SWEDEN NATIONAL LIBRARY GOES UNDERGROUND

The Swedish Royal Library is the national library of the country and o ne of its most important cultural and research institutions Originally planned for 200,000 books and ten employees, the Royal Library today employs 250 people and stores 3 million books and prints. The building , completed in 1877, is surrounded by buildings of high architectural and cultural value, and is located in one of Stockholm's most beloved parks. Responding to the need of the library and to the environmental restrictions, all future book storage will be in true large caverns ex cavated in the hard bedrock below the library building A system of ele vators and staircases will connect the storage caverns with the buildi ng Inside the cavern, a five-story concrete structure is being erected to house the books. All works will be completed in 1996-with no inter ruptions in library service. The location of the caverns called for ex treme rock engineering control, particularly of blasting vibrations an d groundwater inflow. The paper describes the reconstruction process, the layout, reek mechanical design and excavation of the caverns, as w ell as the monitoring program for groundwater. Of special concern was the use of appropriate grouting techniques to minimize inflow of groun dwater. Active research carried out during the rock excavation works, in this field and in other areas, is briefly outlined.