Deformation Law and Control Measures of Gob-Side Entry Filled with Gangue in Deep Gobs: A Case Study

Abstract

Aiming at the large deformation problem of gob-side entry in solid filling mining, the roof subsidence of gob-side entry retaining (GER) was studied under the influence of gangue filling, by taking a deep filling working face in Shandong Province as the engineering background and using theoretical derivation as well as FLAC3D numerical simulation. Research shows that the stiffness of the gangue filling body in the gob and the stiffness and width of the entry protection coal and rock mass (EPCARM) are positively correlated with the GER roof subsidence, which is much less affected by the EPCARM parameters than by the GER stiffness. The GER failure to meet the application requirements is mainly attributed to the insufficient stiffness of the gangue filling body and excessive advance subsidence, which inhibit the roof stress transfer. The GER replacement by the gob-side entry driving (GED) scheme, which implies replacing the entry protection gangue bag wall with the coal pillar with a width of 5 m, will reduce the roof subsidence to 0.114 m, according to the proposed equation. The results obtained are considered quite instrumental in deformation control of the gob-side entry filled with gangue, as well as substantiation of GED and GER applicability options.