地下水封洞库施工中湿喷混凝土回弹率控制关键技术研究

Research on Key Technologies for Rebound Rate Control of Wet Sprayed Concrete in Underground Water-Sealed Cavern Construction

摘要: 湿喷混凝土支护是地下水封洞库等大型地下空间工程施工中的关键工序，其回弹率高低直接影响工程质量、成本与施工环境。针对此类工程中喷射混凝土回弹损失率居高不下的行业共性难题，本研究系统剖析了回弹形成的力学机理与主要影响因素。研究表明，回弹率主要受材料体系性能、喷射工艺参数及岩面作业条件三大类因素共同制约。其中，混凝土拌合物的工作性能、速凝剂效能与掺量是内在主因；喷射机手操作技能，特别是喷嘴与受喷面的距离、角度以及风压的匹配性是关键工艺参数；而开挖面的平整度、洁净度及渗涌水状况则是重要的外部边界条件。基于此，本文提出了一套综合性的回弹率控制关键技术体系，包括：优化混凝土配合比并采用纤维增强与高性能速凝剂以提升材料粘聚性与早期强度；通过标准化培训与过程监控，严格将喷射距离控制在0.8~1.2 m、角度保持近垂直(针对立面)、风压稳定于0.4~0.6 MPa的优化区间；以及对超挖凹槽进行挂网补喷、对渗涌水面实施引排或预注浆等岩面预处理措施。在QZGC工程实践表明，集成应用上述技术可使边墙与拱部综合回弹率有效降低至15%以下，显著节约材料成本、提升支护质量并改善洞内作业环境，为类似地下工程的绿色、高效施工提供了可靠的技术路径。

Abstract: Shotcrete support is a critical process in the construction of large underground spaces such as groundwater-sealed caverns, and the ate directly affects engineering quality, cost, and the construction environment. Addressing the industry-wide challenge of persistently high rebound loss rates in such projects, this study systematically analyzes the mechanism and primary influencing factors of rebound formation. The research indicates that the rebound rate is primarily constrained by three categories of factors: material system performance, spraying process parameters, and rock face work in conditions. Among these, the workability of the concrete mixture, the efficiency and dosage of accelerators are the intrinsic primary causes; the operator’s skill, particularly the matching of nozzle distance and angle with the receiving surface, and air pressure, are key process parameters; while the flatness, cleanliness, and seepage conditions of the excavation face constitute important external boundarytions. Based on this, this paper proposes a comprehensive technical system for rebound rate control, including: optimizing concrete mix proportions and adopting fiber reinforcement and high-performance accelerators to enhance material on and early strength; strictly controlling spraying distance within 0.8~1.2 m, maintaining a near-vertical angle (for vertical faces), and stabilizing air pressure at 0.4~0.6 MPa through standardized training and process monitoring; and implementing rock face pre-treatment measures such as mesh hanging and supplementary spraying for over-excavagrooves, and drainage or pre-grouting for seepage surfaces. Practical application in the QZGC project demonstrates that the integrated application of these technologies can effectively reduce the comprehensive rebound f side walls and arches to below 15%, significantly saving material costs, improving support quality, and improving the working environment within the cavern, providing a reliable technical pathway for green construction of similar underground projects.