Chapter 12
Maintenance and refurbishment of existing tunnels S. Miliziano and A. de Lillis Sapienza University of Rome
S. Santarelli Consultant
CONTENTS 12.1 Introduction..................................................................................................... 333 12.2 Degradation phenomena and damages ........................................................... 334 12.3 Inspections and monitoring ............................................................................. 336 12.3.1 Inspections............................................................................................ 337 12.3.2 Monitoring ........................................................................................... 339 12.4 Maintenance activities, repair works and protective measures ....................... 340 12.5 Refurbishment works....................................................................................... 341 12.5.1 Methods ................................................................................................ 342 12.5.1.1 Water control .......................................................................... 342 12.5.1.2 Structural improvement .......................................................... 344 12.5.2 Design ................................................................................................... 346 12.6 Concluding remarks ........................................................................................ 347 Authorship contribution statement ........................................................................... 348 References ................................................................................................................. 349 12.1 INTRODUCTION The extensive construction of tunnels started at the end of the 19th century as a consequence of the railway development and after the diffusion of hydroelectric power plants. Roughly at the same time, the construction of urban tunnels for subways and road tunnels for the urban development started. In the second half of the 20th century, the development of motorways prompted the construction of a large number of road tunnels, including very long ones across the Alps. During this long period of time, the construction methods evolved in terms of both excavation techniques and lining types and materials. The stone elements initially employed for the construction of the linings were progressively replaced by bricks, concrete, reinforced concrete and reinforced concrete precast elements. With time, several degradation phenomena started to appear – induced by the action of natural agents, the ageing of the materials and the use of the tunnels and
DOI: 10.1201/9781003256175-12
