Tunnel linings constructed using traditional methods typically consist of two layers. The outer layer, known as the primary or first-stage lining, is installed immediately after excavation and is designed to provide the necessary ground stability, allowing for partial stress release within the rock mass. The inner layer, or secondary lining, is usually applied at a later stage and is intended to bear the long-term ground load and, potentially, water pressure. Current design practices for simulating the load transfer between the two lining are based on semi-empirical approaches, assuming that the full load presented at the primary lining is eventually transferred directly to the secondary lining at the end of the primary lining’s service life.