恒定主应力轴偏转循环荷载下饱和软黏土累积孔压特性分析

Analysis on Pore Pressure of Saturated Soft Clay Subject to Cyclic Loading Considering Principal Stress Axis Deflection

现有的饱和软黏土循环荷载累积孔压显式模型未能反映路基土体单元在土体自重作用下主应力轴的偏转现象。在确定饱和软黏土固结时间的基础上,在固结压力分别为100、150、200 kPa下,对软黏土进行主应力轴偏转角为15°、30°、45°的不排水循环加载试验,得到了固结围压、主应力轴旋转角及动应力比对循环累积孔压影响的规律。基于第一次循环加载累积孔压变化规律和修正动偏应力水平,建立了能考虑恒定主应力轴偏转角循环加载下累积孔压显式模型,并利用恒定主应力轴偏转角循环加载试验结果验证了模型的合理性。建立的循环荷载下饱和软黏土累积孔压显式模型参数易于确定,参数具有明确的物理意义且能考虑主应力轴的恒定偏转现象。

The traditional accumulative pore pressure model of saturated soft clay under cyclic loading can not reflect the phenomenon of principal stress axial deflection. With the determination of consolidation time, under the condition of 100,150,200 kPa consolidation pressure, the undrained cyclic loading test with the principal stress axes angle of 15°,30°,45° was conducted on soft clay. The effects of confining pressure, the principal stress axis rotation angle and the static deviator stress on cycle cumulative pore pressure were obtained. On the basis of the cumulative pore pressure of the first cyclic loading and the revised dynamic deviatoric stress level, an explicit model was proposed to calculate the cumulative pore pressure of saturated clay subjected to cyclic loading. The validity of the model was verified based on undrained cyclic tests of consolidated soft clay. The parameters were of physical significance and are easy to be obtained. The proposed explicit model could reflect the phenomenon of principal stress axial deflection.