| The soil-water characteristic of unsaturated soil mainly refers to the relationship between matric suction and volume water content,namely soil-water characteristic curve,which is one of the important curves to describe the constitutive relationship of unsaturated soil.The soil-water characteristic curves of different unsaturated soils are very different,especially the unsaturated loess,which leads to different seepage characteristics of unsaturated soils.Therefore,in order to study the influence of soil water characteristics on the seepage characteristics of unsaturated soil,the influence of soil water characteristics on the seepage and stability of loess slope under rainfall conditions was studied in the p aper,which was based on the relationship between classical model parameters and soil-water characteristic curves.The most widely used Gardner model,Fredlund&Xing model and Van Genuchten model were used to fit the loess soil-water characteristic curves,and the model expression is most suitable for describing the loess soil-water characteristic curves was selected.The influence of Van Genuchten parameters on seepage and stability of unsaturated ideal slope under rainfall conditions was calculated by Geo-Studio software.Finally,the influence of rainfall intensity and duration on the seepage and stability of loess slope in Baoji,Gansu and Zichang areas under rainfall conditions was studied.Based on the example of Yan'an high fill loess slope,the changes of seepage field and stability of yan 'an high fill loess slope were studied.The main work and achievements are as follows:(1)Soil-water characteristic curve data of loess in three regions were selected,and the soil-water characteristic curve of loess was fitted by Gardner model,Fredlund&Xing model and Van Genuchten model,respectively.It is found that three classical soil-water characteristic curve models can simulate the soil-water characteristic curve of loess well,and Van Genuchten model has the best fitting effect.(2)Some conclusions are obtained from the study on the influence of Van Genuchten model parameters on the seepage and stability of uns aturated id eal slope under rainfall co nditio ns,the change of parameter a is directly proportional to the seepage velocity in the process of rainfall.The calculation of slope stability under different rainfall conditions of parameter a shows that,as the value of parameter a increases,the safety factor is affected more and the range of safety factor changes more.The change of parameter b is inversely proportional to raimfall infiltration depth and infiltration rate.After the end of rainfall,the capacity of soil drainage is proportional to parameter b.The influence degree of safety coefficient is inversely proportional to parameter b.The change of parameter ?s is inversely proportional to the depth of infiltration,and the degree of influence on the safety coefficient is inversely proportional.The change of reference ?r has little influence on the variation degree of seepage field in soil,and it has little influence on the initial safety coefficient and the minimum safety coefficient,and the change of safety coefficient has little influence.(3)Based on the model parameters of Van Genuchten in three regions,the changes of seepage and stability of unsaturated loess slope in different areas were calculated by using Geo-Studio software.The effects of rainfall intensity and duration on seepage and stability of unsaturated loess slope under rainfall conditions are obtained.(4)The changes of seepage field and stability of loess slope of a high filling side in Yan'an under heavy rain and rain were calculated.n the process of rainfall,the natural loess slopes of profile 6-6 and profile 8-8 are in a stable state,the filled loess slope of profile 6-6 is in a stable state,and the filled loess slope of profile 8-8 is in an unstable state.It is found that the junction between the filled soil and the original slope surface is the weak place of the slope and prone to landslide. |
PDF Full Text Request