基于应力应变曲线类型的邓肯张模型修正

Duncan-Chang model modification based on stress-strain curve type

邓肯张模型应用于钙质结核土三轴试验的分析时,发现部分应力应变曲线不能有效地被预测。文章基于本构模型所具有的特性,结合土的结构性及应力应变曲线的特性,分析本构方程参量的作用并引进能有效描述S型应力-应变曲线的参量(密实点D为切线弹性模量为最大值时对应的应力应变点)。通过推广邓肯张模型、建立和修正反正切模型,结合钙质结核土应力应变曲线类型,探究本构模型各自的实用性与适应范围。结果表明:应用于应变硬化的反正切修正模型与邓肯张修正模型,由于变量的增加,而使得对应力-应变曲线的拟合度有所增加;邓肯张修正模型适应于反映应变软化岩土的性质,但其表现岩土物理性质的形式随着参量增加而更加复杂;反正切修正模型能较为简单地体现S型应力应变曲线的性质,表达密实点D的位置。

When Duncan-Chang model was applied to the analysis of three axis test of calcareous soil, it was found that some stress-strain curves could not be predicted effectively. On account of the charac- teristics of constitutive model, and in view of the soil structure and the characteristics of stress-strain curves, the function of the constitutive equation parameters is analyzed and the parameters which can effectively describe the stress-strain curves of S type are introduced（density point D is the correspond- ing strain when the tangent elastic modulus is the maximum）. By generalizing the Duncan-Chang model, establishing and modifying the arctangent model and considering the type of stress-strain curves of calcareous nodules, the practicability and adaptability of the constitutive model are explored. The results show that the arctangent correction model and Duncan-Chang correction model which are applied to strain hardening make the fitting degree of stress-strain curve increased due to the increase of variables~ Duncan-Chang correction model is adapted to reflect the properties of strain softening of rock and soil, but the physical properties of rock and soil expressed by it are more complex with the increase of parameters; the arctangent correction model can simply reflect the character of S type stress-strain curve and express the position of density point D.