ignores dr/hd, but does insufficient damage to break stone walls or pillars.
... hit more than one time?
except that becomes a bit difficult without very specific optimization choices due to mountain hammer requiring a standard action and the bonus damage not affecting any subsequent extra hits.
however, taking your basic concept...
if i go (for example) psionic monk, i can expend focus as a free action, and ignore hd/dr for a single blow (3) or for the entire flurry (8). plus i can tack on mongoose maneuvers and snap kick for extra hits towards the end.
i could also go decisive strike for double damage, but i need to calculate whether that combined with mongoose and snap kick would total more damage than a full flurry plus mongoose and snap kick.
and i could always throw in iajutsu focus via the frcs cosmopolitan feat.
i'd really like to get the 5' to 10' stonebreaking all within one round, if possible. hence my considering burrow refluffed as "martial breaking technique" as an OTB approach.