A Study On The Infiltration Characteristics And Stability Under Rainfall Condition Of The Cutting Slope Of Carbonaceous Shale

With the continuous development of social economy,there will be more highways,railways and other large-scale infrastructure construction in China,especially in the mountainous southwest which is rich in carbonaceous shale.Carbonaceous shale is a kind of soft rock;abundant in active organic compounds,making it easy to softening and disintegration.Under the condition of natural rainfall,the seepage flow field of the side slope changes,and thus has an adverse impact on the stability of cutting slope of the carbonaceous shale.This thesis is based on the seepage theory,and the author has carried on experiments on carbonaceous shale,thus getting its basic parameters on physical mechanics.Furthermore,the author analyzed the influences of rainfall infiltration on seepage characteristics and the stability of cutting slope,meaning to provide some reference value on engineering design,construction and preventive maintenance.(1)The sampling study on carbonaceous shale is mainly about the bulk volume density and triaxial compression test,thus obtaining a series of related testing results.The author uses the least square method and the random-fuzzy method to analyze the data,and gets the more accurate parameter values by using the latter method.By V-G model,the author gets the accurate fitting of the permeability coefficient of the non-saturation area and the volumetric water content,as well as the curve graph of the relationship among the volumetric water content,the permeability coefficient and the matric suction.The results laid basis for the calculation of seepage and stability in the following part.(2)Combined with engineering examples,the author built the corresponding model of cutting slope using the finite element analysis software Geo-studio(seep).Three schemes of rainfall are designed based on the reality of the experiment area after the study of the meteorological data.The regular patterns of the rainfall infiltration on water pressure of the pore and the volumetric water content are the main concern.The author found that rainfall has a relatively greater influence on the surface of the cutting slope than on other parts,and it is on this part that transient saturation zone appeared,and matric suction decreased.Furthermore,the cutting slope would be influenced in a greater way when the rainfall is in a greater intensity or lasts for a longer time,and by that way,there would be landslides and other unstable circumstances.(3)Based on the theories of Bishop and Fredlund,the author chose the method of rainfall infiltration stability analysis that fits his thesis.The regular patterns under different rainfall intensity and rainfall length as well as permeability coefficient of the safety factors of the cutting slope of the carbonaceous shale are found.