CYCLIC UNDRAINED SHEAR PROPERTIES OF HIGH QUALITY UNDISTURBED TOKYO GRAVEL

概要

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Responding to the increasing need for determining the strength and deformation characteristics of gravels in situ, an improved method of sampling by in situ freezing to obtain a high quality undisturbed sample of saturated gravel from a depth of about 20 m below the ground surface was developed. Two different types of undrained cyclic triaxial test for determination of liquefaction strength and deformation characteristics were conducted on the undisturbed deluvial gravel samples after they had been thawed. For studying the effects of sample disturbance, undrained cyclic triaxial test were also conducted on the reconstituted specimens. Based on the above studies it was shown that (1) three new developments in the technique of sampling by in situ freezing on gravel were successfully achieved in the field, (2) the shear modulus of undisturbed samples at minute strain level matches the value calculated from shear wave velocity, which assures a high quality of samples taken by this method, (3) the shear modulus of undisturbed samples is approximately 30% greater than that of reconstituted samples, and (4) the liquefaction resistance of the reconstituted samples is only about 50% of the value of undisturbed samples, even though they have the same density.
社団法人地盤工学会の論文
1988-12-15