Research On The Influence Factors Of Lateral Response Of Pile Foundations

Piles are often placed within a group connected to a pile cap in order to constitute one and strong foundation that can support heavy structures located on the soil where engineering properties are not favorable for the use of shallow foundations.These piles may be subjected to lateral forces,vertical forces and even combined forces,in that case they exhibit some behaviors that need to be investigate in order to ensure the safety of structures.Research on the influence of the factors of lateral response of pile foundations is widely discussed by many researchers for safer and more economic design purposes.However,the prediction of the behavior of groups of piles is a very complex problem because it is governed by a lot of parameters such as soil,pile,pile-soil interaction,group effect and footing.This thesis firstly presents a field test on 2×1 double pile and secondly a three-dimensional finite element simulation done using Plaxis 3D Foundation 2013.This research is based on the horizontal static load field test of the double-pile cap,and mainly discusses the influence of the pile top constraint conditions,the horizontal force direction and the vertical load on the horizontal bearing capacity of the pile foundation,and provides a theoretical basis for future design work and reference.The field test revealed that as the vertical load on the top of the pile increases,the horizontal bearing capacity of the piles weakens,the influence of pile top restraint on the horizontal bearing capacity of double piles is related to the horizontal load direction,the horizontal bearing capacity of the double piles along the long and short sides of the cap has different responses to the vertical load on the top of the piles.For numerical simulation,two pile group configurations(i.e.2×1 double pile and 2×2 pile group)were evaluated,the spacings from 2D to 10D(where D is the pile diameter)and the diameter of 0.5 m,0.8 m and1 m were considered in order to assess the influence of change in pile spacings,pile diameters and row location within a group.The embedded pile element and the plate element were used to model piles and pile cap respectively.It is observed that group lateral efficiencies were larger when the center to center pile spacing were greater,for pile groups with fixed head the leading row(the front row in the group perpendicular to the direction of loads)carries the highest load,the trailing rows(middle and back row piles perpendicular to the direction of loads)carry smaller loads for a given displacement.