Bentonite and Grout Flow Around a TBM

AB This article focuses on the possibility that grout can flow from the tail of a tunnel boring machine to its face. A one-dimensional numerical model was developed to better understand the order of magnitudes of the flow of grout and bentonite, the pressure distribution, as well as the soil deformation around the TBM’s shield. The author explains that although a TBM shield appears to be a tube of a constant diameter, it is ever so slightly smaller at the tail end. The article includes a number of charts and graphs, which illuminate the fact that there is a direct relation between grouting pressure and volume loss, and that a good pressure control is needed when tunneling through soft soil.