近距离垂直交叠盾构隧道的列车振动响应特性及损伤规律

Train Vibration Response Characteristics and Damage Rule of Vertically Overlapping Shield Tunnels in Close Distance Space

基于拟合的列车振动荷载,采用数值模拟方法研究当列车在上部隧道行驶时近距离垂直交叠盾构隧道的动力响应特性,以及在不同隧道净距时上部隧道的损伤分布规律。结果表明:在列车振动荷载作用下,列车距离分析断面越近,分析断面上隧道衬砌的振动加速度和振动最大主应力增量均越大;拱底的振动加速度最大,拱腰次之,拱顶最小;在交叠中心断面处,上部隧道的最大主应力增量远大于下部隧道;压致损伤和拉致损伤主要集中在上部隧道底部附近130°的范围内,且在交叠中心处达到最大。随着两个隧道净距的减小,上部隧道的压致和拉致损伤均增大;当两个隧道净距为6m时,仅交叠中心处上部隧道拱顶出现较小的压致和拉致损伤,当两个隧道净距为4和2m时,交叠中心处上部隧道的压致和拉致损伤增量较大,远离交叠处上部隧道仅出现较小的压致和拉致损伤,说明两个隧道近距离垂直交叠时,下部隧道对上部隧道的振动加速度、最大主应力增量和压致及拉致损伤具有放大效应。

Considering the fitting train vibration load,the numerical simulation method was used to study the dynamic response characteristics of the vertically overlapping shield tunnels in close distance space when the train was running in the upper tunnel and the damage distribution law of the upper tunnel at different clear distances of tunnels.Results show that,under the train vibration load,the closer the train distance to the analysis section is,the larger the vibration acceleration and the maximum principal stress increment of the tunnel lining on the analysis section will be.The vibration acceleration of the arch bottom is the largest,the hance is the second and the vault is the smallest.At the cross section of the overlapping center,the maximum principal stress increment of the upper tunnel is far greater than that of the lower tunnel.The compressive and tensile damage is mainly concentrated in the range of 130°near the bottom of upper tunnel,and reaches the maximum in the overlapping center.With the decrease of the clear distance between two tunnels,both the compressive and tensile damage of the upper tunnel increase.When the clear distance between two tunnels is 6 m,only the vault of upper tunnel at the overlapping center appears smaller compressive and tensile damage.When the clear distances between two tunnels are 4 and 2 m,the increment of the compressive and tensile damage in the upper tunnel at the overlapping center is larger,only smaller compressive and tensile damage occurs in the upper tunnel away from the overlap.It shows that when two tunnels overlap vertically in close distance space,the lower tunnel has an amplification effect on the vibration acceleration,the maximum principal stress increment,the compressive and tensile damage of upper tunnel.