振动频率对饱和黏性土动力特性的影响

Effect of vibration frequency on dynamic properties of saturated cohesive soil

在回顾加荷频率对土样动力特性影响的研究基础上,采用某土石坝心墙防渗黏性土饱和试样,通过动三轴试验,研究了振动频率f对土样动力特性的影响。动强度试验结果表明:当f=0.1～4Hz时,动强度随f的升高而增大,但f继续升高后,动强度却有下降趋势。当f=0.1～1.0Hz时,频率愈高动孔压比愈大;当f=1.0～6.0Hz时,总的趋势为频率愈高,动孔压比愈小。表明频率较高时,动孔隙水压力来不及上升和扩散。较高频率f持续作用下,试样有吸水现象并伴随动孔压的下降。动模量阻尼试验结果是:f愈低,试样动变形开展愈充分;f愈高,动模量和阻尼比愈大。

To study the effect of vibration frequency on soil dynamic characteristics, firstly the related research outcomes are reviewed, then the dynamic triaxial tests which used core material of one rockfill dam were performed. The results of dynamic intensity tests show that with the increasing of vibration frequency f, dynamic intensity increases when f equals to 0.1-4 Hz; and with the increasing off, dynamic porewater pressure ratio increases duringfequals to 0.1-1.0 Hz while decreases during f equals to 1.0-6.0 Hz. Under the sustaining operation of higher frequency, there are phenomena of sample sopping up and dynamic porewater pressure declining. This means it hasn＇t enough time for dynamic porewater pressure to climb and extend whenfis much higher. And the results of dynamic modulus and damping ratio tests show that the lower the vibration frequency acting on the sample, the more sufficiently dynamic deformation could develop; both dynamic modulus Ea and damping ratio D increase with vibration frequency.