Heated fiber-optic cables for distributed dry density measurements of granulated bentonite mixtures: Feasibility experiments

Sakaki, Toshihiro; Lüthi, Berrak Firat; Vogt, Tobias; Uyama, Masao; Niunoya, Sumio

doi:10.1016/j.gete.2018.09.006

Cited by 16 publications

(4 citation statements)

References 26 publications

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“…However, the structure and shape of soil particles may lead to deformation or destruction of a sample, affecting the measurement accuracy and making certain soil types difficult to sample. In addition to the cutting ring method, there are some in situ measurement methods for the dry density of soil [20,21], among which time domain reflectometry and the thermal probe method can be used to make point measurements with low accuracy. Georadar and the resistivity method are suitable for a large range of measurements but have low accuracy and are seldom used in practical engineering.…”

Section: Introductionmentioning

confidence: 99%

A method for the simultaneous determination of the soil dry density and moisture content based on thermal effects

Zeng,

Chen,

Xiong

2024

Meas. Sci. Technol.

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The thermodynamic parameters of soil are affected by both dry density and moisture content, leading to uncertainty in measuring moisture content using the heat source method. This study proposes a combined approach using a back propagation (BP) neural network and the point heat resource method to simultaneously determine soil dry density and moisture content. The segmented mean value extracted from the temperature time-history data during the cooling process of the heat source serves as the feature input, while measured values of dry density and moisture content serve as outputs. A calibrated BP neural network model is trained and utilized for simultaneous determination of both parameters. Numerical simulations and modeling tests demonstrate good agreement between inverse identification results and measurements, with root mean square errors of 1.65% for moisture content and 34.09 kg∙m−3 for dry density, along with coefficients of determination at 0.9482 and 0.9359 respectively. It is proved that the method combining soil thermal effect and BP neural network to measure soil dry density and moisture content is feasible.

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Section: Introductionmentioning

confidence: 99%

A method for the simultaneous determination of the soil dry density and moisture content based on thermal effects

Zeng,

Chen,

Xiong

2024

Meas. Sci. Technol.

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“…To overcome the problem of the dam temperature being close to that of seepage water, the heating technology of the DFOS was studied to amplify the temperature difference. Sakaki et al 23 applied a DFOS with an active heating function to estimate the dry density distribution of granulated bentonite mixtures. Although DFOSs have been widely investigated, it is rather surprising that the literature has seldom reported the application of DFOSs in the detection of grouting defects in prestressed tendon ducts.…”

Section: Introductionmentioning

confidence: 99%

Detection of grouting defects in prestressed tendon ducts using distributed fiber optic sensors

Gong

Feng

2019

Structural Health Monitoring

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To compensate for the shortcomings of the existing point detection methods for grouting defects in prestressed tendon ducts, such as low detection efficiency, stringent detection environment, and easy omission of grouting defects, this article presents a distributed detection approach to detect the grouting defects in tendon ducts. The main objective of the research pertained to the development of a method for accurate identification and location of grouting defects and qualitative evaluation of the size of grouting defects using distributed fiber optic sensors with active heating. Using the thermal analysis of grouting defects in the tendon duct and the research on distributed fiber optic sensors measurement characteristics, our work proposed a method for identifying and locating grouting defects and explored the effect of the grouting defect length and the grouting compactness on the temperature rise of distributed fiber optic sensors. The feasibility of the proposed approach is evaluated through an experimental program. The experimental program involved use of heating distributed fiber optic sensors for the distributed measurement of temperature after the heating and detection of grouting defects in tendon ducts in a concrete beam. The results indicate that distributed fiber optic sensors can monitor the temperature distribution of the tendon duct during a temperature rise in real time. Grouting defects in the tendon duct can be quickly detected and located by identifying temperature anomalies in the temperature contour of the distributed fiber optic sensors. Furthermore, there is a linear relationship between the defect length and the abnormal temperature length on the distributed fiber optic sensors, and the defect length can be identified based on the abnormal temperature length obtained by the measurement. Plane-equivalent thermal conductivity can be used to evaluate the grouting compactness of the tendon duct. When the grouting compactness is greater than 70%, the smaller the plane-equivalent thermal conductivity is, the lower the grouting compactness is. The plane-equivalent thermal conductivity is basically the same when the grouting compactness is less than 70%.

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“…Os dispositivos DTS mais avançados são capazes de fornecer medidas de temperatura dos cabos de FO com intervalos de amostragem espacial e temporal de 0,127 m e 5 s, respectivamente. Além disso, a resolução espacial dos DTS, que consiste na distância ao longo da qual os 10% e os 90% de uma mudança abrupta de temperatura pode ser detectada, alcança valores de 0,25 m (SAKAKI et al, 2019;SAYDE, 2022). Para informações detalhadas sobre a performance dos sistemas FO-DTS, recomenda-se ao leitor a consulta de Bolognini e Hartog (2013) e de Tyler et al (2009).…”

Section: Medição Distribuída De Temperaturaunclassified

“…Os instrumentos DTS são capazes de realizar medições de temperatura ao longo de cabos de fibra óptica (FO) com extensões que abrangem uma ampla faixa de escala espacial (de poucos metros até mais de 1 km) (REIS et al, 2022;SELKER et al, 2006) e com intervalos de amostragem temporal e espacial de 5 s e 0,127 m, respectivamente (SAKAKI et al, 2019). A principal metodologia que tem sido aplicada com os sistemas FO-DTS para estimativas de 𝜃 é o método do aquecimento ativo (Actively Heated Fiber Optic method -método AHFO), em que o cabo monitora a resposta térmica do solo à aplicação de um pulso de calor (STRIEGL; LOHEIDE II, 2012).…”

Section: Introductionunclassified

Investigação da umidade do solo por meio da combinação entre o aquecimento de uma liga ferrítica (Fe-Cr-Al) e a medição distribuída de temperatura (DTS)

Bertotto¹

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Aos meus pais, Fernando e Márcia, que nunca mediram esforços para me apoiar durante esses anos.À minha companheira Lara, por ser meu porto seguro. Seu incentivo, compreensão e confiança tornaram os dias mais fáceis e agradáveis.Aos demais familiares, em especial meu irmão Fernando e minha cunhada Samantha, que, apesar da distância, sempre demonstraram incentivo.Ao professor Edson Wendland, pela orientação e oportunidade concedida de realizar esta pesquisa.Um agradecimento especial ao amigo Alan Reis, por sempre se mostrar disposto, paciente e atencioso durante as inúmeras horas de conversa que contribuíram com o amadurecimento desta pesquisa.Ao conterrâneo Érick, pelas sugestões que contribuíram com o aprimoramento desta dissertação, e também pela amizade e ótimas risadas do dia a dia.Agradeço também aos demais amigos do time de monitoramento da Bacia do Ribeirão da Onça, Rubens, Gescilam e Yuri, que tornaram os dias de campo mais leves.Ao Dimaghi, pela ajuda fornecida durante o manuseio dos sensores utilizados no trabalho.

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Heated fiber-optic cables for distributed dry density measurements of granulated bentonite mixtures: Feasibility experiments

Cited by 16 publications

References 26 publications

A method for the simultaneous determination of the soil dry density and moisture content based on thermal effects

A method for the simultaneous determination of the soil dry density and moisture content based on thermal effects

Detection of grouting defects in prestressed tendon ducts using distributed fiber optic sensors

Investigação da umidade do solo por meio da combinação entre o aquecimento de uma liga ferrítica (Fe-Cr-Al) e a medição distribuída de temperatura (DTS)

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