Abstract The Brenner Base Tunnel (BBT), a 64 km long railway tunnel between Austria and Italy, is under construction at the time of writing. The complete tunnel system of the BBT will comprise railway tunnels as well as exploration, emergency, ventilation and access tunnels. The latter are tunnels with generally lower requirements on the serviceability, watertightness, durability, surface quality or availability. In some cases, a single permanent shotcrete lining can fulfill the reduced requirements and offers a very economic tunnel design. Realistic assessment of the load-bearing capacity of shotcrete linings is particularly required for early and large deformations in deep tunnels. This is the motivation for a more sophisticated approach to the back-analysis of a permanent shotcrete lining of a single lined rescue tunnel of the BBT. Thus, a detailed finite element model is developed for analyzing the bearing capacity of the permanent shotcrete lining on the basis of an advanced constitutive model considering the time-dependent and nonlinear material behavior of shotcrete. The material model represents the time-dependent evolution of material properties due to hydration of shotcrete, hardening and softening material behavior, the latter resulting in cracking or crushing of shotcrete, creep and shrinkage. In the finite element model, the time-dependent construction process of the drill-and-blast method for tunnels driven by partial face excavation is considered. The material parameters for the shotcrete model were calibrated based on an experimental program, performed with specimens sampled directly on the construction site of the BBT.

中文翻译：

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布伦纳隧道单层永久喷射混凝土衬砌承载力非线性时变分析

摘要 布伦纳基线隧道 (BBT) 是一条连接奥地利和意大利的 64 公里长的铁路隧道，在撰写本文时正在建设中。BBT的完整隧道系统将包括铁路隧道以及勘探隧道、应急隧道、通风隧道和进出隧道。后者是对适用性、水密性、耐久性、表面质量或可用性的要求通常较低的隧道。在某些情况下，单个永久性喷射混凝土衬砌可以满足降低的要求并提供非常经济的隧道设计。对喷射混凝土衬砌的承载能力进行现实评估对于深隧道的早期和大变形尤为重要。这就是采用更复杂的方法对 BBT 单衬里救援隧道的永久喷射混凝土衬砌进行反分析的动机。因此，在考虑了喷射混凝土的时间相关和非线性材料行为的先进本构模型的基础上，开发了详细的有限元模型，用于分析永久喷射混凝土衬砌的承载力。材料模型表示由于喷射混凝土的水合作用、硬化和软化材料行为（后者导致喷射混凝土开裂或压碎、蠕变和收缩）导致的材料特性随时间的演变。在有限元模型中，考虑了局部开挖隧道的钻爆法施工过程的时效性。喷射混凝土模型的材料参数根据实验程序进行校准，使用直接在 BBT 施工现场取样的试样进行。