min respectively with different pressures of 50 kPa,100kPa,200 kPa and 400 kPa,respectively.Respectively under different confining pressure and shear rate on the stress,strain results are reshaping of saturated loess corresponding stress-strain analysis and strength characteristics analysis,study of confining pressure and shear rate on saturated reshape the shear strength of loess are studied.The discrete element simulation parameters were selected according to the parameters obtained in the experiment.The confining pressure and shear rate were used to study the shear strength of saturated remolded loess in PFC 3.0.The conclusions are as follows:(1)There are two stress-strain behavior of saturated remolded loess in CU tests,weak strain softening and strain softening.The faster the shear rate is,the more obvious the softening is.(2)The confining pressure and shear rate have a great influence on the shear strength of the saturated remolded samples.The shear strength of saturated and remolded loess will gradually increase,and then gradually decrease after reaching a certain value the increase of shear rate under the same confining pressure.The shear strength of the saturated remolded loess increases with the confining pressure increase gradually under the same shear rate.(3)Under the same dry density and confining pressure,the total cohesion and effective cohesion of saturated remolded loess decrease first and then increase with the increase of shear rate,and the total internal friction angle and effective cohesion The friction angle first increases and then decreases with the increase of shear rate.(4)Discrete element numerical simulations show that the soil under different conditions shows a weak-softening and softening stress-strain curve.The shear strength of soil increases with the increase of confining pressure and shear rate.The test results in this paper can provide some basis for forecasting and scope prediction of loess landslides in the study area,and the PFC3.0 simulation results and rules can provide some reference for the analysis of soil mechanical behavior and the subsequent numerical simulation of PFC3.0.