How do you fill in holes under concrete that rats have left?

Next to the foundation and under the concrete patio I have rat holes. The concrete is actually starting to crack. How do I fill in the holes. I can take care of the rats but the holes are causing a problem. I have heard of pouring in cement but I'm not sure how to do this.How do you fill in holes under concrete that rats have left?
wow i was just doing this today at my mother's house... hers was from a ground mole....


she didnt have the money to hire someone, but a local person suggested this.... and it is what we did....





dig around the small holes, until you can see that all of the small holes are dug out and then take the dirt along with top soil if you need more dirt.. mix it half and half with gravel and stuff the hole back up.. make sure to pack it up as you go along





the gravel helps for stability as the dirt will continue to sink on its own....





i am not sure how well this will work long term, but it is an easy fixHow do you fill in holes under concrete that rats have left?
If they've dug out under the concrete where you can't reach it, put lots of loose soil near the edge of the concrete and use a 2x2 block of wood as long as it needs to be and use it as a battering ram to force the dirt underneath as far as it can go and pack it very tightly.