振动频率对饱和松砂动力特性影响试验研究

利用DDS-70微机控制电磁式振动三轴仪,在均压固结条件下对福建标准砂进行了不同振动频率的循环三轴试验,研究了振动频率对其动力特性的影响。研究表明:在围压相同且均压固结条件下,饱和松砂的动强度随着振动频率的增大而增大;达到同一峰值孔压的水平,振动频率越高,所需要的振次越多;对应于相同的轴向动应力,动轴向应变随着振动频率的增加,达到5%的应变所需的振次增多,动轴向应变与动孔压的发展不是一致的。振动频率越高,达到液化所需要的振动时间急剧减少,较高频率比较低频率的动荷载作用更能迅速地使饱和砂土达到某一变形、孔压和强度发挥水平,也使饱和砂土产生液化的可能性显著增大。

Experimental Study on Effect of Vibration Frequency on Dynamic Behaviors of Saturated Loose Sands

A series of cycling triaxial experiments of different vibration frequencies for the standard land in Fujian are accomplished by using DDS-70 microcomputer control electromagnetic vibration triaxial apparatus under the condition of equal consolidation,so as to study the effect of vibration frequencies on its dynamic behaviors.The study results show that the dynamic strength of saturated loose sands is increased with the increasing of vibration frequency under the condition of same ambient pressure and equal consolidation.The vibration frequency is bigger with higher vibration frequency in order to reach the peak pore pressure.Corresponding to the same axial dynamic stress,the vibration frequency is increased to reach 5% of dynamic axial strain with the increasing of vibration frequency.The development of dynamic axial strain and dynamic pore pressure is not consistent.It takes less time to reach the liquefaction with higher vibration frequency.The dynamic load of high vibration frequency can more quickly make the saturated loose sands reach some level of deformation,pore pressure and strength than that of low vibration frequency.The possibility of liquefaction for saturated loose sands is also much increased.