Even not underestimating the scale, I'm not sure it would work because all the debris would need to be ejected from the thousands-of-kilometers-deep hole. And then you'd also have to have a solution to stop the walls from caving in before the next bomb had a chance to arrive. It's almost as if you not only need thousands of extremely powerful (even for nukes) bombs, but also need to deliver them in a continuous stream to keep the blast pressure up and the hole open.

I feel like, at that point, the easier strategy to accomplish your goal would be redirecting a large asteroid to impact the planet, or something like that.