A systematic but straightforward probabilistic approach was adopted for the preliminary design using a tunnel case in Egnatia Odos Highway. This tunnel was excavated in a heterogenous molassic formation in Northern Greece, and more specifically in tectonically undisturbed but lithologically varied sedimentary series. This research aimed to identify sources of uncertainty and evaluate its governance during the selection of the geotechnical design parameters. Rigorous analyses of the critical parameters and factors were undertaken following a standardised method for designing underground structures based on the probability theory. Initially, the statistical analysis of the intact rock strength parameters and project-specific geological and geotechnical factors allowed the development of understanding in determining these sources of uncertainty and assisted in quantifying them. The lithological units encountered in the tunnel alignment were classified into first, Geological Units and, secondly, into Rock Mass Types (Geotechnical Units). Finally, the latter were grouped into anticipated Rock Mass Behaviour Types, which were numerically investigated using RS2 for the Finite Element Method analysis and Unwedge to assess these Rock Mass Types' failure modes. For this purpose, the Point Estimate Method was used in the FEM analysis to evaluate the effect of uncertainty in the strength parameters. Ultimately, the numerical analysis results subsequently led to the preliminary design of the respective support sections. Although this investigation was limited by the geotechnical information provided, it was concluded that the approach followed proved to be adequate in identifying the primary sources of uncertainty and its impact on geotechnical design. It was also noted that with more detailed geological information, this probabilistic approach could be used to produce a robust final support tunnel design.

在Egnatia Odos高速公路的隧道中，采用了系统的但简单的概率方法进行初步设计。这条隧道是在希腊北部以异质的黏性地层开挖的，更具体地说，是在构造上不受干扰但岩性变化的沉积系列中开挖的。这项研究旨在确定不确定性的来源，并在选择岩土工程设计参数期间评估其治理。根据基于概率论的地下结构设计标准化方法，对关键参数和因素进行了严格的分析。原来，对完整岩石强度参数和特定于项目的地质和岩土工程因素的统计分析，使人们在确定这些不确定性来源和量化量化方面有了进一步的了解。在隧道定线中遇到的岩性单元首先分为地质单元，其次是岩体类型（岩土工程单元）。最后，将后者分组为预期的岩体行为类型，然后使用RS2对其进行有限元方法分析和Unwedge数值研究，以评估这些岩体类型的破坏模式。为此，在有限元分析中使用了点估计法来评估强度参数不确定性的影响。最终，数值分析结果随后导致了各个支撑部分的初步设计。尽管这项调查受到所提供的岩土工程信息的限制，但得出的结论是，事实证明，采用这种方法足以确定不确定性及其对岩土工程设计的影响的主要来源。还应注意的是，有了更详细的地质信息，这种概率方法可用于产生可靠的最终支护隧道设计。