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An Innovative Sensing Technology to Measure Thin Interfaces for Geotechnical Applications

QUAN, GAO
http://rave.ohiolink.edu/etdc/view?acc_num=case1457987819

Abstract Details

2016, Doctor of Philosophy, Case Western Reserve University, Civil Engineering.
Time Domain Reflectrometry (TDR) is a useful and effective technique for the detection of discontinuities or interfaces. It has been extensively applied for geotechnical applications by detecting air-water or soil-water interface, such as monitoring reservoir water level and bridge scour. But the current TDR sensor (e.g., conventional straight waveguide) would lose capability for some applications involving detection of very thin interfaces, for instance, the bridge scour surveillance with scouring in the range of centimeters, the measurement of water film due to void redistribution in multiple-layered soil profile, which is even in the range of millimeters. This makes it imperative to further improve the resolution and sensitivity of the TDR waveguide. The concept of the spiral TDR probe is proposed in this dissertation study. It means designing the traditional straight waveguide into a spiral shape to increase the effective propagation path of EM wave per unit length along the direction of the sensor. A FEM analysis is conducted for the optimization design of the new sensor. The effect of geometric configurations on the sampling area is also analyzed, including waveguide diameter and spacing distance, etc. Several spiral TDR sensors are fabricated and evaluated using a series of laboratory experiments. Its performance is also compared with the conventional straight probes. The new spiral TDR sensor is calibrated using several standard liquids or solvents with known dielectric information. A series of simulated scouring tests with two-centimeter sediment scouring are performed with the new sensor and traditional straight probe. The performance of the two sensors and the advantage of the new probe is analyzed and evaluated. The new spiral TDR sensor is then applied for the detection and measurement of water film due to void redistribution in the layered soil column. A group of static and dynamic shaking table tests are carried out in the laboratory to assess the performance of the new sensor. The results from both experiments indicate that the new spiral sensor is capable to detect and measure the water film within millimeter in layered ground. However, further refinements and improvements are still required to explore applications of the new spiral sensor in future studies.
YU XIONG (Committee Chair)
SAADA ADEL (Committee Member)
ZENG XIANGWU (Committee Member)
GUO WEIHONG (Committee Member)
Civil Engineering; Engineering; Geotechnology

Recommended Citations

Citations

  • QUAN, G. (2016). An Innovative Sensing Technology to Measure Thin Interfaces for Geotechnical Applications [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1457987819

    APA Style (7th edition)

  • QUAN, GAO. An Innovative Sensing Technology to Measure Thin Interfaces for Geotechnical Applications. 2016. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1457987819.

    MLA Style (8th edition)

  • QUAN, GAO. "An Innovative Sensing Technology to Measure Thin Interfaces for Geotechnical Applications." Doctoral dissertation, Case Western Reserve University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1457987819

    Chicago Manual of Style (17th edition)

case1457987819
680
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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.