悬索桥隧道式锚碇和下穿公路隧道相互作用机制研究

结合矮寨悬索桥的工程实践，采用MIDAS/GTS对茶洞岸锚碇和下穿公路隧道之间的相互作用机制进行研究。研究表明，开挖阶段锚-隧相互作用程度具有不对等性，即锚-隧影响大于隧-锚影响。在设计大缆拉力荷载作用下，下穿隧道的存在明显地改变了锚碇附近围岩的位移分布，导致锚碇附近围岩节点位移曲线发生整体下沉、旋转，并产生最大达0.76 mm的竖向附加位移。锚碇附近围岩竖向位移受下穿隧道影响较为显著，而水平向位移受影响相对较弱。对于锚碇隧道而言，下穿隧道单次爆破引起振动较小，距离爆心40 m范围以外围岩质点峰值振动速度小于2 cm/s，与实测资料吻合。工程项目现场的爆破振动监测及围岩波速测试成果显示：下穿隧道爆破掘进对40 m以外围岩的振动效应可以忽略。

Research on interaction mechanism of tunnel-type anchorage with undercrossing tunnel for suspension bridge

Based on engineering practice in tunnel-type anchorage for Aizhai suspension bridge,the interaction mechanism of tunnel-type anchorage with undercrossing tunnel were obtained by numerical analysis in MIDAS/GTS.The results show that asymmetry interaction exists between tunnel-type anchorage and undercrossing tunnel in excavation stage; namely, the effects which tunnel-type anchorage acting on undercrossing tunnel is more significantly than its back face. In addition, the nodal displacements nearby the anchorages was changed obviously by the undercrossing tunnel; and in consequence,the vertical displacement curve of tunnel-type anchorage occurred sinking and rotating but there is some limited influence on the horizontal displacement; the vertical extra displacement can reach 0.76 mm because of the undercrossing tunnel. Finally, it is found that the blasting vibration which caused by development blasting of the undercrossing tunnel is weak in view of the tunnel-type anchorage, the vibration velocity less than 2 cm/s when the blast center distance exceeds 40 m; it is anastomosed with the measured data, the monitoring data show that the vibration effect is negligible to the tunnel-type anchorage when the blast center distance exceeds 40 m.