关键词: 一维压缩试验, 三轴固结不排水蠕变试验, 时间效应, 分数阶导数Merchant模型

Abstract: A series of 1D secondary consolidation tests and undrained triaxial creep tests are conducted to investigate the creep characteristics of soft dredger fill in the estuary of eastern Shantou. In 1D secondary consolidation tests，the stress-stain relationship of the soft soil shows significant nonlinear characteristics. The deformations of primary compression and secondary compression in overconsolidation state is smaller than normal consolidation case; and preloading can increase the yield strength. Pore pressure develops over time in the undrained triaxial creep tests, i.e., effective stress decreases with time. When the deviatoric stress is smaller, the deformation of soil tends to be stable, and the strain rate decreases with time; however, once the deviatoric stess reaches the critical value, the deformation develops with time rapidly, and the soil sample is damaged due to the accelerated creep. The concept of fractional order derivative is introduced to establish the fractional derivative Merchant model; and the ranges of parameters are determined. By comparison with the fitting results of traditional Merchant model, it is found that the fractional Merchant model can simulate the creep deformation better. The fractional Merchant model has a simple form and a few parameters, which can be well applied to the practical engineering.

Key words: 1D consolidation tests, undrained triaxial creep test, time-dependent behavior, fractional derivative Merchant model