Location

St. Louis, Missouri

Session Start Date

3-11-1991

Session End Date

3-15-1991

Abstract

The foundation of the proposed Polavaram Earth and Rockfill Dam (India) has a sand deposit about 15 to 30 meters deep. The medium size sand is poorly to uniformly graded having relati.ve density in the range of 40-45% and angle of internal friction 30°. Standard Penetration Tests have been conducted in 22 bore holes at site and the N-counts have been observed to range between 4 to 111. The liquefaction potential of deposit under maximum credible earthquake (MCE) for the site has been evaluated by analyzing the data on the basis of prevailing empirical approaches and by the results of the experiments conducted on the sand in laboratory. The results of the analyses indicate that for the design earthquake the liquefaction would occur at some spots where N-counts are very low. The experiments have been conducted by depositing the sand, with the relative density close to that at site, in a box placed on a shaking table. The table was subjected to equivalent number of sinusoidal cycles corresponding to 75, 65 and 50% level of maximum acceleration of the time history of the design earthquake. As the dam provides an overburden pressure to the foundation, experiments have been conducted with loading on sand deposit in the shake table. The effect of frequency of motion has also been observed. The results of these experiments show that for the design acceleration levels of 0.1 g (65% of maximum acceleration) the maximum pore water pressure would be 31% of the effective overburden. The frequency of 3 cps seems the optimum frequency for generation of pore water pressure and at 8 cps this is less by about 20 percent. Thus the experiments indicate only partial loss of shear strength and not the total liquefaction of the foundation sand.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

3-11-1991

Document Version

Final Version

Rights

© 1991 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 11th, 12:00 AM Mar 15th, 12:00 AM

Evaluation of Liquefaction Potential for an Earth Dam Site

St. Louis, Missouri

The foundation of the proposed Polavaram Earth and Rockfill Dam (India) has a sand deposit about 15 to 30 meters deep. The medium size sand is poorly to uniformly graded having relati.ve density in the range of 40-45% and angle of internal friction 30°. Standard Penetration Tests have been conducted in 22 bore holes at site and the N-counts have been observed to range between 4 to 111. The liquefaction potential of deposit under maximum credible earthquake (MCE) for the site has been evaluated by analyzing the data on the basis of prevailing empirical approaches and by the results of the experiments conducted on the sand in laboratory. The results of the analyses indicate that for the design earthquake the liquefaction would occur at some spots where N-counts are very low. The experiments have been conducted by depositing the sand, with the relative density close to that at site, in a box placed on a shaking table. The table was subjected to equivalent number of sinusoidal cycles corresponding to 75, 65 and 50% level of maximum acceleration of the time history of the design earthquake. As the dam provides an overburden pressure to the foundation, experiments have been conducted with loading on sand deposit in the shake table. The effect of frequency of motion has also been observed. The results of these experiments show that for the design acceleration levels of 0.1 g (65% of maximum acceleration) the maximum pore water pressure would be 31% of the effective overburden. The frequency of 3 cps seems the optimum frequency for generation of pore water pressure and at 8 cps this is less by about 20 percent. Thus the experiments indicate only partial loss of shear strength and not the total liquefaction of the foundation sand.