循环荷载作用下软土动力特性试验研究

Experimental Study on Dynamic Characteristic of Soft Soil under Cyclic Loading

为研究循环荷载作用引起的软土动力特性变化及由此导致的地基承载力不足等问题,以营口软土为研究对象,通过动三轴试验,研究了动应力幅值、固结围压、固结比、振动频率和振动次数对软土动力特性的影响。试验结果表明:营口软土具有明显的结构性,其动应变-振动次数(εd-lg N)曲线和动骨干曲线存在明显的应变转折点,超过此应变转折点后,土体变形迅速增加;动强度随固结围压的增加而增大,固结比和振动频率对软土动强度的影响却并非简单的一致增大或减小;动弹性模量随固结围压、固结比和振动频率的增加而增大,而动阻尼比则随着固结围压和固结比的增加而减小,随振动频率的增加而增大。

In order to research the dynamic characteristics change of soft soil due to cyclic loading and the induced particular inadequate bearing capacity of roadbed, taking the soft soil in Yingkou area as the research object, a series of dynamic triaxial test are performed to research the influence of dynamic stress amplitude, consolidation confining pressure, consolidation ratio, vibration frequency and vibration times on dynamic characteristics of soft soil are researched. The test results show that （1） Yingkou soft soil has a significant structural property, there is a strain turning point in the 6d - N curves and the dynamic backbone curves, the deformation of soil increases rapidly when the strain is larger than this turning point strain; （2） the dynamic strength increases as consolidation confining pressure increasing, but the influences of consolidation ratio and vibration frequency on soft soil dynamic strength are not always increasing or decreasing; （3） the dynamic modulus increases as consolidation confining pressure, consolidation ratio and vibration frequency increasing, while the dynamic damping ratio decreases as consolidation confining pressure and consolidation ratio increasing but increases as vibrational frequency increasing.