Abstract Until recently, when sprayed concrete was accelerated by silicates, whether non-reinforced or reinforced by welded mesh, it was logically considered as unsuitable in the long term and only used for temporary support behind a cast-in-place concrete lining. The introduction of polyvinyl chloride (PVC) sheets to waterproof tunnels perpetuated the use of poured concrete because spraying concrete on PVC requires many precautions. However, important changes have occurred over recent years: (a) alkali-free accelerators have replaced silicates, improving long-term performance, personnel safety and environmental protection; (b) the use of fibers has given sprayed concrete ductility and good flexural strength; and (c) an alternative waterproofing method has emerged: membranes are sprayed onto the sprayed concrete and protected by sprayed (or poured) concrete. Thanks to these developments and to improvements in equipment, quality control and design methods, it is now possible to consider sprayed concrete for “permanent” use. Rethinking the design of tunnels provides an opportunity to reduce the concrete thickness and the excavated section, thereby saving time and money. The space saved can also be kept available to facilitate further repair works. This paper highlights past and current practices, and provides several case studies in terms of loads, loads allowability, section optimization, time and cost savings. It provides inputs and perspectives for improving current practices.

中文翻译：

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纤维增强喷射混凝土作为永久隧道衬砌

摘要 直到最近，当喷射混凝土被硅酸盐加速时，无论是非增强还是焊接网增强，从逻辑上讲，它都被认为不适合长期使用，仅用于现浇混凝土衬砌后面的临时支撑。将聚氯乙烯 (PVC) 板引入防水隧道使浇筑混凝土的使用得以延续，因为在 PVC 上喷涂混凝土需要采取许多预防措施。然而，近年来发生了重要变化：(a) 无碱促进剂取代了硅酸盐，提高了长期性能、人员安全和环境保护；(b) 纤维的使用赋予了喷射混凝土延展性和良好的抗弯强度；(c) 出现了另一种防水方法：膜被喷射到喷射混凝土上，并由喷射（或浇注）混凝土保护。由于这些发展以及设备、质量控制和设计方法的改进，现在可以考虑“永久”使用喷射混凝土。重新思考隧道的设计提供了减少混凝土厚度和开挖截面的机会，从而节省时间和金钱。节省的空间也可以保持可用以促进进一步的维修工作。本文重点介绍了过去和当前的做法，并提供了几个关于载荷、载荷容许度、截面优化、时间和成本节约的案例研究。它为改进当前做法提供了投入和观点。现在可以考虑将喷射混凝土用于“永久”用途。重新思考隧道的设计提供了减少混凝土厚度和开挖截面的机会，从而节省时间和金钱。节省的空间也可以保持可用以促进进一步的维修工作。本文重点介绍了过去和当前的做法，并提供了几个关于载荷、载荷容许度、截面优化、时间和成本节约的案例研究。它为改进当前做法提供了投入和观点。现在可以考虑将喷射混凝土用于“永久”用途。重新思考隧道的设计提供了减少混凝土厚度和开挖截面的机会，从而节省时间和金钱。节省的空间也可以保持可用以促进进一步的维修工作。本文重点介绍了过去和当前的做法，并提供了几个关于载荷、载荷容许度、截面优化、时间和成本节约的案例研究。它为改进当前做法提供了投入和观点。并在载荷、载荷容许度、截面优化、时间和成本节省方面提供了多个案例研究。它为改进当前做法提供了投入和观点。并在载荷、载荷容许度、截面优化、时间和成本节省方面提供了多个案例研究。它为改进当前做法提供了投入和观点。