Experimental Study On Characteristic Strength And Creep Characteristics Of Soil In The Slip Zone Of Creeping Slope

Jinpingzi landslide area?belongs to creep slope with obvious long-term creep deformation.This landslide is located on the right bank of the Jinsha River,about 2.5km from the dam site of Wudongde Hydropower Station.The landslide deformation instability mode mainly manifests as "loose traction" creep deformation and small-scale collapse in areas with high slope.The deformation of the landslide is closely related to the rainfall.The deformation rate of the landslide is relatively large during the rainy season.Frequent rainfall causes the groundwater level of the slope to rise.If a large amount of water stored in the slope cannot be effectively discharged,it will inevitably increase the large-scale instability of the landslide.The prevention measures of water interception and drainage should be considered to reduce the risk of landslide instability.The landslide is the key part of the landslide deformation.The nature of the landslide has a profound effect on the evolution of the landslide.In order to study the stability of the Apen-Xiongjiajing landslide,this paper takes the landslide soil of the landslide as the research object,and conducts triaxial compression tests and ring shear tests to control the drainage conditions to explore the characteristic strength change of the landslide soil.Using laboratory creep test methods,and by establishing creep soil creep models under different drainage conditions,the creep characteristics of the slip soil are studied,and the landslide is simulated with the help of FLAC3D software to analyze the evolution of the landslide.With a view to providing references for long-term stability analysis and prevention of instability of landslides.The specific research contents are as follows:(1)The physical and mechanical indexes of the slip zone soil were obtained by means of laboratory physical and mechanical tests.According to the triaxial compression tests under different drainage conditions,it was found that the slip zone soil would undergo strain softening under undrained conditions.Shear strength is greater than undrained shear strength.(2)The ring shear apparatus was used to study the strength characteristics of the slip zone soil under large shear displacements.The results show that during the shear process,the slip zone soil will soften after reaching the peak shear strength.As the shear displacement increases,The strength gradually decreases to the residual strength.In the shear test under undrained conditions,the strength attenuation of the slip zone soil is more obvious.(3)The "consolidation-shear-reconsolidation-reshear" ring shear test scheme was used to prove that the soil in the slip zone in the residual state has been consolidated over a period of time,and the lost soil structure will recover.The strength regeneration phenomenon occurs,and the strength after regeneration will be affected by normal stress and consolidation time.(4)By carrying out the triaxial creep test of the sliding soil sample in stages,the creep curve and stress-strain isochronous curve of the sliding soil under different conditions are obtained.Analyzing the creep law of the sliding soil,it can be found that unfavorable Drainage conditions will aggravate the creep effect of the slip zone soil;Singh-Mitchell model is used to fit the test data to obtain various model parameters,and an empirical model suitable for describing the creep characteristics of the slide zone soil is determined.(5)Based on the results of geological data and experimental research,FLAC3D was used to perform elasto-plastic simulation calculations without considering time effects and visco-elasto-plastic simulations considering time effects.And stress distribution.