摘要
高原寒区矿山岩体受低温环境和动载扰动等影响会产生失稳现象。现有研究大多围绕裂隙砂岩在不同冻结温度下的静力学特性,考虑到工程开挖的影响,需要进一步研究冻结裂隙砂岩在动载作用下的力学及声发射特征。开展了冻结单裂隙砂岩的落锤冲击试验,结合声发射监测技术分析了冻结单裂隙砂岩力学及声发射特征。试验结果表明:①裂隙倾角增加会引起应变时程曲线在应变峰值前回弹幅度增大,裂纹由裂隙两侧分布转变为裂隙上下两端分布;落锤下落高度增大后,应变时程曲线在应变峰值前出现明显双峰回弹,破坏明显加剧;冻结温度降低会使应变峰值出现时间提前,且应变峰值增大。②微裂纹扩展具有阶段性特征,在应变峰值处对应较强的微破裂活动并伴有剧烈的能量释放。③微破裂活动性随裂隙倾角增大呈先增后减趋势;落锤下落高度增大,微破裂活动剧烈程度阶段性递减;冻结温度降低使微破裂活动发生时间提前。④微裂纹主要以张拉裂纹为主,与宏观的破坏模式对应。⑤熵值急剧增加是砂岩破坏前兆,可作为砂岩动态失稳的预警指标。
Mining rock masses in high-altitude cold regions can experience instability due to low temperature environments and dynamic load disturbances.Existing research mostly focuses on the static features of fractured sandstone under different freezing temperatures.Considering the influence of engineering excavation,further research is needed to investigate the mechanical and acoustic emission features of frozen fractured sandstone under dynamic loads.Therefore,a drop hammer impact test is conducted on frozen single fractured sandstone.The mechanical and acoustic emission features of frozen single fractured sandstone are analyzed using acoustic emission monitoring technology.The experimental results show the following points.①An increase in the inclination angle of the crack will cause an increase in the rebound amplitude of the strain time curve before the peak strain.The crack will change from being distributed on both sides of the crack to being distributed on both ends of the crack.After the drop height of the hammer increases,the strain time curve shows a significant bimodal rebound before the strain peak,and the damage is significantly intensified.A decrease in freezing temperature will lead to an earlier onset of strain peak and an increase in strain peak.②The propagation of microcracks has stage features,corresponding to strong microcracking activity at the peak strain and accompanied by intense energy release.③The activity of microcracking activity increases first and then decreases with the increase of inclination angle of the crack.The drop height of the hammer increases,and the intensity of microcracking activity gradually decreases.The decrease in freezing temperature leads to an earlier occurrence of microcracking activity.④Micro cracks are mainly tensile cracks,corresponding to macroscopic failure modes.⑤The sharp increase in entropy value is a precursor to sandstone failure and can be used as a warning indicator for dynamic instability of sandstone.
作者
贺馨瑶
常远
任富强
HE Xinyao;CHANG Yuan;REN Fuqiang(School of Civil Engineering,University of Science and Technology Liaoning,Anshan 114000,China)
出处
《工矿自动化》
CSCD
北大核心
2024年第5期135-141,156,共8页
Journal Of Mine Automation
基金
国家自然科学基金资助项目(52074299)
辽宁省科技厅博士启动基金项目(2022-BS-280)。
关键词
裂隙砂岩
冻结砂岩
落锤冲击
动态力学
声发射
熵值
fractured sandstone
frozen sandstone
drop hammer impact
dynamic mechanics
acoustic emission
entropy
