A good, cheap way to stop them uprooting your pile is to pay a visit to a carpet shop! No, no ... not for a replacement carpet, but for those sample squares that they often sell off cheap. Get their own cat smell onto it, or maybe some catnip, and job's a good 'un! Well, it's worked for my friend's cat, Tigger. To the extent that not only does Tigger only ever scratch his 'mats', he only ever sits on them too - never on the carpet itself! Bless him
Oh, and they make good playmats too! For 'fighting' and playing 'sticky carpet' and the like! (sticky carpet = stick and one mat - stick under mat and wiggle!) Plus, if they get too skanky you can simply throw them in the washing machine, although they sometimes come out a bit wilted (not Wilton) looking! The mats that is, not the cats!