Supporting Mechanism and Effect of Artificial Pillars in a Deep Metal Mine

Abstract

The supporting mechanism for overburden strata supported by artificial pillars is a complex issue. A calculation method for the size optimization of an artificial pillar in a deep area based on Protodyakonov’s ground pressure theory was proposed. In this study, the sizes of artificial pillars in different mining sections in a specific mine were calculated. In addition, the stability of these artificial pillars and the supporting effect for the overburden strata in the gob areas were studied. First, the size parameters of the artificial pillars in different mining sections were determined. Second, the supporting mechanism and stability of the artificial pillars were studied by means of numerical calculation. A regular pattern in which a larger gob area span corresponds to greater settlement of the overburden strata were found. The overburden strata are stable based on the distribution condition of the plastic zone. Finally, field measurements were performed, revealing continuous increases in both the pressure borne by the artificial pillars in two middle sections at the primary stage and the settlement displacement of the overburden strata. After reaching a certain level, the increasing trend slowed and finally plateaued. The maximum stress of the artificial pillar at a depth of -430 m was 0.78 MPa, and its maximum relative settlement of the overburden strata was 4.4mm. Similarly, the maximum stress of the artificial pillar at a depth of -460 m was 0.43 MPa, and its maximum relative settlement of the overburden strata was 2.7 mm. The study results showed that the designed artificial pillars are capable of supporting the overburden strata with good stability in the mining process and can effectively prevent the destruction of surrounding rocks and overburden strata in the gob area for the purpose of supporting the mine.