| Pile foundation as a covert project, so that the quality of the pile is not easy to control, pile testing is particularly important, but also the focus and difficulty of the project. This paper mainly studied one comprehensive test of the theory of pile foundation detection and its application, through different methods, it researched and analyzed signal characteristics and differences of defective piles, which determine the correct pile defects effectively, given the integrity of determination.In this paper, we combined with the construction of the project of Fujian province, using the low strain reflection wave method, ultrasonic transmission method and drilling core method to complete the evaluation of pile foundation. The main work completed and the conclusions obtained are listed as follows:(1) On the basis of extensively reviewing literatures, commonly used method of pile integrity testing concepts, testing procedures and precautions were elaborated, and then analyzing the advantages and disadvantages of the method. The domestic and foreign research development and current situation of the related technology are discussed.(2) The theory of ultrasonic wave reflection method and low strain pile integrity testing are elaborated, including acoustic and vibration, characters of wave propagation, reflection and transmission, pile vertical vibration wave equation, the principles of determining the defect of pile body by reflection wave method. It is convenient for the testers to know how to find the right way, reduce the difference and analyze the problems in the practical application, so that the theory can serve the practice well.(3) It introduces the preparing work of low strain reflected wave method, sensor installation and technology of vibration hammer, and combined with the existing codes for the time-domain reflection curve of typical defects of pile foundation are analyzed. In this paper, the embedded operation and the field detection technology of pile integrity testing of ultrasonic method are expounded, and the calculation of wave velocity, wave amplitude and PSD criterion are analyzed, then sums up the rules of physics parameters and defects.(4) Combined with the engineering practice of pile foundation detection, studied the sound wave transmission method, low strain reflected wave method and drilling core method of comprehensive inspection of necessity, qualitative and quantitative characteristics and location of defects. Each method has drawbacks, synthesis the two methods, learn from each other, testers can avoid unnecessary errors. At the same time we can improve pile detection accuracy and reliability.Low strain method can inspect the quality of pile body as a whole, according to the characteristics of its use, it can be used as a census method. But its qualitative and quantitative description of the quality of pile still seems weak, ultrasonic transmission method happens to compensate for this shortcoming, it can pinpoint defects through the calculation of relevant parameters. However, ultrasonic transmission method only has a high accuracy in the detection of the profile, if there are several defects in the detection blind area, but also need the low strain detection. Synthesis the two methods, improving the accuracy of detection for the effect of icing on the cake. |
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