EXPERIENCE GAINED IN MADRID DURING THE CONSTRUCTION OF TUNNELS CROSSING URBAN FILLS WITH T.B.M.

During the construction of the Madrid new subway extension (1996-99) the boring of more than 37 km (23.7 mi) of tunnels has been carried out. Several different procedures have been used, crossing the characteristic Madrid soils: pliocenic sediments from the erosion of granite formations; miocenic clays; and very soft antropic fills. This paper discusses the experience obtained in the cases with predominance or big influence of antropic fills. The solutions for protecting nearby buildings and the theoretical analysis used to estimate the ground settlement are included.