Analysis On Bearing Behaviour Of Single Pile Under Combined Loads

Many pile foundations bear vertical loads as well as fairly large horizontal loads and moments at the top,which have a great influence on the pile's vertical bearing characteristics.On the basis of previous research,this thesis conducts a systematic study on the bearing characteristics of a single pile under combined loads by the combination of field static load tests,theoretical analyses and numerical simulations.The major contents and results are as follows.1.The load transfer mechanism of vertical compressive pile is analyzed,and the lateral load transfer function of the pile considering the influence of the horizontal load is introduced.Given the assumption that the influence depth of the horizontal load is no more than 20 times the pile diameter,and the maximum horizontal displacement of the ground surface is no more than one tenth of the pile diameter,the effects of a horizontal load on the vertical bearing capacity of the pile is analyzed.Results show that when the soil's internal friction angle is less than 15 degrees,the existence of horizontal load reduces the pile's vertical bearing capacity,and vice versa.2.According to the data from static load tests of single piles under combined load in different loading order,the vertical and horizontal bearing capacities are determined.Then the results are used to verify the numerical simulation approach.3.Numerical simulation approach is applied to further study the bearing characteristics of a single pile under combined loads.It is indicated that for rock socketed piles,pre-applied horizontal loads and bending moment loads have insignificant influence on the vertical bearing capacity,while for friction piles,pre-applied horizontal loads and bending moment loads lessen the vertical bearing capacity,pre-applied vertical loads increase the horizontal bearing capacity and reduce the horizontal displacement.