Mechanical Behavior And Failure Mechanism Of Piles Under Horizontal Load

At present, the studies of mechanical properties of pile mainly focus on bearing load at top of the pile under horizontal load. In this paper, the mechanical properties and failure mechanism of reinforced concrete pile are studied when the middle parts of pile bear horizontal load.At first, these commonly computing methods for studying pile under horizontal load, including Zhang method, c method, k method, m method and P-y curve method, are introduced in the paper. The displacement and rotation angle of single pile which bears the horizontal load at the middle parts of pile are obtained by m method. By introducing small deflection differential equation of elastic beam, the deflection equation of pile is deduced when pile beard horizontal load at the top of pile or the middle parts of pile. The equation basically describes the mechanical properties of pile bearing horizontal load. The relationship between internal force of pile and depth is obtained by the deflection equation of pile. The displacement and rotation angle of pile are 4-th polynomial with buried depth.Secondly, the constitutive relations of concrete, steel bar, soil and pile-soil interface are discussed and the geometric model is built in the paper. The numerical simulation to pile bearing horizontal load is computed by using finite element software, ANSYS. There are three cases of the horizontal displacement:(1) The displacement at the top of pile is max when the load is little; (2) The displacements from the top of pile to the location of load are near when the load is middle; (3) The displacements at location of load is max and gradually reduces on top and end of pile. The horizontal stress is olive-distribution when pile beard horizontal load. When the end of pile is fixed, the max stress lies on the end of pile and the second extreme point lies on the location beard load. Due to the influence of soil resistance and soil deformation, the stress on the contact surface of pile-soil is interspersed along the length direction between compressive stress and tensile stress.At last, the effects of work performance of pile are discussed when the elastic modulus of pile, the diameter of pipe piles and wall thickness of pipe pile are changed. Because of the influence of soil resistance, the variation of stress is large when the elastic modulus of pile is changed. The stress at location of load is gradually variable from tensile stress into compressive stress with increasing the elastic modulus of pile. The influence of diameter of pile on horizontal displacement is large at the end of pile. The influence of diameter of pile on stress is only on the value changes. And the form of stress-depth curve isn't changed. The influence of the thickness of pipe pile on the displacement and stress is not obvious.