动载作用下锚固体应力波传递及破坏特征研究

Study on Stress Wave Propagation and Failure Characteristics of Anchor Solid Under Dynamic Load

为研究动载作用下锚固体的应力波传播规律及破坏特征,利用分离式霍普金森杆(SHPB)对锚固体试件开展了不同预应力及不同冲击次数的冲击试验。研究结果表明:随着预应力增加,锚固围岩中应力波峰值逐渐增加,衰减速度逐渐减小,增大锚杆预应力,锚固自由端拉伸波峰值明显减小;随锚固体试件预应力增加,锚固体轴力损失越快,轴力损失率呈二次线性增加的趋势;预应力较小时,锚固自由端围岩产生裂缝较多,多次冲击下裂缝距离较为接近;随着预应力的增加,自由端头破坏程度减弱;随着预应力增加,拉拔最大位移量越来越小,未受动载作用的原始试件拉拔后未出现明显的破坏;动载作用后,随着预应力增大,锚固端头发生一定程度的劈裂破坏,预应力持续增加劈裂破坏程度越来越弱。

In order to study the stress wave propagation law and failure characteristics of anchor solid under dynamic load,separate Hopkinson bars(SHPB)were used to conduct impact tests on anchor solid specimens with different prestress and impact times,and the propagation law of stress waves and the characteristics of anchor failure were studied.The research results indicate that as the prestress increases,the peak value of stress waves in the anchored surrounding rock gradually increases,and the attenuation rate gradually decreases.Increasing the prestress of the anchor rod significantly reduces the peak value of tensile waves at the free end of the anchor;As the prestress of the anchor specimen increases,the axial force loss of the anchor increases faster,and the axial force loss rate shows a quadratic linear increase;when the prestress is small,there are more cracks in the surrounding rock at the anchoring free end.Under multiple impacts,the crack distance is relatively close,and as the prestress increases,the degree of damage at the free end weakens;as the prestress increases,the maximum displacement during pulling decreases.The original specimen that was not subjected to dynamic load does not show significant damage after pulling.After dynamic load,as the preload increases,a certain degree of splitting failure occurs at the anchor end,and the degree of splitting failure becomes weaker as the prestress continues to increase.