APPLICATION OF RECENTLY DEVELOPED GROUTING PROCEDURES FOR TUNNELLING IN THE MILAN URBAN AREA --TUNNELLING 88. PAPERS PRESENTED AT THE 5TH INTERNATIONAL SYMPOSIUM, TUNNELLING 88, ORGAINZED BY THE INSTITUTION OF MINING AND METALLURGY, WITH THE COOPERATION OF THE BRITISH TUNNELLING SOCIETY, THE INSTITUTION OF MINING ENGINEERS AND TRRL, LONDON, APRIL 18-21, 1988

The "cut and cover" method predominantly used in the fifties for the construction of line 1 could no more be applied for the extension of the Milan underground railway network in the central urban area, involving more and more problems related to the treatment of cohesionless alluvial soil, partly to be excavated under the water table. The often complex design features and strict specifications about potential pollution led to the application of recently developed techniques such as sub-horizontal jet-grouting, and the use of quite new types of suspensions and chemical solutions for permeation grouting. Main design features and ground improvement criteria are briefly outlined with reference to the works in progress within the lots awarded to specialist contractor rodio co. More detailed information is given on the first large scale application of a new type of fine grained cement grout with special additives enhancing permeation and minimizing the hydro-fracturing effects involved by other suspensions. The performance is emphasized in terms of ground surface movements continuously monitored during injection and tunnelling stages.(a) for the covering abstract of the symposium see IRRD 812521.