Browsing by Author "Charlie, Wayne A., advisor"

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Open Access
Development of the piezovane for estimating liquefaction potential of saturated sands
(Colorado State University. Libraries, 1994) Butler, Leo Wm., author; Charlie, Wayne A., advisor; Siller, Thomas J., committee member; Doehring, Donald O., committee member
The Piezovane was developed for determining in situ liquefaction potential of saturated sands by measuring the porewater pressure response oi saturated sand during and after shearing of the soil. A negative porewater pressure response is an indication that the material is in a dense (dilative) state; therefore is not susceptible to liquefaction failure. Positive porewater pressure response is an indication that the sand is in a loose (contractive) state and is susceptible to liquefaction-type failure. This project included design, fabrication of the Piezovane apparatus and the calibration chamber for the initial laboratory testing. Sands were placed within the calibration chamber at densities greater than or less than densities at the steady state which had been developed by using CU triaxial and CD direct shear tests. Trends indicate that the Piezovane testing can predict contractive or dilative behavior of soils. Additional testing both in the laboratory and in the field is required to determine whether these measured porewater pressure responses and measured shear resistances provide parameters needed for evaluating liquefaction potential and their possible use for design. A patent for the Piezovane has been awarded.
Open Access
Estimating liquefaction potential of sands using the piezovane
(Colorado State University. Libraries, 1989) Scott, Clinton E., author; Charlie, Wayne A., advisor; Doehring, D. O., committee member; Siller, T. J., committee member
Laboratory test results are presented indicating feasibility of estimating liquefaction potential of saturated cohesionless soil using the piezovane, a shear vane incorporating pore pressure measurement. Utilizing a calibration chamber, piezovane shear tests are conducted on medium-fine subrounded quartz sand. Partially drained tests show small negative pore pressure peaks in dense samples and small positive peaks in relatively loose samples, indicating a reasonable trend of volumetric strain tendencies during shear. The piezovane induces positive pore pressure at denser initial states than steady states (zero contraction) determined by CU triaxial tests, but peak shear strength trends and direct shear test results indicate that observed pore pressure response adequately reflects actual contractive and dilative tendencies during piezovane shear.