轴向静载对红砂岩中应力波传播特性的影响试验研究
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摘要
由于开挖卸荷效应以及原岩应力的复杂性,围岩体承受的静应力大小具有动态变化特点。为了研究静应力大小对岩石应力波传播的影响,利用动静组合加载试验装置,对红砂岩长试件进行小扰动的应力波传播试验,试件轴向静应力分别设置为13个等级。通过应力波传播速度和幅值随传播距离、传播时间以及静应力的衰减规律,研究不同静应力条件下应力波的传播衰减特性。结果表明,相同轴压下,不同测点处应力波形状基本相同;不同轴压下,相同测点处应力形状变化较大,轴压越大,应力波尾部出现的拉伸波越大。随着轴向静应力的增加,岩石纵波波速呈"快速增加–平缓发展–急剧减小"的趋势,轴向静应力与单轴抗压强度之比?s/?c=30%和?s/?c=55%是其2个应力分界点。相同轴压下,应力波幅值随传播距离及传播时间都具有良好的指数关系;随着轴压的增加,空间和时间响应强度逐渐减小,幅值空间衰减系数和时间衰减系数呈"快速减小–平稳发展–急剧增大"的趋势。随轴压增加,相同测点处幅值随轴压衰减系数??s先减小后增大,离冲击端越近测点处的??s变化越敏感。
The unloading of excavation and the complexity of in-situ stress result in the variation of static stresses in the surrounding rock. The effect of static stress on stress wave propagation was investigated with the modified Hopkinson pressure bar testing system to measure the stress wave propagation through the long specimens of red sandstone. The dynamic disturbances were approximately equal and relatively small so that the damage caused by the stress wave is insignificant. The axial static stresses were divided into 13 levels. The variation of P-wave velocity,space attenuation coefficient of amplitude,time attenuation coefficient of amplitude,and amplitude attenuation coefficient with the static stress were investigated. The results show that the stress waveforms at different locations are approximately the same when the axial static stress is constant,but there are obvious differences in the wave shapes obtained at the same location under the different axial static stresses. The tensile wave appearing at the tail of stress wave increases with the increasing axial static stress. With the increase of the axial static stress,the longitudinal wave velocity of rock increases rapidly at first,then develops gently,finally decreases sharply. The stresses of 30% and 55% of uniaxial compressive strength are two critical points. Under the same axial static stress,the amplitude of stress wave varies exponentially with the propagation distance and the propagation time respectively. As the increase of axial static stress,the spatial and time response amplitudes of stress wave decrease gradually,and both the spatial attenuation coefficient and time attenuation coefficients have the tendency of rapid decrease-steady development-sharp increase. The amplitude attenuation coefficient ?σs at the same location decreases firstly and then increases with the increasing of the axial static stress,and the ?σs at the measuring points closer to the incident side are more sensitive to the static stress than the ?σs at measuring points farther from the incident side.
The unloading of excavation and the complexity of in-situ stress result in the variation of static stresses in the surrounding rock. The effect of static stress on stress wave propagation was investigated with the modified Hopkinson pressure bar testing system to measure the stress wave propagation through the long specimens of red sandstone. The dynamic disturbances were approximately equal and relatively small so that the damage caused by the stress wave is insignificant. The axial static stresses were divided into 13 levels. The variation of P-wave velocity,space attenuation coefficient of amplitude,time attenuation coefficient of amplitude,and amplitude attenuation coefficient with the static stress were investigated. The results show that the stress waveforms at different locations are approximately the same when the axial static stress is constant,but there are obvious differences in the wave shapes obtained at the same location under the different axial static stresses. The tensile wave appearing at the tail of stress wave increases with the increasing axial static stress. With the increase of the axial static stress,the longitudinal wave velocity of rock increases rapidly at first,then develops gently,finally decreases sharply. The stresses of 30% and 55% of uniaxial compressive strength are two critical points. Under the same axial static stress,the amplitude of stress wave varies exponentially with the propagation distance and the propagation time respectively. As the increase of axial static stress,the spatial and time response amplitudes of stress wave decrease gradually,and both the spatial attenuation coefficient and time attenuation coefficients have the tendency of rapid decrease-steady development-sharp increase. The amplitude attenuation coefficient ?σs at the same location decreases firstly and then increases with the increasing of the axial static stress,and the ?σs at the measuring points closer to the incident side are more sensitive to the static stress than the ?σs at measuring points farther from the incident side.
