STUDY OF FEASIBILITY OF USING WISSA-TYPE PIEZOMETER PROBE TO IDENTIFY LIQUEFACTION POTENTIAL OF SATURATED FINE SANDS
A two-phase study was performed to investigate the feasibility of using the pore pressure response from a penetrating Wissa piezometer probe to indicate the potential for liquefaction in saturated fine sand. The Wissa probe is a cone penetrometer, similar to the Dutch cone penetrometer, with a sensing element at the tip for measurement of pore pressures. Phase I was a field study consisting of three piezometer probe tests to a depth of about four and one-half meters in each of two areas. Phase II was a laboratory study consisting of four tests, each on a freshly prepared specimen of Reid-Bedford Model sand. Relative densities in these tests were between 30 and 81 percent, the mid-height vertical effective stress was approximately 17-5 psi, K sub zero was approximately 0.46, and the degree of saturation approximately 97 percent. The pore pressure response in these tests was qualitatively similar to that in the field tests, but of a magnitude about one-tenth as great. The reduced response was attributed to imperfect saturation of the test specimens. Comparison of pore pressure data with relative density , as estimated from approximate correlations with penetrometer resistance, suggest that this type of probe sounding can detect very unstable, saturated, clean, fine sands with relative densities below about 20 percent. However, there may be a broad range of relative density in which the piezometer probe response is insensitive to relative density. Additionally, the magnitude of pore pressure generated at the tip of a Wissa-type probe depends not only on the effective stresses and dilatancy behavior of the in situ sand but also on its permeability and the rate of penetration used. This study was done with only one rate of penetration, 2 cm/sec. In applying this method for field estimation of liquefaction potential, associated measurements of permeability will be required. Possibly these can be obtained from the rate of pore pressure decay when penetration is stopped. /Author/
- Prepared for U.S. Army Office of Chief of Engineers and monitored by Waterways Experiment Station.
University of Florida, GainesvilleGainesville, FL USA 32611
- Schmertmann, J H
- Publication Date: 1978-2
- Features: Figures; Tables;
- Pagination: 73 p.
- TRT Terms: Acoustic equipment; Alternatives analysis; Cone penetrometers; Laboratory tests; Permeability; Piezometers; Pore pressure; Sand; Telemetry
- Uncontrolled Terms: Loudspeakers
- Old TRIS Terms: K sub zero (Coefficient of earth pressure at rest)
- Subject Areas: Geotechnology; Highways;
- Accession Number: 00177299
- Record Type: Publication
- Report/Paper Numbers: Tech Report S-78-2 Final Rpt.
- Contract Numbers: DACW39-76-M-6646
- Files: TRIS, ATRI
- Created Date: Jul 29 1978 12:00AM