Experimental Study On The Lateral Response And P-Y Curve Of Negative Batter Passive Piles

In engineering,when batter piles are used as lateral restraint structures,partial lateral load can be converted into axial force of piles,which has obvious advantages in resisting horizontal deformation and slip of soil,but its working mechanism is still unclear.The model test was used to study the passive load response of batter piles under lateral load on sandy soil foundation.Single piles with different inclination angles and pile bottom constraints were set respectively.The horizontal displacement,pile strain,soil pressure and elastic resistance of single pile under vertical load of soil behind the pile were tested.The p-y curve and its fitting curve characteristics were analyzed,providing experimental basis for further research and application of engineering properties of passive batter piles.The results show that:(1)The peak value of earth pressure in the loading area of passive batter pile is located in the upper part of the pile.The position of inflection points moves up with the increase of batter angle and pile bottom constraint.The peak value of earth pressure at the upper part of the inflection points decreases with the increase of batter angle and enhanced pile bottom constraint,and the peak value of earth pressure at the lower part of the inflection point moves up with the increase of batter angle.(2)The peak soil resistance of passive batter pile decreases with the increase of batter angle,and the peak position moves down with the increase of batter angle.The peak value of soil resistance before pile decreases with the enhanced constraint degree of pile bottom,and the peak position moves up with the enhanced constraint degree of pile bottom.(3)Under the vertical load behind the pile,the straight pile is "translation+large rotation around the bottom of the pile",and the batter pile is "translation and rotation around the bottom of the pile".The translation and rotation decrease with the increase of the batter angle and the constraint degree of the pile bottom.(4)The passive batter pile generally occurs bending failure in the middle of the pile,and the passive embedded batter pile will occur bending failure at the embedded point.The failure load increases with the increase of batter angle.Embedding the bottom of the pile into the hard bearing layer will significantly increase the failure load.(5)The p-y curve of passive batter pile can be fitted by formula P/Pu=α(y/y50)β,and the a at each monitoring point varies from 0.45 to 0.54.The a changes of straight pile,10° batter pile,20° batter pile and 20°embedded batter pile are 0.03,0.05.0.03 and 0.05,respectively.βof each monitoring point varied from 0.36 to 0.90,and β of straight pile,10° batter pile,20°batter pile and 20° embedded batter pile varied by 0.18,0.37,0.41 and 0.3,respectively.The batter angle and constraint degree of pile bottom have little effect on α,and the variation range of β increases with the increase of batter angle and decreases with the enhanced constraint degree of pile bottom.(6)Increasing the batter angle of the slope foot pile and embedding the bottom of the pile into the hard bearing layer will significantly reduce the rotation,translation and horizontal displacement of the batter pile.The batter pile at the slope foot will reduce the embankment settlement by 0.020(θ is the batter angle,unit:degree).Compared with the non-rock-socketed batter pile,the rock-socketed batter pile at the slope toe will reduce the embankment settlement by 0.03θ.