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针对剑桥模型不适用于超固结土和结构性土的局限性,引入上下加载面模型以描述Boom clay的结构性;基于Boom clay的屈服面的特点,通过修改能量耗散函数对上下加载面的形状进行了修正,构造一个更好地反映其特性的弹塑性模型;以有限元程序ABAQUS的UMAT子程序接口为平台,采用隐式积分算法——最近点映射法(closest point projection method,CPPM)实现了模型的二次开发;最后利用该模型对不同围压下的Boom clay不排水三轴试验进行了模拟,并将该模型的计算结果与修正剑桥模型的计算结果以及试验实测结果进行比较,结果表明,该模型能较好地反映Boom clay在剪切过程中的结构性演化,且在一定程度上纠正了常规上下加载面模型高估重超固结土峰值强度而低估正常固结土和轻超固结土峰值强度的问题。
Aiming at the limitation that the Cambridge model is not suitable for overconsolidated soil and structural soil, the upper and lower loading surface models are introduced to describe the structure of Boom clay. Based on the characteristics of the yield surface of Boom clay, by modifying the energy dissipation function, The shape of the elastic-plastic model is modified to construct an elastoplastic model which can better reflect the characteristics of the elastic-plastic model. Based on the UMAT subroutine interface of finite element program ABAQUS, the implicit integration algorithm-closest point projection method (CPPM ) Is used to realize the secondary development of the model. Finally, the model is used to simulate the undrained Boom clay triaxial tests under different confining pressures, and the calculated results of the model are compared with those of the modified Cambridge model and experimental results The results show that this model can better reflect the structural evolution of Boom clay during shearing and to a certain extent correct the effect of conventional upper and lower loading surface models overestimating the peak strength of heavy overconsolidated soil and underestimation of normal consolidated soil And light over consolidation soil peak intensity problems.