A multi-measuring-point low-strain detection method for high-cap pile foundations

Abstract

The invention discloses a multi-measuring-point low-strain detection method for pile foundations with high caps, which comprises the following steps: arranging three velocity sensors at equal intervals vertically along the exposed part of the pile body to receive the velocity response of the pile body in the horizontal or vertical direction component; apply test excitation to the pile above all sensors; decompose the velocity response signals collected by the sensors into up-going and down-going waves, and construct a pan frequency response function in the frequency domain through integral transformation; through pan-frequency response function and virtual half-sine excitation Obtain the virtual velocity response results excluding the vibration characteristics of the complex upper structure; use the existing analytical solution of foundation pile vibration, adjust the pile length in the analytical solution, fit the virtual velocity response results, and search for the best fitting pile length as a prediction Valuation, and use this to judge the integrity of the pile body. The method overcomes the limitations of the prior art, and the processed pile bottom reflection signal is clearly identifiable, which is conducive to accurately judging the pile length and pile body defects, and can be used for the integrity detection of high cap pile foundations.

Description

technical field [0001] The invention relates to a multi-measuring-point low-strain detection method for pile foundations of high caps, belonging to the field of pile foundation detection. Background technique [0002] In recent years, in the construction of bridges, railways, expressways and bridge piers, pile foundations with high pile caps with more pile bodies exposed to the ground have been more and more used. As the main force-bearing member supporting the superstructure, considering the importance of the part of the pile body exposed to the ground and the superstructure it supports, it is necessary to ensure the integrity of the high cap pile foundation under the existing building during the long-term service period. and health status to ensure the quality of the pile foundation and reduce potential safety hazards. [0003] There are usually two detection methods for pile foundation integrity detection. One is low-strain detection. By applying an excitation on the top...

AI Technical Summary

Problems solved by technology

However, for long piles with a lot of piles exposed to the ground, considering that the length of the pile on the ground is relatively long, sometimes the influence of the vibration characteristics of the upper structure on the vibration response of the soil cannot be ignored.

In addition, the use of the side hole test method involves drilling holes in the soil around the pile, lifting sensors, etc., and the workload is often large and laborious. Therefore, the reliability of using this method to evaluate the integrity of the pile remains to be studied.

[0004] It can be seen that it is difficult for staff to use conventional methods to directly detect and draw accurate conclusions about the integrity detection of high cap pile foundations under existing buildings

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