静水压环境下岩石动态压剪耦合力学响应与本构模型

Dynamic Responses and Damage Constitutive Model of Hydrostatically Pressurized Rocks Subjected to Combined Compressive-Shear Impacting

静水压环境是深部岩石的典型应力赋存状态,并且岩石内存在多尺度的结构面,易遭受压剪耦合的复杂动力扰动。因此,探究静水压环境下岩石动态压剪耦合力学响应及损伤本构模型对于深部岩石结构安全评估和动力灾害防控极为重要。本文应用霍普金森压杆试验装置,对倾斜砂岩试样进行动态压剪耦合试验,揭示静水围压、动态荷载压剪耦合比及加载率对岩石力学特性的影响规律;基于Drucker–Prager准则和Weibull分布,建立静水压环境下深部岩石动态压剪耦合损伤本构模型。结果表明:1)岩石动态强度及变形模量随着加载率及静水围压的增大呈增加趋势,强度的围压效应及加载率效应明显,动态荷载中的剪切分量能削减岩石承载能力并提升岩石的变形能力。2)随着动态荷载剪压比和静水围压的增加,岩石冲击破坏模式由拉伸主导的内部锥形破裂面及表面劈裂转变为剪切主导的单一平面破坏;动态荷载中的剪切分量对静水围压作用下岩石的动态破碎存在明显的限制作用。3)采用极值解析法推导了模型分布参数F0和m的解析表达式,探究了模型分布参数F0、m和损伤修正系数q的物理意义及其对本构模型的影响规律;同时,对比不同工况下试验和理论应力应变曲线,验证了该模型的合理性。本文揭示的静水压环境下岩石动态压剪耦合动力响应与建立的损伤本构模型,可为复杂动力扰动下深部岩石工程安全建设与灾害防护提供理论支撑。

Rocks in the deep underground are commonly situated in a hydrostatic stress state,and it is susceptible to complex dynamic compress-ive-shear disturbances due to the existence of a multi-scale structural surface.Thus,it is of great significance to investigate the dynamic responses and the constitutive model of hydrostatically pressurized rocks subjected to combined compressive-shear impacting for rock stability assessment and disaster prevention in the deep underground.Using the modified split Hopkinson pressure bar(SHPB),the dynamic compression-shear im-pacting tests were conducted on the oblique sandstone specimens with hydrostatic confinement.The effects of hydrostatic confining pressure,the shear component in the dynamic loading and the loading rate on the rock mechanical properties have been revealed.Based on the Drucker-Prager criterion and Weibull distribution,the damage constitutive model of hydrostatically pressurized rocks under combined compressive-shear impact-ing was established.Results showed that as loading rate and hydrostatic confining pressure increased,dynamic strength and deformation modulus of rock showed an increasing trend.It indicated that both the hydrostatic confining pressure and loading rate had an enhancement effect on the rock dynamic strength.The shear component in dynamic load weakened the stiffness of rocks and improved its deformation ability.As the tilting angle and hydrostatic confining pressure increased,the impact failure pattern of rocks under coupled hydrostatic confining pressure and compress-ive-shear impacting changed from the tensile-dominated failure with a truncated conical surface to the shear-dominated failure with a single shear plane along the short diagonal of the specimen.The shear component in dynamic load had obvious limitations on the fragmentation of rock with hydrostatic confinement.Furthermore,the analytical expression of distribution parameters F0,m,and q were deduced,and the influence of such distribution parameters on the constitutive model was explored for a better understanding of their physical significance.Experimental and theoret-ical stress-strain curves were compared,and the consistency between these two category curves indicated that the established damage constitutive model could characterize the mechanical properties of hydrostatically pressurized rocks under combined compressive-shear impacting.This study could provide some theoretical support for safety construction and disaster protection of deep rock engineering under complex dynamic disturb-ance.