| The pile foundation is one of the most effective foundation forms to bear the horizontal load.It has good bearing characteristics,and can reach the requirements of ordinary building.Prefabricated piles will cause deformation of the surrounding soil when they penetrate the soil and create a great deal of lateral pressure on the surrounding soil.Squeezing the soil equivalent to the volume of the pile in the soil makes it dense,resulting in differing degrees of disturbance and remodeling of the soil in a certain range around the pile and pile tip.In addition,the bearing capacity of pile foundation will be affected by the compaction effect.The bearing capacity of a compacted pile is subjected to horizontal cyclic loads such as wind loads,wave loads,and earthquake loads will change greatly.If the design does not consider the impact of the cyclic loads that the pile may suffer during subsequent use on the bearing capacity of the pile foundation,it may result in an uneconomical design or early damage to the pile foundation.The compaction effect of pile foundation in sandy soil is closely related to the ratio of length to diameter of pile foundation,pile diameter and relative density of soil.The cyclic loading of different displacement amplitudes will also have different effects on the bearing capacity of pile foundation.In this paper,through indoor model tests and numerical simulation methods,the deformation characteristics and bearing capacity of single pile foundations under different horizontal-diameter ratios,pile diameters and relative soil density under horizontal static and cyclic loads are researched.Based on the numerical control biaxial-axis servo motion platform developed by Shenzhen University Geotechnical Engineering Laboratory,the horizontal static and cyclic loading tests under different pile diameters,different buried depths,different sand relative densities,different displacement amplitudes,and different types of pile heads(open and closed piles)were developed in sandy soil.Pile in sandy soil were carried out.In loose sand and medium dense sand,under open and closed piles,the bearing capacity of the open piles is always weaker than that of closed piles under the action of static load.In addition,with the increasing of displacement amplitude and depth,the difference in bearing capacity between open pile and closed pile gradually decreases.The test found that the pile diameter and the relative density of soil will have a greater impact on the difference in bearing capacity between open and closed piles.The larger the pile diameter,the greater the relative density of soil,the less difference in bearing capacity between different pile type.Through the numerical simulation of the indoor model test,it is found that the pile diameter and the relative density of the soil have a great influence on the compaction effect of the pile foundation.The value of parameter h in the elastoplastic p-y model of single pile is generally within 1.0.and the parameters are taken.The value of parameterc_p takes 3.0 to 12.5 depending on the compaction effect.The greater effect of compaction on the pile foundation,the greater value of the parameter h and the value of the parameterc_p. |
