Dynamic Response Of Pile-surrounding Soil Induced By Excitation At/near Pile Top And Its Application

With the continuous development of our country's construction industry,the quality control and detection of pile foundation have also received great attention in the field.So far,the low-strain pile integrity test(PIT)technique has been widely used,and its theoretical work has been significantly developed as well.However,this non-destructive method still has some limits:i.e.for a pile with excessively large aspect ratio or severe defects,or a pile with existing superstructure and the test excitation is hard to be conducted at the pile top,the PIT results are always unsatisfactory.In comparison,the parallel seismic(PS)method has a better scope of application,which can also be employed to investigate pile foundations with severe defects and with existing superstructure.Nevertheless,the theoretical research on PS method is not perfect,and the existing pile dynamic theory pays more attention to the dynamic response of the pile itself rather than the soil around the pile foundation.Based on this,this thesis presents the pile-fictitious soil pile-three dimensional(3D)continuum model,the half-space soil inversion model excited by the known pile vibration,and investigates the vertical and lateral dynamic response of pile-surrounding soil.The main work and novel achievements are as follows:1)An intact pile-fictitious pile soil-homogeneous surrounding soil model is proposed,which can be employed to analyze the soil around and beneath the pile,and overcomes the limits of existing pile dynamic theory.According to the proposed model,the analytical solution in frequency domain and semi-analytical solution in time domain of dynamic response of homogeneous ground can be solved by integral transform method.By employing the proposed model and analytical solution,this thesis investigates the vibration law of pile-surrounding homogeneous ground.2)A defect pile-fictitious soil pile-layered soil model is proposed,which can further account for the pile defect and pile-surrounding layered condition.Based on the proposed model,the analytical solution in frequency domain and semi-analytical solution in time domain of dynamic response of layered ground can be solved by integral transform method.According to the proposed model and analytical solution,this thesis investigates the vibration law of layered ground around a defect pile,and proposes a data processing scheme for the PS method to evaluate the pile defect and the layered condition.3)A half-space inversion soil model excited by the known vertical pile vibration is proposed:i.e.the analytical solution to the vertical vibration of an intact/defect pile can be solved at first by employing plane strain model;the dynamic response of the half-space around an intact/defect pile can then be solved by considering the known pile vibration as dynamic load and employing pile-soil displacement continuous condition as boundary condition.The proposed model can overcome the limit of pile-fictitious soil pile-3D continuum model,where the solving process requires artificially stratification.Based on the proposed model and analytical solution,this thesis investigates the effect of the high-frequency disturbance induced by the environment.4)A half-space inversion soil model excited by the known lateral vibration of an extended pile shaft is proposed:i.e.the analytical solution to the lateral vibration of an extended pile shaft can be solved at first by employing dynamic Winkler model;the dynamic response of the half-space around an extended pile shaft can then be solved by considering the known pile vibration as dynamic load and employing pile-soil displacement continuous condition as boundary condition.Based on the proposed model and analytical solution,this thesis investigates the vibration law of pile-surrounding homogeneous ground around the lateral vibration pile.5)According to the proposed model and analytical solution,this thesis investigates the effect of technical indicators of PS method,proposes testing scheme and data processing optimization method for PS method on vertical and lateral pile vibration,respectively,and provides theoretical support and guidance advice for engineering application.