土体本构模型参数的不确定性评估研究

Uncertainty quantification in the parameters of soil constitutive models

模型参数评估是本构模型发展的重要研究内容。为了考虑本构模型参数评估过程中存在的误差,采用基于结构可靠度、子集模拟和自适应条件抽样方法的贝叶斯框架,提出一种基于试验数据反演的本构模型参数不确定性评估方法。分别以表征岩土体剪应力−剪应变的节理剪切本构模型和描述土体非线性应变增量−应力增量的亚塑性黏土本构模型为例,研究了本构模型参数、土体偏应力−应变和孔隙比−压力曲线的不确定性表征结果,并分析了模型参数对试验结果的敏感性。结果表明该方法可以评估验数据驱动下本构模型参数的拟合不确定性。对于应力−应变曲线的表征,节理模型参数■和η的贡献相对较大,而亚塑性模型的多数参数贡献度差异较小。研究结果有助于加深对这两种本构模型的理解以及提高本构模型预测的可靠性。

The assessment of model parameters is crucial in developing constitutive models.However,the results of parameter assessment for these models are inevitably subject to errors.Hence,a Bayesian framework utilizing structural reliability,subset simulation,and adaptive conditional sampling methods is employed to assess the uncertainty of constitutive model parameters through test data inversion.Using the joint shear constitutive model for shear stress-shear strain characterization of rock-soil mass and the hypoplastic clay constitutive model for nonlinear soil stress-strain increment description as case studies,this study investigates the uncertainties in model parameters,shear stress-strain curves,and pore ratio-pressure curves.Furthermore,it analyzes the sensitivities of model parameters to test outcomes.The research demonstrates that this approach evaluates parameter uncertainty driven by test data.The joint shear constitutive model parameters are primarily influenced by η in stress-strain curve representation,while most parameters of the hypoplastic model have a notable impact.These results enhance comprehension and enhance the predictive reliability of these two constitutive models.