摘要
研究表明,循环载荷作用下饱和黏土将发生软化,其机制主要有两个:一是孔压的积累;二是土体原有结构的不断损伤和新结构的不断重塑。针对上述机制,基于广义各向同性硬化准则建立了考虑饱和黏土循环软化的损伤单面模型。该模型在有效应力空间中引入损伤变量,表征土体结构的损伤和重塑程度,在连续的循环加载下,损伤不断累积,边界面则随着损伤的累积不断收缩,以模拟饱和黏土刚度和强度的软化;以应力反向点作为边界面的广义各向同性硬化中心和映射法则的映射中心,灵活地选择塑性模量的插值公式以模拟塑性变形和孔压的累积以及应力-应变的滞回特性。应用该模型对不排水循环三轴试验进行模拟,并且考查了循环周次、循环应力水平和固结历史对饱和黏土循环软化特性的影响,并与相关试验比较,验证了模型的有效性。
Degradation of saturated clay during cyclic loading can be assumed to be caused mainly by two mechanisms,pore water pressure build-up and the damage and remolding of soil fabric.Based on these mechanisms,a damage-dependent bounding surface model for cyclic degradation of saturated clay is proposed using the generalized isotropic hardening rule.In the model,the degree of damage and remolding of soil during cyclic loading is quantified by introducing a damage variable and the size of the bounding surface decreases with damage accumulation to characterize progressive degradation and nonlinear behavior of the saturated clay.By taking the stress reversal point as the generalized isotropic hardening center of the bounding surface as well as the mapping origin,the forms of hardening modulus can be adopted flexibly so as to predict the accumulation of plasticity deformation and pore pressure and the hysteresis property of clay.The cyclic behaviors for undrained one-way cyclic triaxial tests are predicted by the model.Moreover,the effects of the number of cycles,cyclic stress level and consolidation history on the cyclic degradation behaviors are analyzed.The agreement of predicted results with experimental data indicates that the model can realistically simulate the cyclic degradation behaviors of saturated clay.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2012年第2期459-466,共8页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目(No.50639030)
关键词
循环载荷
循环软化
边界面模型
广义各向同性硬化准则
饱和黏土
cyclic loading
cyclic degradation
bounding surface model
generalized isotropic hardening rule
saturated clay