引文
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[15]魏晨慧,朱万成,白羽,等.不同节理角度和地应力条件下岩石双孔爆破的数值模拟[J].力学学报,2016,48(4):926–935.(WEI Chenhui,ZHU Wancheng,BAI Yu,et al.Numerical simulation on two-hole blasting of rock under different joint angles and in-situ stress conditions[J].Chinese Journal of Theoretical and Applied Mechanics,2016,48(4):926–935.(in Chinese))
[16]张凤鹏,彭建宇,范光华,等.不同静应力和节理条件下岩体爆破破岩机制研究[J].岩土力学,2016,37(7):1 839–1 846.(ZHANG Fengpeng,PENG Jianyu,FAN Guanghua,et al.Mechanisms of blasting-induced rock fractures under different static stress and joint properties conditions[J].Rock and Soil Mechanics,2016,37(7):1 839–1 846.(in Chinese))
[17]刘少虹,毛德兵,齐庆新,等.动静加载下组合煤岩的应力波传播机制与能量耗散[J].煤炭学报,2014,39(增1):15–22.(LIU Shaohong,MAO Debing,QI Qingxin,et al.Under static loading stress wave propagation mechanism and energy dissipation in compound coal-rock[J].Journal of China Coal Society,2014,39(Supp.1):15–22.(in Chinese))
[18]李新平,赵航,罗忆,等.深部裂隙岩体中弹性波传播与衰减规律试验研究[J].岩石力学与工程学报,2015,34(11):2 319–2 326.(LI Xinping,ZHAO Hang,LUO Yi,et al.Experimental study of propagation and attenuation of elastic wave in deep rock mass with joints[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(11):2 319–2 326.(in Chinese))
[19]FAN L F,SUN H Y.Seismic wave propagation through an in-situ stressed rock mass[J].Journal of Applied Geophysics,2015,121:13–20.
[20]LI X B,LOK T S,ZHAO J.Dynamic characteristics of granite subjected to intermediate loading rate[J].Rock Mechanics and Rock Engineering,2005;38(1):21–39.
[21]陈祥,孙进忠,谭朝爽,等.岩块波速–应力关系及其卸荷效应[J].岩土工程学报,2010,32(5):757–761.(CHEN Xiang,SUN Jinzhong,TAN Chaoshuang,et al.Relation between P-wave velocity and stress of rock samples and their unloading effect[J].Chinese Journal of Geotechnical Engineering,2010,32(5):757–761.(in Chinese))
[22]金解放,李夕兵,尹土兵,等.轴向冲击下弹性杆中轴向静载对入射波的影响[J].工程力学,2013,30(11):21–27.(JIN Jiefang,LI Xibing,YIN Tubing,et al.Effect of axial static stress of elastic bar on incident stress wave under axial impact loading[J].Engineering Mechanics,2013,30(11):21–27.(in Chinese))
[23]金解放,李夕兵,常军然,等.循环冲击作用下岩石应力应变曲线及应力波特性[J].爆炸与冲击,2013,33(6):613–619.(JIN Jiefang,LI Xibing,CHANG Junran,et al.Stress-strain curve and stress wave characteristics of rock subjected to cyclic impact loadings[J].Explosion and Shock Waves,2013,33(6):613–619.(in Chinese))
[2]SHANG J L,HU J H,ZHOU K P,et al.Porosity increment and strength degradation of low-porosity sedimentary rocks under different loading conditions[J].International Journal of Rock Mechanics and Mining Sciences,2015,75:216–223.
[3]韩林,刘向君,孟英峰,等.加载途径对深部孔隙性砂岩力学特性的影响[J].岩石力学与工程学报,2008,27(3):596–600.(HAN Lin,LIU Xiangjun,MENG Yingfeng,et al.Effect of loading paths on mechanical properties of deep porous sandstone[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):596–600.(in Chinese))
[4]NUR A.Effects of stress on velocity anisotropy in rock with cracks[J].Journal of Geophysical Research,1971,76(8):2 022–2 034.
[5]KHAKSAR A,GRIFFITHS C M,MCCANN C.Compressional and shear-wave velocities as a function of confining stress in dry sandstones[J].Geophysical Prospecting,1999,47(4):487–508.
[6]鞠杨,杨永明,毛彦喆,等.孔隙介质中应力波传播机制的实验研究[J].中国科学E辑:技术科学,2009,39(5):904–918.(JU Yang,YANG Yongming,MAO Yanzhe,et al.Laboratory investigation on mechanisms of stress wave propagations in porous media[J].Science in China Series E:Technological Sciences,2009,39(5):904–918.(in Chinese))
[7]赵凯,王肖钧,刘飞,等.多孔材料中应力波的传播[J].爆炸与冲击,2011,31(1):107–112.(ZHAO Kai,WANG Xiaojun,LIU Fei,et al.Propagation of stress wave in porous material[J].Explosion and Shock Waves,2011,31(1):107–112.(in Chinese))
[8]WANG X Q,GE H K,WANG J B,et al.Evaluation of the micro-cracks in shale from the stress sensitivity of ultrasonic velocities[J].Rock Mechanics and Rock Engineering,2016,49(12):4 929–4 934.
