1.0 Introduction
Cracks were observed on the concrete lining of both Meru and Menora tunnels.Changes instresses in the tunnel wall will induce strains which may cause the concrete to crack and where cracks were existing, to widen.Evidence of stress changes can therefore be observed from the changes in crack pattern and in the existing crack width.
2.0 Objective
The main objectives of the mapping and monitoring is to study the pattern of the cracks and behaviour.
3.0 Tests
The various types of monitoring carried out were:
- Crack mapping
- Crack monitoring using ‘Avongard’ crack gauge, Tell Tale glass, crack microscope and Demac gauge.
4.0 No. of Test
| Type of Test | No. of Test |
| Crack mapping | 20 panels |
| “Avongard” crack gauge | 20 nos |
| Tell Tale glass | 100 nos |
| Demac points | 50 nos |
| Crack width | 50 nos |
4.0 Results and Conclusion
Based on the crack pattern observed, the cracks are reasonably random. Crack width measured are between 0.2mm to 1.25mm.