Pipe Pile Under The Concentrated Loads In Low-strain Transient Speed Response

In recent years,prestressed pipe piles become more and more popular day by day in China,especially in Guangdong Province and Shanghai City etc.. Now the most available method of pile integrity testing is low strain pile integrity test(LSPIT). With the help of finite element method (FEM),stress wave propagation in pipe piles was studied in this paper for the benefit of engineering tests.At first,the propagation and influence of stress wave on the top of the pipe pile were discussed in the paper and a formula was obtained about the time difference between two initial signals which were received from two different points. The main achievement of the paper is to recommend the 90 point as the best place for sensor by the contrast of numerical calculation results and test signals. On the point the high frequency disturbing signal was weakened very much when the load impulse was changed,which could be explained when vibration shape was considered. Other factors that would influence the high frequency disturbing signal,the influential depth and defect piles were also discussed in the paper.Certainly,the dynamic problems such as what discussed in this paper was simplified. More work need to do for a better case which approaches to an engineering pile or a good theory result.