Study On The Stability Of Loess Slope Under Rainfall Infiltration

Most loess slope failures will follow by the rainy season in northwest regions. Modelingthe effects of rainfall on the stability of unsaturated loess slope and forecasting geologicalhazards is an urgent and complicated engineering problem worldwide.The distribution of pore water pressure and suction will change by the infiltration of soilwater constantly in process of rainfall.And then which lead to the changes of shear strengthof the soil, meanwhile, the depth of infiltration by rainfall also affected to positioning thelocation of the sliding surface as slope instability. The conventional slope stability analysismethod based on the saturated soil and steady saturated seepage theory is difficult to reflectthe influence on infiltration of rainfall to slope instability.This article selected the niujiaogou landslide in xi’an city as the research object.Firstly, based on the site investigation in the landslide area, discussed the environmentgeological conditions and the engineering geological characteristics of this landslide.By usinglimit equilibrium method, calculated the side slope stability considering different workingconditions.On this basis, analyzed the causes of the landslide.Secondly, explained the fundamentals of saturated–unsaturated seepage, simulated theseepage field of the landslide under different engineering condition by the GTS software,finally got the pore water pressure and the seepage speed of different depth in this slope.Combining with In situ test data and simulation results defined the rule of rainfall infiltrationand slope suction changes.Finally, by using the finite element strength reduction method, carried on the seepage-strain coupling analysis, obtained the side slope displacement and the plastic area distributionunder the condition of different rainfall holds; Further more,used the improved limitequilibrium method of unsaturated soil to obtain the most dangerous sliding surface under theaction of rainfall infiltration.At the end, analysed the loess slope stability under the action ofrainfall infiltration by using the seepage-strain coupling analysis and the seepage-limitcoupling analysis at length. Research results can not only provide basis for practical design, but also make guidancefor forecasting the qinling mountain geological disaster and reducing landslide hazard.