Study on the sustaining effect of concrete-filled steel tubular supports in deep mining roadways

Abstract

Coal production under deep mining conditions is jeopardized by the stability loss of mining roadways: their adequate support has become an urgent technological and economic problem. In this study, a concrete-filled steel tubular (CFST) support applicable to deep mining roadway was proposed, and the related stress state was theoretically analyzed. For a deep mining roadway, the numerical model based on the commercial FLAC3D software package was developed and used to calculate the deep mining roadway behavior with and without the proposed CFST support. Using the self-developed nested similarity simulation experimental system, the physical similarity model of a deep mining roadway was elaborated. The stability loss process in the unsupported roadway, as well as the sustaining effect of support on stresses, deformation, and collapse behavior of the surrounding rock, was investigated in depth. According to the Mohr-Coulomb criterion, the stability loss mechanism in deep mining roadways and the sustaining effect of the CFST support were explored from the perspective of the Mohr circle evolution. The results obtained strongly indicate that the CFST support exerts a strong radial sustaining force on the surrounding rock surface in a deep roadway, increasing its minimum principal stress and reducing the respective stress concentration. The resulting reduction of the Mohr circle diameter implies that the roadway under study remained under safe conditions below the failure envelope. Finally, the feasibility of the CFST support was validated via the field test, which proved the adequate control of stability of the surrounding rock in a deep mining roadway.