Study On Pile-Soil Interaction Of Bridge Pile In Loess Area By Test And Numerical Simulation

The soil engineering characteristics and soil layer's distribution in loess foundation have special quality. More and more study on cap-pile groups-soil interaction of bridge pile in loess area has been paid attention to. In this dissertation, based on the existing theory, by the result of tests in situation , centrifugal tests and numerical simulation, the cap-pile groups-soil interaction of bridge pile in loess area has been analyzed systemically.1 , Based on the Visual-Fortran flat, the second development of the large common finite element MARC programme is more done. The subroutines is programmed including initial and release stress subroutine, motion load subroutine, changing parameter nonlinear elasticity model subroutine, three-dimensional and two-dimensional gap element subroutine dynamic contact subroutine, and so on.2, Field tests on bridge pile in loess ground have been carried out .The top displacement, the axial stresses, the skin resistance and the point resistance have been measured by installing various measuring gauges. The bearing capacities before and after saturation are analyzed. It is found out that effect of surface water on the property of bearing capacity of pile foundation in loess area is significant. The regularity of settlement of pile foundation and soil around is summarized.3, The spatial axisymmetric finite element model is established. Based on the model, a superposition method is proposed to calculate proper pile length in the self-weight collapsible loess, and it is concluded that, when the distribution of skin friction at the upper and lower parts of soil is of same pattern, added pile length has no significant influence on distribution of skin friction, but it has on ultimate friction resistance. By this method, the influence of property of the self-weight collapsible loess on pile beating performance is analyzed. It is observed that: (1)when pile is under ultimate capacity, the depth of neutral point is related to pile length, and(2)the influence of collapse coefficient on rest bearing capacity of pile is nonlinear, and(3)the quantitative range of the depth of neutral point and the added pile length is given. Based on shear displacement method and elasticity theory, the formula of estimating the settlement and axial force and the depth of neutral point of pile in self-weight collapsible loess is given. A close matching between the emulation results with the actual test data assures that the model is appropriate for analysis.4, The spatial three-dimensional finite element model is established considering...