Has anyone raised the soil level (grade) around the trunks of pine trees?

[E-String]

Hi folks. I'm considering filling native grey schist earth (unsorted grey schist rocks, gravel, dirt etc.) about 2 feet above normal grade, around ~50% of the root system of 3 of my pine trees (~1.5 ft diameter). Understandably I would be reducing the water and oxygen flow from the air to the roots due to the grade increase. Has anyone done this grade increase and found it to be overwhelmingly detrimental to the trees (i.e. death, and I definitely shouldn't do this). Has anyone put in an aeration/irrigation system successfully, thus mitigating the deleterious effects of the grade increase, that would be willing to give advice? Thanks millions, E-string

[kew]

Here area some web sites you might want to look at.

http://findarticles.com/p/articles/mi_m1216/is_n3_v181/ai_6607074
http://www.ipm.iastate.edu/ipm/hortnews/1995/7-14-1995/prot.html
http://osuextra.okstate.edu/pdfs/F-6429web.pdf