多孔岩体蠕变诱发延迟压实局部化失稳特性

Characteristics of Delayed Compaction Localization Instability of Porous Rocks

针对多孔岩体蠕变诱发的延迟压实局部化失稳问题,提出了一种基于弹黏塑性及可控性理论的压实局部化失稳判别准则。通过构建局部常微分方程系统,定义定常外部摄动条件下的弹黏塑性本构算子,用于识别自发传播压实局部化带内的不稳定加速变形。通过检查方程系统的可控性损失,得出了多孔岩体压实局部化的失稳指数。基于弹黏塑性本构模型,分析了平面应变条件下多孔岩体中的拟瞬时和延迟压实局部化,对所提出的失稳指数进行验证。进一步地,利用有限元数值模拟,验证了该失稳指数在分析边值问题中延迟压实局部化失稳的适用性。

To assess creep-induced delayed compaction localization in rate-dependent porous rocks,a theoretical criterion for compaction localization is proposed based on elastic-viscoplasticity and the theory of controllability.By establishing systems of local ordinary differential equations,the elastic viscoplastic constitutive operator is defined under the stationary external perturbation condition to identify the unstable acceleration deformation inside the spontaneously propagating strain localized bands.By detecting the loss of controllability in the systems,an instability index for compaction localization in rate-dependent porous rocks is derived.The proposed index is verified by simulating the quasi-instantaneous and delayed compaction localization in a porous rock based on the viscoplastic constitutive model.Furthermore,the applicability of the proposed index in analyzing delayed compaction localization in boundary value problems is validated by using finite element simulation of plane strain compression tests.