Risk evaluation of rockfall disaster in the cave entrance of western mountain railway tunnels based on the improved G1-EWM-UMT model

Abstract To avoid the impact of rockfall on railroad safety, it is crucial to accurately predict the risk level of rockfall disaster in advance for the safe construction, operation, and maintenance of railroads. We take the western mountainous railroad tunnel opening as the research background and construct a western mountainous railroad tunnel opening rockfall disaster risk evaluation index system, including 15 core indexes and 6 alternative indexes. The unascertained measure theory (UMT) is chosen to evaluate the risk of rockfall disaster in tunnel openings. The improved G1 method and entropy weight method (EWM) are introduced to calculate the identify the risk of rockfall disaster based on the confidence level criterion. Furthermore, the criterion is used to recognize the risk level of a rockfall disaster. Ten typical tunnel openings of a railroad in the west are selected to validate engineering examples, and the evaluation results of the improved G1- EWM- UMT model are compared with those of the TOPSIS model (the technique for order preference by similarity to the ideal solution (TOPSIS)) and the actual rockfall situation in the project. The comparison results show that the accuracy of the improved G1- EWM- UMT model in evaluating the risk of rockfall is 90%, which is 30% higher than that of the TOPSIS model. This study has certain application value and engineering subjective and objective weights, and the UMT model and Lagrange optimal multiplier combination method are combined to significance, which provides a theoretical basis and technical reference to design the rockfall protection structure of western mountainous tunnels such as the Sichuan–Tibet railway under similar engineering geological conditions and proves the operability and applicability of the evaluation model.