塑弹塑性岩石的非线性损伤模型研究

通过分析岩石常规三轴试验应力应变曲线,发现某类岩石在峰前具有明显的压密阶段,表明该类岩石具有塑弹塑性材料的特征。基于塑弹塑性材料非线性应力应变曲线,引入非线性指标,并考虑损伤门槛值,应用统计损伤理论,提出具有塑弹塑性特征的岩石非线性损伤模型。该模型不仅能反映岩石应变硬化软化特性,而且能够刻画压密区的特性,更为准确地表征了该类岩石应力应变的非线性关系。采用辉绿岩试验数据对本文模型进行验证,结果表明,试验曲线与理论曲线吻合较好,从而验证了模型的合理性和适用性。采用峰前具有明显线弹性变形特征的岩石常规三轴试验数据进一步分析,结果显示,模型通过峰后引入非线性指标同样可以反映岩石应变软化特性。

Research on the Nonlinear Damage Model of Plastic Elastic-plastic Rock

The stress strain curves of some rocks in conventional triaxial test have obvious compaction stage,showing plastic elasto-plastic material characteristics of the rocks.According to the plastic elasto-plastic nonlinear stress-strain curves,the statistical damage theory and nonlinear index were used to establish a nonlinear damage model.The model concludes the damage threshold.The proposed model can describe not only the strain hardening and softening behavior of rock,but also the characteristics of the compression stage,thus the nonlinear relationship of stress and strain of the rock is more accurately characterized.Finally,the stress-strain curves of diabase experimental data were used to verify the model.The results show that the experimental curves and the theoretical curves are in good agreement which verify the model's rationality,feasibility and applicability.Further analysis were conducted utilizing the triaxial test data of the rock with obvious linear elastic deformation characteristics before its stress peak,it is shown that the model could also reflect the strain softening properties of rock by using the nonlinear indexes after peak.