Abstract: For surrounding rock of roadway under large loosing zone， the interaction of anchor and surrounding rock forms “anchor bearing layer“ within the loose zone. In order to study the influence of “anchorage bearing layer“ on stress distribution of surrounding rock in roadway under large loosing zone， it is obtained that the support strength [pid] provided by “anchorage bearing layer“ in plastic zone under ultimate equilibrium state consists of two parts: bolt support strength [pi] and anchorage bearing structure strength， by theoretical deduction and practical analysis. According to the relationship between support strength [pi] and thickness of anchorage layer b， the concept of “anchorage limit thickness“ is proposed. For the surrounding rock outside the loosening zone， the stress distribution around the roadway can be recalculated and compared with the traditional Finner-Kastner solution. The practice shows that the bearing structure plays a dominant role in keeping the stability of roadway， and the coordination of support strength and bearing structure is more conducive to the maintenance of the roadway. Modified Finner-Kastner solution can provide some reference for understanding supporting mechanism of deep roadway，and also provide corresponding theoretical basis for supporting parameter design of roadway.

Key words: Large loose zone, Anchorage bearing layer, Anchorage limit thickness, Modified Finner-Kastner solution