Grouting Techniques as Part of Modern Urban Tunnelling in Europe

Grouting techniques are more widely accepted and used in urban tunnelling because the impact on existing structures is minimal or non-existent. The compensation of settlements due to tunnel excavations became a part of underground projects within the last twenty years as grouting techniques were adapted to the specific needs of controlled soil treatment. Not only permeation grouting is being used, but fracture grouting and compaction grouting are also being used in various geological and geometrical conditions. This paper deals with the elements of compensation grouting and the organizational aspects of grouting measures in combination with different tunnelling methods. Special emphasis is placed on the contractual approach to integrate compensation grouting in a design-and-built concept. The main objective is to give a general overview about the logical sequences of decisions to make regarding settlement control during tunnelling operations.