Transient Response And Wave Identify Of Defective Piles Embedded Partially In Soil

Pile foundation has been widely applied in many engineering fields,for example highway and railway bridges,tall buildings,port wharfs,offshore platforms and soon.There is mature theory and detection technique for monitoring the quality of pile body at present, and which has been massively applied in practice.There isn't an effective method to analyze pile embedded partially in soil under transient load.The paper does systematic research on transient response of integrate pile or defective pile embedded partially in homogeneous soil or layered soil with reverberation-ray matrix method.The major contents of this research include:Firstly,the transient wave motion of defective pile embedded in homogeneous soil is researched.Pile-soil interaction is simplified to single Voigt model,axial wave motion is presented in pile-soil system.Scattering matrix at joints is obtained from motion's equation and compatibility conditions.The reverberation-ray matrix is determined in terms of scattering matrix,phase matrix and permutation matrix.Thus,the transient response of pile embedded in homogeneous soil under semi-sine exciting force is determined from inverse Fourier transforms and convolution theorem,which is compared with the solution obtained by the properties of impedance function presented by Wang Kui-hua to validate the method.The comparison of the velocity wave of the integrate pile with that of defective pile is analyzed. Furthermore,the influence of defect degree and defect type on response is analyzed.It is illustrated that the reverberation-ray matrix method can accurately determine responses of pile head and describe propagation process of elastic wave in detail.Secondly,the reverberation-ray matrix method is adopted to do research on the transient response of integrate pile embedded partially in homogeneous soil under semi-sine exciting force.The effect of outcrop length,soil parameters on the velocity wave of pile head is analyzed.The velocity of integrate pile embedded partially in homogeneous soil is compared with the one of integrate pile embedded in homogeneous soil.The results show that velocity mobility response of integrate pile embedded partially in soil has characteristic cycle.The outcrop length has great effect on reflection wave and velocity mobility.Thirdly,the transient response of integrate pile embedded partially in layered soil is obtained.The velocity wave of integrate pile embedded partially in homogeneous soil, upper-soft -and-lower-hard or upper-hard-and-lower-soft two-layered soil,soft interlayer or hard interlayer three-layered soil are analyzed.The influence of soil shear modulus,covering soil thickness,soft interlayer or hard interlayer thickness on velocity wave of pile head is discussed.It shows that the thickness of covering soil,soft interlayer or hard interlayer have great effect on velocity mobility and reflection wave of pile head. Fourthly,the paper works out the transient response of defective pile embedded partially in homogeneous soil.The effect of defect type,defect length,defect position,defect degree and impulse duration on velocity wave of pile head is addressed.Moreover,its result is compared with the corresponding velocity wave of single defective pile,integrate pile.R is found that impulse duration cannot make effect on vēlocity mobility.Reflection of pile-end of concrete segregation pile has delay phenomenon.Fifthly,the transient response of defective pile embedded partially in layered soil is researched.The velocity wave of defective pile embedded partially in two-layered soil, three-layered soil is analyzed,which is compared with that of integrate pile.The result shows that defect information of defective pile embedded partially in layered soil is better than information caused by change of media around pile.Finally,main conclusions are drawn and further research and suggestions are proposed.The paper is supported by the Key Project of Education Ministry in 2008(208150),the Natural Science Funds of Gansu Province(3ZS061-A-042),the "Qing Lan" Talent Engineering Fund of Lanzhou Jiaotong University(QL0507A) and the Scientific Technological Project of Construction Department of Gansu Province(JK2005-20).