Dynamic Response And Quantification Analysis Of Defective Piles In Low Strain Situations

With the developement of construction industry, pile foundation has become one of the most important forms. But some kind of defects such as gapping, broaching, break, separation were usually found in bored cast-in-place piles, which maybe reduces bearing value of pile and does harm to the superstructure. Furthermore, these defects can lead to ruin of abuilding. So measurements can be taken to strengthen defective piles after accurately judging defect's type, location and degree. Otherwise it must threaten the safety of building and human beings' life. Thereafter, test for iniegrity of pile foundation is a problem, which engineers pays elose attention to.The article introduces the developing state and strong and weak points of dynamic testing method forfoundation piles and some other detection methods of pile foundation at first. Secondly, by indoor simulation experiments, to discuss the reflected wave curve characteristics of the integrate pile with the change of the pulse width of exciting force,and use the analysis of each concrete disfigurement's affection which is one of the typical disfigurement in the simulated pile to summarize the skill of judging accurately the response-time curve in the low strain reflec-tion wave method, then set up two-dimension model to simulate by using GTS finite element procedure, obtain all kinds of defective waveform, and analyze indoor experiment results and the waveform,in order to make reflex wave method detect the integrity of piles more exactly. Finally, fit relation formulae between swing ratio of incidence wave and reflection wave in velocity respond curve and defective degree of reduced neck of different kinds of soil, and achieve quantification analysis of the flaws.