Crack width identification for underwater concrete structures using temperature tracer method

Abstract

Based on the particularity of underwater concrete structure, a temperature tracer method based on heat transfer theory for crack detection was proposed. The basic way to identify cracks is to change the thermodynamic boundary conditions around cracks after cracking, which will lead to the change of cooling rate of the heat source near cracks. Based on this idea, a set of crack monitoring system composed of a temperature sensing system, a heating system, a monitoring tube and multiple casing tubes was designed. By using this system, a series of crack monitoring tests were carried out on two kinds of concrete specimens. The results show that the monitoring scheme with casing tube can detect the crack position in still water, and this monitoring scheme can detect both crack position and width in flowing water. The sensitivity of it is higher than that of the monitoring scheme without casing tube.

Detecting Underwater Concrete Cracks with Machine Learning: A Clear Vision of a Murky Problem

“…[48] provided a strategy for evaluating the statistical distribution of water's level slopes using flash photography. Researchers introduced a temperature tracer approach for fracture identification in sub-sea concrete structures based on heat transport theory in [49][50][51]. A method for controlling concrete cracking in underwater marine structures using basalt fiber was presented in [6].…”

A fine extraction algorithm for image-based surface cracks in underwater dams

“…Therefore, early detection of dam defects has become the cornerstone of ensuring safe operation and even prolonging service life [3]. With regard to the problem of dam fault detection, various enlightening methods have been proposed, such as high-density resistivity, ultrasonics, elastic waves, ground-penetrating radar, sonar, temperature tracing and visual imaging methods [4,5]. Among them, the highdensity resistivity method detects the cracks by calculating the dam resistivity in different areas, but electromagnetic interference and underground capacitance affect the measurement accuracy.…”

“…A hidden variable w (i) is introduced to represent the probability that the sample point ith belongs to each Gaussian component. It conforms to the multiple distribution, which is defined as, P w (i) = j = p j , (5) where p j ⩾ 0, k j=1 p j = 1. The expression P( x (i) w (i) ) obeys the jth Gaussian distribution, which is expressed as,…”