What are the possible methods to reduce downdrag on piles?

The possible methods to reduce downdrag on piles are mentioned below:-

(A) Coating piles with friction reducer such as bitumen.

(B) Predrill a hole firstly, followed by putting in the pile and subsequent filling of annulus with bentonite slurry.

(C) Drive the piles with an oversize shoe and fill the annulus with bentonite slurry.

(D) Adopt double tube method in which the inner pile takes up the structural load and the outer pile carries the downdrag load.

(E) Preload the soils to accelerate settlement.

(F) Use electro-osmosis to enhance water content around the piles and reduce the friction between pile and soils.

(G) Increase the pile capacity by using larger diameter or longer length so that the effect of downdrag is thereby reduced.

This question is taken from book named – A Closer Look at Prevailing Civil Engineering Practice – What, Why and How by Vincent T. H. CHU.