Sideslide Deformation Mechanism And Stability Analysis Of Pile Supported Embankment On Soft Foundation

The composited ground reinforced with rigid piles is used extensively because of high bearing capacity and convenient construction.However,most designs only consider the settlement problem,ignoring the stability problem at present.In the condition of soft soil on the inclined base,the problem of the stability and the disease for the subgrade gradually get the attention of the experts.Based on the three typical sections of the soft foundation in the southeast section of Fuzhou circle highway,three-dimensional geological model was established by ADINA finite element software and the concrete model was used to be pile materials.In this paper,the failure process and failure mode of piles during filling process and load action was studied.Then similarities and differences of pile damage characteristics under the elastic model and the concrete model.Final,soft embankment stability and failure mode reinforced by different types of piles.The main conclusions were summarized as follow:(1)The failure mode of the natural inclination soft foundation was different from horizontal soft foundation in the upper fill-loads.Potential sliding was produced on the top of fill,from interface for the soft and hard soil,end on the embankment foot.The vertical settlement mainly concentrated on the downhill side,the more closed to the embankment,the greater extent of settlement,and some soil uplift in embankment foot.The horizontal displacement was produced from the center of the embankment,along the soft and hard soil boundary,and then expands to embankment foot.(2)The failure of pile in soft foundation embankment is a progressive and dynamic process.The pile which is located in the toe was damaged first,and then the pile bear the external load by the residual strength due to the strength and stiffness reduced.So the upper load was shared by neighboring pile.The pile under inclined soft foundation embankment damaged successively from the toe to the center.(3)The mechanism of skid resistance in pile at different position was different.The pile in lateral toe bore bending moment and tensile stress mainly,the pile at the foot bore bending moment mainly and shear stress less,the pile in the shoulder bore bending moment and shear stress mainly,the pile at the center of the embankment bore bending moment and compressive stress mainly.The horizontal displacement in embankment foot and the settlement quantity in center were greatest.The pile occur bending failure other than shearing failure.The different positions of the pile body is divided into five zones according to the failure mechanism,including tension bending zone,push bending zone,flexural shear zone,compression bending zone,bearing zone.(4)The deformations of pile and soil were inconsistent,which produce a large number of negative frictions,then caused the separation of cap and soil,also the local separation of pile and soil,the decrease of global bending resistance or even the destruction of pile in the zone of separation were most likely to happen,It brings some hidden troubles for the overall shear failure in the pile supported embankment(5)Elastic modulus keeps invariant when pile material used by elastic model,it leads to unable simulate stiffness and strength decrease of the pile due to damage.Comparing result showed that the progressive and dynamic process of pile was exemplified by concrete model.(6)The pile soil composite occur integral sliding due to low strength of sand pile,CFG pile has a certain compressive strength,the tensile strength and bending strength of PTC piles are lower so that the bending stress and tensile stress are more important,Bored Pile has the high bending strength and compressive strength.