Mechanized tunneling in boulder-laden glacial soils poses a significant risk to TBMs. Impacts with boulders and even cobbles can cause significant damage to cutting tools and the cutterhead body. Such damage can go unnoticed given the nature of closed face TBM tunneling, slowing productivity and increasing damage.While boulders cannot be avoided, the TBM operator can reduce the risk of damage by reducing thrust and cutterhead rotation speed. However, the operator needs guidance on when to make these adjustments. To date, TBM operating data such as torque, thrust, advance rate, etc. are not sensitive to initial boulder impacts, unless the boulder is significant in size. And, the operator's cabin is now well back from the cutterhead where the operator cannot hear or feel boulder impacts.This paper presents the implementation of a novel real-time vibration monitoring system installed on a Hitachi-Zosen (Hitz) EPB TBM during the Seattle N125 Northgate Link tunneling project in Seattle, Washington. A real time signal from cutterhead impacts with boulders was provided directly to the operator's cabin for immediate reaction, e.g., torque and thrust control. The system was used to record boulder/ cobble activity along the alignment, and the information was used to help operate the TBM to avoid and minimize damage.
展开▼
