Effect Of Slope Geometry And Water Content On Three-dimensional Slope Failure Of Sandy Slope Model Tests

The slope stability problems,as one of the research hotspot in geotechnical engineering,are widespread in the water resources and hydropower engineering,highway engineering,railway engineering,mining engineering,urban construction and retrofit engineering construction.Slope stability analysis is gradually moving from a two-dimensional analysis to three-dimensional analysis which is more realistic situation.The crest load,as one of important factor,can not be ignored in stability analysis for bulldozers fill,excavation,railway slope,road slope,crest building activities.Therefore,accurate analysis and evaluation of the three-dimensional slope instability mechanism and sliding characteristics under the crest load is important to meet the exact requirements of engineering and excavation slope stability analysis.It is one of the important topics in geotechnical engineering research.In this study,a model test and numerical simulation was performed to study failure mechanism and the sliding surface characteristics of 3-D sandy slope.The tests considered the effect of slope geometry(flat?convex and concave)and initial water content.The main research findings are summarized as follows.1.The model test systems and measuring systems were designed for three-dimensional under the crest load.Four model tests were conducted using this model test systems and measuring systems.2.The failure of slope was induced by load at the slope crest.Top displacement and soil pressure of slope was recorded by LVDT and earth pressure cells,respectively.The location and shape of sliding surface was measured by sand layer measurement method.The failure process of 3D slope were analyzed.The tests considered the effect of slope geometry(flat?convex and concave)and initial water content.Result shows a depth understanding of slope failure mechanism.3.The effect of slope geometry(flat?convex and concave)and initial water content on failure process,failure patterns,the overall shape of failure slope,sliding surface characteristics,deep of sliding surface,range of Sliding,the degree of difficulty for failure is discussed through the comparison of the model tests.The main model test result are listed as follows.(1)The form of slope failure is three dimensional.The geometry of slope and initial water content had a great influence on instability characteristics and sliding mechanism.In order to get the location and three-dimensional shape of sliding surface,the model test used a 3D sliding surface measurement method by sand layer which can find the location of sliding surface,and then,using a software called surfer to develop a digital elevation model.The sliding surface is three dimensional shape.(2)The geometry of slope had a great influence on sliding characteristics.With the same height of slope,slope angle and initial water content,the concave slope can bear the maximum load,and the flat slope can bear higher load than the convex slope.The situation which slope can bear the biggest peak load of the crest of slope indicates the degree of difficulty for slope failure.The convex slope can bear the smallest peak load and it is most easily destroyed.Sliding surface of slope shows shallow landslide.The concave slope sliding surface is the most shallow,and the flat slope sliding surface is the deepest.In terms of sliding ranges,the sliding ranges of the concave slope is the biggest,and the failure ranges of the flat slope is bigger than the convex slope.Because of the geometry of slope,the volume of landslide had a great difference.The volume of landslide of the concave slope is the biggest,and the volume of the flat slope is bigger than the convex slope.(3)The response of soil pressure in slope have a good agreement with the crest loading force for four model test.And the stress increment is not obvious as the depth increases.The crest load can not affect this depth of slope.(4)The initial water content had a great influence on sliding characteristics.With a higher water content,slope can bear lower load than the lower water content,and it is easily destroyed.Sliding surface of G2 and G4 slope both show shallow landslide.The depth of sliding surface for G2 is more deeper than G4.With a higher water content,the failure ranges of the slope is wider and the volume of landslide is bigger.4.Numerical simulation by SVOffice was performed to study slope stability and the sliding surface characteristics.Water content,Load and slope geometry were analyzed by finite element method for slope stability and the sliding surface characteristics.With a higher water content,the shear strength is lower and slope is more instability.The crest load of slope increases the burden on the slope,the slope is more easily damaged.With the same slope height,slope angle,the concave slope is the most stable,and the flat slope is more stable than the convex slope...