动载作用下全锚锚固体应力波传播及破坏特征

Propagation and failure characteristics of stress wave of full anchor solid under dynamic load

  • 摘要: 深井巷道受动载扰动变形严重,明晰动载作用下锚固支护体的应力波传播及破坏特征具有重要意义。基于霍普金森杆(SHPB)试验系统,研究了不同冲击气压下锚固体试件的应力波传播规律,基于一维应力波理论计算了锚固体的层裂强度;利用ABAQUS数值模拟软件还原了动载冲击试验,再现了锚固体试件的应力波传播全过程,分析了锚固体轴向不同位置处的应变–时序特征。研究结果表明:① 随冲击气压增大,应力波衰减速度越快,空间响应幅值及衰减系数逐渐增大,锚固体试件层裂强度与冲击气压呈正相关关系,0.6 MPa冲击气压下的层裂强度相较于0.4 MPa冲击气压下增加了41%,呈现出明显的应变强化效应;② 锚固尾部及中部锚固剂的应力波峰值应变略大于围岩峰值应变,而锚固端部由于净拉应力作用导致围岩峰值应变骤增;③ 锚杆、锚固剂及围岩3者动力响应具有时序性,锚固围岩与锚固剂率先受到压缩应力波作用,锚杆产生滞后于锚固剂与围岩的拉伸应力波,阻止锚固体试件发生协同破坏;④ 锚固尾部锚杆、锚固剂及围岩应变起跳时间间隔为0,随着应力波向锚固中部及端部传递,3者应变起跳间隔时间逐渐增加,锚杆峰值应变随之增加,锚固端部锚杆破坏最严重,随冲击气压的增大,3者不协同作用逐渐加剧,锚固体试件加速劣化。

     

    Abstract: Dynamic stresses severely disrupt and distort deep shaft roadways. It is critical to understand the stress wave propagation and damage characteristics of anchor support body under dynamic loads. On the basis of the SHPB test equipment, the stress wave propagation law of solid anchor specimens under varied impact air pressures was investigated, and the laminar cracking strength of anchor solids was determined using the one-dimensional stress wave theory. The stress wave propagation of anchor solid specimens exposed to dynamic load impact was simulated using the ABAQUS numerical simulation software. The strain and time sequence features of the anchor solid along the axial direction at various cross-sections were examined. The findings demonstrate that ① as the impact air pressure rises, the spatial attenuation amplitude and attenuation coefficient steadily increase. Moreover, there is a discernible strain reinforcing effect as the laminar fracture strength of the solid anchor specimen is strongly associated with the impact air pressure. ② The peak strain of the surrounding rock at the tail and middle of the anchor is somewhat greater than the peak strain of the surrounding rock, however the peak strain of the surrounding rock quickly increases at the anchor end due to the net tensile stress. ③ The dynamic responses of anchor rod, anchor agent and wave are time-ordered, with the anchor rock and anchor agent being the first to receive the compressive stress wave and the anchor rod being the first to receive the compressive stress wave. The anchor rod generates a tensile stress wave that follows behind the anchor rock, protecting the anchor specimen from synergistic damage. ④ The peak strain of the anchor and rock at the tail of the anchor is somewhat greater than the peak strain of the surrounding rock. Anchor rod, anchor agent and wave have a strain start interval of 0. And the peak strain of the anchor increases as the stress wave is transferred to the middle and end of the anchorage, and the larger the impact air anchor is, the anchor end is severely damaged, and the non-synergistic effect gradually increases.

     

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