... formation Ande excavation construction volcanic formation matrix tunnel drilling fluid property Upstream Oil & Gas reinforcement lining rock mass degradation abanico formation Rock Engineering and Rock Mechanics: Structures in and on Rock Masses Alejano, Perucho, Olalla & Jiménez (Eds...

... of the volcanic formations and the high urban occupancy rate of the soil, led to significant civil works associated with the lay-out of these new accesses, amongst which a significant number of tunnels, some built in urban areas. 1. INTRODUCTION TUNNELS GENERAL CHARACTERISTICS The Santa Cruz tunnels...