| The slope of the accumulation body composed of soil-rock mixed media has a wide distribution in China.Due to the complexity and variety of material composition and structure of this type of slope,it has special physical and mechanical properties,among which the creep characteristics are particularly prominent.The deformation and long-term stability of this type of slope are of great significance.This paper takes the soil-rock mixture of the Hongshisi Village Landslide in Lushan County as the research object.Through large-scale triaxial creep tests and numerical simulations,the creep characteristics of the soil-rock mixture are revealed and the creep mechanism is analyzed.The main results and understandings are as follows:(1)The shear strength characteristics of the soil-rock mixture are obtained through conventional triaxial tests.It is found that the strength of the soil-rock mixture decreases significantly under saturation,which is mainly due to a significant decrease in cohesion.(2)The creep tests of different confining pressure(100kPa,200 kPa,400kPa),different stress levels(SL=0.2,0.4,0.6,0.8)and different water content(natural water content and saturation)are carried out in the soil-rock mixture of the Hongshisi Village Landslide with SZLB-4 Coarse Soil Triaxial Creep Instrument,and the graded loading creep curve of soil samples is obtained.The creep curves are used to analyze the main factors that affect the creep properties of the soil-rock mixture,and the long-term strength of the soil-rock mixture is obtained by analyzing the stress strain isochronous curve.(3)Through the observation of the shape of the creep curve,the "step phenomenon" of creep is put forward innovatively and the microscopic mechanism of creep is analyzed.It is considered that the creep of the soil-rock mixture is the dynamic equilibrium process of the transition from a "stable state" to another "stable state".(4)The Burgers model and the Mesri model are selected to fit the creep test curve of the soil-rock mixture,and the parameters of the model are obtained by analyzing the test curve.The model curve is plotted and compared with the test curve,and the constitutive equation which can predict and describe the creep law of soil-rock mixture is obtained.By comparison,the advantages and limitations of the Burgers model and the Mesri model are analyzed.(5)Using the CVISC model in FLAC3 D combined with the calculated parameters of Burgers model to calculate the landslide of Hongshisi village,the stress distribution,displacement change and plastic zone development of the landslide body are analyzed respectively.The simulation results are basically consistent with the actual situation of the landslide body. |
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