摘要:
层状岩体在受到爆破等冲击荷载作用后,极易造成层理结构面开裂甚至发生大面积塌方破坏,工程中常采用锚杆或锚索对其进行锚固支护。本研究对无锚、端锚、半锚及全锚层理砂岩进行动态冲击试验研究,分析了不同锚固方式对层状砂岩动态力学特性、能量耗散规律及破裂分形特征的影响。研究结果表明:无锚试样强度随层理倾角增大,曲线表现先减小后增大,呈“V”型特征,试样在锚固后,强度得到明显提高,随锚固长度增大,曲线向倒“V”型特征转化;从能量方面来看,四类试样透射能变化规律均与强度变化规律相似,随层理倾角增大,反射能曲线呈倒“V”型特征,透射能逐渐减小,耗散能则逐渐增大,锚固方式仅影响了曲线整体水平;试样破坏后的碎屑具有明显分形特征,分形维数D受层理倾角影响曲线均表现为倒“V”型特征,全锚试样破碎程度最小,无锚试样最剧烈,在此基础上计算了单位耗散能指数,曲线则呈现"V"型特征,全锚试样的单位耗散能指数曲线整体水平最高,表明其抗破坏能力最强。研究成果可为层状岩体工程锚固支护提供参考。
Abstract:
Layered rock masses are prone to bedding plane cracking or even large-scale collapse under impact loads such as blasting. In engineering practices, bolts or cables are commonly employed for anchoring support. This study conducted dynamic impact tests on bedded sandstone specimens under four anchoring conditions: unanchored, end-anchored, half-anchored, and fully-anchored. The effects of different anchoring methods on the dynamic mechanical properties, energy dissipation patterns, and fracture fractal characteristics of layered sandstone were analyzed. The results show: The strength of unanchored specimens decreases first and then increases with the increase of bedding plane angle, showing a "V"-shaped curve. After anchorage, the strength of the specimens is significantly improved. As the anchorage length increases, the curve gradually transforms into an inverted "V"-shaped characteristic. From an energy perspective, the transmitted energy trends of all four specimen types are similar to their strength variations. With increasing bedding angle, the reflected energy curve exhibits an inverted "V" shape, the transmitted energy gradually decreases, while the dissipated energy increases. The anchoring method primarily influences the overall magnitude of these curves. The fragments from failed specimens exhibit distinct fractal characteristics. The fractal dimension D shows an inverted "V" trend with bedding angle variation. Full-anchor specimens display the least fragmentation, while no-anchor specimens suffer the most severe damage. Based on this, the unit dissipated energy index was calculated, presenting a "V"-shaped curve. Full-anchor specimens exhibit the highest overall unit dissipated energy index, indicating their superior resistance to damage. The research findings provide valuable references for the anchoring support design of layered rock mass engineering.