How do you fix the concrete on a porch this sinking in the ground?

Dig and Cement in Foundations before it collapses.........

There are companies that will drill a hole in the concrete and pump in an expanding foam that jacks the slab up. Checked into this and unfortunately it was way cheaper to replace the 15 x 30 patio in my back yard.

It would be a good idea to shim under the posts to temporarily provide support for the roof.

Eventually the slab will need to be replaced. This time the contractor should properly prepare the substrate to provide support for your new porch.

concrete porches are usually hollow. You could build a deck over the concrete? Just an idea.

This article should help you out! http://homeguides.sfgate.com/resurface-cracked-sunken-concrete-porch-36470.html

You can patch it, but it is not a permanent fix and depending on how fast it's sinking you may be right back where you started from a year from now. The porch will need to be demolished and rebuilt. As it stands now, it sound like it's not safe. Good luck.

Don’t know if you’ve seen the commercials or not, but they now have a machine that pumps this product that kind of works like spray insulation from how it looks on the video on TV that will raise your concrete right back in place where it needs to be! Don’t know the cost? But be the best and easiest solution I think

Get a contractor as your this is not a DIY project. You have to raise the roof and porch floor to do this correctly.