Research on the Influence of Tunnel Invert Excavation on the Rheological Deformation of Different Levels of Surrounding Rock

The closed section of the inverted arch, formed by surrounding rock, acts as a bearing ring. Combined with upper initial support, it ensures stable support. However, excavating arch can disturb original balance, significantly affecting tunnel’s stability. To determine optimal exposure length and excavation elevation arches at different rock levels, numerical analyses were conducted. These used classical Burgers creep intrinsic structure model for three-step mode. Various closure distances considered. study aimed to investigate influence these factors on stability primary lining, comparing maximum displacement vault. results indicate that strength primarily affects crown. Lower corresponds greater crown displacement. Additionally, increasing distance leads increased On other hand, has minimal impact Longer result in findings serve basis improving current standards adapting them meet spatial requirements large-scale mechanized operations.