摘要
利用落锤冲击试验设备对石英砂岩进行循环冲击加载,在0.3~0.6 m各冲击高度下均选取3个试样,每个试样进行8次循环冲击,应变率分别选取为26.33 s^(-1)、29.7 s^(-1)、32.03 s^(-1)和35.17 s^(-1),研究中应变率下石英砂岩受循环冲击加载下的力学性能。通过对试验数据进行分析总结,讨论循环加载次数对石英砂岩动态抗压强度、弹性模量和能量效率的影响以及中应变率下石英砂岩的破坏过程。结果表明:不同中应变率条件下,第8次循环冲击加载作用下试件的动态抗压强度均较第一次循环冲击减小约13 MPa,抵抗变形能力减弱,同时弹性模量明显降低,试件动态抗压强度与弹性模量表现出正向相关关系;从能量角度研究,在8次循环冲击加载后,试样耗散能、能量效率、单位体积耗散能均有提高,其中在冲击能为70.27 J效果最为明显,岩石耗散能提高6 J、能量效率提高8.8%、单位体积耗散能增幅50%;从破碎分形角度进行研究,中应变率下岩石破碎形态有劈裂破坏、边缘崩落破坏、块状破坏和粉碎破坏,当应变率由26.33 s^(-1)增大至35.17 s^(-1)时,试样碎块块度平均粒径特征值由24.49 mm减小到21.15 mm;分形维数由1.07增加至1.75,岩石分形维数呈线性增大趋势。
Quartz sandstone samples were tested under cyclic impact loadings by the drop weight impact test equipment to study its mechanical properties and failure process under medium strain rates.Three specimens were selected at each impact height of 0.3~0.6 m,and each specimen was subjected to 8 cycles of impact with medium strain rates of 26.33 s^(-1),29.7 s^(-1),32.03 s^(-1)and 35.17 s^(-1),respectively.Then,the influence of cyclic loading times on the dynamic compressive strength,elastic modulus and energy efficiency of quartz sandstone were discussed.The results show that under different medium strain rates,the dynamic compressive strength of the specimens under the impact loading of the 8th cycle is about 13 MPa,which is lower than that of the first cycle.During the process,the resistance to deformation is weakened,and the elastic modulus is significantly reduced.The dynamic compressive strength of the specimens has a positively correlation with the elastic modulus.From the perspective of energy,the dissipated energy,energy efficiency and unit volume dissipated energy of the specimen are improved after 8 cycles of impact loading.The effect is most obvious when the impact energy is 70.27 J,the dissipated energy of rock is increased by 6 J,the energy efficiency is increased by 8.8%,and the unit volume dissipated energy is increased by 50%.For fracture fractal,the fracture morphology of rock under medium strain rates includes splitting failure,edge collapse failure,block failure and crushing failure.When the strain rate increases from 26.33 s^(-1)to 35.17 s^(-1),the characteristic value of the average particle size of the sample fragments decreases from 24.49 mm to 21.15 mm.The fractal dimension increases from 1.07 to 1.75 linearly.
作者
王军祥
马宝龙
李树昊
李林
寇海军
孙港
WANG Jun-xiang;MA Bao-long;LI Shu-hao;LI Lin;KOU Hai-jun;SUN Gang(School of Architecture and Civil Engineering,Shenyang University of Technology,Shenyang 110870,China;China Railway 19th Bureau Group Fifth Engineering Co.,Ltd.,Dalian 116100,China)
出处
《爆破》
CSCD
北大核心
2023年第2期30-42,共13页
Blasting
基金
国家自然科学基金(No.51974187)
辽宁省自然科学基金(No.2019-MS-242)
辽宁省教育厅重点攻关项目(No.LZGD2020004)。
关键词
中应变率
循环冲击
破坏特性
medium strain rate
cyclic shock
failure behavior
