循环剪切荷载作用下软土的力学性状研究

SOME MECHANICAL CHARACTERISTICS OF SOFT CLAY UNDER CYCLIC AXIAl SHEARING

利用从现场取得的原状土样,通过室内动三轴试验对循环荷载作用下的变形、孔压和强度特性进行研究。试验研究主要考虑了周围固结压力、循环剪切应力比、荷载频率和循环次数等因素的影响。研究表明,在循环荷载作用下,孔隙水压力和轴向应变均是一个波动上升的过程。当循环应力比增大时,动孔隙水压力变化幅值显著增加,而残余孔压也较大。同时,孔隙水压力值也随着周围压力的增大而明显增大。当作用荷载频率比较大时,需要更多的循环次数才能达到小频率作用荷载能达到的孔隙水压力值。但是,随着循环荷载作用次数的增加,频率对孔隙水压力的影响有减小的趋势。

The mechanical characteristics on the deformation, pore pressure and shear strength of undisturbed soft clay samples are studied with cyclic axial shear tests. The effects of confining pressure, cyclic stress ratio, frequency of cyclic loading and cyclic numbers are considered. The study results show that the pore pressure and axial strain took on a fluctuant increasing process under cyclic shear loading. The amplitudes of pore pressure increased notably with the increase of cyclic stress ratio, and the residual pore pressure also increased obviously. In the meantime, the pore pressure also increased with the increase of confining pressure. More cyclic numbers were needed under a high frequency of cyclic loading than a low frequency of cyclic loading in order that the residual pore pressure could achieve the same value. However, the effect of frequency was not obvious with the increase of cyclic numbers.