how to fill driveway gap on a slope?

[lemonbarz_]

I've got a bit of a head scratcher with my driveway and hoping some of you seasoned DIYers or contractors can chime in.

Underneath my driveway, there's this pretty significant gap: we're talking 6 inches high, about 5 feet wide, and almost 3 feet deep! To make things trickier, the driveway itself has a 20% grade, so it's a good slope.

Any ideas on how to best remedy this situation? I'm worried about erosion getting worse or potential instability.

What's the best approach to fill a void of this size, especially with the slope? And for those who've tackled something similar, what's the best product or material to use here?

I'm looking for something durable that will hold up.

Thanks in advance for any wisdom!

 

[Sero.tonin]

If it were me, I'd look into flowable fill or a polyurethane void fill foam, depending on access and budget, foam is great for tight spots and won't add much weight, but for a gap that big, controlled low strength material might be the better long term fix

 

[SetInCement]

If it were me, I'd look into flowable fill or a polyurethane void fill foam, depending on access and budget, foam is great for tight spots and won't add much weight, but for a gap that big, controlled low strength material might be the better long term fix

polyjacking might work for this but I think that mudjacking is better, plus it's cheaper and I think for a gap that big it should offer better support. Wheteverr you do, before you start this, make sure the drainage is good and you sealed all cracks.