KanjiJLPT N1
Barracks

barracks, police station, camp, ton

Mnemonic

A comet streaks over the mountain and slams into the barracks below. Every soldier rushes out, covering their nose against the acrid smoke. The mountain trembles, the comet's crater glows, and all nose their way through the haze back to barracks.
Additional thoughts
Picture the comet trail arcing over a peaked mountain, smashing into rows of military tents. The nose detail anchors the sensory panic — sulfur and dust filling nostrils. The three radicals stack visually just like the kanji itself.
Quick recall
A comet over a mountain crashes into the barracks, making every nose burn with smoke.

Details

The keyword for 屯 is barracks. This kanji conveys the idea of a military encampment or garrison where soldiers are stationed and housed. It carries the sense of troops gathering and being stationed in one place, evoking the image of an army setting up camp. By extension, it can also suggest the notion of things accumulating or massing together in a concentrated area.
On'yomi
とん
Kun'yomi
たむろ