They can be tied down, actually. It all depends on the designed bearing load. They're typically called 'deadmen', or tie-backs. See ~4:45 in the video on this

They can be tied down, actually. It all depends on the designed bearing load. They're typically called 'deadmen', or tie-backs. See ~4:45 in the video on this page: https://www.thisoldhouse.com/landscaping/21018759/how-to-build-a-timber-retaining-wall https://www.thisoldhouse.com/landscaping/21018759/how-to-bui...