增设压力阀对隧道防排水影响

Influence of incorporating valve pressure on the tunnel waterproof and drainage

针对隧道主动控制式防排水系统难以实现对排水量和水压的动态控制、易造成隧道开裂渗漏的问题,提出在环向排水盲管处增设压力阀,控制排水量和外水压力,并推导隧道排水量的计算公式。基于稳定渗流场基本微分方程,运用保角变换方法推导围岩渗流场公式,建立包含环向排水盲管间距和泄水压力的隧道渗流计算模型,推导隧道排水量及二衬结构外水压力的计算公式。通过退化解和数值模拟方法,验证解析解的合理性。在此基础上,建立增设压力阀的隧道防排水设计方法。结果表明:土工织物渗透系数和排水管间距对水压和流量有很大影响,建议土工织物渗透系数不小于500μm/s,排水盲管的间距可综合泄水压力进行设置。与现有主动控制式防排水系统相比,增设压力阀可以减少灌浆圈的厚度和施工成本。

The current active control waterproof and drainage system was difficult to achieve dynamic control of water inflows and pressure,which could lead to tunnel cracking and leakage,a pressure valve was installed at the circumferential drainage blind pipe in order to control the water inflow and water pressure.Additionally,the formula for calculating the tunnel water inflow was derived.Using the conformal transformation,the seepage field formula of the surrounding rock was derived from the basic differential equation of the stable seepage field.The tunnel seepage calculation model was further established,incorporating the parameters of circumferential drainage blind pipe spacing and discharge pressure.The calculation formula of tunnel drainage volume and external water pressure of the external water pressure of secondary lining and tunnel water inflow calculation formula was obtained.The decomposition and numerical simulation techniques confirmed the analytical solution′s reasonableness.This served as the foundation for the establishment of a tunnel drainage design solution with a pressure valve.The findings indicated that the water pressure and flow rate were significantly impacted by the geotextile permeability coefficient and the spacing between drainage pipes.It was recommended to select a geotextile which permeability coefficient of at least 500μm/s,and the spacing between drainage blind pipes could be adjusted based on the drainage pressure.The grouting ring thickness could be decreased by adding a pressure valve in comparison to the current active control waterproof and drainage.