摘要:
在实际工程中,岩体经常会遭受频繁往复的动力扰动,对工程安全造成严重威胁。为探究节理岩体在循环动力扰动作用下的动态力学行为,采用分离式霍普金森压杆试验系统,对含单节理辉长岩进行了单轴循环冲击试验,从试件的抗冲击能力、应力应变性质、能量和损伤的演化对其动态力学行为进行了全面分析。结果表明,试件在循环冲击作用下的破坏模式为劈裂,节理倾角显著影响了试件的抗冲击能力;试件在循环冲击过程中均出现了应变回弹现象,其力学性质并不随着冲击次数的增加而单调弱化;用耗散能表示的累积损伤系数随着冲击次数的增加近似线性增加,增幅随节理倾角的增大而减小。在低应力冲击作用下,单节理试件内的压剪应力不足以产生剪切裂纹,试件的破坏主要是由拉应力引起的张拉裂纹逐渐扩展并与节理相互贯通造成的。最后讨论了完整岩石、单节理岩体和多节理岩体在循环冲击作用下的破坏机理和模式的异同。
Abstract:
In practical engineering, rock masses frequently suffer from recurrent dynamic disturbances, posing serious threats to engineering safety. To investigate the dynamic mechanical behavior of jointed rock masses under cyclic dynamic disturbances, cyclic impact tests were conducted on single-jointed gabbro (SJG) using a split Hopkinson pressure bar test system. The stress equilibrium during the tests was verified using the three-wave method and the force balance coefficient method. The dynamic mechanical behavior of the specimens was comprehensively analyzed in terms of impact resistance, stress-strain relationships, energy and damage evolution, as well as dynamic failure mechanisms. The results show that single-jointed rock specimens can achieve stress equilibrium under cyclic impact conditions. The failure mode of the specimens under cyclic impacts is splitting, and the joint inclination angle significantly influences the impact resistance of the specimens. As the joint inclination angle increases, the impact resistance of the specimens also increases. During the cyclic impact process, strain rebound occurs in all specimens, and their mechanical properties do not monotonically degrade with an increasing number of impacts. The peak stress of the specimens generally exhibits a decreasing trend with the number of impacts. The cumulative damage coefficient, represented by dissipated energy, increases approximately linearly with the number of impacts, while the rate of increase decreases with larger joint inclination angles. Under low-stress impacts, the compressive-shear stress inside the specimens is insufficient to produce shear cracks, and tensile stress causes tensile cracks at the initiation points, which propagate along the loading direction and ultimately lead to splitting failure of the specimens.