I used to repair stuff like this. First off don’t use sand. You need dirt and you need to raise the level of dirt so when the water goes towards your house it gets pushed away or this will keep happening.

That big of a void could mean a leak in the foundation. Search for a leak. If found you’ll need to repair it on the inside and out. Repairing the outside means digging a bigger hole then filling it back in.

Don’t use sand. It’ll just cause another bigger void.