Investigations Instability Mechanism And Accumulations Morphology Of Soil-rock Mixture By Rock Distribution Under The Difference Rainfall

China is one of the countries with frequent occurrence of geological disasters such as landslides and mudslides.The soil-rock mixture often deforms instability under the rainfall,which directly threatens people's lives and property.Due to the different structures of soil and rock in the slope,caused there were significant differences in disasters.In particular,the soil-rock mixture by rainfall of complicated boundary conditions influenced with multiple factors is more sudden and destructive,and further investigation.Meanwhile,the concept of the criterion of deformation and instability of soil-rock mixture by rainfall is not clear,and further research.Therefore,investigate the instability mechanism and accumulation form of soil-rock mixture with the distribution of rocks under rainfall has very important practical significance and social value for the prevention and control of the landslides and mudslides.In the present study,based on the researched results of scholars,and according to the field survey results and literatures data self-organization constructed a soil-rock mixture model platform under the rainfall,and carried out physical model experiment of three factors and four levels of the rocks spatial distribution,rainfall intensity,and slope.Analyzed the instability modes of the slope with different rocks spatial distribution,and the changes law of macro-deformation characteristics including the displacement,tension cracks,erosion channel,slides area and accumulation form et al.of the slope with each instability mode.In addition,this study revealed the internal relationship between the sliding area of slope and the accumulation form after sliding,provided the mathematical equation that the sliding characteristics value of slope index to evaluate the post-disaster characteristics value of accumulation form,provided the multiple criteria for the deformation and instability of the soil-rock mixture under the rainfall,and discussed the sensitivity of various influencing factors(including the rocks spatial distribution,the rainfall intensity,and the slope)to the deformation and instability of soil-rock mixture by rainfall.Furthermore,numerical simulation was used to investigated the response mechanism of soil-rock mixture infiltration by rainfall,and the experimental results were used to verified the numerical simulation results.The conclusions obtained in this paper are intend to provide references for prevention and controling measures of geological disasters such as soil-rock mixed landslides by rainfall in mountainous,and to provide ideas for in-depth research on the theory,experiment and numerical simulation of various slope deformation and instability mechanisms.The mainly results showed that:(1)The four types of significant failure modes of slope instability with different rocks spatial distribution including the cracking-sliding,the erosion-gully erosion,the slope toe sliding-surface erosion,and the gully sliding-surface erosion.(2)The active period of the displacement growth of the slope with each instability mode were the early rainfall period,and the slope top vertical displacement is more obvious than the slope surface.Both the main tension cracks and the erosion channel of the slope increase with the increase of rainfall duration.(3)Slope sliding characteristics and accumulation form characteristics both increase with the increase of rainfall duration,and rainfall damages its width and length more significantly.The final accumulation contour from largest to smallest is: top layer > rear edge > middle and lower layer > front and middle.(4)As the rainfall intensity and slope increase respectively,the mean values of te(crack),tu(crack),t'e(crack),and t'u(crack)decrease.The slope factorhas the most significant impact on the discrete degree of the instability result of the soil-rock mixture by rainfall,followed by the rainfall intensity,and the rocks spatial distribution is the smallest.The slope has the most significant influence on the significance level of the multiple criteria for deformation and instability of the soil-rock mixtures under the rainfall,and its influence on slope surface sliding is more significant than that on tension cracks.