He almost took Obi-Wan out with that kick, so I'm not sure why that's seen as a separating tactic. He was just continuing to land physical blows on the duo.
The forcefields may have been a tactical way to separate them because Maul took a bad hit from Qui-Gon just prior, and may have need a bit of recovery time. Or perhaps that was just the direction the fight went through random chance (or the Will of the Force).