土体渗透各向异性对水下隧道渗流量的影响研究

Influence of anisotropic permeability on seepage flow in underwater tunnels

本文以考虑衬砌作用的水下隧道模型为依托,同时考虑隧道洞周土竖向和侧向渗透性差异,结合坐标变换、保角映射法,推导了考虑衬砌等水压和等水头渗水模式下的渗透各向异性水下圆形隧道渗流量解析解式,通过数值模拟分析验证了解析解的正确性。此外分析了衬砌渗水模式、衬砌渗透性、隧道埋深、弱透水体、地表压力水头高度对隧道渗流量的影响。研究表明,渗透各向异性会影响隧道渗流量,忽略洞周土体渗透各向异性将低估隧道渗流量,尤其是渗透各向异性能够改变浅埋隧道中水流的渗流路径,对浅埋隧道渗流量的影响更显著;等水压和等水头渗水模式下的隧道渗流量随隧道埋深的增大而趋于一致,浅埋隧道考虑衬砌渗水模式更有意义;衬砌能够削弱渗透各向异性对渗流量的影响,削弱能力随衬砌渗透性的降低而增强;软黏土等弱透水土体中考虑渗透各向异性对渗流量的影响更大,地表压力水头越大,隧道渗流量越大,渗透各向异性对于隧道渗流量的影响也越明显。

Based on the underwater tunnel model considering the effect of lining,and the vertical and lateral permeability differences of the surrounding soil of the tunnel,this paper deduces the water seepage model under the mode of lining equal water pressure and equal head by using coordinate transformation and conformal mapping method.The analytical solution of seepage flow in an underwater circular tunnel with seepage anisotropy is verified by numerical simulation analysis.In addition,the effects of lining water seepage mode,lining permeability,tunnel burial depth,weakly permeable body,and pressure head of water surface on the seepage flow of the tunnel are analyzed.The research shows that the seepage anisotropy can affect the seepage flow of the tunnel,and ignoring the seepage anisotropy of the soil around the tunnel wil underestimate the seepage flow.In particular,seepage anisotropy can change the seepage path in shallow tunnels,and has more significant impact on the seepage flow of shallow tunnels.The seepage flow rate of the tunnel under the seepage mode of constant water pressure and constant head tends to be consistent with the increase of the buried depth of the tunnel;so it is more meaningful to consider the seepage mode of the lining in the shallow tunnels.Lining can weaken the effect of seepage anisotropy on seepage flow,and the weakening ability increases with the decrease of lining permeability.In low permeable soils such as soft clay,the influence of seepage anisotropy on seepage flow is greater.The greater the pressure head of water surface,the larger the tunnel seepage flow,and the more obvious the effect of seepage anisotropy on the tunnel seepage flow.