Kinematic Response Of Single Piles To Seismic Excitation Based On The Modified Vlasov Model

Piles are usually designed as deep foundations for their large bearing capacityand excellent stability. However, some investigation after earthquake found that thepiles are also destroyed and even make the superstructure collapsed duringearthquakes. At present, the available calculation methods cannot explain the pile-soilkinematic response very well. Calculation of pile-soil kinematic response is theessential issue of seismic analysis. In the available methods, Winkler model is themost popular approach to investigate this issue. Although other approaches such asboundary element method and finite element method can solve more complexproblems, the calculation is complicated, and the results also need analytical methodtoverify. Therefor, it is of significant importance to focus on the pile-soil kinematicresponse bothin theory and in engineering application.Based on the modified Vlasov model, this thesis deal with the research on singlepiles to vertical and horizontal earthquake excitations, respectively. Firstly, to verticaland horizontal earthquake excitation, a novel displacement model is proposed,respectively. And then, accordingto the Hamilton’s principle the control equationsand boundary conditions will be obtained under the proposed model. An iterativeprocedure used is introduced to get the solutions of the unknown functions. Theaccuracy of the present approach is verified by comparing the present results withavailable researches. At last, some important conclusions are obtained through theparametric analysis. To vertical and horizontal earthquake excitation, the majorcontribution of this study is:(1) A novel displacement model is proposed for thepile-soil system, respectively;(2)the analytical solutions is obtained based on themodified Vlasov model;(2)A physical model of great significance is abstracted fromthe present method, respectively. And the explicit expressions of the membrane andthe equivalent Winkler modulus are also obtained.The results of the analysis reveal that, to vertical earthquake excitation, theinfluence of pile’s slenderness ratio, pile-soil modulus ratio and incident frequencyare significant but the soil damping’s influence is small; To horizontal earthquakeexcitation, the influence of pile’s mechanical slenderness, pile’s slenderness ratio andpile-soil modulus ratio are all significan.