考虑排水条件的软土蠕变特性及模型研究

为了研究珠江三角洲软土在不同的排水条件和应力水平下的蠕变特性，进行了一系列室内三轴排水及不排水蠕变试验。试验结果表明，在排水情况下软土的瞬时变形大，而蠕变变形小，而在不排水情况下蠕变随时间的发展更为显著。在工程中可以提高软土地基的排水性能，来减小蠕变破坏的可能性。引入Singh-Mitchell蠕变方程，建立了珠江三角洲软土排水和不排水的Singh-Mitchell蠕变模型，其中应力-应变关系采用指数函数，应变-时间关系采用幂函数。该模型较好地表达了土体的应力-应变-时间关系。随着排水条件的改变，模型参数的取值有着较大的变化，其原因可归结为，在不同的排水条件下土体的应变-时间关系和应力-应变关系均有很大的不同。

Study on creep characteristics and model of soft soil considering drainage condition

In order to investigate the creep behaviors of soft soil in Pearl River Delta, a series of laboratory drained and undrained triaxial creep tests were performed. The test results show that in drained condition, soft soil has large initial deformation but small creep deformation. While in undrained condition, creep effect is significant. It indicates that enhancing the drainage ability of soft soil foundation can reduce the probability of creep rupture. By introducing Singh-Mitchell creep equation, the drained and undrained creep models of soft soil are proposed, in which exponential function is adopted for stress-strain relationship and power function for strain-time relationship. Predicted results are in good agreement with the experimental results. The values of model parameters change a lot with the variation of drainage condition, which results from the dependence of strain-time and stress-strain relationships on drainage condition.