ABSTRACT
The Jakarta Mass Rapid Transit (MRT) Project, currently under construction, to relieve traffic congestion within the city, has both elevated and underground sections with a transition between them immediately north of Sisingamangaraja station. The tunnel runs from there to Bunderan Hotel Indonesia for 4 km beneath major roads in central Jakarta. Four Earth-Pressure-Balance (EPB) machines with outer diameters of ~6.7 m are being used to excavate the northbound and southbound tunnels. The tunnels are mostly located in dilluvial strata which comprise stiff to hard silts or clays. Surface settlement predictions have been performed and field measurements analysed to assess the ground response to tunnel construction around the Bunderan Hotel Indonesia. In the early stages of tunnelling, in the northern part of the project (CP106), small degrees of heave, up to about ~6 mm, occurred directly above the centre-line of the southbound tunnel, reducing with transverse distance to small settlements. Once the Tunnel-Boring Machine (TBM) reached about 320 m southwards, surface movements changed from heave to settlement. The responses suggest that vertical displacements (heave or settlement) depend on TBM variables such as face and tail skin grouting pressures in conjunction with depth of overburden.
