确定水下隧道覆盖层厚度的经验公式及其应用

Empirical Formulas for Determining Overburden Thickness of Underwater Tunnel and Their Applications

覆盖层厚度是水下隧道纵断面线路设计的主要参数之一,直接制约着工程的安全和造价。为了应对我国大规模建设的水下隧道的浪潮,必须给设计者提供确定覆盖层厚度的简便方法。对于不同的水深和开挖面积,编程求解了日本最小涌水量法的基本公式,并拟合出了经验公式。在介绍挪威经验曲线的基础上,对不同基岩纵波速度提出了相应的回归公式。根据大量数值计算的结果,利用最小位移法判据,分别针对Ⅱ～Ⅳ级围岩条件推导出了覆盖层厚度和开挖面积、水深之间的函数关系。最后,对各种方法的适用性进行了评价。

The overburden thickness of underwater tunnel is one of main issues in its longitudinal section design,and the construction cost and safety are directly governed by the overburden thickness.In order to cope with the tide of underwater tunnel construction in China,convenient methods for determining the overburden thickness must be provided to designers.The basic equation of Japanese minimum leakage method is derived by programming under different water depths and excavation areas.According to these results,the empirical formula is fitted.Regression formulas are presented for several longitudinal wave velocities in bedrock with the Norwegian empirical curves.Based on lots of numerical calculation results and the minimum displacement criterion,functional relationships of overburden thickness,the water depth and excavation area are derived forⅡ～Ⅳclasses of surrounding rock.In the end,the applicability of all the empirical formulas is evaluated.