水底隧道涌水量预测方法的应用分析

讨论了水底隧道涌水的预测计算问题,利用经验法和有限元法对某拟建海底隧道工程方案的涌水量进行了预测计算和对比分析,探讨了竖向和水平走向裂隙发育情况对隧道涌水的影响。结果表明:①与有限元相比,用经验公式计算得到的水底隧道涌水量偏小;②当水底岩层张性裂隙(尤其是竖向裂隙)较发育时,隧道涌水量增长较大;③当隧道临近或穿越断层破碎带时,隧道周边的渗流场具有显著的三维特征;④如果水底隧道上覆地层中没有显著的隔水层,则由于水源无限充足,隧道的涌水量将主要受到水位相对高度和隧道围岩渗透系数的影响,与隧道上覆地层的厚度关系不大。

An analysis of application of the methods of predicting water influx to under-water tunnels

Methods and related issues for estimating the water influx of underwater tunnels are discussed. Using empirical and finite element methods,comparative calculations are conducted for the water influx of a potential undersea tunnel in southern China,and the effects of the strikes of the fractures in the seafloor rocks on the tunnel water influx are examined. The results indicate that the water influxes estimated by the empirical formula may be smaller than those obtained from the finite element calculations. The amount of influx increases greatly if the fractures, especially those transverse to the tunnel alignment, are intensive and open. The flow field around the tunnel sections with nearby faults may be of three dimensional features. Since the source of seawater is virtually unlimited and there exists no aquitards or aquicludes in the seafloor rocks, the tunnel water influx is mainly dependent on the relative height of the seawater level and the characteristic hydraulic conductivity of the surrounding rocks, with only a weak correlation to the thickness of the overlying formations.