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Project
Stormwater Management and Road Tunnel (SMART) Project was initiated to alleviate the flooding problem in the city centre, with a motorway tunnel integrated into the system to relieve traffic congestion at the main Southern Gateway to the city centre of Kuala Lumpur. The 13.2m diameter tunnel covering a distance of 9.7km was constructed within the KL Limestone formation. The construction of this tunnel using 2 numbers of Slurry Shield Tunnel Boring Machines passes through soft soil and limestone cavities prone to subsidence within a densely built-up area.
Ground Condition
The KL Limestone formation comprises of upper Silurian marble, finely crystalline and variably dolomitic rock and is highly weathered and cavernous. Coupled with past mining activities, the overburden largely comprises soft silty and loose sandy soils. Occurrence of subsidence is common, particularly due to construction works
Open excavation of junction boxes and ventilation shafts and tunnelling activities will also cause drawdown of groundwater table and may trigger collapse of cavities.
Solution
Keller was engaged to carry out grouting works to mitigate the occurrences of subsidence and collapses within the KL Limestone formation along the tunnel alignment. The range of grouting techniques that were applied in this context involve fissure grouting and cavity grouting in the rock and jet grouting and compaction grouting in the soil layer.
Performance of Grouting Works
The SMART project afforded ground engineers with the unique challenge of mitigating ground disturbance associated with construction work in Limestone, using grouting technology. Experience from more than 3 years of grouting at this site has shown that the available technology is effective in minimizing water seepage and ground disturbance. It has demonstrated that the success of grouting depends on proper identification of the problem by experienced engineers and subsequent implementation of appropriate mitigating measures.
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