基于蠕变试验下的海相黏性土蠕变模型研究

Study on the Creep Constitutive Model of Marine Clays Based on Triaxial Creep Tests

为研究海相黏性土的蠕变规律,采用三轴流变仪,在变动围压与分级加载下,对某大型人工岛下不同深度处海相黏性土原状样进行了三轴固结排水蠕变试验。基于耦合Adachi-Oka模型与Biot固结理论控制方程的推导,编写了2维有限元计算程序CFEM 2D。由常规试验结果给出不同土层海相黏性土的Adachi-Oka模型参数,采用上述程序对蠕变试验进行了数值模拟,得出Adachi-Oka模型适用于描述该地区海相黏性土的蠕变特性。在验证模型的基础上,采用程序CFEM 2D对该人工岛深厚黏性土地基的长期沉降特性进行了计算。结果表明:在荷载施加初期,人工岛沉降速率较大;100年时,超孔压已基本消散完成,地表沉降量达到了88.5 cm;通过与分层总和法结果的对比可知,二者误差约为2.5%,表明数值计算结果具有一定的精度,从而验证了计算程序的可靠性。

In order to study the creep law of marine clays, a large number of drained triaxial creep tests with undisturbed samples were carried out under different confining pressure and stepwise loading,by using the triaxial rheological apparatus. The two-dimensional fi- nite element program CFEM 2D was developed which incorporate Adachi-Oka model with Blot＇s consolidation theory. The creep tests were simulated by the program CFEM 2D,and the results revealed that the model can describe the creep behavior of marine clays. The long-term settlement behavior of deep marine clays was analyzed by the program, and the results showed that the settlement rate is bigger in the initial stage of loading. In 100 years, the surface settlement attained 88.5 cm, and the excess pore water pressure nearly dissipated completely. The results error between the numerical analysis and the layer-wise summation method is about 2.5% ,which verified the re- liability of the finite element program.