Experimental Study On Unloading Of Pillar Excavation Face With Subsequent Filling

Subsequent excavation and unloading under filling conditions is prone to destabilization damage of underground space structures,among which abrupt changes in energy release from the new free surface due to excavation of mine pillars are most common,the bearing capacity of the filling body also changes with the energy release rate during the unloading process.Therefore,it is an important topic in underground excavation and unloading engineering to investigate the damage mechanism of unloading surface from the perspective of energy mutation combined with unloading stress.1)It showed that the energy in the single-face unloading process undergoes four abrupt changes,and the damage warning interval is formed in the bearing stage,and the short-lived destabilization warning interval is formed after unloading,which greatly shortens the warning duration and provides a theoretical basis for the prevention and control of disasters caused by excavation and unloading.2)To explore the influence of different excavation rates on the unloading of ore columns,different unloading rate unloading tests were conducted on the filling body to analyze the influence of unloading rate on the energy accumulation and release pattern of the filling.It showed that the stress curves of the unloading process at different rates show obvious phase characteristics.3)The filler-pillar system was established in the context of the subsequent filling and mining pillar,and the self-stabilization effect of the arch was used to analyze the mechanical load-unloading mechanism of the system.It showed that the increase of the capping rate changed the bearing form of the roof plate and improved the overall compressive strength of the system.4)It showed that the degree of strain energy accumulation in the column is related to the tangential stress: on the one hand,the higher the tangential stress,the longer the duration of the elastic zone,and the more significant the energy accumulation;on the other hand,the increase of the tangential stress will lead to a shorter energy release time.Figure 33;Table 8;Reference 93...