在动载作用下山岭隧道锚杆的动态响应分析

基于现场监测数据,采用数值分析方法研究了拱桥铺山岭隧道在底部动载作用下隧道锚杆的轴力和锚固水泥浆应力的动态响应规律。随着爆炸应力波传播,无衬砌影响的锚杆轴向拉应力在极短的时间里增加至峰值,最后趋于稳定,有衬砌锚杆轴力一开始都是向受压方向达到峰值,然后逐渐向反方向振动。每根锚杆从锚头到锚尾锚杆单元轴力都是先增加后减小,中间锚杆单元受拉较大。随着动载作用时间推移,无衬砌影响锚杆在动载作用下,锚杆锚固水泥浆应力逐渐上升到峰值并逐渐趋于稳定,每根锚杆的锚固水泥浆应力从锚头至锚尾由负向正方向转变,正负方向水泥浆应力峰值都是由中间向两端逐渐增大。受衬砌影响锚杆锚固水泥浆应力在动载作用后,锚杆锚固水泥浆应力发生多次振动,除了拱腰附近锚杆受到锚固水泥浆应力较小外,其他锚杆的锚固水泥浆应力从锚头至锚尾由正向负转变,峰值大小是先减小再增加。

Dynamic Response of Mountain Tunnel Bolts under Dynamic Load

Based on the field monitoring data,the dynamic response law of tunnel bolts axial force and anchorage grout stress of Gongqiaopu Mountain Tunnel under bottom dynamic load is studied by numerical analysis.With the propagation of explosive stress wave,the axial tension stress of bolts without lining increases to its peak value in a very short time,and then tends to be stable.The axial force of bolts with lining reaches its peak value in the direction of compression at first,and then gradually vibrates in the opposite direction.The axial force of each anchor bolt element increases first and then decreases from the anchor head to the anchor tail,and the tension of the middle anchor element is larger.With the time lapse of dynamic loading,the stress of anchoring grout stress increases gradually to peak value and tends to be stable.The anchoring grout stress of each anchor changes from negative to positive direction from anchor head to anchor tail,and the peak stress of grout stress in positive and negative direction increases gradually from middle to both ends.After the stress of the bolt anchoring grout stress with lining subjected to dynamic load,the bolt anchoring grout stress is vibrated many times.Except that the anchor bolt near the arch waist is less stressed by the anchoring grout stress,the anchoring grout stress of other bolts from the anchor head to the anchor tail changes from positive to negative,and the peak value is first reduced and then increased.