Analysis Of Vertical And Horizontal Response Of Pile To Impulse Force

Pile is a prevailing mode of foundation in geotechnical engineering. In the course of dynamic test of pile and designing the structure which is subjected to dynamic load, such as machine vibrator, wind, earthquake, vehicle, pile driving, and so on, vertical and horizontal response of pile to impulse force are basic topics.There are two kinds of the method for analysis of pile dynamic response: numerical method and analytical method. The convergence and stability of the former cannot be ensured effectively as time interval should not be chosen too short due to the dynamic response of pile being mainly composed of long period parts, and it should be chosen very short again due to taking the influences of high frequencies parts on the dynamic response of pile into account.In this thesis, the response of pile to impulse force was researched. Its main contents are composed of two parts, the vertical response and horizontal response.The analysis of vertical dynamic response got a start in the problem of point elastic impact of bar, and the responses of bar were studied before and after the impactor departing from target. The time of departure between impactor and target was determined, and the effect of various support condition on dynamic response was developed. Then, assuming that action of soil on pile may be represented by series of vertically distributed springs and dashpots, one obtained analytical solution to dynamic responses of pile with uniform section and variable section in layered soil by using method of Fourier transform, and applying this analytical solution, the influences of soil parameters, variation of section area, layered soil distribution and duration of exciting force on dynamic response of pile were analyzed respectively. According to the analytical solution to velocity response of pile, one still designed software which can realized signal matching and estimation of pile shape by means of the data of in-situ measurement of integrity test. Finally, taking account of elastic-plastic model of soil around pile, analytical solutions to response of pile when the soil below pile-toe being at the stages of elasticity, plasticity and rebound were gained respectively by the method of variables separation, and the influences of soil parameters and time of hammer force on pile drivability were discussed.In the procedure of analysis of horizontal response to pile, firstly, on theassumption of that pile-soil interaction may be represented by the model of elastic foundation beam, one carried out comparing the dynamic response of Winkler model, Pasternak model and the model based on Timoshenko beam theory, and found that it is necessary to introduce the Timoshenko model into computation of horizontal response to pile. Secondly, the formulas of solution to dynamic horizontal response of pile in layered soil based on Timoshenko beam theory was deduced by Fourier transform and the method of transfer matrix, and studies of the influences of soil parameters on horizontal response to pile show that the propagation deep of dynamic response along pile has close relation with relative stiffness between pile and soil and the layered soil distribution. Finally, in view of structure wave theory, the analytical solution to dynamic horizontal response of pile was obtained by Fourier transform and the method of reverberation matrix, and the dynamic responses of being computed by the methods of transfer matrix and reverberation matrix are in complete agreement with each other. The method presented here can compute the scattering matrix of base which is combined with that of superstructure to form global reverberation matrix of superstructure-base so that it is possible to realized the computation of response of superstructure-base to an impulse force.â– END-END Key words: vertical dynamic response, horizontal dynamic response, analytical method, Fourier transform, Timoshenko beam, method of transfer matrix, method of reverberation matrix...