VOLUME LOSS CAUSED BY TUNNELLING IN KENNY HILL FORMATION

Abstract

The Klang Valley MRT Sungai Buloh – Kajang (SBK) Line, Malaysia’s first mass rapid transit
line involved the construction of 9.5km twin bored tunnels in the densely populated urban area of Kuala
Lumpur city. The underlying geological conditions can be distinctly demarcated to two main formations
namely Kuala Lumpur Limestone and Kenny Hill Formation, of which 5.262km of bored tunneling was carried
out in the Kenny Hill Formation. The bored tunnel construction in the Kenny Hill Formation was undertaken
with the use of Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM). The ground settlement due to
tunneling is largely dependent on the volume loss induced by the tunnel excavation. At present, little
information has been published on actual volume loss encountered during tunnel construction in the various
soil types in Malaysia. Surface settlement markers among other instruments that were placed at selected
intervals along the SBK Line tunneling route as an instrumentation and control measure offer an opportunity
to evaluate and back analyze the ground response due to tunneling works. This paper presents and discusses
the volume loss caused by EPB TBM tunneling in the Kenny Hill Formation. Back analysis on trough width
parameter from the available data has also been carried out. The findings of this study could be useful as a
reference for future tunneling projects in similar ground conditions.