Abstract: On the basis of the analysis on the downward drift slicing without sublevel backfilling method，a overlying filling mechanical model which applied the single route type of roadway was established.In order to avoid the “cantilever beam” of artificial roof，the “fixed-end beam” model was ultimately determined as the mechanical model of upper overlying filling body.Based on the elastic-plastic mechanics knowledge，we calculated the filling body bearing layer thickness at 0.92 m，and the maximum deflection value 23.4cm.Combined with the engineering practice，the surrounding rock and plastic zone and their stress distribution under different mining depth were studied by using the FLAC3D numerical simulation software.The results showed that except for the first layer，other bearing layers experienced no plastic failure.Meanwhile，the maximum principal stress of each layer on filling bodies were less than their compressive strength，so the selected bearing layer thickness and matching parameters of the filling pulp could guarantee the stability of filling body.The research results provide a theoretical basis to achieve a safe and efficient mining for thin ore body with crushed surrounding rock.

Key words: A single route type of roadway, Mechanical model, Bearing layer thickness, Numerical simulation, Backfill stability