混凝土主动围压SHPB试验波形数值分析
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摘要
为探究主动围压SHPB(分离式霍普金森压杆)试验中反射波形与混凝土动态响应的关系,采用LS-DYNA软件,基于H-J-C本构模型,模拟了混凝土的主动围压SHPB试验,从波形特征的变化分析了围压对混凝土动态力学性质的影响。结果表明:围压条件下混凝土的破坏形式为压剪破坏,试件的平均损伤度随围压的增大而降低。试验中反射波具有"双峰"特性,且围压对第二峰值应力的影响较大,其值随着围压的增大而减小,表征了试件的变形破坏程度;而第一峰值应力几乎不受围压的影响,其主要与冲击波的幅值有关;反射波尾存在压缩波段,该段的峰值应力随着围压的增大逐渐增大,表征了围压下试件的完整性比较好,且其变形能力和残余承载力均有所提高。研究结果可为评估三轴应力下混凝土构件的动态损伤和残余承载力提供参考。
In an attempt to explore the relationship between dynamic response of concrete and waveform of reflected waves during Split Hopkinson Pressure Bar( SHPB) tests under confining pressure,we simulated the SHPB tests under active confining pressure using LS-DYNA based on the Johnson-Holmquist Concrete constitutive model. We also analyzed the influence of confining pressure on dynamic properties of concrete in terms of changes in waveform characteristics. Results show that the failure mode of concrete under confining pressure is compression-shear failure,and the average degree of damage decreases with the climbing of confining pressure. The reflected wave in SHPB test is featured with double peaks,of which the first peak stress is barely affected by confining pressure,but by the magnitude of impact wave; while the second peak stress is significantly affected by confining pressure,declining with the increase of confining pressure,which implies the deformation degree of specimens. Compressive wave was found in the end of the reflected wave; with the increase of confining pressure,peak stress of the compressive wave increased as well,indicating an enhancement in deformation capacity and residual bearing capacity of the concrete specimen. The research achievements could serve as a reference for evaluating the dynamic damage and residual bearing capacity of concretes under triaxial stress.
In an attempt to explore the relationship between dynamic response of concrete and waveform of reflected waves during Split Hopkinson Pressure Bar( SHPB) tests under confining pressure,we simulated the SHPB tests under active confining pressure using LS-DYNA based on the Johnson-Holmquist Concrete constitutive model. We also analyzed the influence of confining pressure on dynamic properties of concrete in terms of changes in waveform characteristics. Results show that the failure mode of concrete under confining pressure is compression-shear failure,and the average degree of damage decreases with the climbing of confining pressure. The reflected wave in SHPB test is featured with double peaks,of which the first peak stress is barely affected by confining pressure,but by the magnitude of impact wave; while the second peak stress is significantly affected by confining pressure,declining with the increase of confining pressure,which implies the deformation degree of specimens. Compressive wave was found in the end of the reflected wave; with the increase of confining pressure,peak stress of the compressive wave increased as well,indicating an enhancement in deformation capacity and residual bearing capacity of the concrete specimen. The research achievements could serve as a reference for evaluating the dynamic damage and residual bearing capacity of concretes under triaxial stress.
引文
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[15]陈腾飞,许金余,刘石,等.混凝土与岩石类脆性材料的动态破坏机制研究[J].混凝土,2013,(7):20-22.
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[18]陈荣,林玉亮,卢芳云,等.Barre花岗岩动态压缩破坏特性研究[J].岩石力学与工程学报,2009,28(增1):2743-2748.
[19]王礼立.应力波基础[M].2版.北京:国防工业出版社,2005:45-48.
[2]黄仕超,彭刚,邹三兵,等.不同龄期混凝土动态力学性能研究[J].长江科学院院报,2015,32(12):129-133,143.
[3]胡伟华,彭刚,黄仕超,等.基于声发射技术的混凝土动态损伤特性研究[J].长江科学院院报,2015,32(2):123-127,132.
[4]CANDAPPA D P,SETUNGE S,SANJAYAN J G.Stress Versus Strain Relationship of High Strength Concrete under High Lateral Confinement[J].Cement and Concrete Research,1999,29(12):1977-1982.
[5]谢和平,董毓利,李世平.不同围压下混凝土受压弹塑性损伤本构模型的研究[J].煤炭学报,1996,21(3):265-270.
[6]GONG J C,MALVERN L E.Passively Confined Tests of Axial Dynamical Compressive Strength of Concrete[J].Experimental Mechanics,1990,30(1):55-59.
[7]薛志刚,胡时胜.水泥砂浆在围压下的动态力学性能[J].工程力学,2008,25(12):184-188.
[8]YIN Z Q,LI X B,JIN J F,et al.Failure Characteristics of High Stress Rock Induced by Impact Disturbance under Confining Pressure Unloading[J].Transactions of Nonferrous Metals Society of China,2012,22(1):175-184.
[9]张华,郜余伟,武守锋.混凝土材料SHPB主动围压实验的数值模拟[J].合肥工业大学学报(自然科学版),2012,35(2):217-220.
[10]HAO Y,HAO H.Dynamic Compressive Behavior of Spiral Steel Fiber Reinforced Concrete in Split Hopkinson Pressure Bar Tests[J].Construction and Building Materials,2013,48:521-532.
[11]李夕兵,古德生,赖海辉.冲击载荷下岩石动态应力-应变全图测试中的合理加载波形[J].爆炸与冲击,1993,13(2):125-130.
[12]吴赛,赵均海,李楠.被动围压下混凝土的动态力学性能研究[J].应用力学学报,2015,32(6):992-998.
[13]巫绪涛,孙善飞,李和平.用HJC本构模型模拟混凝土SHPB试验[J].爆炸与冲击,2009,29(2):137-142.
[14]潘城,赵光明,孟祥瑞.爆炸荷载作用下围岩累积损伤效应的数值分析[J].爆破,2016,33(1):30-33,44.
[15]陈腾飞,许金余,刘石,等.混凝土与岩石类脆性材料的动态破坏机制研究[J].混凝土,2013,(7):20-22.
[16]GRADY D E,KIPP M E.Continuum Modeling of Explosive Fracture in Oil Shale[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1980,17(2):147-157.
[17]金解放,李夕兵,殷志强,等.循环冲击下波阻抗定义岩石损伤变量的研究[J].岩土力学,2011,32(5):1385-1393,1410.
[18]陈荣,林玉亮,卢芳云,等.Barre花岗岩动态压缩破坏特性研究[J].岩石力学与工程学报,2009,28(增1):2743-2748.
[19]王礼立.应力波基础[M].2版.北京:国防工业出版社,2005:45-48.