Study Of Mechanics Character And Load-Bearing Mechanism On Screw Pile Foundation Under Inclined Loading

On the general concept, the loading form of engineering pile can be seen as the inclined loading, which the loading combination of axial and horizontal loading acts on pile at one time. For the variable cross-section and abnormity screw pile, the mechanism of load transfer and its failure model by inclined loading condition are more complex than the mechanics property of screw pile under axial or horizontal loading condition, because of the mechanics property of pile, mechanics response of pile-ground, inclination of loading and couple effect of loading. Therefore, the load-bearing mechanics and designing theory of screw pile and pile group under inclined loading are studied by the examination, some theory and finite element method (FEM).First, by6times of2group of screw pile test under horizontal loading,11times of2group of static load-bearing test under inclined press, and6times of2group of screw pile pullout test under inclined pull-loading, the displacement and loading of pile cap and ground stress are measured. Some key problem under3kinds loading are studied, for example the action rule of pile-soil, the couple effect of horizontal and vertical component of inclined loading, estimated ultimately inclined loading and the failure model of screw pile foundation, and the estimating method of ultimately inclined loading. From these research effect, the base of failure model and designing theory that be applied to the load-bearing and pullout screw pile under inclined loading are established.Secondly, on the base of loading test for3kinds form of horizontal loading, inclined press, inclined pull force and vertical loading test, some failure models are put out on the condition of inclined loading, for example the failure model of single pressure screw pile under inclined press, the failure model of single screw pile and pile group. Used some theoretic of the soil mechanics, foundation engineering, continuum mechanics, elastic mechanics and math, the designing theory of the pressed screw pile, pullout screw pile and pile group are established for the condition of inclined loading, and the estimated method for calculating the ultimately inclined loading of the pressed or pull-out screw pile are advised. At the settlement designing of vertical pressed screw pile group, based on some theoretic of the Mindlin’s solution of elastic mechanics, soil mechanics and foundation engineering, the limiting deepness of ground stress by the interactive effect of the twin force in ground is deduced, and the calculating settlement method is put out.Thirdly, in the aspect of engineering designing and application, the bearing property and influencing factors of the prototype screw pile group foundations under inclined loading are respectively studied by the elastic-plasticity3-D analysis of FEM(ANSYS8.0software) and loading field test. Used the designing theories of ultimately inclined loading and settlement of screw pile foundation, the ultimately inclined loading and settlement of screw pile group are calculation. The results of FEM and theory calculations are near to the results of field tests, and it shown that these theories in the paper may direct the designing screw pile foundation in fact.