近距离上层隧道施工对下层隧道的扰动影响

Influence of Construction Disturbance from Close Upper Tunnel on Lower Tunnel

针对近距离上层隧道施工时给下层隧道稳定性造成扰动影响的现状,基于简支土体梁力学模型,研究下层隧道顶部在周期性扰动力作用下的系统振动特性,得到顶部垂直位移的动态响应数学表达式,为定量掌握最大位移峰值的大小与出现时刻提供理论依据,指出考虑振动因素时上下层隧道安全距离的确定方法。结合具体算例探索扰动力等因素对最大位移的作用规律,结果表明:扰动力振幅和隧道跨度分别增加1倍和2倍时,最大位移峰值相应增大1倍和23.9倍;隧道层间垂距和土体弹性模量分别增加2倍和3倍时,最大位移峰值相应减小88.2%和70%。当主要影响因素变化时,最大位移的波动大周期延长、波动震荡性加剧,特别是峰值处的震荡幅值增大,隧道顶部稳定性受到明显影响。

Based on the mechanical model of a simply supported beam,this study investigates the influence of periodic construction disturbances from a close upper tunnel on the vibration characteristics of the roof of a lower tunnel.The mathematical expression for the dynamic response of vertical displacement at the top of lower tunnel is deduced.The mathematical expression can provide a theoretical basis for determining the occurrence time and peak displacement,and provide a method for determining the safe distance between the two tunnels.The law of the action of influencing factors such as the disturbance force on maximum displacement is explored with a specific example.The results show that when the disturbance amplitude and the tunnel span increase by 1 and 2 orders of magnitude,respectively,the corresponding peak displacements increases by 1 and23.9 orders,respectively and when the vertical distance between tunnel layers and the elasticmodulus of soil increase by 2 and 3 orders,respectively,the corresponding peak displacements reduces by 88.2%and 70%,respectively.When the main affecting factors change,the maximum displacement and its oscillations increase,which influences the top stability of the tunnel.