Controlling grout spreading in tunnel grouting - Analyses and developmentsof the GIN-method

In order to choose the best grouting technique, predictions of the grouting result can be made. Due to uncertainties in the predictions, control of th e grouting during ongoing work is an important step towards a successful re sult. One method to control the grouting is the GIN-method developed and pr esented by Lombardi and Deere (1993). The method focuses on controlling the grout spreading in order to minimise the risk of hydraulic uplift and achi eve a more uniform spreading around a bore hole. However, this method is de scribed with emphasis on dam grouting. In this paper, theories are analysed and developed from a tunnel grouting point of view. A concept of a normali sed pressure and normalised grout spreading is presented that at the same t ime enables control of the grout spreading distance as well as the risk of hydraulic uplift. Calculations based on field data are also done in order t o visualise and discuss the potential use of developed theories. Some concl usions from the performed analyses are that other mathematical relations th an those stipulated by the GIN-method better account for the risk of hydrau lic uplift and that higher pressures than the "rule of thumb" stipulates co uld be used in good rock. So far, the concept of normalised pressure and no rmalised grout spreading is in its first stage and is studied mainly from a theoretical point of view. Further studies are thus needed. (C) 2001 Publi shed by Elsevier Science Ltd. All rights reserved.