Spells like Blockade to aid dungeoncrasher?

Maybe it's possible to construct a small mobile wall of stone (5 ft square, but as a T-piece, so that it cannot fall or get pushed away) which lies within the size limits of the Shrink Item Spell (PH, 279).

If you manage to do so, you could use the spell to shrink the mobile wall. Consider making it permanent with the Permanency Spell so that you can shrink and unshrink the wall for an indefinite number of times.

Objects changed by a shrink item spell can be returned to normal composition and size merely by tossing them onto any solid surface or by a word of command from the original caster.

In order to speed that up and to let the wall appear at a convenient range you could use a quickened version of the 0-level Spell Launch Item (Spell Compendium, 130) making it a 4th level spell effectively. That would - as a swift action - give you a wall exactly where you need one.

You might try Dark Way from the Spell Compendium (p.58). It's level 2 instead of level 3, but is similarly a standard action. It only lasts 1r/lvl instead of the 1m/lvl found in Wall of Chains. It makes a shadow wall that is indestructible. Note, though, that if an object sets foot on the bridge that would exceed the weight tolerance, the offending object (and only the offending object) will pass through the bridge and fall as though the bridge were not there.

It's basically the poor man's wall of force, but it can only hold back things up to a certain weight.