Abstract:

 In order to interpret the deformation behavior of mine backfill and surrounding rock when mining Xinli deposit of Sanshandao gold mine，a quasi-two dimensional mechanical model was built as a plane strain problem.According to the mechanical behavior of fill mass，double-yield plasticity model was adopted for the body of the fill mass and strain-hardening or softening plasticity model was used in the grid of pillars and surrounding rocks.Several displacement monitoring points were set in positions of interest in a FLAC3D model and their results relatively really reflected the movement and deformation rules of the backfill and surrounding rock in cut-and-fill stoping by overhand method.The results showed that the body of fill mass was mainly subjected to compressive deformation in horizontal direction and had a cumulative effect on its volume deformation.And after the compressive deformation of the backfill in vertical direction reaches a maximum value，roof surrounding rock have a vertical upward component of movement under the action of horizontal tectonics stress.

Key words: undersea mining, backfill, roof surrounding rock, numerical simulation, Sanshandao gold mine