ABSTRACT
Tunnels, like any other structure require proper maintenance, which calls for periodical structured inspection and follow up action. The design of the tunnel including its profile depends greatly on the characteristics of surrounding ground and ground-structure interaction. Each tunnel located in varying types of soils and climatic condition is designed to suit local conditions and even in the same tunnel, the supporting arrangement may differ in different lengths. Practices regarding tunnel inspections vary from country to country. The Assistant Engineer himself is required to inspect all the tunnels in his jurisdiction before the monsoon, accompanied by the Section Engineer. Seepage and leakage are among the major maintenance problems in tunnels, especially in old tunnels. Tunnels found to be in distress need to be inspected more frequently. Modern practices in many countries abroad are to do non invasive study of the condition of tunnels and overburden.
