公路隧道排水系统结晶堵塞机理及处治措施

Study on Crystallization Blockage Mechanism and Treatment Measures of Highway Tunnel Drainage System

山岭隧道处于地下水的包围环境中,在一定的特殊水文地质条件下会导致隧道混凝土钙离子溶出,不仅影响结构外观质量还会造成排水系统的结晶堵塞,给隧道施工及运营造成困扰。通过现场调研及取样分析,对隧道排水系统结晶堵塞的机理进行了分析,结果表明:隧道排水系统结晶堵塞具有区段性,结晶物主要化学成分为CaCO_(3),结晶体产生的原因为地下水与初期支护混凝土的相互作用。在隧道动态地下水持续渗流作用下,初支喷射混凝土中水泥水化析出大量的Ca^(2+)与水环境中游离的CO_(2)或HCO^(-)_(3)反应生成CaCO_(3)并沉积在排水管或水沟内,从而引发排水设施的结晶型堵塞危害。针对病害特征提出了增加边墙泄水孔和井点降水孔、排水沟改为明沟等处治措施,显著减少了隧道渗漏水的发生,有效预防了水沟结晶堵塞。

As the mountainous tunnel is in an environment surrounded by groundwater,under certain special hydrogeological conditions,it will cause the dissolution of calcium ions in the tunnel concrete,which will not only affect the appearance quality of the structure,but also cause the crystal blockage of the drainage system,which could bring a lot of troubls for the tunnel construction and operation.Through on-site investigation and sampling analysis,the mechanism of crystallization blockage of tunnel drainage system has been analyzed.The results have shown that:tunnel drainage system crystallization blockage is segmental,the main chemical composition of crystals is CaCO_(3),and the cause of crystals is interaction of groundwater and initial support concrete.With continuous seepage of dynamic groundwater in the tunnel,a large amount of Ca^(2+)precipitated by cement hydration in the first shotcrete reacts with free CO_(2) or HCO_(3)-in the water environment to form CaCO_(3) and deposit in the drainage pipe or ditch,thereby triggering the crystallization of drainage facilities.According to the characteristics of the disease,treatment measures such as adding side wall drainage holes and well point dewatering holes,and changing the drainage ditch to open ditch have been proposed,which could significantly reduce occurrence of tunnel leakage and effectively prevent crystal blockage of drainage ditch.