Every major construction project requires foundations and there are many excavation methods which can be adopted depending on the specific site and contract conditions for the project. Methods include open cut, braced, anchored, island, zoned, top-down or bottom-up. Whichever method is adopted well-considered performance monitoring of the excavation is essential to ensure the safety of the construction process, to confirm design assumptions, protect workers, safeguard adjacent structures and provide assurance to all parties. The consequence of poor excavation performance can be severe and may even be catastrophic so monitoring has to be considered as a crucial part of the construction process.
If the monitoring has been designed well, it can also provide significant value to the project. Providing evidence of better structural/geotechnical performance than anticipated which in turn can justify modification of temporary works or even allow the redesign of the permanent works. These changes can lead to less material usage, better accessibility, increased efficiency and potentially significant reductions in construction programme and costs.
For monitoring to provide optimum benefit: –
- The specification should be specific about what question the monitoring is there to answer. The monitoring specialist then has the opportunity to advise on how this can best be achieved.
- Early deployment provides an understanding of the geotechnical and structural ‘at rest’ state prior to any construction period, allowing the effect of construction activities to be determined.
- Whole life structural monitoring should be considered at the earliest project development stage so that systems can be selected with the characteristics necessary for long-term monitoring throughout the lifetime of the structure.