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通过物理模型试验,研究在爆炸动载作用下临近工作面支护锚杆的应力状态。根据相似条件和简化假设,采用集中装药进行工程掏槽爆破模拟,利用粘贴在锚杆上的应变片测得近区端锚和全锚锚杆的轴向应变波。测试结果表明,爆破引起锚杆振动时间约为6 ms,经过9 ms的缓降期锚杆变形趋于稳定值;动载期间端锚锚杆在杆体中部锚固段测得峰值应力比杆体尾部自由段的值大,但相差不大,动载过后尾部的残余应力较大;全锚锚杆在杆体尾部测得的峰值应力和残余应力都远大于杆体中部测得值。利用无限体内一点受法向集中力作用的位移势函数,推导锚固体及周围岩体的轴向应力分布,并计算一定预应力在锚固区产生的附加轴向应力,结合动应力的作用分析锚杆的受力状态。
Through the physical model test, the stress state of anchor bolt near working face under the action of explosive dynamic load is studied. According to the similar conditions and simplifying assumptions, the project is carried out by using a centralized charge, and the axial strain wave of the near-end anchor and the full-anchor bolt is measured by using the strain gauge attached to the anchor rod. The test results show that the vibration time of the rock bolt caused by blasting is about 6 ms and the deformation of the rock bolt tends to be stable after the 9 ms slow down. The peak stress of the anchor bolt in the middle part of the rod body during the dynamic load is higher than the peak stress of the rod body The value of the segment is large, but the difference is not large, the residual stress of the rear part is larger after the dynamic load. The peak stress and residual stress of the whole anchor bolt measured at the tail of the rod body are far greater than those measured in the middle of the rod body. Based on the displacement potential function of infinitesimal body under the action of normal concentration, the axial stress distribution of the anchor body and the surrounding rock mass is deduced. The additional axial stress of a certain prestressing force in the anchorage zone is calculated. Combined with the effect of dynamic stress, the anchor Rod force state.