Behavior Of Vertical Loaded Pile Influenced By Side Surcharge

The large surcharge load adjacent to buildings can have a great effect on behavior of piles. First, large settlement of soil beside piles due to the surcharge load can cause negative skin friction of piles. Second, lateral deformation of soil extrude the adjacent piles and cause lateral and deflection deformation of piles. The load on top of piles interact with negative skin friction and lateral extrusion influence the behavior of piles, which can cause additional bending moment and shear stress to lead to pile fracture. This paper uses indoor model test and numerical simulation methods to discuss the behavior of vertical loaded piles influenced by side surcharge.This paper uses indoor model test to study the behavior of vertical loaded pile influenced by side surcharge. Design load device and testing program and do the model test in different situations, including different surcharge load, surcharge positions, vertical load on pile top and pile top constraint conditions. The results show that, the lateral displacement of pile increase with increasing value or decreasing distance of surcharge load. The internal force of pile, axial force and bending moment, increase with increasing value of surcharge load. The distribution of negative skin friction is close to middle or below of pile influenced by increasing of surcharge load distance. Compare with unrestrained pile top, restraint of pile top can enlarge the axial force and bending moment of pile by side surcharge, respectively increase 40% and 65%. The vertical load on top of pile causes additional bending moment apparently. 3D-FEM is used to back analyze the results of model test and the numerical results of pile behavior coincidence well. The working results demonstrate that the method of indoor model test and numerical analyze are feasible and effective.In this paper, 3D-FEM is used to analyze vertical loaded piles influenced by side surcharge, test and verify the behavior of pile influenced by side surcharge and vertical load on pile top. The results of parameter analysis show that, the lateral displacement, axial force, bending moment of pile increase with increasing of value of surcharge load. The lateral displacement and axial force of pile decrease with the increasing distance of surcharge load. The bending moment of pile reaches a maximum as the distance of surcharge load comes to 5 multiple of pile diameter. When the distance between surcharge load and pile is close, comparing with unrestrained pile top, the maximum lateral displacement of upper section of pile decreased 8% as the pile top is restrained, the lateral displacement of pile top decreased 30%. When S=2.5D, comparing with unrestrained pile top, the maximum bending moment of pile increased nearly 35% as the pile top is restrained, the maximum shear stress of upper section of pile increased 30%. Under the lateral surcharge load, vertical load on pile top enlarge the internal force of pile, the maximum bending moment and shear stress of upper section of pile increase 6%. Research results provide basic ideas for analysis of lateral force resistance, shear stress resistance and bending deformation of piles. This paper has reference value for the design and construction of analogous projects.