A novel concrete-filled flange steel tubular composite supports for tunnels: a numerical perspective

In this study, a new type of concrete-filled flange steel tubular composite support (referred to as a concrete-filled flange steel composite support) was designed to address the inadequate bending load-bearing performance of concrete-filled steel tubular supports. The bending load-bearing performance of concrete-filled flange steel tubular beams was studied through numerical simulations, revealing the improvement effect of welded T-section steel on the bending performance of the beams. The load-bearing characteristics of the concrete-filled flange steel composite and tubular supports were explored through theoretical analysis. Using a coal mine tunnel, the effectiveness of the concrete-filled flange steel composite support for controlling tunnel deformation was verified. The results indicated that the improvement in the bending load-bearing performance of concrete-filled flange steel tubular beams was mainly due to the bending load-bearing capacity of the T-section steel. Increasing the height of the T-section steel web effectively enhanced the bending load-bearing performance of the concrete-filled flange steel composite support when the same amount of steel was used, and the load-bearing performance of the concrete-filled flange steel composite support was significantly better than that of the traditional concrete-filled steel tubular support. With a lateral pressure coefficient farther from 1, the superiority was more pronounced.