ABSTRACT
When a shallow tunnel is excavated in non-homogeneous and poor ground by means of a shield TBM, the ground above the body of the machine and above the lining behind the machine is not actively confined. The lack of confinement results in ground settlement which poses risks to the buildings and utilities. An in-house research and development effort was initiated by Geodata and NFM to realize a self-compensating TBM, starting with the development of a ground Settlement Reducing Device, SR Device, for use in boring with a shield TBM. The conceptual design of the SR Device is presented in this paper. The innovative features of the SR Device, to be eventually demonstrated by a field test, will include: (1) improving and creating a safe and efficient system by enhancing the capacity of the existing systems and making it easier for the contractors to master and apply the system; (2) minimizing the settlement; and (3) creating an intelligent system for the TBM operators. The industrial application of the SR Device is expected to provide considerable savings in time and cost of excavation and ground improvement, in addition to providing a protective measure for any structures above the tunnel.
