Abstract In conventional tunnelling, the shotcrete lining is loaded at an early stage, so consideration of the time dependency of material properties during construction is vital. An important property of shotcrete concerning rock deformation is its early strength, which can influence the development of rock pressure and support resistance. The mechanical properties of the shotcrete change continuously during the hydration process. Material models exist to describe the mechanical behaviour, but these were mostly validated with dry shotcrete or older shotcrete mix designs. Continual improvements in admixture technology have improved the performance of shotcrete. Therefore, strength developments of a test series and practical projects are evaluated and a shotcrete test to determine the time-dependent material properties is carried out with a reference mix design. An empirical prediction model, which serves as a qualitative estimation of shotcrete strength processes, is designed based on the results of the evaluated strength developments. Based on the experimental investigations, a first basis for in-depth investigations of the time-dependent material behaviour of shotcrete is created.

中文翻译：

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喷射混凝土的随时间变化的材料行为——强度发展和基础实验研究的新经验模型

摘要 在常规隧道施工中，喷射混凝土衬砌在早期加载，因此在施工过程中考虑材料特性的时间依赖性至关重要。喷射混凝土关于岩石变形的一个重要特性是其早期强度，它会影响岩石压力和支护阻力的发展。在水化过程中，喷射混凝土的力学性能不断变化。存在材料模型来描述机械行为，但这些模型大多是用干喷射混凝土或旧的喷射混凝土混合设计进行验证的。外加剂技术的不断改进提高了喷射混凝土的性能。所以，评估测试系列和实际项目的强度发展，并使用参考配合比设计进行喷射混凝土测试以确定随时间变化的材料特性。基于评估的强度发展结果设计了一个经验预测模型，作为喷射混凝土强度过程的定性估计。在实验研究的基础上，创建了深入研究喷射混凝土随时间变化的材料行为的第一个基础。