Grouting Reinforcement Mechanism and Multimodel Simulation Analysis of Longwall Goaf

Table 1

Classification table of geological mining model of goaf.

Model type	Mode of action	Specific conditions
Stable	Mainly for mining function, longwall mining; reaching or close to full mining, caving method to manage the roof; more than 3 years from the final mining time	(1) ; (2) topography and stratum are close to level; (3) there are no faults or penetrating fissures within the range of mining influence; (4) thickness of ; (5) ground construction load does not affect the old goaf area
Basically stable	Mainly for mining, longwall mining; reaching or close to full mining, caving method to manage the roof; 1 to 3 years from the final mining time	(1) ; (2) terrain level and shallow hills; (3) ; (4) no faults or perforated fissures within the range of mining influence; (5) thickness of ; (6) the ground construction load has a certain influence on the old goaf
Unstable	Mainly mining, underground mining leads to fault slip and mountain slip; large deformed voids remain, which may cause discontinuous deformation of the ground; within 1 year from the final mining time	(1) Longwall caving method mining with depth to thickness ; (2) pillar mining; (3) ; (4) the ground is mountainous; (5) the strata contains quicksand layers; (6) the strata is loose and the thickness of the layer is less than 10 m; (7) the fault dip and the mining area ; (8) the ground construction load has a large impact on the old goaf