Re: drain channel in concrete driveway
There is no telling how thick the concrete is. It should be at least 4" thick, which would hold up to what you propose. What will likely happen is the section you channel out will crack off from the main slab, no harm no foul.
The thing is, I've had instances where the area was not graded properly, allowing for dangerously thin concrete, conversely, within the same driveway, thicknesses over 12 inches. How do I know this? A tree root cracked and lifted the driveway, during the replacement process, the poorly graded area was discovered. This, unfortunately, is pretty typical of tract construction, so who knows how thick your driveway is, the thinner it is, the more likely it's going to crack. Now, one way you can prevent the rest of the slab from cracking is to make the primary scoring cut deeper than all the rest, this will give a stress relief point for the crack to follow, rather than having it spiderweb the rest of the slab.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!