Evaluation of Liquefaction Potentials of Soils Using Cone Penetration Tests

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ABSTRACT

A review of field liquefaction behavior during several recent earthquakes was made with emphasis on the Cone Penetration Test (CPT) qc-values and the grain size of the soils. The field correlation between the earthquake-induced cyclic stress ratio and normalized cone resistance indicates that fine-grained soils with a mean grain size of D50 < 0.25 mm have greater resistance to liquefaction than do clean sands (D50  O.25mm) having the same qc-values.

On the basis of this finding, we have developed a liquefaction assessment method for soils using the CPT. The normalized critical value of the CPT, (qc1)cr, which separates liquefiable from nonliquefiable conditions, is defined as a function both of the cyclic stress ratio, and the mean grain size of a soil. A simple chart showing variation in the critical CPT value, (qc)cr, with depth was developed for various earthquake magnitudes, maximum surface accelerations and ground water levels. Our proposed CPT-based liquefaction assessment method was evaluated by data on the known performance of soils in the field.

Key words

case history
earthquake
grain size
in-situ test
liquefaction
penetration test
sand
silt (IGC : D7/C3)

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Written discussions on this paper should be submitted before January 1, 1989, to the Japanese Society of Soil Mechanics and Foundation Engineering, Sugayama Bldg. 4 F, Kanda Awaji-cho 2-23, Chiyoda-ku, Tokyo 101, Japan. Upon request the closing date may be extended one month.

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