循环荷载作用下软基上大圆筒结构弹塑性有效应力分析

Elasto-plastic effective stress analysis on soft soil foundation of large-diametercylindrical structure subjected to cyclic loading

采用隐式积分算法将改进的剑桥弹塑性动力本构模型引入大型通用有限元软件ABAQUS,对循环荷载作用下软土地基与大圆筒结构耦合系统的失稳破坏机理进行了探讨。与前人的循环三轴试验结果比较表明,该模型可以合理的模拟软黏土在循环荷载作用下的变形、孔压累积效应。进而基于忽略土骨架和孔隙水惯性效应的广义Biot固结理论的简化形式,建立软基上大圆筒结构的有效应力分析模型,探讨不同幅值循环荷载作用下结构的不同变形模式以及失稳机理。计算结果表明:当循环荷载幅值较大时,大圆筒结构与地基耦合系统的瞬时位移较大,而残余变形相对较小;而当循环荷载幅值较小时,大圆筒结构与地基耦合系统的残余位移相对较大。

An improved CAM-clay constitutive model for cyclic load is incorporated into the framework of general-purpose FEM software ABAQUS by using the implicit integration algorithm to investigate the failure mechanism of instability of the large-diameter cylindrical-soft soil foundation coupling system. The comparison result of experimental data given by the other authors with the numerical analysis using the proposed model verifies that this model can simulate the accumulation effect of deformation and extra pore pressure in soft clay. On this basis an elasto-plastic effective stress analysis model for soil foundation of large-diameter cylindrical structure is established. The different deformation modes and failure mechanisms of instability of the cylinder-foundation coupling system under wave-induced cyclic load with different amplitudes are investigated. The result indicates that the larger the amplitude of cyclic load, the larger cyclic displacement of soil-structure coupled system will be, but the residual displacement is smaller. When the amplitude is smaller, the residual displacement will be larger and leads to instability of the cylindrical structure.