【摘要】 利用霍普金森压杆装置对干燥和水饱和大理岩进行多次冲击波在长杆岩石试件中传播的实验研究。结果表明,冲击动态模量随应变或应力的改变而不断地变化。对于干燥大理岩,当冲击应力小于屈服强度时,随应力波传播时间或距离的拉长,模量表现为降低;并且,由于卸载模量大于加载模量,导致卸载波不断追赶加载波,使应力波形由宽变窄,应力波幅不断衰减。随着冲击次数的增加,实验显示出干燥岩石的模量增大,应力波形变窄,弥散效应减弱,衰减幅值减小,残余应变也随之减小的冲击压实效应。对于饱水大理岩,当冲击应力大于屈服强度时,其模量、应力波形特征均与干燥大理岩的冲击结果相类似;随着冲击次数的增加,饱水大理岩出现波形拉长散开,后沿缓波更显著,应力-应变曲线的模量降低,残余应变增大,这与干燥大理岩正好相反。这是因为超过屈服点的冲击导致饱水大理岩的裂纹扩展和新裂纹的生成,引起体积膨胀,模量下降。这些实验结果对大型工程尤其是防护工程的设计和施工是有现实意义的。更多还原

【Abstract】 The experimental research on the propagation of repeated shock wave through dry and water saturated marble has been performed by means of Hopkinson bar.The results suggest that impact modulus varies with stress and strain.When repeated shock stress in dry marble is less than yield stress,the dynamic modulus reduces with the increase in distance or time of wave propagation.Due to the modulus of unloading is larger than one of loading,the unloading wave pursues the loading wave,resulting in the narrowing of stress wave and the amplitude decreasing continuously.With the increase in the number of shock,the modulus of dry marble becomes larger,dispersion and amplitude of attenuation decrease,stress wave gets narrow and the impact compaction effect appears.When the shock stress in water saturated marble is larger than yield stress,the modulus and the properties of stress waveform are similar to ones of dry marble.With the increase in the number of shock,the experimental results show that waveform gets longer and scattered,the residual strain increases.These are inverse to the results in dry marble.It is because that shock exceeding yield stress causes crack growth and new crack initiation,volumetric expansion and modulus decrease in water saturated marble.All these results are helpful to the design and construction of large projects,especially for the defense engineering.更多还原