Consolidation takes place within 24 hours as we know in Soil Mechanic. But, but if consolidation takes place in 48 hours. and logt data support that. I mean logt curve becomes horizontal after 48 hours. What does it mean?
Gokhan,
Consolidation does not necessarily take place completely within 24 hours during testing. The time really depends on the type of soil, the load increment ratio, and whether the preconsolidation pressure has been exceeded or not. You should construct your deformation reading versus log t curve, or deformation versus square root of time curve as you perform the consolidation test, and calculate either t100 (from log curve) or t90(using Taylor's square root of time method). Compare this time to the actual time elapsed and decide whether the specimen is ready for the next load increment. With the Taylor square root of time method you usually don't have to wait too long to see how long you should wait. This way, you may be able to apply the load increment without waiting the sort of standard 24 hours and that way eliminate the effect of the secondary compression on the results, or you may see that you might need to wait more.
Gokhan,
For a given loading during the consolidation test, the soil starts to consolidate i.e., the water seeps out from the voids and the soil sample in the consolidation starts to compress. This expulsion of water is noted in form of decreasing height. This is more during the start of the test. As time progresses during the test for a given loading, the soil particles rearrange themselves , attains some equilibrium and no further expulsion of water happens (in primary consolidation). Even if the particular loading is kept for longer time also, there is negligible expulsion of water. Hence, you can notice that the logt curve tends become horizontal for a given load.
If you change the loading, by adding more surcharge, this equilibrium state attained by the soil particles and water is disturbed, pore water pressure builds up and again the process of expulsion of water takes place.
Regards
Sravan MV
Consolidation process is very slow process. it is depend on load. When water come out from voids thus soil starts to consolidate.
- Badges
- Science topic
- Similar topics
- Agriculture
- Soil Science
- Soil