考虑扩容碎胀特性的岩石本构模型研究与验证

CONSTITUTIVE MODEL OF ROCKS CONSIDERING DILATANCY-BULKING BEHAVIOUR AND ITS CALIBRATION

高应力卸荷条件下岩石扩容碎胀非连续变形行为研究对揭示深部巷道围岩稳定性演化及控制机制,分析预测围岩稳定性具有至关重要的意义。为此,依托室内岩石三轴卸荷试验,首先研究全应力–应变曲线各特征应力值随围压变化的演化特征,提出岩石进入峰前损伤扩容与峰后破裂碎胀阶段的临界条件准则,并考虑扩容碎胀破裂演化过程中岩样力学性质劣化规律,建立描述卸荷条件下岩石损伤扩容和破裂碎胀演化机制的本构模型,采用VC++编程语言将该模型嵌入到UDEC软件中,实现其非线性数值计算功能。同时,通过室内岩石试验曲线的模拟拟合,表明该模型在描述岩石扩容碎胀特性方面的合理性。最后,将该模型应用于一典型深部巷道围岩破损区分布的模拟研究中,通过与经典模型的对比分析,验证该模型在工程应用方面的可行性,并有针对性地提出深部巷道稳定性分析与维护的合理化建议。

The rock dilatancy-bulking deformation characteristics under high geostress unloading condition are critically important to understand the stability evolution and control mechanism of deep roadways, and to evaluate the stability of surrounding rocks. Using the triaxial unloading tests on the rocks sampled from the Gubei colliery, the evolution characteristics of the typical stresses with confining pressure are first studied. The criterion of rocks approaching pre-peak damage dilatancy and post-peak bulking deformation under critical condition is proposed. Then, the damage and degradation process of mechanical parameters of rocks during unloading are considered, and a progressive failure constitutive model is subsequently constructed. Finally, the distinct element code UDEC is embedded into the model to realize nonlinear numerical calculation. Simulation results of triaxial unloading tests show that the proposed model is suitable for describing the rock dilatancy-bulking deformation characteristics. Besides, the proposed model is used to evaluate the excavation damaged zone（EDZ） around a deep roadway. Compared with classical Mohr-Coulomb strain softening model, the performances of the proposed model are suggested to be applicable for practical engineering, and helpful for stability analysis and maintenances of deep roadways.