The Role of Ground Improvement
In the early days of development, only the best available lands having reasonably good soil conditions are being developed. This is due to the high cost of foundations on poor soils. In fact, potential foundation problems have played a significant role in site selection. If a site investigation has shown that the soil conditions have been found unusually bad, it has been prudent to move to a more favourable site.
However, due to the rapid development as described above, the relative importance of good soil conditions in site selection has diminished. The growing scarcity of sites having good soil conditions had made it necessary to utilize all the remaining land regardless of its soil conditions. Some sites are now being developed that were once tin mining lands underlain by soft slime.
The main functions of ground improvement are:
- to control deformation and accelerate consolidation;
- to increase bearing capacity and to provide lateral stability
- to increase resistance to liquefaction. Liquefaction has become very important in view of the increasing incidents (due to frequent seismicity in Indonesia) in recent years.
List of sites that may require improvement:
- Filled ground – When a natural stratum is excavated and/or deposited as fill without compaction, the resulting filled-up ground can often be deficient.
- Disturbed ground – This mainly refers to natural ground that has been disturbed by mining activities such as in tin mining operations.
- Infilled valley – This is usually refers to present-day valleys that contain soft alluvium deposited in the past.
- Riverine deposit – This refers to recent deposits within a general watercourse that has been repeatedly deposited in times of flood and recession of waters. They are usually granular materials mingled with clayey materials.
- Coastal and estuarine deposit – They are usually very loose to loose silty sand often presents as coastal deposits and soft marine clay that occurs both as coastal and estuarine deposits.
Ground improvement techniques and its applications