海相软土一维固结流变特性及模型

Study on Creep Characteristics and Model for One-dimensional Consolidation of Marine Soft Soil

通过分别加载和分级加载2种方式进行了一维固结流变试验,研究了上海海相软土一维固结流变特性和计算模型.试验结果表明：分别加载试验影响因素较多,试验结果易出现偏差,而分级加载试验结果容易得到保证;上海软土具有非线性流变特性,垂直压力较低时（分别加载垂直压力低于100 kPa;分级加载垂直压力低于200 kPa）,ε-lnt曲线近似为平行直线,可直接采用对数函数描述土的流变行为;垂直压力较高时（分别加载垂直压力超过100 kPa;分级加载垂直压力超过200 kPa）,ε-lnt曲线近似为平行折线,分别加载试验和分级加载试验斜率变化分别在49 min和16 min,此时可采用分段对数函数描述土的流变行为.建议应力-应变关系采用幂函数,应变-时间关系采用双曲线函数建立流变方程,该模型能较好的描述垂直压力在400 kPa范围内上海海相软土一维固结流变分级加载全过程.

Creep properties and model for one-dimensional consolidation of Shanghai marine soft soil was studied by each loading and gradation loading for the one-dimensional consolidation creep test. There were more influencing factors in each loading one-dimensional consolidation creep test,so that the results were more prone to errors than that in gradation loading test. Shanghai soft soil wss of nonlinear creep characteristics. When the vertical pressure was less than 100 kPa in each loading test or 200 kPa in gradation loading test,ε-lnt curve was approximately parallel line. The logarithmic function was used directly to describe the rheological behavior of the soil. When the vertical pressure was more than 100 kPa in each loading test or 200 kPa in gradation loading test,ε-lnt curve was approximately parallel broken line. The slope of ε-lnt curve changed at 49 min and 16 min in each loading test and gradation loading test. Creep models of Shanghai soft soil were proposed,in which power function was adopted for stress-strain relationship and hyperbolic function was adopted for strain-time relationship. The model which loading was below 400 kPa,was bettle to describe the creep behavior for one-dimensional consolidation of Shanghai marine soft soil in gradation loading.