The Melta Rifle can deal significant damage (if you have one available). Heavy weapons like this will enable you to kill it quickly so it can't have many opportunities to burrow underground.

Warhammer 40K: Space Marine 2 is a pulse-pounding ... I’m partial to the shotgun-like Melta, which makes fighting Tyranids feel like playing whack-a-mole with a sledgehammer. Plenty of weapon variety ...