间歇循环荷载和循环围压共同作用下软黏土变形特性试验研究

    Experimental study on coupling effects of cyclic confining pressure and intermittent cyclic loading on deformation behavior of saturated soft clay

    • 摘要: 对软黏土开展两类循环三轴试验,即连续循环加载和间歇循环加载三轴试验,研究了间歇循环荷载和循环围压共同作用下软黏土变形特性,分析了循环围压和间歇停振阶段对软黏土累积轴向应变的影响。试验结果表明,与连续循环加载条件对比,间歇停振阶段的存在对软黏土变形特性影响显著,间歇停振阶段因超孔隙水压力的消散而引起的变形不容忽视。另一方面,随着循环围压的增大,对应的累积轴向应变增量减小。不同循环围压条件下累积轴向应变增量的差异在第一加载阶段循环荷载作用期间较为显著,而在随后循环加载阶段中可以忽略不计。基于上述试验结果,提出了一个间歇循环荷载作用下考虑循环围压影响的软黏土累积轴向应变计算模型,预测结果与实测数据较为吻合。上述研究成果可加深对间歇性循环荷载作用下软黏土变形规律的认识。

       

      Abstract: The deformation characteristics of soft clay under intermittent cyclic loading and cyclic confining pressure are studied by conducting two types of cyclic triaxial tests, i.e., continuous cyclic loading and intermittent cyclic loading triaxial tests, and the influences of cyclic confining pressure and intermittent period on the accumulated axial strain of soft clay are analysed. The test results show that compared with the continuous cyclic loading conditions, the existence of intermittent period has a significant effect on the deformation characteristics of soft clay, and the deformation caused by the dissipation of the excess pore water pressure during the intermittent period cannot be ignored. On the other hand, with the increase of the cyclic confining pressure, the corresponding accumulated axial strain increment is small. The difference of the increment of accumulated axial strain under different cyclic confining pressures is significant during the cyclic loading period at the first loading stage, and can be ignored at the subsequent cyclic loading stage. Based on the above test results, a model for the accumulated axial strain of soft clay under intermittent cyclic loading considering the effects of cyclic confining pressure is proposed, and the predicted results are in good agreement with the measured data. The above research results can deepen the understanding of the deformation behavior of soft clay under intermittent cyclic loading.

       

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