循环荷载作用下黏土改进边界面模型

An improved bounding surface model for clay under cyclic loading

为克服边界面模型应用不便、不能反映卸载过程中土体的弹塑性性质的缺陷,提出了一个循环荷载作用下可考虑弹塑性加、卸载过程的重塑黏土改进边界面模型。模型采用了简单的边界面形式,可大大简化该模型理论的推导与计算;采取了不预先定义边界面大小的方式,有效地降低了改进边界面模型在应用过程中的经验性;加入边界面胀缩规则,使模型可考虑土样卸载过程中的弹塑性性质,进而可反映土样的滞回特性。通过对重塑黏土进行循环三轴数值模拟试验,并与真实试验结果进行对比分析,验证了改进边界面模型的合理性和有效性。数值验证结果表明,改进边界面模型具有物理意义明确、参数易于确定、形式相对简单的特点,且该模型计算精度较高,计算结果与试验结果吻合得较好。

This paper proposes an improved bounding surface model for remolded clay, which overcomes the defects that it is inconvenience to apply and not related with elastoplastic property in the unloading process of the bounding surface model, by considering elastoplastic loading and unloading processes under cyclic loading. The model uses a simple bounding surface formula, which significantly simplifies the derivation and calculation of the model; which also effectively reduces the empirical dependence in the application process of the improved bounding surface without predefining the bounding surface. It introduces bounding surface expansion and contraction rules, which makes the model consider the elastoplastic property of the soil in the unloading process and then reflects the hysteretic behavior of the soil. This improved bounding surface model is verified by comparison between numerical simulation of remolded clay cyclic triaxial test and the cyclic triaxial lab test. The results show that the improved bounding surface has following advantages： clear physical significance and simple form, parameters easy to determine, high precision of calculation and the calculation results fitting the real test results.