Civil Engineering - Soil Mechanics and Foundation Engineering - Discussion

I agree with you @Biswa because it is totally wrong clay has less porosity than sand.

Clay particles are small in size, and pore water pressure is large, on the other hand for sand pore space is large but small in number for the same volume as clay and poor water pressure low. That's why the quick range of gravitational water (permeability).

Can anyone explain option C?

Regarding porosity:

Number of pores in fine-grain soil>>> Number of pores in CGS. Therefore porosity is high.

Imagine the number of FGS particles present in 1kg soil v/s number of cgs particles present in 1kg soil. Fgs outnumber the cgs zillion times.

Option A is wrong I think.

According to me, the correct answer is "Clay is more porous than the sand".

Porosity refers to the open spaces within a material. Porosity values are based on the ratio of pore volume to total volume and it is more in clayey soil.

Porosity of gravel: 25-40%.

Porosity of sand: 25-50%.

Porosity of clay: 40-70%.

Permeability refers to the ability of a material to allow for the passage of a fluid due to interconnected voids. Permeability of gravel>sand>clay.

Pore size and it's connectivity determines the porosity of the soil. It is possible to have almost zero permeability for large spacing.

At what % of shear strain the interlocking resistance in loose sand break? Please give details.

Porosity and permeability are directly proportional. As your porosity increases, so does your permeability. Porosity is related mathematically to your void space as porosity, let's call it p, p = v_v/v_t where v_v is volume of voids and v_t is volume total.

If your void space is increased then the ability for water to flow through is also increased because there is more space for fluid to flow naturally. Therefore, Biswas's confusion above is legitimate. This question is improperly worded.