The influence of grout and bentonite slurry on the process of TBM tunnelling / Der Einfluss von Ringspaltmörtel und Bentonitsuspension auf den TBM-Vortrieb

The bentonite and grout flow around a TBM is elaborated, as well as grout flow along the lining. The calculated grout flow along the lining is compared with the results of measurements. Measurement data for the flow around the TBM are not available. Both the bentonite and the grout are modelled as a Bingham liquid and it will be shown that, due to the relatively low flow velocities, the yield stress is the governing parameter. The results of the calculations show that both the flow around the TBM and the flow around the lining may significantly influence loading on the TBM, the soil, and the lining. The bentonite and grout flow around the TBM may result in a lower volume loss than calculated when assuming that the soil follows the tapered TBM. The grout flow and especially grout consolidation lead to lower pressures around the lining if the tunnel is constructed in sandy soil.