Abstract:Because of the change of mining method in the vertical adjacent middle section, the eccentric load of horizontal pillar will worsen the stability of roof rock mass and bring bad influence to production safety. Based on the principle of structural mechanics,the mechanical model of eccentric load acting on the dislocation arrangement of the upper and lower ore pillars were established, and the formulas for calculating the bending moment, shear force and factor of safety of the horizontal ore pillars were derived. The results show that the effect of eccentric load on the mechanical properties of the reserved horizontal pillar is obvious. With the decrease of the thickness of horizontal pillar, the factor of safety becomes smaller and smaller, based on the mechanical model of the eccentric load pillar, the weakening relationship of the reserved horizontal pillar under different eccentric load can be quickly calculated.