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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。
By analyzing the stress-strain curve of conventional rock triaxial tests, it is found that some types of rock have obvious compaction stage before the peak, indicating that the rock has the characteristics of plastic-plastic material. Based on the non-linear stress-strain curve of plastic-plastic material, the nonlinear index is introduced and the damage threshold is considered. By applying the statistical damage theory, a nonlinear rock damage model with plastic-plastic-plastic characteristics is proposed. The model can not only reflect the strain hardening and softening properties of rock, but also depict the characteristics of the compacting zone and more accurately characterize the nonlinear relationship between the stress and strain of the rock. The diabase test data are used to validate the model. The results show that the experimental curve is in good agreement with the theoretical curve, which verifies the rationality and applicability of the model. The results of rock triaxial test with obvious linear elastic deformation before the peak show that the model can also reflect the rock strain softening characteristics by introducing nonlinear indexes after the peak.