90% consolidation is based on the JKR Needs Statement which consider that remaining 10% settlement will take a very long time to achieve. If we plot Time vs Settlement, the remaining 10% is nearly flat and asymptote (the line approach 0 or nearly infinity)
There are at least 2 aspects to consider :
- Magnitude of settlement
- If the calculated total settlement = 300 mm. 10% remaining settlement is 30.0 mm. Thus, the magnitude of settlement after treatment is not significant. Most building component can tolerate it!
- If the calculated total settlement = 1500 mm. Remaining settlement (10%) would be 150 mm of half a feet! The magnitude of settlement may not favorable to certain building components.
- I use the word calculated total settlement because the actual settlement must be monitor on site (via soil instrument) and be verified by competent Geotechnical Engineer!
- Rate of settlement (mm/day , mm/months or mm/year)
- Even the treatment nearly achieving 90%, the rate of settlement must be monitor. At least we can predict during DLP or after 5 years of project completion, the remaining settlement still acceptable!
- The rate of settlement must be analyze by using actual settlement reading & not by prediction.
My past experience handling soft soil in Klang, Muar, riverbank of Melaka, Sarawak etc, the settlement is more than 1.0 m and proper assessment of the site & project must be done by competent Geotechnical Engineer.