Abstract:
The need for additional considerations on this topic are based on recent experiences of the author involved in some grouting projects and noticing that there are still, in 2020, non-engineered approaches in the definition of the maximum grouting pressure to be used. Obvious considerations that are already known, but it’ s good to remember that grouting is a well-defined engineering branch even if different opinions and approaches exist in our industry. There are endless discussions about what pressure to use in grouting in rock; a lot of fear, sometime justified, sometimes not, that lead to the predominant use of the so called ‘ conventional’ Rule-of-Thumb criteria (RoT) especially in North America; rule-of-thumb= 1 psi/ft= 0.23 bar/meter or 1 bar/meter (in Europe). North Europe (Norway-Sweden), due mainly to rock conditions and applications, use slightly higher numbers. So the question: what is the right pressure to use to optimize the grouting process? And what pressure should be used for Lugeon WPT? The same as the grouting pressure, as is usually done today? This article will not provide all the answers, nor will it enter into the basics of rock grouting, grout mixes or termination criteria, but it will try to suggest what the right pressure to apply in rock grouting should be. It will additionally provide some comments on the matter with some case histories that can help the grouting designer in her or his own analyses and evaluations.