so how do i keep a spider mine from burrowing?
None.

I do stuff and thingies... Try widening and reducing the number of small nooks and crannies to correct the problem.
give them to player 12 (neutral).
-> they will not burrow, if unburrowed.
-> they will not unburrow, if burrowed.
-> they will not attack
-> they will not move
->They will smile at you unceasingly, like this:
None.
I'm not sure about this: Place multiple Spider Mines and have them find a target. I don't think they displace each other, so they'll continually follow their target without moving. The downsides are that they're always animating and making the walking noise, and that they'll blow up if their target moves to them.
None.

We can't explain the universe, just describe it; and we don't know whether our theories are true, we just know they're not wrong. >Harald Lesch
In order for a spider mine to stay unburrowed, the spider mine must be owned by Player 12. You have to preplace it in the map editor, or else it won't stay unburrowed. If you use a trigger such as "Give all Spider Mine owned by Force 1 to Player 12", the spider mine will burrow anyways. It is teh uber gay. >:O
Haha, thats the exact opposite answer someone gave on the same topic at maplantis. I must admit I don't know this detail for sure. The best is you just experiment what works best.
One thing works for sure though: They unburrow for a defeated player.

I do stuff and thingies... Try widening and reducing the number of small nooks and crannies to correct the problem.
ok, I tested it....
1. giving spider mines from a player to p12: they will burrow.... :S
2. preplaced mines owned by p12 will burrow.... :S
the solution:
3. spider mines owned by a player who is not human or computer, he is neutral, will not burrow...