ABSTRACT
Our focus will be Machico’s region, where the expressway closely follows the right bank of Machico’s stream mid-slope until turning eastwards where it crosses this stream. On this initial stretch, with an extension of 2050 m, are inserted the Piquinho and Fazenda double tunnels, as well as the Queimada II tunnel (Fig. 1). The Machico and Natal valleys on the Caniçal side are reached via the double tunnel of Caniçal, a tunnel with 2100 m which crosses the mountain bedrock with more than 300 m covering. On the final stretch on the Caniçal side, with approximately 2145 m,
1 INTRODUCTION OVERALL CONSIDERATIONS
The geotechnical works associated with the new roadways of the Madeira Island, in particular the tunnels, are substantially affected by both the extensive heterogeneity, the structural and lithological complexity of the volcanic formations and the rugged terrain. In addition to this, a dense occupation of the land is often found along the defined road profiles (Brito et al. 2005). The combination of these factors led to the conception of a varied range of structural solutions with specific characteristics, at times with a degree of originality in order to achieve economic solutions adapted to the topographic and geological conditions, based on the latest technologies and most evolved construction processes.
