Study Of Transient Wave Response Of Cushion Cap-single Pile System Buried Partially In Homogeneous Soil

Pile foundations are widely used in a variety of engineering structures with high capacity requirement, as the quality testing of pile foundation, there have more mature research results about it, and is used in engineering practice widely. There is few research about the pile of bridges, port wharfs, offshore platforms, built structures, when the pile of a structure was hit or used a long time, to test its security, integrity often have greater difficulty, this type of pile can be simplified to cushion cap-pile system buried partially in homogeneous soil under oblique impulse. The paper does systematic research on transient response of cushion cap-pile integrate or defective buried partially in homogeneous soil and under oblique exciting force based on reverberation-ray matrix method.Firstly, study of transient wave response of cushion cap-integrated pile system buried partially in homogeneous soil is researched, pile-soil interaction is simplified to Winkler foundation model, with a spring and a damper related to the speed coupled in parallel way to simulate the interaction between pile and soil, considering soil and pile material damping, pile material is viscous damping, and the damping of pile is proportional to the strain rate, axial wave motion equation is established. Flexural wave propagation in pile-soil system, pile-soil interaction is simplified to Winkler foundation model. The model of flexural wave propagation in pile-soil system(or rod) depend on the Timoshenko beam theory, and obtain the flexural wave motion equation. Using reverberation-ray matrix method to study of transient wave response of cushion cap-integrated single pile system buried partially in homogeneous soil, study on excitation force(horizontal, oblique) effect of transient fluctuations in response to the receiver, furthermore, analysis the influence of impulse angle, material damping, outcrop length on the transient response of the receiver. It is shown that the larger angle between impulse and horizontal, the amplitude of axial velocity is greater, the amplitude of transverse wave, shear force wave, moment wave is smaller; outcrop has little effect on reflected wave.Secondly, study of transient wave response of cushion cap-variable sections pile system buried partially in homogeneous soil under oblique impulse is researched, based on reverberation-ray matrix method, calculation and analysis of the axial velocity, transverse wave, shear force wave, moment wave, to compare the transient response wave of integrated and variable sections pile; the effect of defect position, defect length, defect degree and impulse duration on transient response wave of the receiver. It is illustrated that there is great different from the response of cushion cap-variable sections pile and integrated pile system buried partially in homogeneous soil, the reflected wave in the opposite direction of cushion cap-neck reduced single pile system and neck expanded single pile system buried partially in homogeneous soil. the greater defect degree, the larger reflected wave amplitude of the defective element. The larger defect depth, the reflected wave of defective element joint arrival time is later.Thirdly, to simulate the variable modules pile with reduced young’s modulus, study of transient wave response of cushion cap-variable modules pile system buried partially in homogeneous soil under oblique impulse is researched, to compare the transient response wave of integrated and variable modulus pile, the effect of defect position, defect length, defect degree and impulse duration on transient response wave of the receiver. The results show that axial velocity reflection of defection element has delayed. When the defect depth is different, there is no effect on the reflection of the pile-bottom and layer interface.Finally, main conclusions are drawn and further research and suggestions are proposed.