Rankine’s theory of earth pressure suits well for both R.C.C.-Cantilever type retaining walls and R.C.C.-Counterfort type retaining walls. Here's why:



Rankine's theory of earth pressure is a widely used theory to calculate the lateral earth pressure acting on retaining walls. It was formulated by William John Macquorn Rankine, a Scottish civil engineer and physicist, in the 19th century. The theory assumes that the soil is a dry granular material and obeys the laws of friction and cohesion.



Cantilever Retaining Walls:
- Cantilever retaining walls are rigid walls that are usually made of reinforced concrete (R.C.C.).
- These walls are designed to resist lateral pressure from the retained soil and water.
- They have a large base slab and a vertical stem that acts as a cantilever beam.
- The stem is usually thicker at the base and tapers towards the top.

Counterfort Retaining Walls:
- Counterfort retaining walls are also rigid walls made of reinforced concrete.
- These walls are similar to cantilever walls but have additional vertical concrete columns called counterforts.
- The counterforts are connected to the base slab and the stem, providing additional stability and strength to the wall.



Both Cantilever and Counterfort Retaining Walls:
- Rankine's theory of earth pressure is applicable to both cantilever and counterfort retaining walls.
- The theory assumes that the soil exerts pressure on the wall in a triangular distribution, with its peak at the backfill surface.
- This assumption aligns well with the behavior of the soil behind these types of retaining walls.

Uniform Pressure Assumption:
- Rankine's theory assumes that the lateral earth pressure acting on the wall is uniform throughout the height of the wall.
- This assumption is reasonable for cantilever and counterfort walls, as the height of these walls is typically much larger than the thickness of the retaining element.
- Therefore, the uniform pressure assumption is valid for practical purposes.

Conclusion:
Rankine's theory of earth pressure is suitable for both R.C.C.-Cantilever type retaining walls and R.C.C.-Counterfort type retaining walls. The theory's assumptions align well with the behavior of the soil behind these walls, and the uniform pressure assumption is reasonable for practical design purposes.