Force Effects - Overcome with Damage
A simple start that is already a common houserule in many games, make it that force effects can be taken down with damage. Maybe you give the effect some kind of regeneration or minimum damage threshold to prevent teh "rif raf" from breaking it, but a high level martial can break down a wall of force or a resilent sphere with just raw power.
All are good interesting ideas but I would rather change this one to be based on a strength challenge instead of damage, because spellcasters can typically deliver a higher peak damage, but don't have a higher strength.
Then of course spellcasters can also acquire higher strength through spells or shapechanging, but maybe something can still be done to reward the basic strength.
One of the best suggestions I have is to do what 4E did with rituals: put ritual casting up as a feat and let anyone who takes that feat cast rituals from one spell tradition. Let them have a ritual book to put them in.
Mmm... sounds a bit like to solve the problem that spellcasters have the edge over martial then let's make all martials spellcasters
So this points to a very important division in this discussion. My goal is this discussion is not to change the PCs as much as the environment in which they operate.
Otherwise we are back to just the standard debates, make Martials stronger, make them more epic, etc etc. The goal in this discussion is how to make the world and magic elements more "martial friendly"
It's probably too cheap, but there is also always the old option of using areas where magic just doesn't work or monsters immune to spells.
All that said, I still can't brush off the idea in the back of my head, that if we had the courage to forsake the mantra that everyone must be equally good at combat, and a warrior character would be allowed to be effectively much better in combat than everybody else, then we'd have less pressure to rebalance the out-of-combat parts of the game.