This work is part of a licentiate assignment at KTH and the BeFo report therefore consists of an English part that is the original Licentiate Kappa (without the journal papers, due to copyright) together with an Extended Swedish Abstract (to cope with the omitted journal papers). 

Cement grouting during construction of rock facilities to primarily control water flow in rock fractures is an important, timely and relatively costly operation. By improving prediction, design and grouting operation a better grouting result will be achieved. And in the long run that is the purpose of this research. 

This report describes research work performed to further understand the flow of yield stress fluids, flowing radially in planar fractures by using an experimental radial model. This type of flow constitutes the basis for today´s methodology for design of grouting in fractured rock. 

At present there exists a controversy, in the grouting community, regarding the prevailing analytical solutions for two-dimensional radial flow of yield stress fluids. The controversy concerns the shape of the plug-flow region at the radial cross-section boundary, where the shear stress is below the yield stress. The question is if the plug is constant, or not, along the penetrated radial distance. 

This project aims at verifying the shape of the plug flow region for yield stress fluids in a laboratory model using ultrasound to get a ”picture” of the plug region during steady-state flow between Plexiglas plates. 

The research presented in this report was mainly carried out at the Division of Soil and Rock Mechanics, at KTH Royal Institute of Technology. Most of the experimental work related to the radial flow model was performed at Incipientus AB, Gothenburg. 

The work was carried out by Tafadzwa John Shamu who was supervised by Dr. Ulf Håkansson, Skanska Sweden AB and Dr. Lianchao Zou, KTH, with technical support from Dr. Johan Wiklund at Incipientus AB.

The input from the project reference group is also gratefully acknowledged. The following have participated in the reference group:

Patrik Vidstrand (SKB), Magnus Zetterlund (Norconsult AB), Emmelin Ann (Golder Assoc. AB), Christian Butron (Trafikverket), Liangchao Zou (KTH), Thomas Dalmalm (Trafikverket), Johan Wiklund (Incipientus AB), Mikael Creutz (Golder Assoc. AB), Tommy Ellison (BESAB AB), and Per Tengborg (BeFo). 

The project was financed by Rock Engineering Research Foundation – BeFo and Skanska contributed with in-kind support.

Stockholm, 2020

Per Tengborg