An approach to analyzing the reliability of tunnel surrounding rock rating results considering uncertainty

The geological environment of underground engineering is complex and full of various uncertainties, and ensuring the reliability of tunnel surrounding rock rating results is crucial for projects. In this study, we first analyze the interrelationships and indicator weights of international mainstream rating methods of tunnel surrounding rock, and summarize the applicability of each method. Next, based on dialectical materialism, we propose that the uncertainties can be divided into multiple levels. Then we analyze the probability distribution law of rating indicators such as rock strength and rock integrity, introduce and use the theory of system reliability analysis, and build functions for the surrounding rocks of different classes. Finally we calculate the reliability probability of surrounding rock rating using Monte Carlo method. The study results indicate that, in view of the uncertainty of surrounding rock rating, the proposed approach fully considers the information of each rating method, and also the data dispersion of local fractured zones, weak interlayers and other tunnel face surrounding rock. Moreover, based on the parameters summary, the proposed approach is proved to be applicable to the current rock mass, and thus makes it possible to evaluate the reliability probability of the tunnel surrounding rock rating. This study helps site personnel to assess surrounding rock rating results more conveniently and accurately, and provides precise guidance for reasonably determining the construction method transition interval and optimizing support parameters.