Strength degradation of saturated soft clay under cyclic loading
(2.Institution of Geotechnical Engineering, Ningbo University, Ningbo, China 315211)
【Abstract】In this paper, the dynamic and static triaxial tests of Ningbo rail transit silty clay are carried out. The strength degradation behaviors of the silty clay and the development law of the undrained shear effective stress path under different confining pressure, static deviatoric stress and dynamic stress are discussed, and the parameters of strength degradation are obtained. The results show that the pore pressure curves behave as the characteristics of overconsolidated soil in comparison to the test results of conventional undrained triaxial shear, and the dilatancy occurs in the test, and increases more obviously with the increase of dynamic stress ratio and initial static deflection stress ratio. In addition, the pore pressure increases and the effective stress decreases, so the shear strength decreases with the increase of static deviator stress. The linear expression of u/σ3–qsd/qs established in this paper can describe the relationship of strength degradation ratio and normalized pore pressure of the silty clay, and the stress path curve shifts to the left with the increase of static deviatoric stress. The results can provide as a reference for dynamic design of rail transit.
【Keywords】 cyclic loading; silty clay; static deviatoric stress; strength weakening; stress path;
(Translated by SUN Z)
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