Study on Overlying Strata Movement Law of Shortwall Fully-Mechanized Working Face with Different Sizes of Remnant Pillar Based on 3DEC Simulation Software

Based on 3DEC simulation software, the numerical model of remnant pillar resource recovery was established, and the overlying strata movement law of different sizes of remnant pillar in shortwall fully-mechanized working face was analyzed. The results show that the influence on the overlying strata of the “coal face of adjacent goaf” gradually decreases with the increase of the size of the remnant pillar, which is similar with the overlying strata displacement of the “coal face of facing goaf” working face. The vertical displacement distribution of the coal pillar is small at both ends and large in the middle. The horizontal displacement of overlying strata in “coal face of surrounding goaf” working face is concentrated in 20 m coal pillar, which is more vulnerable to the influence of goaf. With the increase of the angle between the goaf and the working face, the effective length of the “coal face of through empty roadway” roadway decreases significantly, and the open leakage area of the roof also decreases, leading to the roof subsidence of the goaf increases.