Physics on a stake in the ground

i'm trying to figure out how much force it would take to remove a three inch piton driven into rock or concrete. For example, assuming the concrete in a 50 square foot parking lot was more than three inches deep, and you drove a 3 inch piton into the center of it, how many pounds of force would it take to pull it out? The only factor i havent been able to find is how much force the rock, which you forced apart while driving in the piton, is pressing against the sides of the piton or stake. if anyone can tell me or lead me to anywhere or formula that would be helpful, thanks in advance. I've found that the coefficient of friction of steel on concrete to be .5 (on one surface of the piton) so probably closer to .8 figuring the other sides.... i'm really just looking for a rough answer:tongue2: