Effect of loading level and sequence of vertical and lateral load on bearing capacity of single pile

It was a common practice to determine the vertical bearing capacity and lateral bearing capacity separately in the design of pile foundations without consideration of the interaction between the vertical load and the lateral load.It would certainly not reflect the real conditions.Piles with the length of 80 m or even longer were usually adopted in the foundations of super-high building in the soft soil area.At present,there were few documents about the interaction between the vertical load and the lateral load for the unusually long piles.Based on modeling the vertical and lateral load-test results of a pile with the length of 79 m,the necessary characteristics of soil for FEM analysis were obtained,and then the bearing capacity and deformation of extra-long piles under the vertical and lateral loads were studied.For piles under the vertical and lateral roads,effects of the vertical loads on the lateral bearing capacity and the deformation varied with the loading sequence of the vertical and lateral loads,the load level and the strength of soil.As far as the piles and loading condition being concerned,there was a critical vertical load under which the lateral deformation was reduced mostly at high loading level when the vertical load was applied before the lateral one.The weaker the soil,the greater the effect of the vertical load on the lateral displacement at the pile top.The vertical load did not help to reduce the lateral displacement at the pile top anymore when it was applied after the lateral load.The effect of loading sequence of the vertical load and lateral loads on the lateral bearing capacity was larger than that on the vertical one.