Stress and deformation analysis of gob-side pre-backfill driving procedure of longwall mining: a case study

Abstract At present, non-pillar entry protection in longwall mining is mainly achieved through either the gob-side retaining (GER) procedure or driving (GED) procedure. The GER leads to difficulties maintaining roadway both previous and current panels. A narrow coal pillar about 5–7 m must be left GED procedure; therefore, it causes permanent loss of some coal. pre-backfill (GPD) effectively removes wasting resources that exists finds an alternative way handle maintenance problem FLAC 3D software was used numerically investigate stress deformation distributions failure rock mass surrounding panel roadways during each stage GPD which requires "twice excavation mining". results show distribution slightly asymmetric around after “primary excavation”. stronger stiffer backfill compared turned out main bearing body "primary highest vertical stresses 32.6 23.1 MPa, in-situ 10.5 appeared wall seam, respectively. After mining", peak under seam at floor level higher (18.1 MPa) than (17.8 MPa). "secondary excavation", lower (18.7 (19.8 MPa); maximum heave roof sag were 252.9 322.1 mm, During affected by superposition front abutment pressure from side panel. reached a 321.8 mm 5 ahead working face; increased 828.4 face. alternately whole mining" provided strong capacity all stages exhibited reliable support for roadway. provide scientific insight engineering practice