ABSTRACT
In Malaysia, Klang Valley Mass Rapid Transit Line 2 (KVMRT2) is consisting of 38.7km elevated tracks and 13.5km underground tunnels with several shafts. For intervention shaft 2 (IVS2), deep soil mixing (DSM) block was designed to provide excavation support in overburden alluvial soil, followed with vertical rock excavation until 57.5m deep in Kuala Lumpur limestone formation. Ground treatment in limestone was established to minimize groundwater drawdown during deep excavation to prevent excessive ground settlement. A mined adit was constructed to connect from the shaft at mid-depth to south-bound tunnel. Meanwhile, north-bound tunnel at bottom of the shaft was constructed by tunnel boring machine cutting through concrete-filled block inside the shaft compartment. This paper covers the challenges in design and construction of the deep excavation works for the shaft, ground improvement scheme for the bored tunnelling near the shaft, temporary works for mined adit and unconventional construction sequence of bored-through tunnel.
