摘要
新建隧道钻爆施工过程中,邻近既有隧道机制砂喷射混凝土支护结构往往会承受循环冲击荷载。为研究轴压对循环冲击荷载下机制砂喷射混凝土动力特性的影响,采用改进的大直径分离式霍普金森压杆试验装置,开展4个轴压水平下的机制砂喷射混凝土循环冲击试验,分析循环冲击荷载下机制砂喷射混凝土的动力特性。研究结果表明:轴压和冲击速度对机制砂喷射混凝土的破坏形态、峰值应力、峰值应变和应变率均有较大影响,轴压的增加能够有效抑制试样的变形;轴压相同时,冲击速度越大试样破坏所需的冲击次数越少,冲击速度相同时,试样破坏所需要的冲击次数随轴压增大而不断增加;冲击速度和轴压均相同时,随着冲击次数的增加,试样峰值应力和动弹性模量不断降低,峰值应变和应变率不断增加,轴压对试样动弹性模量的影响不显著;随着冲击次数增加,试样的累计比能量吸收值呈线性增加趋势,冲击速度相同时,轴压越大,试样破坏时所需累计比能量吸收值越大,亦即轴压的增加可以显著提高试样的耗能能力,从而减缓试样力学性能的劣化进程。
In the drill-and-blast construction of a new tunnel,the manufactured sand shotcrete supporting structure of the adjacent existing tunnel would be subjected to cyclic impact load.In order to study the effect of axial compression on the dynamic properties of the manufactured sand shotcrete under cyclic impact load,a modified large-diameter split Hopkinson pressure bar(SHPB)test system is employed to conduct cyclic impact tests on the manufactured sand shotcrete under four axial compression levels,and its dynamic properties under cyclic impact load are analyzed.The results reveal that the axial compression and impact velocity have great influence on the failure mode,peak stress,peak strain and strain rate of the manufactured sand shotcrete and the increased axial compression helps effectively inhibit the deformation of the specimens.Under the same axial compression,the higher the impact velocity,the less the impact cycles required for specimen failure.At the same impact velocity,the number of impact cycles required for specimen failure grows with the increase of axial compression.When the impact velocity and axial compression remain unchanged,the peak stress and dynamic elastic modulus of the specimen decrease with the increase of impact cycles,while the peak strain and strain rate increase.The axial compression shows no significant effect on the dynamic elastic modulus of the specimens.As more impact cycles are applied,the cumulative specific energy absorption value of the specimens increases linearly.At the same impact velocity,the larger the axial compression,the larger the cumulative specific energy absorption value required for specimen failure.In other words,the increase of axial compression can significantly increase the energy dissipation capacity of the specimens,thus slowing down deterioration of the mechanical properties of the specimens.
作者
刘仲阳
王新宇
李庆东
李鹏飞
王俊波
宋林
LIU Zhongyang;WANG Xinyu;LI Qingdong;LI Pengfei;WANG Junbo;SONG Lin(School of Civil Engineering,Henan Polytechnic University,Jiaozuo 454000,China;Key Lab of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology,Beijing 100124,China;CREC Cloud Net Information Technology Co.,Ltd.,Beijing 100039,China)
出处
《铁道标准设计》
北大核心
2024年第4期153-160,202,共9页
Railway Standard Design
基金
国家自然科学基金项目(51978019)
关键词
循环冲击
机制砂喷射混凝土
动力特性
冲击速度
轴压
累计比能量吸收值
repeated impact
manufactured sand shotcrete
dynamic characteristic
impact velocity
axial pressure
cumulative specific energy absorption value
