Device and method for integrity detection of cast-in-situ piles based on densely distributed fiber grating temperature sensing technology

Abstract

The invention discloses a device and method for detecting the integrity of cast-in-place piles based on densely distributed optical fiber grating temperature sensing technology. A metal material with a large thermal expansion coefficient is used as a temperature-sensitizing element, and the temperature-sensitizing element is hoop-bonded on an optical fiber. Where there is no protective layer, the optical fiber is fixedly bound on the main reinforcement of the steel cage; after the steel cage is lowered, the optical fiber is first connected to the dense distributed temperature interrogator; the concrete is poured and the quality and amount of the concrete are recorded; according to the amount of concrete and the The quality determines the monitoring time of the pile body temperature; the intensive distributed temperature demodulator starts collecting temperature data immediately after the concrete pouring of the pile body is completed; according to the collected temperature data, the difference of the concrete hydration heat along the pile body is obtained to judge whether the concrete pouring Uniformity and the range of pile diameters further obtain the integrity of cast-in-place piles. The invention greatly improves the temperature measurement accuracy and positioning accuracy, does not need active heating, can detect pile foundation defects early and repair them in time.

Description

technical field [0001] The invention discloses a device and method for detecting the integrity of cast-in-situ piles based on densely distributed optical fiber grating temperature sensing technology, and relates to the technical field of quality detection of cast-in-situ piles. Background technique [0002] Cast-in-situ piles have large bearing capacity and strong adaptability, and are widely used in most high-rise buildings, bridges and other projects in my country. With the rapid development of infrastructure projects, the demand for cast-in-situ piles will inevitably develop in the direction of larger and deeper. However, affected by factors such as the uncertainty of geological conditions and the complexity of the construction process, the possibility of integrity defects (defects such as broken piles, diameter shrinkage, segregation, and mud inclusions) will appear during the formation of cast-in-situ piles. As high as 15% to 20%. Due to the large depth and high conce...

AI Technical Summary

Problems solved by technology

However, the existing traditional temperature measurement methods need to deploy a large number of temperature sensors, which increases the cost of pile foundation detection and cannot guarantee the survival rate of the sensors; while the existing thermal method based on distributed optical fiber temperature measurement technology (DTS) The body integrity detection technology is limited by the spatial resolution and temperature measurement accuracy of the distributed optical fiber temperature measurement technology (DTS), and the detection accuracy for small-scale defects is low, especially for low-quality concrete and short pile lengths. Pouring pile detection accuracy is low

Another method is the pile body integrity detection technology based on the active heating distributed optical fiber temperature measurement technology (DTS), which also judges the integrity of the pile foundation based on the heat conduction characteristics of the pile body, but this method requires Sensing optical fiber heating in cast-in-situ piles is used to detect pile foundation defects, which is complicated to operate and prolongs the time of pile foundation detection

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