海相沉积土一维蠕变试验与经验模型研究

Study of one-dimensional creep test and empirical model of marine deposit soils

人工岛地基通常以深厚的海相沉积土为主,过大的工后沉降会对人工岛的使用产生不利影响.针对大连海相沉积土原状样,采用一维蠕变试验对黏性土的蠕变特性进行了研究.基于蠕变试验结果,建立了可以考虑沉积土主、次固结效应的经验模型.研究结果表明:该地区沉积土具有典型的非线性蠕变特性.随固结压力的增加,土体应变随之增大,稳定时间越长,主次固结分界点越不明显.沉积土属中等次压缩性土,次固结系数随固结时间的增加而减小,次固结系数与压缩指数的比值介于0.052~0.065之间,与Mesri结论相符.模型计算结果与试验结果吻合较好,表明新建模型适用于描述大连海相沉积土的蠕变特性.

The foundation of artificial island is mainly constituted by marine deposits, and the great settlement after construction has adverse effect on the working of artificial island. The creep behaviors of Dalian marine deposits are studied according to one-dimensional creep tests. Based on the test results, the empirical model is established which considered the primary consolidation and secondary consolidation in the meantime. The results show that, Dalian deposits have typical nonlinear creep behaviors. With the increasing of consolidation pressure, the strain is increased;stability time is extended;and the demarcation point between primary and secondary consolidation is not obvious. The deposits belong to medium secondary compressibility soil;and the secondary consolidation coefficient is decreased with the increasing of consolidation time. The ratio between secondary consolidation coefficient and compression index change from 0.052 to 0.065, which conform to Mesri conclusion. The test results agree well with the calculation results, so as to show that the new model is suitable for describing the creep behaviors of Dalian marine deposits.