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Degree

Doctor of Philosophy, Case Western Reserve University, Civil Engineering, 2004.

Abstract

Piezoceramic as a smart or adaptive material has been widely used in engineering measurement and control. When used in soil testing, the material can work as a wave transmitter or a wave receiver. Among the piezoelectric sensors, the bender element and the extender element are the most widely used. While the bender element is used to generate and receive shear waves, the extender element is used to produce and detect P-waves. One application of piezoelectric sensors is to measure shear wave velocities in centrifuge tests. Measurement techniques for both dry and saturated specimens were developed. A series of centrifuge model tests were performed. Bender element tests were carried out during the spin-up, spin-down, and in-flight stages of a centrifuge. Dynamic centrifuge tests were conducted on both dry and saturated models to investigate the influence of earthquake motions. Shear wave traveling times, accelerations, and pore water pressures were monitored during the tests. Based on the test results presented in this study, the current shear wave velocity-based liquefaction evaluation criteria were examined. Piezoelectric sensors were also used to develop a new piezo cone penetrometer. The piezo cone penetrometer is equipped with one set of bender elements and one set of extender elements. The equipment is designed for the purposes of measuring stiffness of the subgrade and the sublayer of a pavement in the field. Compared to the conventional CBR test, this method is quick and simple as well as being theoretically sound. The results in the laboratory have shown it to be a promising tool.Finally, a large odometer was developed for testing gravelly materials. The advantages of the device include that it can measure the stiffness of a soil with large grain sizes and can measure moduli in different planes. In conclusion, measurement of soil properties using piezoelectric sensors is direct and accurate. The technique is theoretically sound. The application of the technique is limited to low strain levels, which are in the elastic range of soil deformations.

Subject Headings

Engineering, Civil

Keywords

Shear Wave; Bender Elements; SOIL; Centrifuge; Shear; Bender; Earthquake

Advisor

Xiangwu Zeng

Document number: case1089850793
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=case1089850793

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