Development of dynamic grouting, Stage 2

Water ingress into any underground infrastructure from the surrounding formations leads to several environmental, economic and sustainability issues. Adequate spread of grout into the rock fractures is necessary to obtain the desired sealing. In BeFo reports 149, 181 and 197, we showed that in laboratory-scale dynamic grouting improves the spread of grout in microfractures. The experiments were carried out using both short-slot and long-slot (shown in the figure) with air pressure and screw pump as pressure source.

Within the framework of this project, we will continue the development of dynamic grouting in the field-scale. The objective of the project is to verify the efficiency of the new technology by adapting our experiences gained from the laboratory to the field conditions. The aim is to introduce and demonstrate the effectiveness of dynamic grouting to all the stakeholders. Hence, a distribution unit will be first developed and tested in the laboratory conditions. This unit is aimed to provide the designated dynamic pressure and supply several boreholes in sequence to both improve the spread of grout and reduce the grouting time, simultaneously. Thereafter, the effectiveness of the method will be investigated in Äspö HRL using field equipment in more realistic conditions.

The method is anticipated to increase the safety of the tunnel projects during both construction and operation. It is also expected to reduce the construction time and costs, which leads to socio-economic benefits. In addition, reduction in machinery work, fuel consumption and carbon dioxide emission are expected to make the method more environmentally friendly. The new technology reduces the need for chemical grouting and thus the risk of the environmental problems as happened in the Hallandsås project. Finally, less water ingress into the underground facilities leads to longer service life and decrease in maintenance costs, making the method more sustainable. The project, which is funded by SBUF and BeFo, will be carried out during 2020-2021.