煤系砂岩动态拉伸破坏及能量耗散特征的试验研究

Experimental research on the dynamic tensile fracture and the energy dissipation characteristics of coal-serial sandstone

我国深部开采过程中,围岩处于显著的高应力扰动环境。动载作用下岩石拉伸力学特性的研究,是实现矿井围岩稳定性有效控制及安全生产的重要基础。利用分离式霍普金森压杆(SHPB)试验系统,对煤层顶板砂岩进行动态巴西圆盘试验。研究结果表明:砂岩动态拉伸强度随加载速率的升高逐渐增强,这种依赖性在较高加载速率时更加显著;砂岩动态拉伸破坏经历主裂纹产生、微裂纹发育及裂纹相互贯穿3个阶段;随着加载速率的升高,试样破坏方式逐渐从单一张拉破坏逐渐发展为张拉破坏与局部剪切破坏共存,碎块平均体积逐渐减小,破坏程度逐渐提高;试验过程中,试样破坏所需的耗散能量随加载速率的升高逐渐增加,并且其占输入能量的比例逐渐提高,即砂岩破坏过程中能量利用率逐渐提高。

The surrounding rock is in a high-stress disturbed environment in the process of deep mining. A detailed study on the tensile mechanical properties of rock under dynamic loading is an important foundation for the effective control of the stability of surrounding rock and safe production. Dynamic Brazilian disc tests on coal roof sandstone were performed through Hopkinson pressure bar（ SHPB） test system. The following conclusions can be drawn： the dynamic tensile strength of sandstone gradually increases as the loading rate increases,which is more significant at higher loading rates; the dynamic tensile failure of sandstone can be divided into three stages： the generation of main crack,the development of micro-crack and crack penetration; under the influence of increasing loading rate,the failure mode of the specimen gradually develops from the single tensile failure to the coexistence between tensile failure and local shear failure with decreasing average fragment size and more obvious deterioration; in addition,the dissipated energy required by the failure of the specimen increases with the increasing loading rate,and the proportion of input energygradually augments,that is,the energy utilization rate of sandstone gradually increases.