黏塑流变本构模型力学参数敏感性分析

Sensitivity Analysis of Mechanical Parameters of Viscoplastic Rheological Model

在岩体流变数值模拟中,岩体本构模型力学参数成为计算结果准确性的一个关键因素。在前期研究的基础上,开展了黏塑流变本构模型的力学参数敏感性分析。以3个围压下整体参数辨识结果作为基准值,将此基准值中的每一个参数分别增加20%,40%和减少20%,40%,其他参数保持不变,先推导流变本构计算应变值,然后求得计算应变值与试验应变值的差值,根据该差值求得总误差相对变化量,以此总误差相对变化量来衡量因参数变动而使得计算应变值偏离试验应变值的趋势和程度。在参与敏感性分析的6个参数中,E的敏感性最高,m,β2个参数分区段具有较高敏感性,γ,n 2个参数次之,参数g敏感性最差。通过6个参数敏感性分析,明确了该本构模型中力学参数对计算结果准确性的重要程度,从而为参数取值提供了参考。

In the design and construction of rock engineering,mechanical calculation is an important way to under-stand the properties of rock mass.In the rheological simulation of rockmass,mechanical parameters of constitutive model of rock mass become key factor to the accuracy of the calculation results.In this paper,on the basis of previ-ous researches,sensitivity analysis of the mechanical parameters of viscoplastic rheological model is conducted.The parameter identification result under three confining pressures is regarded as the reference value,and each parame-ter of these reference values is increased by 20%,40%,and decreased by 20%,40% respectively.The other pa-rameters remain unchanged.The strain value can be calculated by deduced rheological constitutive model and then the difference between calculated strain value and test strain value is obtained.According to the difference,the rel-ative change of total error can be obtained and is used to measure the trend and degree of the deviation between cal-culated strain value and test strain value caused by parameter alteration.Among the 6 parameters in the sensitivity analysis,the sensitivity of E is the highest,the sensitivities of m and βare high in different regions,followed by γ, n,and g.Through the sensitivity analysis,the importance of mechanical parameters to the accuracy of calculation results are verified.