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基于采动卸荷岩体破坏实验,提出了采用三段模型来近似描述采动卸荷岩石应力-应变关系模型。从经典的应变梯度塑性出发,建立了弹塑性局部化应变单元模型,推导出应变局部变形带与内禀材料尺寸的关系,用简单的线性关系描述了宏观局部变形带与材料内部参数—内禀材料尺寸的关系,建立的本构关系将采动卸荷应力-应变曲线分成弹性阶段、采动卸荷弹塑性阶段和采动卸荷破坏软化阶段。讨论了孔隙度、比例系数和材料内禀尺寸对采动塑性屈服面的影响。在采动卸荷弹塑性阶段,本文假设塑性变形主要产生在局部变形带中。岩石处于高度压密状态,此时孔隙度基本不变,亚临界微裂纹也主要产生于局部变形带中。通过选择合适的内禀尺寸和其他参数代入构建的本构模型中,证实了理论结果与实验结果较为吻合。
Based on the experiment of unloading rock mass destruction, a three-section model is proposed to describe the stress-strain relationship model of rock unloading rock. Based on the classical strain gradient plasticity, an elastic-plastic localized strain element model is established, and the relationship between the strain local deformation band and the intrinsic material size is deduced. The relationship between the macroscopic local deformation band and the material internal parameters The relationship between the material size and the established constitutive relation is divided into three stages: the unloading stress-strain curve is divided into the elastic phase, the unloading elastic-plastic phase and the unloading and softening phase. The effects of porosity, proportionality coefficient and material intrinsic dimension on the plastic yield surface are discussed. In the mining unloading elastoplastic stage, this paper assumes that plastic deformation mainly occurs in the local deformation zone. The rock is in a highly compacted state, in which case the porosity is essentially constant and the subcritical microcracks also mainly occur in the zone of local deformation. By choosing suitable intrinsic dimensions and other parameters into the constructed constitutive model, the theoretical results are in good agreement with the experimental results.