ABSTRACT
In the practice of bored tunneling by TBM, the geotechnical aspects shown in Table 3 are of the most importance and should be well considered.
Bakker & Bezuijen (A, B) shared their invaluable experiences and findings on shield tunneling in soft ground obtained in last ten years. During the construction of the 2nd Heinenoord Tunnel that is approximately in the middle underneath the river Oude Maas in the Netherlands.They found out that because “blowout” occurred during TBM driving under the river, face support pressure dropped within 15 seconds after the cutter face working, shown as Figure 1. According to their investigation, they pointed out that face support pressure should be controlled between lower and upper limits for situations with little overburden or the soil cover itself is relatively light. We also are interested in the “15 seconds”, which indicted that the front instability occured without any omen, a careful control of front pressure is necessary. Some analysis results of
surface settlement were also displayed, shown in Figure 2. It was concluded that for an adequate prediction of deformations it is important to model the grouting pressure as a boundary condition, in combination with the use of small strain material model.
