| The accumulated soil in the spoil disposal site is mostly formed by long-term and large-scale spoil dumping during engineering construction.The spoil has obvious looseness,large deformation,and especially under rainfall conditions,the slope of the spoil disposal site is likely to become unstable.This paper comprehensively adopts methods such as model test and numerical simulation,focusing on the study of the seepage mechanism of engineering spoil accumulation under rainfall conditions,and based on the logistic regression model,proposes a landslide risk assessment method for accumulated soil under rainfall conditions.The main research results are as follows:(1)The value range of initial water head height and reading time interval in variable water head permeability test was studied.Based on soil particle gradation curve and variable water head test and other geotechnical test data,the evolution law of permeability coefficient,particle gradation and compaction degree was explored.A gradation equation suitable for engineering spoil was established,and a correlation expression between permeability coefficient,particle gradation and compaction degree was derived.(2)The effects of initial water content,compaction degree,rainfall pattern,rainfall intensity,and slope on rainfall infiltration were studied through indoor artificial rainfall model experiments and numerical simulations.The rainfall infiltration mechanism of the engineering waste soil accumulation was revealed.The results showed that under the rainfall condition of 70mm/d for three days,when the initial water content increased by 10% from 9.3%,the volume water content increment decreased by 46.7%,and the peak pore water pressure decreased by 88.9%.The larger the initial water content,the larger the surface runoff and the more severe the surface erosion.When the compaction degree increased to above 75.6%,the deformation rate of the accumulation decreased rapidly to a stable value.The infiltration rate of the first peak rainfall pattern was lower than that of the double peak and middle peak rainfall patterns.The middle peak and first peak rainfall patterns reached saturation first,and the accumulation had the strongest water holding capacity under the second peak rainfall pattern.When the slope reached 35°,the rainfall infiltration rate decreased to a stable value,and the rainfall began to be mainly lost in the form of runoff.(3)The Monte Carlo method is used to calculate the landslide probability under different rainfall conditions.Based on the six parameters of rainfall time,saturated permeability coefficient,rainfall intensity,slope and soil shear strength index,the logistic regression model is used to fit the landslide probability prediction formula by SPSS27 software,and the landslide risk assessment method of engineering slag soil accumulation soil under rainfall conditions is proposed.(4)Based on the actual engineering of the engineering waste soil accumulation in a waste soil disposal site in Beijing,the slope stability under three typical heavy rain conditions was analyzed,and the feasibility and accuracy of the proposed method were verified. |
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