ABSTRACT
A four level basement has been constructed at a distance less than 5m away from the existing MTRC tunnels in soft ground. The principal constraint on the design and construction is the need to avoid the disruption of the existing tunnels operation. A comprehensive monitoring system with real time design review have been carried out in the integrated manner. These were achieved by comparisons of monitoring results with defined acceptable limits, and by planned contingencies in the event that these limits were approached. This paper presents the integrated approach (numerical and observational) developed during design and construction which incorporates finite element modeling and construction monitoring. The overall leads to the success to control the tunnels movements less than 20mm caused by the underground construction work without interruption to the existing tunnels operation.
