摘要
为深入研究冲击载荷下加锚岩体抗剪力学特性,采用实验室试验的方法对2种锚杆材质的加锚岩体开展了不同冲击能量和预紧扭矩下的侧向冲击试验,分析了不同锚杆材质和预紧扭矩对加锚岩体在冲击载荷下抗剪力学性能的影响,监测了落锤冲击力-时程曲线,并利用高速摄像机捕捉了试样冲击变形的全过程。试验结果表明:加锚岩体冲击过程可分为落锤释放、锤岩下移和分离回弹等3个阶段。试样顶底面均为轴向剪切裂缝和伴随竖向裂缝;前面和背面均为腹剪斜裂缝和竖向裂缝;交界面裂缝以钻孔为中心向四周呈放射状分布,且上半部分裂缝数量明显多于下半部分,裂缝宽度多在10 mm以内。在一定范围内,中部混凝土块顶面和交界面破坏程度均随冲击能量的增大而增大,随预紧扭矩的增大而减小。锚杆受动态剪切会发生弯曲、径缩甚至断裂。在一定范围内,冲击能量越大,锚杆弯曲变形越大;预紧扭矩越大,锚杆抗冲击变形能力越强。CRM700型锚杆的抗冲击变形及破断能力均优于HRB500型锚杆,其能够显著提高加锚岩体的整体抗冲击性能。根据冲击力-时程曲线又可将冲击过程分为强冲击阶段、震荡阶段和衰减阶段。强冲击阶段时间仅1 ms左右,主要为锤头与试样发生接触;震荡阶段持续时间达10 ms左右,主要发生混凝土块的破裂失效和锚杆的弯曲变形。锚杆材质和预紧扭矩对加锚岩体在冲击载荷下的抗剪力学性能影响显著,使用CRM700型锚杆或施加适当的预紧扭矩均可提高加锚岩体的抗剪力学性能。
In order to study the shear mechanical properties of anchored rock mass under impact load,the lateral impact tests under different impact energy and pretension torque were carried out on the anchored rock mass of two kinds of bolt materials by using the laboratory test method,the effects of different bolt materials and pretension torque on the shear mechanical properties of anchored rock mass under impact load were analyzed,and the time history curve of drop hammer impact force was monitored.The whole process of impact deformation of the sample was captured by a high-speed camera.The test results show that the impact process of the anchored rock mass can be divided into three stages:drop hammer release,hammer rock downward movement and separation rebound.There are axial shear cracks and accompanying vertical cracks on the top and bottom of the sample.The front and back are abdominal shear oblique cracks and vertical cracks.The interface cracks are distributed radially around the borehole,and the number of cracks in the upper part is significantly more than that in the lower part,and the crack width is mostly within 10 mm.In a certain range,the damage degree of the top surface and interface of medium block concrete increases with the increase of impact energy and decreases with the increase of pretension torque.The bolt will bend,shrink or even break under dynamic shear.In a certain range,the greater the impact energy is,the greater the bending deformation of the bolt is.The greater the pretension torque is,the stronger the impact deformation resistance of the bolt is.The impact deformation and breaking capacity of the CRM700 bolt are better than that of the HRB500 bolt,which can significantly improve the overall impact resistance of anchored rock mass.According to the time history curve of impact force,the impact process can be divided into strong impact stage,oscillation stage and attenuation stage.The time of the strong impact stage is only about 1 ms,mainly due to the contact between the hammerhead and the sam
作者
山世昌
吴拥政
付玉凯
周鹏赫
SHAN Shichang;WU Yongzheng;FU Yukai;ZHOU Penghe(China Coal Research Institute,Beijing 100013,China;Coal Mining and Designing Department,Tiandi Science and Technology Co.,Ltd.,Beijing 100013,China;CCTEG Coal Mining Research Institute,Beijing 100013,China;State Key Laboratory of Coal Mining and Clean Utilization,Beijing 100013,China)
出处
《采矿与岩层控制工程学报》
北大核心
2021年第4期20-29,共10页
Journal of Mining and Strata Control Engineering
基金
国家自然科学基金资助项目(51974160,51804159)。
关键词
冲击载荷
巷道支护
加锚岩体
剪切破坏
落锤试验
impact load
roadway support
anchored rock mass
shear failure
drop weight test
