Civil Engineering - Soil Mechanics and Foundation Engineering - Discussion

Both A and C are correct.

Both options are indeed correct, but the statement that cohesion is more in well-compacted clays is more accurate.

Cohesion refers to the internal molecular attraction or bonding between soil particles. It is one of the factors that contribute to the strength and stability of soils. The cohesion of soil is influenced by several factors, including moisture content and soil composition.

Option A states that cohesion decreases as the moisture content increases. This statement is generally true because as the moisture content increases, the water fills the voids between soil particles, reducing the contact and interparticle forces.

This reduces the cohesive forces between the soil particles, leading to a decrease in cohesion. However, it is important to note that this relationship is not linear and can vary depending on the specific soil type and its characteristics.

Option C states that cohesion is more in well-compacted clays. This statement is also true. Well-compacted clays have a higher degree of compaction, meaning the soil particles are tightly packed together.

This dense arrangement leads to stronger interparticle forces and, consequently, greater cohesion between the soil particles.

In summary, while both options are correct, the statement that cohesion is more in well-compacted clays is more accurate because well-compacted clays typically exhibit higher cohesion due to their denser structure.

So, C is the correct answer.

If we increase the water content in soil then up to a certain point cohesion increase but after increasing more and water moisture content, soil ultimately losses all its cohesive property as well as its shear strength.

So, the answer is C.

Soils with higher water content tend to have lower shear strength capacity, while cohesion of soil increases at a small amount of water but decreases very rapidly after its optimal moisture content is reached.

It is internal molecular attraction which resists the shear of the material. It decreases as the moisture content decreases and is more in well-compacted clay.

So, C is right.

Option A is correct.

Clay type and content influence strength through their role in cohesion. As water content increases " cohesion decreases. This is because increasing water content causes greater separation of clay particles (and thus easier slippage) and further, causes softening of soil cements.

The phenomenon of increase or decrease the moisture content can happen in the sand also. But sand is not cohessive. So the most appropriate answer is option C.

I think option D is correct.

Just like a soil with higher over consolidation ratio has high cohesion, more compaction or confinement results in more cohesion imagine a soil at a ground surface and at 10 m depth which will have more cohesion.

@Jayaram.

The ucc is not unconfined cohesion test. But unconfined compression test.

No @Imtiyaz Ahmed.

It decreases as if water content increases towards liquid limit.