塌埳都是在靠墙处,对不对?

it's likely that the builder didn't fill back the soil to the wall. Usually happenes around the building. We had the situation. It's could be as deep as the bottom of the building. We had several places around the house with this situation. We had to dump over 10 bags of sand into the hole at the side of our garage and then seal it and repair the driveway.