Studies On Initial Transient Response Of A Platform-Pile System Embedded Partially In Layered Soil

Pile foundation has been widely used in practical engineering, which is due to its high bearing capacity, small settlement, anti earthquake performance and applicable to special soil. The quality testing which is for common embedded type and pile embedded partially in layered soil has more mature theory and technology, and has been widely applied in practice. While the quality testing which is for platform-pile system embedded partially in layered soil, there are still no effective methods and techniques now. Based on the method of reverberation-ray matrix, setting the expose lateral position for the impact position, considering influence of the axial and radial pile damping and layered properties of foundation soil, this paper has a deep research on initial transient response generated by platform-integrate pile system embedded partially in layered soil and platform-defective pile system embedded partially in layered soil under effect of oblique impulse. The major contents include:Firstly, the initial transient response of platform-integrate pile system embedded partially in layered soil is researched. In consideration of pile damping, damping surrounding the pile and soil stiffness of surrounding the pile, according to the theory of elastic waves, the basic equation describing the dissemination of axial wave and flexural wave in platform-integrate pile system embedded partially in layered soil is proposed and sloved, finally, the transient response of platform-integrate pile system embedded partially in layered soil under semi-sine exciting force is determined. The comparison of the velocity wave of this system when it receive action of different conditions, and the influence of soft (hard) soil layer location in layered soil, overlying soil thickness and soft (hard) interlayer thickness is analyzed. It is shown that the signal strength reflect from surface of hard soil layer stranger than surface of soft soil layer, and the thickness of hard soil layer is thicker, the strength of signal attenuation becomes more obvious.Secondly, the initial transient response of platform-variable sections pile system embedded partially in layered soil is researched, to compare the time domain response wave of integrated and variable sections pile, further studies on the time domain response wave of variable sections pile system embedded partially in layered soil, which soil is upper-soft-and-lower-hard or upper-hard-and-lower-soft two-layered soil and soft interlayer or hard interlayer three-layered soil. The effect of variable hard and soft soil position, defective position, and defective degree to transient response is analyzed. It shows that the wave will scatter through the defectice sections of platform-variable sections pile system embedded partially in layered soil, and the reflected wave direction is opposite at the defective sections of the neck-expanded and neck reduced pile.Thirdly, the initial transient response of platform-variable modules pile system embedded partially in layered soil is researched. To compare the time domain response wave of integrated and variable modules pile, further studies on the effect of variable hard and soft soil position, defective position, defective degree to transient response. It is shown that the wave will scatter through the defective sections of platform-variable modules pile system embedded partially in layered soil, reflection has delayed after it through the defective sections.Finally, main conclusions are summarized and further research suggestions are proposed.