Civil Engineering - Building Construction - Discussion

The depth of exploration of soil should not be less than 2 times the width of foundation. Am I right?

Generally, in the case of square footing, the depth of exploration should be 1. 5 times the width of footing and in the case of strap footing, it is 3 times the width of footing. But here, for heavy embankments and dams, where the depth of footing is considered deep footing, here the depth of soil exploration is 2times the depth of footing.

Here, They asked for heavy embankment and dams. Generally, for strong and durable structure 2H height will require.

What is the logic in 2h? if the height of the dam is 50m then soil exploration depth should be 100m?how and why? I don't think it is the right answer, maybe h/4.