Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop...Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.展开更多
针对带圆弧结构模具体积的减小、制造成本的降低、工艺操作的简化,利用斜导柱驱动方式设计了一种新颖的圆弧抽芯机构。深入分析了大圆弧角模具抽芯结构的功能特征与结构需求,设计基于斜导柱抽芯机构将驱动机构的直线运动转换为圆弧运动...针对带圆弧结构模具体积的减小、制造成本的降低、工艺操作的简化,利用斜导柱驱动方式设计了一种新颖的圆弧抽芯机构。深入分析了大圆弧角模具抽芯结构的功能特征与结构需求,设计基于斜导柱抽芯机构将驱动机构的直线运动转换为圆弧运动,从而完成抽芯动作。利用Pro E Mechanism运动仿真模块仿真分析了模具抽芯机构的运动轨迹,获得了滑动运动轨迹包络面;基于运动轨迹包络面上设计出相应的滑块导槽孔,以保证斜导柱与滑块之间的运动匹配。经运动仿真验证,圆弧拉芯机构不存在动态体积干涉和可实现良好的间隙配合,配合间隙为单边2mm;基于该方法所开发的模具已经获得了生产验证,取得了良好的效果,具有较好的推广价值。展开更多
基金CCTEG Coal Mining Research Institute(No.TDKC-2022-MS-01)the National Natural Science Foundation of China(No.52274123)the Mining Education Australia(MEA),Collaborative Research Grant Scheme(No.RS-59041).
文摘Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.
文摘针对带圆弧结构模具体积的减小、制造成本的降低、工艺操作的简化,利用斜导柱驱动方式设计了一种新颖的圆弧抽芯机构。深入分析了大圆弧角模具抽芯结构的功能特征与结构需求,设计基于斜导柱抽芯机构将驱动机构的直线运动转换为圆弧运动,从而完成抽芯动作。利用Pro E Mechanism运动仿真模块仿真分析了模具抽芯机构的运动轨迹,获得了滑动运动轨迹包络面;基于运动轨迹包络面上设计出相应的滑块导槽孔,以保证斜导柱与滑块之间的运动匹配。经运动仿真验证,圆弧拉芯机构不存在动态体积干涉和可实现良好的间隙配合,配合间隙为单边2mm;基于该方法所开发的模具已经获得了生产验证,取得了良好的效果,具有较好的推广价值。
