上海地区软土的循环累积孔压模型

基于上海地区饱和软土动三轴试验成果；通过对累积孔压和累积变形影响因素及发展规律相似性进行分析,将Parr提出的循环累积变形方程进行转换,引入动强度参数并提出等效循环动应力水平概念,建立能综合考虑列车荷载循环次数、静偏应力和和动偏应力耦合作用、固结方式等影响因素的上海地区软黏士累积孔压模型.结合试验结果对模型进行验证,确定不同试验条件下模型中试验常数.结果表明:模型能够较好地反映多种因素对软土循环累积孔压影响.模型仅适用于正常固结软黏土且循环应力比大于循环应力比阈值而小于临界循环应力比的情况.为提高模型计算和预测精度,用室内试验确定模型中试验常数值时,应采用跟现场实际相符的加载和固结条件.

Cyclic Accumulative Pore Pressure Model of Soft Clay in the Shanghai Region

On the foundation of the results of dynamic triaxial tests of soft clay in the Shanghai region,through analysis on the similarities of influencing factors and developing laws of accumulative pore pressures and accumulative deformations and by transformation of the Parr’s cyclic accumulative deformation equation and introduction of the parameter of the dynamic strength and the concept of the equivalent cyclic dynamic stress level,the model of accumulative pore pressures of the soft clay in the Shanghai region was established in comprehensive consideration of the cyclic number of train loads,coupling effect of static deviator stress and dynamic deviator stress and ways of consideration.The model was verified by test results.Test constants of the model were gained under different test conditions.The test results show as follows: the model can well reflect the influence of multiple factors on cyclic accumulative pore pressures;the model is just applicable to normally consolidated soft clay on the condition that the cyclic stress ratio is less than the critical cyclic stress ratio but more than the threshold cyclic stress ratio;in order to improve the calculating and predicting precision of the model,the loading and consolidating conditions should be made in accordance with actual field circumstances in laboratory tests which aims at determining the test constants of the model.