Monitoring water seepage velocity in dikes using distributed optical fiber temperature sensors

Su, Huaizhi; Tian, Shiguang; Kang, Yuhao; Xie, Wei; Chen, Jian

doi:10.1016/j.autcon.2017.01.013

Cited by 58 publications

(29 citation statements)

References 17 publications

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“…Using the equation of heat convection between the seepage water and the heated cable (Equation (15)), Su et al [ 67 ] studied the seepage velocity by the optical fiber active temperature measurements in a laboratory model for the soil-concrete contact. If the water properties and structure size in Equation (16) are considered constant, then the heat transfer coefficient is only a function of flow velocity.…”

Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

“…Their study demonstrated that the detection of small flow velocity requires a higher heating power. Also, the higher heating power [ 67 ] and increased heating time [ 51 ] can highlight the seepage anomalies better.…”

Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

“…Various researches on the active method show that the accuracy of seepage and the saturation estimation depends on the heating power and heating period [ 14 , 51 , 67 ]. For the detection of a concentrated leakage, a heat impulse of 3 to 5 Watts per meter of the cable length is enough, however, the measurement of the distributed flow velocity may require about 10 Watt per meter [ 65 , 73 ].…”

Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

See 2 more Smart Citations

A Review of Measurement Calibration and Interpretation for Seepage Monitoring by Optical Fiber Distributed Temperature Sensors

Ghafoori

Vidmar

Říha

et al. 2020

Sensors

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Seepage flow through embankment dams and their sub-base is a crucial safety concern that can initiate internal erosion of the structure. The thermometric method of seepage monitoring employs the study of heat transfer characteristics in the soils, as the temperature distribution in earth-filled structures can be influenced by the presence of seepage. Thus, continuous temperature measurements can allow detection of seepage flows. With the recent advances in optical fiber temperature sensor technology, accurate and fast temperature measurements, with relatively high spatial resolution, have been made possible using optical fiber distributed temperature sensors (DTSs). As with any sensor system, to obtain a precise temperature, the DTS measurements need to be calibrated. DTS systems automatically calibrate the measurements using an internal thermometer and reference section. Additionally, manual calibration techniques have been developed which are discussed in this paper. The temperature data do not provide any direct information about the seepage, and this requires further processing and analysis. Several methods have been developed to interpret the temperature data for the localization of the seepage and in some cases to estimate the seepage quantity. An efficient DTS application in seepage monitoring strongly depends on the following factors: installation approach, calibration technique, along with temperature data interpretation and post-processing. This paper reviews the different techniques for calibration of DTS measurements as well as the methods of interpretation of the temperature data.

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Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

Section: Seepage Detection Techniques From the Temperature Measurementioning

confidence: 99%

See 1 more Smart Citation

A Review of Measurement Calibration and Interpretation for Seepage Monitoring by Optical Fiber Distributed Temperature Sensors

Ghafoori

Vidmar

Říha

et al. 2020

Sensors

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“…This interrogator has the integrated functions of heating the CFHC, measuring the distribution of temperature, deducing the soil moisture, and demonstrating the results. The working principle of this interrogator is based on the actively heated fiber optic (AHFO) method [38], which is suitable not only for laboratory experiments [38,39], but also for in situ tests [40][41][42][43]. Hence, the results measured with the AHFO method in these laboratory experiments can be compared with those in the field tests.…”

Section: Setup Of Calibration and Validation Testsmentioning

confidence: 99%

Feasibility Investigation of Improving the Modified Green–Ampt Model for Treatment of Horizontal Infiltration in Soil

Cao

Shi

Zhu

et al. 2019

Water

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Water infiltration in soil is a complex process that still requires appreciation of interactions among three phases (soil particles, water and air) to enable accurate estimation of water transport rates. To simulate this process, the Green–Ampt (GA) model and the Modified Green-Ampt (MGA) model introduced in the paper “A new method to estimate soil water infiltration based on a modified Green–Ampt model” have been widely used. The GA model is based on the hypothesis that the advance of the wetting front in soil under matric suction can be treated as a rectangular piston flow that is instantaneously transformed after passage of the infiltration front, and the MGA model does not contain the influence of pore size change. This cannot accurately reflect the soil moisture change process from unsaturation to saturation. Due to soil stratification and other inhomogeneity, predictions produced with these models often differ widely from observations. To quickly obtain the soil moisture distribution after passage of the wetting front for horizontal infiltration, an improved modified Green–Ampt (IMGA) model is presented, which estimates the soil moisture profile along a horizontal column in a piecewise manner with three functions. A logarithmic function is used to describe the gradual soil saturation process in the transmission zone, and two linear functions are used to represent the wetting zone. The algorithm of the IMGA model for estimating the water infiltration rate and cumulative infiltration is configured. To verify the effectiveness of IMGA model, a lab model test was performed, and a numerical model was built to solve the horizontal one-dimensional Richards equation using the finite–element method. The results show that the IMGA model is more accurate than the GA and MGA models. The horizontal soil moisture profiles obtained by the IMGA model are closer to the measured data than the numerical simulation results. The relative errors of the MGA and IMGA models decrease with an increase in infiltration time, whereas that of the GA model first decreases and then increases with infiltration time. The primary novelty of this study is nonlinear description of soil moisture content distribution, and derivation of unit transfer coefficient.

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“…This can be implemented by introducing heat into a metal wire within the optical fiber coating [16] or a separate wire along the optical fiber cable. The active method was used to estimate the seepage velocity [15,17] and the degree of saturation [15] in the vicinity of the optical fiber cable. The accuracy of the method depends on the heating power [17] that is introduced into the embankment, thus, for long cables, a high power source is required.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Seepage in a Laboratory Scaled Model Using Passive Optical Fiber Distributed Temperature Sensor

Ghafoori

Maček

Vidmar

et al. 2020

Water

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Seepage is the key factor in the safety of dikes and earth-fill dams. It is crucial to identify and localize the seepage excesses at the early stages before it initiates the internal erosion process in the structure. A proper seepage monitoring system should ensure a continuous and wide area seepage measurement. Here, continuous monitoring of seepage at the laboratory-scale is achieved by a passive optical fiber Distributed Temperature Sensing (DTS) system. An experimental model was designed which consists of initially unsaturated sand model, water supply, seepage outflow, optical fiber DTS system, and water and air temperature measurement. Initially, the sand temperature was higher than the temperature of the seepage water. An optical fiber DTS system was employed with a high-temperature resolution, short sampling intervals and short time intervals for temperature monitoring in the sand model. In the system, the small variation in the temperature due to groundwater flow was detected. The numerical analysis was conducted for both the seepage process and the heat transfer progression in the sand model. The results of the heat flow simulation were evaluated and compared with the measured temperature by the optical fiber DTS. Obvious temperature reduction was obtained due to seepage propagation in the sand. The rate of temperature reduction was observed to be dependent on the seepage flow velocity.

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Monitoring water seepage velocity in dikes using distributed optical fiber temperature sensors

Cited by 58 publications

References 17 publications

A Review of Measurement Calibration and Interpretation for Seepage Monitoring by Optical Fiber Distributed Temperature Sensors

A Review of Measurement Calibration and Interpretation for Seepage Monitoring by Optical Fiber Distributed Temperature Sensors

Feasibility Investigation of Improving the Modified Green–Ampt Model for Treatment of Horizontal Infiltration in Soil

Analysis of Seepage in a Laboratory Scaled Model Using Passive Optical Fiber Distributed Temperature Sensor

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