高频、循环振动条件下含砂量对软土流动性影响

Influence of Sand Content on the Flow Characteristics of Soft Soil under Cyclic and High Frequency Vibration

软土在振动作用下的动力学特性与土体中的大颗粒含量有着密切联系。本文通过固定围压下的拖球试验,研究了在局部、高频循环振动条件下,不同含砂量对软土流动特性的影响;并总结出在不同振动频率作用下,含砂量变化对软土流动性所表现出的作用规律。研究表明:当振动频率较低时,含砂量的增加对土体流动性有抑制作用;当振动频率超过一个临界值时,该抑制作用变得不再显著。对于高频循环振动,随着含砂量的增加,土体流动性呈现出越来越快的收敛趋势;且收敛速率和振动频率之间没有明显关系。同时,在整个循环振动过程中,首次振动对土体流动性的增强作用占据主导地位,后续振动过程对土体流动性的增强作用非常微弱。由此可见,掺砂可以有效促进路基软土在高频、循环振动作用下的流动性收敛。研究结果对解决地铁路基工后持续沉降问题有一定的指导意义。

The mechanical properties of soft soil under vibration may have a close relationship with large particle content.In order to investigate the influence of sand content on flow characteristics of soft soil under localized,cyclic and high frequency vibration,pulling sphere tests were carried out on clay mixed with varying amounts of coarse sand.It is found that the increase in sand concentration exhibits inhibition effects on the flow characteristics of sand-clay mixtures when the vibration frequency is relatively low;if the frequency exceeds one critical value,the reduce of flow characteristics becomes not obvious anymore.On condition of cyclic vibration,the flow characteristics of mixtures appears convergent tendency which is getting faster and faster with the increase in sand content in the presence of high frequency vibration.There is no significant relationship between convergent velocity and vibration frequency.Meanwhile,the motivation effects of first vibration on flow characteristics of specimens occupies a dominated position within the cycle,the enhancement to flow characteristics of sandy clay during follow-up vibration is infinitesimal.Therefore,mixing coarse sand is able to accelerate the convergence of flow characteristics of soft soil under cyclic and high frequency vibration.The research makes sense for solving the problem of non-convergence post-construction settlement.