The paper presents a brief analysis into the main issues related with the safety control of old railway tunnels, with special emphasis to the maintenance of these underground structures. The paper also refers to the most important aspects associated with the application of the knowledge-based-system technology and to its use in the field of geotechnical structures. A computer code designated as MATUF was developed in order to computerize data processing evolution. The code was applied to an old railway tunnel in a mountainous region of Portugal.
Most of the existing European underground railway patrimony was built in the 19th Century, egllln1l1g of the 20th Century. Therefore, as a result of the old age of works and of the deficient construction methods used at the time a significant deterioration in the condition of the tunnels has been observed, which may endanger the safety of these underground structures. In addition, In certain works, some shafts or auxiliary access tunnels were excavated in order to increase the velocity of construction. These works form zones with anomalous behaviours due to the existence of voids, to significant loads on the support and, sometimes, due to the large amount of water flowing into these structures. Due to needs related with the modernisation of railway lines and to ensure the safety and serviceability, the rehabilitation of these works has been under way. Therefore the observation of the works becomes essential. The inspections are an extremely effective observation means. Actually, they make it possible to carry out a timely election of anomalies that are likely to damage the stability of these underground structures and to propose some corrective measures. At the most sensitive or problematic zones, appropriate monitoring using measuring equipment most complement the inspections. Furthermore, and whenever possible automatic data collection devices should be used, in view of the difficulty in carrying out measurements in the whole tunnels. The computer processing of data collected in the inspections and observation of works, and also the use of artificial intelligence techniques, are extremely effective aiding tools for data storage and also valuable help as regards decision-making related with the safety and rehabilitation of works. This paper presents a brief analysis into the most relevant issues in the field of safety control of old railway tunnels, and presents an overview of the issues related to the application of artificial intelligence techniques, namely of KBS systems. A computer code designated as MATUF has been developed for the purpose. The code was applied to a railway tunnel in a mountainous region of Portugal.
The railway history in Portugal begins with the construction of the stretch Lisboa-Carregal in 1856. The first tunnel with a 650m length was soon been completed. Almost all the tunnels are one hundred years old. From among the classic construction methods, used in old tunnels, the Belgian method was the one that prevailed in the excavation of tunnels (Cabral, 1987; Silva Domingues), (Figure 1).