动力扰动下既有隧道的动态响应及衬砌影响分析

Dynamic Response and Lining Impact of Existing Tunnel Analysis under Dynamic Perturbation

基于现场监测数据,利用FLAC3D研究了拱桥铺隧道在动力扰动下的动态响应及衬砌产生的影响.研究结果表明:底部动载下,相对于无衬砌隧道,有衬砌隧道能改变除拱底外其它测点的运动方向,防止隧道内陷并能够有效减少隧道锚固壁位移;隧道锚固壁4个测点均承受压应力,且无衬砌支护时压应力值远小于有衬砌时,前者围岩表现更为"松散";有衬砌支护隧道拱肩处锚杆轴力出现中性点,而无衬砌支护时锚杆均为受拉,后者锚杆轴力峰值位置更靠近锚固壁,衬砌能有效分担围岩荷载并减小锚杆负载;有衬砌时锚杆轴力相对增速快且振幅大,而无衬砌支护隧道在应力波冲击后,锚杆轴力相对增速慢且振幅小,即衬砌能通过动态调整协助锚杆承担动荷载.

Based on the on-site monitoring data,the dynamic response of Gongqiaopu tunnel under the dynamic load and the influence of lining are studied by FLAC3 D.Under the dynamic loading at the bottom,the lining tunnel can change the direction of movement of other measuring points except the arch bottom,compared to the tunnel without lining.To prevent the tunnel from being inverted and effectively reduce the anchorage wall displacement of the tunnel,the wall rock of the tunnel is more'loose'when its four points are subjected to the compressive stress and the pressure value is much less than that of the lining.There are neutral points in the axial force of the anchor rod in the arch shoulder of the tunnel with lining support,while the anchor rod is pulled when the lining is not supported,and the latter is more close to the anchorage wall.The lining can effectively share the surrounding rock load and reduce the load of the anchor rod,the axial force of the anchor rod is relatively fast and the amplitude is large when the lining is in,and the tunnel with no lining supporting is under the shock of stress wave.The axial force of the anchor rod is relatively slow and the amplitude is small,which illustrates that the lining can support the dynamic load by dynamically adjusting the anchor rod.