How does one set up a tent on concrete (how do Occupiers of Wall Street do it)?

I’m setting up a tent in my backyard, a backyard consisting of a wide open space… of flat concrete. I have a nice view, but no lawn. Minutia of my surroundings aside: is there a special way to secure a tent on flat concrete (besides just putting sandbags on the inside corners)? No, I CANNOT drill into the concrete. No damage must be done. Thank you all!