Abstract:The problem of tunnel seepage crystallization is a new type of tunnel disease. To ensure the normal operation of the tunnel drainage system, it is not only necessary to study the crystallization phenomenon and mechanism of the drainage system of non-karst tunnels, but also to have the targeted prevention and treatment schemes. Firstly, the common crystallization treatment methods such as physical and chemical treatments are expounded in detail, and a case study of drainage crystallization in a highway tunnel in Zhejiang is conducted. Through the detection and analysis of parameters such as water solution, soil soluble salts, CO2 content, etc., the causes of drainage crystallization in the non-karst tunnel are analyzed, including water quality characteristics, environmental factors, water flow conditions, etc. The study result shows that the crystals are mainly calcium carbonate formed by the combination of free bicarbonate ions in the surrounding rock of the tunnel and calcium ions in the tunnel support concrete. And the carbon dioxide is an important external factor. Considering the characteristics of the tunnel located in an environmentally sensitive area and a water source protection zone, a high-pressure water flushing device with controllable flow rate is studied and developed, and the original drainage system is optimized, successfully solving the problem of crystallization in the drainage system. The results indicate that the research analysis and disposal methods of this case can provide reference for the mechanism study of tunnel crystallization diseases in non-karst areas, and provide a reference for disposal schemes of similar problems.
