Quantitative Analysis On Pile Foundation's Perfection In Frequency Domain

With vigorous development of construction industry in our country, pile foundation has becoming a kind of importance foundation forms. But some kind of defects such as contraction, separation, break are usually found in bored cast-in-place piles, which maybe reduce bearing value of pile and do harm to the superstructure, furthermore, make pile lose carrying capacity. So measurements can be taken to strengthen defective piles after accurately judging the defective type, location and degree. Otherwise, it must threaten the safety of building and the people's life. Therefore, the test of pile's integrity is a problem, which engineers pay close attention to. Now, the confirmation of defective position has already come to the high level, but the quantitative analysis of defective degree is the most key prombel, which has not realized. The paper has studies how to use frequency determine the defective degree.First, response model in time domain of pile under the transient state of stimulated vibration is reduced according to damping wave equation, initial condition and boundary condition. Then, vibrant response characters in frequency domain are also reduced. These provide basis on analyzing response curve in frequency domain.Second, response model of defective pile is established. By analyzing frequency equation under different bottom condition, response model that measures pile's defect is established, then frequency equation of defective pile is reduced and Matlab calculation program is worked out from it. Based on the program we have acquired large data. Relation formula between defective frequency and defective degree is got according to these data.Last, calculation model and the test of model pile are done to prove the accuracy of quantitative analysis theory.