From what it looks like, the only way to prevent a minehole being built down onto a underground village is to either claim and wall off the land above, or place buildings, stockpiles, signposts, etc all over your village/claim to block the minehole from having space. (http://www.havenandhearth.com/forum/viewtopic.php?f=42&t=47295)
How about a structure you build for a village that blocks the claim from mineholes instead of having to place something every 4ish(?) squares to prevent them.
Maybe make it so a certain building (like a guild hall) blocks the initial size of the village claim, or add it as a feature to soldier statues that they block a 20x20 square around them from mineholes (only if covered by a village claim)...
or something that enhances the village shield to block all mineholes from coming down on it, this allows someone to still break the village shield and then build a minehole down for raiding purposes.
something other than cluttering the whole village with "objects".