Lack of maintenance compromises tunnel structural safety

Abstract

The Chekka tunnels represent a critical section of the Northern Lebanon Highway. The approximately 350 m long twin tunnels are the most important such structures in the country. They are used by regular and freight traffic and are a vital link to the capital, Beirut. The tunnels were completed in the early 1970s on the eve of the Lebanon civil war. Given the state of affairs in the country for about two decades of strife, the tunnels were not maintained nor did they undergo any regular inspection. This unique condition of near-abandonment continued up until recently, when the first signs of distress were documented. These consisted of severe and extensive cracking, particularly in the portal approach of the southbound tunnel, along with significant deterioration of the tunnel lining and radial section joints. The danger to the traffic and potentially to the structure itself was evident. In this paper, the results of an extensive site inspection and evaluation program are presented. The underlying causes of the observed damage are analyzed and discussed using a modeling approach of the evolving loading conditions. Remedial measures are discussed along with a summary of the actual repair and rehabilitation works which have just been completed.