列车振动荷载作用下膨胀岩盾构隧道的动力响应

南宁轨道交通1号线采用盾构法穿越膨胀岩分布区。考虑不同岩层组合对列车振动荷载与膨胀力共同作用下隧道管片与围岩的动力响应进行数值模拟分析。结果表明:距离管片越远列车振动荷载引起的沉降越小;荷载条件相同时岩土体阻尼比越小受列车振动荷载影响越大,因而产生的沉降越大;不同岩层组合条件下隧底相同位置的位移、速度、加速度和竖向应力时程曲线均在加载初期突变,在施加的列车振动荷载稳定后近似呈简谐波动形式;隧道腰部所受的竖向应力最大,顶部所受的竖向应力最小。

Dynamic Response of Expansive Rock Shield Tunnel Under Train Vibration Load

Nanning Rail Transit Line 1 adopts shield tunneling method to cross the expansive rock distribution area.Considering different rock stratum combination,the dynamic responses of tunnel segment and surrounding rock under the combined action of train vibration load and expansive force were numerically simulated and analyzed.The results show that the farther the distance from the segment,the smaller the settlement caused by train vibration load is.When the load conditions are the same the smaller the damping ratio of rock and soil mass,the greater the inf luence of train vibration load will be and the larger the settlement will be.The displacement,velocity,acceleration and vertical stress time history curves at the same position of the tunnel bottom under different rock stratum combination conditions all change abruptly at the initial stage of loading,which is approximately in the form of simple harmoinic wave motion when the applied train vibration load is stable.The vertical stress on the waist of tunnel is the largest and the vertical stress on the top is the smallest.