Geophysical Investigation in Bukit Merah Reservoir

Abstract

The suspected cavity presence in the bedrock of the outlet canal of Bukit Merah Reservoir in Malaysia raised concern that it could undermine the integrity of a check pier structure planned just ahead of the spillway. Boring into a cavity could also compromise reservoir containment capacity. A seismic refraction and electrical resistivity tomography carried out for the subsurface section spanning the two banks revealed not only the presence of a relatively porous zone towards one end but also the undulating material boundaries towards the other. The results called for review of the original foundation of the check pier structure involving bored piles of equal length. The suspected porous zone was avoided in the renewed bored pile design while the bedrock depressions were appointed with deeper bores for adequate pile embedment. The design review resulted in piles resting on a stratum of equal geotechnical quality with each new pile now having a different length.