How does soil plug in open-ended tubular piles affect its loading carrying capacity?

In marine piles, the tubular piles are sometimes purposely designed to be open-ended to facilitate deeper penetration. In this mode of pile formation, soil plug is formed inside the piles.

The plugging ratio (the ratio of length of soil plug to the length of pile penetration) affects the load carrying capacity of piles. It was demonstrated by experiments that the end bearing capacity decreases with an increase in the plugging ratio. Moreover, close-ended piles display a higher end bearing capacity than open-ended piles as close-ended piles prevent soil from entering the piles and force them around the pile tip leading to a higher stress state in this region.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.