Stability Analysis And Reinforcement Research Of Loess Slope Under Rainfall Infiltration

As one of the more geological disasters in China,the instability and failure of loess slope will cause immeasurable losses once it occurs.According to the statistical data of loess landslide,when the landslide occurs,it is mostly accompanied by the formation of rainfall.Therefore,it is of great significance to study the failure mechanism and stability analysis of loess slope under rainfall.Taking a loess slope in Baota District of Yan’an as the research object,this paper uses the combination of theoretical analysis,indoor test and numerical calculation to analyze the seepage,adopts the combined support of pile and anchor to reinforce the unsafe slope and optimize its design parameters.The main results are as follows:(1)Through the saturated unsaturated seepage theory,the rainfall infiltration model Green Ampt model is optimized,the relationship between wetting peak depth and time is obtained,and the slope stability analysis model is established.(2)The basic characteristics of landslide are obtained through geological exploration,and the influencing factors of loess slope instability are analyzed.The undisturbed soil samples in the study area are collected,and the soil water characteristic curve is measured by indoor test filter paper method.It is determined that the most suitable soil water characteristic curve model is Van Genuchten model.(3)Using MIDAS/GTS to analyze the changes of seepage,deformation and stability of loess slopes under different rainfall factors(rainfall type,rainfall intensity and rainfall duration),the results show that when the rainfall types are different,the pore water pressure increases with the increase of rainfall time,and the slope safety factor decreases gradually with the continuous rainfall.The later the rainfall peak appears,the more unfavorable to the stability of the slope.After the rain stops,the slope safety factor still decreases slowly,indicating that the impact of rainfall on the slope has a lag effect;When the rainfall intensity is different,with the continuous increase of the rainfall intensity,the increase of the slope pore water pressure gradually increases,the rainwater infiltration range gradually expands,and the slope safety factor decreases.The safety factor has only a small reduction,and the slope safety factor is greatly reduced under heavy rain and heavy rain conditions;When the duration of rainfall is different,the duration of rainfall is positively correlated with the variation range of pore water pressure,and the range of rainwater infiltration expands with the increase of rainfall time.The safety factor decreases rapidly in the initial stage of rainfall and slowly in the later stage.(4)Adopt the form of prestressed anchor cable combined with anti slide pile support to strengthen the slope,optimize the anchor cable design parameters(prestress size,anchor cable layout angle and anchor section length),select the optimal reinforcement scheme,and verify the rationality of the scheme through simulation calculation.