In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilat...In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilative(ISD)period)and post-liquefaction(late shearing dilative(LSD)period)deformation properties of saturated Fujian sand.The secant shear modulus G and damping ratioλin the entire cyclic loading process,and the unloading tangent shear modulus G_(L1)and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude ca.The test results show that the effect of f on G of saturated Fujian sand in the SC period is not apparent.However,all the G-γ_(a),G_(L1)-γ_(a),and GL2-ca curves in the ISD and LSD periods showed a downward trend with an increase in f.This study also proposes a modified method for calculatingλto compensate for the analytical error caused by the non-closure of hysteresis loop.Compared with the classical curves that mainly applied in geotechnical engineering,theλfirst increases and then decreases with the increase ofγa.Furthermore,theλevaluated by the modified method is approximately 10%–15%more than theλevaluated by the traditional method when theλreaches its peak value.展开更多
基金supported by the National Outstanding Youth Science Fund Project of the National Natural Science Foundation of China(Grant No.51722801)National Natural Science Foundation of China(Grant No.52078020).
文摘In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilative(ISD)period)and post-liquefaction(late shearing dilative(LSD)period)deformation properties of saturated Fujian sand.The secant shear modulus G and damping ratioλin the entire cyclic loading process,and the unloading tangent shear modulus G_(L1)and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude ca.The test results show that the effect of f on G of saturated Fujian sand in the SC period is not apparent.However,all the G-γ_(a),G_(L1)-γ_(a),and GL2-ca curves in the ISD and LSD periods showed a downward trend with an increase in f.This study also proposes a modified method for calculatingλto compensate for the analytical error caused by the non-closure of hysteresis loop.Compared with the classical curves that mainly applied in geotechnical engineering,theλfirst increases and then decreases with the increase ofγa.Furthermore,theλevaluated by the modified method is approximately 10%–15%more than theλevaluated by the traditional method when theλreaches its peak value.
