基于修正邓肯-张模型模拟红黏土应力-应变关系

Simulation of the stress-strain curves of red clay based on modified Duncan-Chang model

分析了原状红黏土的应力-应变关系,从结构性损伤角度进行分段描述:硬化型应力-应变关系分为2个变化阶段,而软化型则分为3个变化阶段。为准确模拟其应力-应变关系,基于结构性修正邓肯-张模型,提出了一种计算损伤参数的方法,并进行原状红黏土三轴固结不排水试验模拟计算,发现模型能较好地反映土体应力-应变在不同阶段的发展规律,其中表征损伤发展速率的参数a^∗与围压以及应力-应变关系曲线类型有关,取值范围在0.15~0.35,对红黏土弹塑性模型的建立具有参考意义。

The relation between stress and strain of intact red clay was analyzed.From the test data of literature and the structural damage,the change of structural red clay was described.The curves of stress-strain hardening were divided into two-stage changes.The curves of stress-strain softening were divided into three stages.Moreover,a method to calculate the damage parameters was proposed to accurately describe the stress-strain curves based on the modified Duncan-Chang model.The test data of un-drained consolidation triaxial tests were used to prove the method.It indicated that the model described curves of stress-strain well during shearing.The parameter a^∗(the rate of structural damage)is related with confining pressure and the type of stress-strain curves,with values ranging from 0.15 to 0.35.These results are significant to establish the elastic-plastic model of intact red clay.