Yes I have done the same thing. I burned MLRS propelleant and MK 104 propellant 10,000 pounds at a time.
The thickness of the propellant layer, wind velocity burn into the wind. When stored in tightly stacked barrels and containers You will get a detonation.
There was an incident were 500 lbs of Amonium Perchlorate detonated. What occurred was a 5 gallon pot of uncured viper propellant was set roughly 10 feet from the AP. The heat from the large burn was to set off the Viper materials. Unfortunately, the pot was not buried. It ignited internally, vented and set a jet of flame across the AP. The AP burned to detonation.
In tight packed storage situations a detonation will occur. following is a picture of an explosion which occurred near Camden AR. This was a standard magazine containing 143,000 pounds of propellant. It was earth covered and stood over 20 fee tall at the peak of the ground cover. Now there is a hole in the ground.
http://www.atf.gov/publications/news...1-09/page2.htm