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Soil Reconsolidation
- Thread starter CAS1
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I believe the question you posed may just be poorly worded, so I'll have to answer in a round about way.
To "reconsolidate" the soil must first "un-consolidate" or "de-consolidate". Assuming we are talking about the existing condition being fully consolidated, the only soils that will de-consolidate will be:
1)Loose topsoil that is swept away by the flood and re-deposited.
2)Deeper soils that will absorb or adsorb the flood waters, creating a new unconsolidated state.
Both of these will then be subject to consolidation again.
The next part of your question is an interesting one. "During a flood". Remember, soils consolidate to typical equilibrium conditions. If that typical condition is after the floods leave, then the soil will continue to consolidate after the flood waters have gone.
If, however, the water stays (e.g. a newly made reservoir, or major change in terrain due to earthquake) then it will consolidate to THAT equilibrium condition.
To "reconsolidate" the soil must first "un-consolidate" or "de-consolidate". Assuming we are talking about the existing condition being fully consolidated, the only soils that will de-consolidate will be:
1)Loose topsoil that is swept away by the flood and re-deposited.
2)Deeper soils that will absorb or adsorb the flood waters, creating a new unconsolidated state.
Both of these will then be subject to consolidation again.
The next part of your question is an interesting one. "During a flood". Remember, soils consolidate to typical equilibrium conditions. If that typical condition is after the floods leave, then the soil will continue to consolidate after the flood waters have gone.
If, however, the water stays (e.g. a newly made reservoir, or major change in terrain due to earthquake) then it will consolidate to THAT equilibrium condition.
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Deeper soils that will absorb or adsorb the flood waters, creating a new unconsolidated state.
The flood waters are receding but the ground is still saturated. Can complete (as in, no further) reconsolidation occur while the ground is still saturated with flood water? Thank you for your answer(s).
The flood waters are receding but the ground is still saturated. Can complete (as in, no further) reconsolidation occur while the ground is still saturated with flood water? Thank you for your answer(s).
My company does geotech and geology investigations, and we regularly indicate hydraulic loosening and re-compaction of sandy soils as a cause of differential foundation movements.
I have seen houses undergo differential slab and foundation movements after flood events (not related to erosion or scour).
I have seen houses undergo differential slab and foundation movements after flood events (not related to erosion or scour).
CAS,
I think we're mixing up definitions here. In the industry some of the terminology is largely opinion. So, let me establish my definitions for what I'm talking about.
Consolidation vs. Compaction. It could be said that consolidation is a subset of compaction.
Compacting simply means that the soil will become more dense. (i.e. It will take the same soil particles and fit them into a tighter space.) It usually means applying pressure either actively (tools or equipment) or passively (gravity) removing voids and allowing the soil particles to fit together more tightly because of angularity, air, water, and other factors that have kept the particles a bit apart.
Consolidation is specifically about removing the water voids (not air voids) over time and allowing pressure to reach an equilibrium with the water pressure that is present at the "permanent" water table and ground pressure conditions.
When we have a flood condition, water loosens some packed particles that may have air voids in them. As they break up, they are subject to sediment action which will cause the soil to compact (take up less space). As water leaves the soil it begins to consolidate. The water leaves allowing soil particles to get closer together. (at this point, it is also possible that the exiting water may leave air voids behind instead of compacting it). This continues until the water content vs the soil pressure reaches an equilibrium.
If the water can continue to drain or evaporate at a rate greater than the rate of recharge, it will continue to consolidate. If, however, this is now the new equilibrium water table, then it will not consolidate further unless more pressure is applied to the soil.
If you just need another method of draining the soil, have you looked into wick drains?
I think we're mixing up definitions here. In the industry some of the terminology is largely opinion. So, let me establish my definitions for what I'm talking about.
Consolidation vs. Compaction. It could be said that consolidation is a subset of compaction.
Compacting simply means that the soil will become more dense. (i.e. It will take the same soil particles and fit them into a tighter space.) It usually means applying pressure either actively (tools or equipment) or passively (gravity) removing voids and allowing the soil particles to fit together more tightly because of angularity, air, water, and other factors that have kept the particles a bit apart.
Consolidation is specifically about removing the water voids (not air voids) over time and allowing pressure to reach an equilibrium with the water pressure that is present at the "permanent" water table and ground pressure conditions.
When we have a flood condition, water loosens some packed particles that may have air voids in them. As they break up, they are subject to sediment action which will cause the soil to compact (take up less space). As water leaves the soil it begins to consolidate. The water leaves allowing soil particles to get closer together. (at this point, it is also possible that the exiting water may leave air voids behind instead of compacting it). This continues until the water content vs the soil pressure reaches an equilibrium.
If the water can continue to drain or evaporate at a rate greater than the rate of recharge, it will continue to consolidate. If, however, this is now the new equilibrium water table, then it will not consolidate further unless more pressure is applied to the soil.
If you just need another method of draining the soil, have you looked into wick drains?
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