Abstract: To solve the problem of Karst tunnel excavation stability, the paper was aimed at working out a new method of excavation stability evaluation. Firstly, the influence factors of Karst tunnel excavation stability were identified, and a stability evaluation index system of karst tunnel excavation was established, in which the weights of evaluation indexes were determined by analytic hierarchy process (AHP) and entropy method. Finally, the fuzzy material element evaluation method was used to evaluate the excavation stability of a rail transit tunnel, and the engineering membership data were processed by the normal membership function to solve the problem of data discretization. The results show that the evaluation results of Karst tunnel excavation by fuzzy matter-element conform with the actual engineering conditions, and that the evaluation method improves the rationality of the evaluation by considering the factors that affect the stability of excavation and simplifying the evaluation process.

Key words: Karst tunnel, tunnel excavation, fuzzy matter-element, evaluation stability, level of evaluation