Study On Low Strain Integrity Testing Of Platform-pile

The stress wave propagation characteristics in platform-pile system are mainlystudied. The definite solution problem about the fluctuations in platform-pilesystem is established in the Cartesian coordinate system according to elastic theory.The definite solution is discretized by staggered-grid finite difference time-domainmethod (FDTD), and then it is programmed in the MATLAB to obtain the velocityand the stress value in the platform-pile system at any one time and any point. Thewave snapshots at different time are obtained, which give a visual interpretation ofwave propagation in the platform-pile system. Different parameters are analyzed todetermine the effect to low-strain curve, including cushion cap surface area,cushion cap thickness, the duration and location of the exciting force, etc. Thestress wave propagation characteristics in integrity and shrink diameter piles arediscussed and the defect responses at different depths are analyzed. At last, thetheoretical result is proved to be reasonable and effective by the matching betweentheoretical calculation and measured velocity curves.