The aim of this publicly funded research project was to develop a mortar-like construction material for mechanical tunnel boring processes, which would be capable of both drainage and pumping.
For this project SEEPEX supplied multiple progressive cavity pumps for conveying mixed materials, surfactant solutions and setting accelerators.
When pumping mixed materials (a cement suspension), progressive cavity pumps offer unique advantages compared to the double-piston pumps that alternatively would be used, thanks to their minimal pulsation capabilities.
This advantage was decisive for the project, because the cement suspension obtains its water permeability through a foaming process that is dependent on pressure and volume. The process essentially creates cavities between the rock and tunnel shell, and the pumps fill these cavities at pressures of up to 20 bar and at flow rates of up to 120 liters per minute.
These new developments are significantly broadening the applications for tunnel boring machines in solid rock. Single-shell structures are now possible, even at water pressures exceeding 5 bar. This allows construction costs and times to be substantially reduced with immediate effect.