An Experimental Study of the Performance of Two-Component Backfilling Grout Used behind the Segmental Lining of a Tunnel-Boring Machine

How to fill the empty annular space behind the segmental lining of tunnels is considered one of the most important questions in mechanized excavation, of which the main aim is to minimize settlement on the earth surface. In addition, the grout is the agent that creates a suitable bed for the segment lining of the tunnel and helps with its tightening. There are different methods of filling the empty space. One of them, using excavation by Earth Pressure Balance-Tunnel Boring Machine (EPB-TBM), is the injection of two-component grout at suitable pressure to the back of the segment as the shield of the excavator moves ahead. The grout utilized has suitable mechanical characteristics and efficiency. The main properties of grout refer to bleeding, fluidity and the results of the Marsh funnel test (ability to pump grout), setting time, gelling time (to avoid grout washing out) and compressive strength of grout (to minimize settlement on the earth level). The present study attempts to review the effect of any constituent materials of two-component grout on the parameters. Consequently, different tests with various constituent materials on the properties of grout were conducted.