The complexity of diseases in tunnel linings and the interference of clutter and the strong reflection of rebar in ground-penetrating radar (GPR) data are the important factors that lead to the low accuracy and poor automation of disease detection. As consequence, this paper carries out an automatic detection method for hidden lining diseases. Firstly, in order to suppress the interference of strong clutter, the state equation and measurement equation of GPR data are established, and the recursive formula of clutter suppression is deduced. Secondly, combined with a convolution neural network, the network which can suppress the strong reflection of rebar is built. Finally, the multi-dimensional characteristics of disease in the time domain, frequency domain, and time-frequency domain are extracted, and then the support vector machine (SVM) data set is established and the automatic detection method for diseases is formed. The proposed method can avoid the low efficiency of manual interpretation and the over-dependence of detection accuracy of relying upon the experience level of technicians.

Due to the particularity of loess engineering geology, loess railway tunnel accidents occur frequently. Based on the theoretical basis of risk management, this study evaluated the service performance of loess railway tunnels. Based on the improved TOPSIS method, the indirect proximity degree of each risk factor was compared, and the appropriate service performance evaluation index was selected. Based on the ISM model and the causality graph modification method, the dependency relationship between nodes was obtained and the Bayesian network evaluation model was constructed. By constructing the database, the EM algorithm was used for data learning, and the model was trained and verified, and the overall accuracy (ACC) and F₁ value are used to comprehensively evaluate the training and prediction effect of the model. Finally, the evaluation model was applied to a tunnel case. The results show that the established Bayesian network model has a high accuracy of 92%, which is easy to operate, effective and practical, and it is also applicable in situations of incomplete index statistical data.