以闽江中细砂层为对象,开展三因素三水平正交设计的小型振动台试验,定性探讨闽江砂土液化特性;同时基于Finn模型,在FLAC3D数值平台上对典型试验过程开展动力时程数值模拟。结果表明:Finn模型可有效模拟地震动作用下饱和砂土孔压的增长与有效应力的降低,能较为准确地反映饱和砂土的液化效应,Finn模型中的关键参数C1、C2对计算结果影响显著。以超孔压比峰值及超孔压比稳定值为指标,通过大量数值模拟结果与试验结果的对比,对上述关键参数进行标定,建议闽江饱和砂土液化Finn模型的关键参数取值为C1=1.30、C2=0.31。饱和砂土激振过程中呈现出轻微剪胀趋势,大致与液化现象同步出现。
Taking the medium-fine sand layer along Minjiang River as prototype, small-scale shaking table tests based on 3 factors and 3 levels orthogonal design were conducted to discuss the liquefaction characteristic qualitatively. Meanwhile, the dynamic numerical simulations for the typical excitation time-history were carried out upon the FLAC3D numerical platform by using Finn liquefaction constitutive model. The simulation results showed that the Finn constitutive model could well reflect the increase of pore pressure, the decrease of effective stress and the liquefaction characteristic of saturated sand under seismic excitation. On the other hand, the key parameters C1 and C2 in the Finn liquefaction constitutive model might influence the simulation results significantly. A large number of numerical simulations with different key parameters were carried out sequentially. The peak value and the stable value in the time-history of excess pore pressure ratio were focused and compared with experimental results. Therefore, the key parameters C1 and C2 for the Finn liquefaction constitutive model of Minjiang saturated sand were calibrated and suggested as 1.30 and 0.31, respectively. Meanwhile, the saturated sand also tended to dilate slightly during excitation time-history, which appeared synchronously with liquefaction.
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