[9]刘向君,刘洪,徐晓雷,等.低孔低渗砂岩加载条件下的声波传播特性实验研究[J].岩石力学与工程学报,2009,28(3):560–567.(LIU Xiangjun,LIU Hong,XU Xiaolei,et al.Experimental research on acoustic wave propagation characteristic of low porosity and permeability sandstone under loading conditions[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(3):560–567.(in Chinese))
[10]金解放,李夕兵,殷志强,等.轴压和循环冲击次数对砂岩动态力学特性的影响[J].煤炭学报,2012,37(6):923–930.(JIN Jiefang,LI Xibing,YIN Zhiqiang,et al.Effects of axial pressure and number of cyclic impacts on dynamic mechanical characteristics of sandstone[J].Journal of China Coal Society,2012,37(6):923–930.(in Chinese))
[11]李夕兵,周子龙,叶州元,等.岩石动静组合加载力学特性研究[J].岩石力学与工程学报,2008,27(7):1 387–1 395.(LI Xibing,ZHOU Zilong,YE Zhouyuan,et al.Study of rock mechanical characteristics under coupled static and dynamic loads[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(7):1 387–1 395.(in Chinese))
[12]金解放,李夕兵,殷志强,等.轴压和围压对循环冲击下砂岩能量耗散的影响[J].岩土力学,2013,34(11):3 096–3 102.(JIN Jiefang,LI Xibing,YIN Zhiqiang,et al.Effects of axial compression and confining pressure on energy dissipation of sandstone under cyclic impact loads[J].Rock and Soil Mechanics,2013,34(11):3 096–3 102.(in Chinese))
[13]殷志强,李夕兵,金解放,等.围压卸载速度对岩石动力强度与破碎特性的影响[J].岩土工程学报,2011,33(8):1 296–1 301.(YIN Zhiqiang,LI Xibing,JIN Jiefang,et al.Effects of unloading rates of confining pressure on dynamic strength and fragmentation characteristics of rock under impact loads[J].Chinese Journal of Geotechnical Engineering,2011,33(8):1 296–1 301.(in Chinese))
[14]范新,王明洋,施存程.初始应力对应力波传播及块体运动规律影响研究[J].岩石力学与工程学报,2009,28(增2):3 442–3 446.(FAN Xin,WANG Mingyang,SHI Cuncheng.Study on effects of initial stress on stress wave propagation and block movement law[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(Supp.2):3 442–3 446.(in Chinese))
[15]魏晨慧,朱万成,白羽,等.不同节理角度和地应力条件下岩石双孔爆破的数值模拟[J].力学学报,2016,48(4):926–935.(WEI Chenhui,ZHU Wancheng,BAI Yu,et al.Numerical simulation on two-hole blasting of rock under different joint angles and in-situ stress conditions[J].Chinese Journal of Theoretical and Applied Mechanics,2016,48(4):926–935.(in Chinese))
[16]张凤鹏,彭建宇,范光华,等.不同静应力和节理条件下岩体爆破破岩机制研究[J].岩土力学,2016,37(7):1 839–1 846.(ZHANG Fengpeng,PENG Jianyu,FAN Guanghua,et al.Mechanisms of blasting-induced rock fractures under different static stress and joint properties conditions[J].Rock and Soil Mechanics,2016,37(7):1 839–1 846.(in Chinese))
[17]刘少虹,毛德兵,齐庆新,等.动静加载下组合煤岩的应力波传播机制与能量耗散[J].煤炭学报,2014,39(增1):15–22.(LIU Shaohong,MAO Debing,QI Qingxin,et al.Under static loading stress wave propagation mechanism and energy dissipation in compound coal-rock[J].Journal of China Coal Society,2014,39(Supp.1):15–22.(in Chinese))
[18]李新平,赵航,罗忆,等.深部裂隙岩体中弹性波传播与衰减规律试验研究[J].岩石力学与工程学报,2015,34(11):2 319–2 326.(LI Xinping,ZHAO Hang,LUO Yi,et al.Experimental study of propagation and attenuation of elastic wave in deep rock mass with joints[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(11):2 319–2 326.(in Chinese))
[19]FAN L F,SUN H Y.Seismic wave propagation through an in-situ stressed rock mass[J].Journal of Applied Geophysics,2015,121:13–20.
[20]LI X B,LOK T S,ZHAO J.Dynamic characteristics of granite subjected to intermediate loading rate[J].Rock Mechanics and Rock Engineering,2005;38(1):21–39.
[21]陈祥,孙进忠,谭朝爽,等.岩块波速–应力关系及其卸荷效应[J].岩土工程学报,2010,32(5):757–761.(CHEN Xiang,SUN Jinzhong,TAN Chaoshuang,et al.Relation between P-wave velocity and stress of rock samples and their unloading effect[J].Chinese Journal of Geotechnical Engineering,2010,32(5):757–761.(in Chinese))
[22]金解放,李夕兵,尹土兵,等.轴向冲击下弹性杆中轴向静载对入射波的影响[J].工程力学,2013,30(11):21–27.(JIN Jiefang,LI Xibing,YIN Tubing,et al.Effect of axial static stress of elastic bar on incident stress wave under axial impact loading[J].Engineering Mechanics,2013,30(11):21–27.(in Chinese))
[23]金解放,李夕兵,常军然,等.循环冲击作用下岩石应力应变曲线及应力波特性[J].爆炸与冲击,2013,33(6):613–619.(JIN Jiefang,LI Xibing,CHANG Junran,et al.Stress-strain curve and stress wave characteristics of rock subjected to cyclic impact loadings[J].Explosion and Shock Waves,2013,33(6):613–619.(in Chinese))