宁波软土流变试验及经验模型

为了研究宁波软土的流变特性及经验模型,进行一维固结流变试验和三轴排水流变试验,并采用西原模型拟合模型参数.试验对比分析表明,固结试验的侧限作用会阻碍试样流变的发展,应力-应变等时曲线偏向应力轴,而三轴流变试验试样的流变能够得到充分地发展,应力-应变等时曲线偏向应变轴,能够更好地体现软黏土的流变性状.将一维西原模型应力-应变关系扩展到三维,采用修正剑桥模型屈服函数描述材料的塑性屈服.推导荷载恒定时土样的轴向应变计算公式,根据三轴排水流变试验结果进行曲线拟合,确定西原模型参数.结果表明,该模型能够较好地符合宁波软土的流变规律.

Rheological test and empirical model of Ningbo soft soil

One-dimensional consolidation rheological tests and triaxial rheological tests were conducted in order to analyze the rheological characteristics and rheological model of Ningbo soft soil.The results of rheological tests showed that the process of rheology was weaken by the lateral confinement in consolidation rheological tests,and the equal-time stress-strain curves deviated to the stress axis;while in triaxial rheological tests,the process of rheology adequately developed,and the equal-time stress-strain curves deviated to the strain axis,which better revealed the rheological characteristics of soft soil.The stress-strain relationship of one-dimensional Nishihara model was extended to three-dimension,and the yield function of modified Cambridge model was used to describe the plastic yield property.The calculation formula of creep strain with const load was developed,with which the triaxial rheological tests datas of Ningbo soft soil were fitted,and the parameters of Nishihara model were determined.Results show that the model is suitable for the rheological law of Ningbo soft soil.