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Proceedings Paper

Measurement of water pressure and deformation with time domain reflectometry cables
Author(s): Charles H. Dowding; Charles E. Pierce
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Paper Abstract

Time domain reflectometry (TDR) techniques can be deployed to measure water pressures and relative dam abutment displacement with an array of coaxial cables either drilled and grouted or retrofitted through existing passages. Application of TDR to dam monitoring requires determination of appropriate cable types and methods to install these cables in existing dams or during new construction. This paper briefly discusses currently applied and developing TDR techniques and describes initial design considerations for TDR-based dam instrumentation. Water pressure at the base of or within the dam can be determined by measuring the water level within a hollow or air-filled coaxial cable. The ability to retrofit existing porous stone-tipped piezometers is an attractive attribute of the TDR system. Measurement of relative lateral movement can be accomplished by monitoring local shearing of a solid polyethylene-filled coaxial cable at the interface of the dam base and foundation materials or along adversely oriented joints. Uplift can be recorded by measuring cable extension as the dam displaces upward off its foundation. Since each monitoring technique requires measurements with different types of coaxial cables, a variety may be installed within the array. Multiplexing of these cables will allow monitoring from a single pulser, and measurements can be recorded on site or remotely via a modem at any time.

Paper Details

Date Published: 12 May 1995
PDF: 9 pages
Proc. SPIE 2457, Nondestructive Evaluation of Aging Structures and Dams, (12 May 1995); doi: 10.1117/12.209393
Show Author Affiliations
Charles H. Dowding, Northwestern Univ. (United States)
Charles E. Pierce, Northwestern Univ. (United States)


Published in SPIE Proceedings Vol. 2457:
Nondestructive Evaluation of Aging Structures and Dams
Soheil Nazarian; Larry D. Olson, Editor(s)

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