Static And Dynamic Response Analysis Of Pier And Pile Foundation Under Lateral Loading

The rapid growth of national economy has brought tremendous demands for bridge constructions and waterway transports, but also leads to increasing the probability of bridge collisions, which seriously endangers the safety of bridge. In light of this, the static and impact dynamic responses of the pier-pile foundation under lateral loading are studied by analytical and numerical methods. The main original works and innovative achievements are as follows:1. The existing methods for computing the horizontal ultimate resistance of clay and sand soils are summarized and compared. Based on the subgrade reaction method and the simplified elastoplastic constitutive relations of soils around the pile, the analytical solutions of a laterally loaded fixed-head pile embedded in a homogeneous soil are deduced.2. Based on the subgrade reaction method and the simplified elastoplastic constitutive relations of soils, the analytical calculations of laterally loaded long pile embedded in both the "Gibson style" foundation and the "generalized Gibson style" foundation are presented respectively, the dimensionless analytical expressions of maximum deflection, maximum rotation and maximum moment of the pile under various conditions are derived. The calculation results show that the load-maximum deflection, load-maximum rotation and load-maximum moment relationships of the pile under combined lateral loads (horizontal force and moment) are nonlinear and asymmetrical, so using the linear superposition method for combined loads will be on unsafe side. Besides, the complex analytical solutions are simplified for more easily applying to engineering calculation within the common load range, and the results of the fitted formulas show high accuracy. The results compared with the measurements and the p-y curve method indicate that the present method is capable of analyzing laterally loaded long pile embedded in a non-homogeneous, elastoplastic soil.3. Based on the subgrade reaction method, the simplified elastoplastic constitutive relations of soils and the proposed ultimate resistance calculation formula of double-layered soils, the closed-form solutions for both free-head and fixed-head laterally loaded long piles embedded in double-layered, non-homogeneous elastoplastic soils are deduced respectively. And the effects of soil parameters of the double-layered foundation on the pile behavior are investigated with the derived solutions. The example analyses show that the results calculated by the proposed analytical solutions are compared well with that of 3D finite element analysis and field measurements of the single pile and pile group.4. Based on an Euler beam resting on a Winkler foundation (E-W model), the analytical solutions of the pile embedded in a homogeneous viscoelastic foundation under lateral impact force are derived with various boundary conditions. In light of the imperfect of dynamic analysis based on E-W model, the semi-analytical solutions of dynamic response of pile based on a Timoshenko beam resting on a two-parameter viscoelastic foundation (T-D model) are developed, and the difference of pile dynamic response based on the E-W model and T-D model are researched. Then the dynamic responses to three commonly simplified impact loads (rectangular impulse, half-sine impulse, and triangular impulse) are compared under the constant impact energy.5. Based on the T-D model, the semi-analytical solutions of dynamic response of both single pier-pile foundation and double piers-pile foundation in layered viscoelastic soils under lateral impact loading are deduced. Then, the effects of the pile cap, the superstructure units upon pier cap, the load position, the riverbed scouring depth and the complex impact loading form on the dynamic responses are investigated using the proposed single pier-pile foundation model. Finally, full-scaled experimental impact tests conducted on two piers are calculated using the proposed models, and the results are compared well with the measurements.6. The measured data of a collided pier-pile foundation are analyzed, and the collision process is speculated and retrieved. Then the most severely damaged pier is analyzed with the pseudo-static three dimensional finite element numerical simulations, the damage and deflection of the pier-pile foundation are systematically investigated, and some of the results are compared well with the measurements. The numerical simulation results not only can be the basis of the further detection and recover design of the piers, but also can offer some references for the similar projects.