Integrity monitoring of cast in-situ piles using thermal approach: A field case study

Sun, Qianchen; Elshafie, Mohammed; Barker, Chris; Fisher, Anthony; Schooling, Jennifer; Rui, Yun

doi:10.1016/j.engstruct.2022.114586

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…This agrees well with the results from the field thermal integrity test, where defect-attributed temperature reductions were the most pronounced at 8 h when temperature increased fastest. 5,33 The temperature difference rose slowly for the first 2 h and then sharply increased until 7 h. The temperature differences DT then sharply decreased after the time of maximum rate of temperature rise. For cables directly in contact with large defects, the difference levelled off at around 10-15 h; namely cable 7 for defect 2 and cable 4 for defects 1 and 3.…”

Section: Optimum Time and Defect Thermal Impactmentioning

confidence: 98%

“…This information can be used to back analyse the defect size and assess its nature. Recent research on thermal integrity testing 5,33 has proposed a novel data interpretation framework, which integrates cement hydration model, optimisation with field temperature data and FE modelling to provide a staged risk-based approach for pile integrity assessment. Thus, thermal integrity testing could be a powerful tool in evaluating as-built pile quality on site.…”

Section: Numerical Simulationmentioning

confidence: 99%

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Pile defect assessment using distributed temperature sensing: fundamental questions examined

Sun,

Elshafie,

et al. 2023

Structural Health Monitoring

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Thermal integrity testing has been successfully used to assess the quality of cast-in-place piles for the past decade. It employs temperature data measured during concrete curing to identify defects along the piles’ length. However, the uptake of this technology has been rather limited in the piling industry. The main concerns are that the method is not standardised and its reliability is not well understood. In order to address these, there are a number of fundamental questions that need to be explored in more detail, including (a) the optimum time to conduct the assessment, (b) the defect thermal impact, (c) the zone of influence on temperature sensors, (d) the minimum detectable size of a defect and (e) the associated optimum sensor location required. In this paper, experimental and numerical studies were conducted to examine these questions. Fibre optic sensors were employed on model concrete piles in laboratory tests to provide fully distributed temperature data throughout the curing process. The test results showed that the optimum time to assess the defects is approximately at 60% of the time to reach peak temperature and the minimal detectable defect size, using the currently available optical fibre sensor technology, is 4% of the cross-sectional area. In addition, the thermal influence of different defect sizes is presented. Following this, it is shown in the paper that the minimum numbers of sensor cables required to identify defects with cross-sectional areas of 4%, 5% and 8% are eight, six and four cables, respectively. The optimum layout of these sensor cables within a pile cross-section has also been discussed. When specifying pile instrumentation for integrity assessment, the findings of this paper enable practising engineers to make informed judgements in relation to the size of defects they would like to detect (and hence the associated risk this entails) together with the corresponding instrumentation layout required.

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Section: Optimum Time and Defect Thermal Impactmentioning

confidence: 98%

Section: Numerical Simulationmentioning

confidence: 99%

Pile defect assessment using distributed temperature sensing: fundamental questions examined

Sun,

Elshafie,

et al. 2023

Structural Health Monitoring

Self Cite

View full text Add to dashboard Cite

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Thermal integrity profiling of cast-in-situ piles in sand using fiber-optic distributed temperature sensing

Wang¹,

Zhu²,

Tan³

et al. 2023

Journal of Rock Mechanics and Geotechnical Engineering

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Data Interpretation Framework for Pile Thermal Integrity Testing

Sun,

Elshafie,

Barker

et al. 2023

The International Conference on Civil Infrastructure and Construction

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Given the inherent nature of how deep cast in-situ concrete foundations (piles and diaphragm walls) are constructed, evaluating their integrity is difficult. Several well-established methods for testing integrity have been established, but each has its own advantages and disadvantages. In recent years, a new integrity test method called thermal integrity profiling (TIP) has been put into use in deep foundation construction. The primary characteristic utilised in this test is the early-age concrete release of heat during curing; abnormalities such as voids, necking, bulging, and/or soil intrusion inside the concrete body lead to local temperature fluctuations. During concrete curing, temperature sensors installed on the reinforcing cage collect precise temperature data along the entire pile, allowing empirical identification of these temperature variations. This paper proposes a staged data interpretation framework for pile integrity assessment, with the thermal integrity test serving as the initial step. The framework, which is adaptable to different concrete mixtures and pile designs, utilises the heat of hydration and the theory of heat transmission, as well as numerical modelling with the Finite Element (FE) method. It also adopts a staged procedure to assess the as-built quality; for a particular pile, more details are revealed about any anomalies being investigated (including location, size and shape) at each subsequent stage. The primary advantage of this staged process is that it enables practitioners to follow a risk-based approach and decide whether or not to pursue subsequent stages of construction depending on the results they get at the end of each stage. This provides practicing engineers with vital information about the quality of the pile immediately after pile building, so permitting immediate and less expensive repair and remedial work if required.

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Integrity monitoring of cast in-situ piles using thermal approach: A field case study

Cited by 3 publications

References 17 publications

Pile defect assessment using distributed temperature sensing: fundamental questions examined

Pile defect assessment using distributed temperature sensing: fundamental questions examined

Thermal integrity profiling of cast-in-situ piles in sand using fiber-optic distributed temperature sensing

Data Interpretation Framework for Pile Thermal Integrity Testing

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