EFFECTS OF PLASTICITY AND SAMPLE DISTURBANCE ON STATISTICAL PROPERTIES OF UNDRAINED SHEAR STRENGTH

概要

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Statistical properties of undrained shear strength c_u are investigated through laboratory and in-situ tests. In laboratory, a series of unconfined compression tests and triaxial UU tests are performed using mixed soil samples. Concerning in-situ soil samples, comparative study is made between disturbed and undisturbed soil specimens. Following findings and method are obtained : (1) When plasticity index I_p is greater than 15%, the difference of c_u between unconfined compression test and triaxial UU test is less than 2% and is almost negligible. However, when I_p is smaller than 15%, unconfined compression test always provides smaller strength than triaxial UU test. c_u of unconfined compression test is about 15% smaller than that of triaxial UU test when I_p≒10. (2) Concerning the coefficient of variation of strength V(c_u), however, there is no significant difference between these two testing methods. Moreover, V(c_u) is found almost independent of both plasticity index and consolidation pressure. (3) When soil specimens are disturbed, the mean value of q_u becomes small while the coefficient of variation becomes large. In the case of E_<50>, however, the coefficient of variation holds constant during disturbance procedure. (4) The method of predicting statistical values of strength of undisturbed specimens from those of disturbed samples is newly presented.
社団法人地盤工学会の論文
1988-06-15