隧道施工排水清污分流是减少隧道施工污水排放的重要工程技术，然而隧道喷射混凝土在未稳定前的浸出物质会影响排水水质，故研究喷射混凝土稳定过程中浸出物影响水质的规律对实现清污分流技术的精准实施具有重要意义。选用隧道施工喷射混凝土原料配制了混凝土试块，通过静态浸出实验对浸出组分进行了分析，在此基础上通过连续14 d动态浸出实验，探究了不同养护时间、水固比（L/S）和接触面积对浸出液pH和碱度的影响，并结合表征分析对浸出过程和机制进行了探讨。静态实验结果表明：喷射混凝土中碱性物质的大量释放导致水质pH值迅速上升，是影响水质的主要原因。动态实验结果表明：混凝土养护时间小于3 d时，其内部的Ca(OH)2晶体未被C-S-H凝胶固化，容易持续析出，导致接触水样pH值超标；随着养护时间的增加，碱性物质的浸出大幅降低，当养护时间达28d时，浸出液的pH值降至9以下，可以满足污水综合排放要求。L/S比值较低时，浸出物质对水样的pH值和碱度影响较大，当L/S比超过40：1，浸出物质对水样水质影响不显著。混凝土与水样的接触面积越大，混凝土中的碱性物质更易溶解析出，对水质的pH值和碱度影响更为显著。本研究为隧道施工排水清污分流技术的现场施工组织提供了重要的理论依据。

Tunnel construction drainage and sewage diversion is an important engineering technology to reduce tunnel construction sewage discharge. However, the leaching substances of unstable tunnel shotcrete can affect the drainage water quality. Therefore, the study of the influence of leaching substances on water quality during the stabilization process of shotcrete is of great significance for the precise implementation of sewage separation technology. The concrete test blocks are prepared using shotcrete materials from tunnel construction. Firstly, the leaching components were analyzed through static experiments. Then, the effects of curing times, the ratio of water to concrete (L/S ratio), and the contact areas on the pH and alkalinity of the leaching solution were explored through 14 days dynamic leaching experiments continuously. The leaching process and mechanism were also explored combined with characterization analysis. The static experimental results indicate that the large release of alkaline substances in shotcrete leads to a rapid increase in the pH value of water, which is the main reason affecting water quality. The dynamic experimental results show that when the curing time of the concrete is less than three days, the calcium hydroxide crystal inside the concrete is not solidified by the C-S-H gel, which is easy to continue to precipitate, leading to the pH value of the contact water sample exceeding the standard. With the increase of curing time, the leaching alkaline substances decrease significantly. When the maintenance time reaches 28 days, the pH value of the leaching solution drops below 9, which can meet the requirements of comprehensive sewage discharge. When the L/S ratio is low, the leaching substance has a significant impact on the pH and alkalinity of the water sample. When the L/S ratio exceeds 40:1, the leaching substance has no significant impact on the water quality of the water sample. The larger the contact area between concrete and water samples, the easier it is for alkaline substances in concrete to dissolve and precipitate, and the more significant the impact on the pH and alkalinity of water quality. This study provides important theoretical basis for the on-site construction design of drainage and sewage diversion technology in tunnel construction.

TU528.44

国家自然科学基金项目面上项目，四川省科技厅重点研发项目