| With the development of construction industry, pile foundation has become one of the most important foundation 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 a building. 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 integrity of pile foundation is a problem, which engineers pays close attention to. This paper emphasized on quantitative study of defect's degree and at the same time discussed the problem that how to use wave form determining type and location of defects.First, instantaneous velocity response model was deduced according to wave damping equation, initial condition and boundary condition. And Visual Basic language program was worked out from it. Based on the program we have acquired velocity response curves effective disciplinarian. The velocity response curves relate to some factors, such as the length and the diameter of pile, the damping coefficient of soil beside the pile and the velocity of elastic wave. This conclusion is very meaningful for engineering practice.Second, this dissertation theoretically probed into feature of echo wave in defective piles and put forward a method of finding defect's type and location.Third, pile-soil system parameter model was established and velocity response model of defective piles was built by Laplace transformation. Then, the characteristic of conductance curves was analyzed. And velocity response model of defective piles in time field was gained by inverse Fouier transformation. Based on this model the relationship between defect's degree and ratio of amplitude was studied.Last, model pile test was done to prove the accuracy of quantitative analysis theory .
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