Study Of The Bearing Capacity Mechanism And Computational Theory Of Grouped Pile Foundation Subjected To Horizontal Force And Torque

In recent years, in the complex circumstances,the bearing behaviors and destraction morphology of the large building has been widely concerned. Different from the conventional environment, combined loading structure under complex environment is more special,such as horizontal load and torque caused by the wind load or the impact of the ship.There are a lot of projects about the building destraction which is caused by the collision of the ship and the wind load.So,It is of significance to study bearing behaviors of pile group foundation and to establish relevant calculation theory.This article started a series of studies, the main work is as follows:(1) Combined with the research status at home and abroad, On the basis of the existing researchs, preliminary analysis of the load distribution, displacement mode and failure modes of grouped pile foundation subjected to Horizontal Force and Torque.(2) The concept of nearness to yield was introduced to study stress path of surrounding soil in front of pile, and results showed that, stress in soil in front of torsional pile go straightly towards yield surface along the plane of ?; while that in front of laterally loaded pile go towards yield surface with an angle to the plane of ?; Coupled loads may assemble both two kinds. These will somewhat explain coupled mechanism of torque and laterally force. With the 3D numerical analysis method, analysis of response characteristic and the coupling effect of grouped Pile foundation subjected to Horizontal Force and Torque. Analysis shows that the soil and the size of the eccentricity effect on the pile foundation load characteristics. The horizontal load and the torque load are exist coupling effect, Horizontal load on the pile group has enhanced the role of torsional stiffness, Torque load on the pile group has weakened the role of horizontal stiffness.(3) Firstly, on the basis of studying the bearing mechanism of pile groups subjected to the coupled load, a set of universal equations for computing displacements and rotation of each pile in the group, which rotate around a determined center, were established based on the force equilibrium conditions. Secondly, the p-y method and the torsion loaded pile theory were introduced to determine horizontal and torsional rigidity of each single pile respectively. Then, the computational method was programmed, and was applied in an experimental data exploration. The comparison indicated that, the method proposed in this paper is practicable and user-friendly. Lastly, the program was utilized to analyze load distribution of a coupled loaded pile group. The result suggested that, longer the eccentricity of the load, larger the rotation of the pile groups, and the bearing behavior of torsionally loaded pile group could be determined mainly on horizontal rigidity of each pile in the group.(4) Based on analysis of basic design principles, the pile type selection method and general design steps of the pile foundation, a design and checking method was suggested.