ABSTRACT
New grouting equipment at the Fornebubanen Metro Line has enabled the collection of high-resolution grout logs with machines now logging at rates of up to 1 per second. The logs contain information about pressure, flow, grouted volume and the recipe used. From the logs it can be shown that some of the grout holes have a pressure curve consistent with Boyle’s law for compressing gases. This can be used to infer the initial state of a grout hole. This study presents a method to categorize a grout hole as being initially air-filled (5-10%), grout filled (9%) and waterfilled (10-17%). The percentages in parentheses differentiate between Colloidal Silica Sol and Micro Cement which are the two main materials used at Fornebubanen. This study also presents aggregated grouting statistics for the tunnel section between Lysaker and Vækerø station.
