A Swedish Grouting Design Concept: Decision Method for Hard Rock Tunneling

Efficient grouting of hard rock requires adequate knowledge of the water-bearing fracture system in the rock mass. The observational method approach involves identifying different possible scenarios and relating them to predefined strategies for grouting design. Parameters useful in preparing a relevant description of the rock mass are presented, as well as a method for choosing a conceptual model. The implications of different fracture systems for the grouting design are discussed. A method is presented for deciding whether grouting is needed in order to ensure a high degree of probability that tunnel leakage will remain below the inflow requirements. The methods presented are applied to data from a real tunnel to illustrate the procedures