Research and application of high performance steel fiber concrete wall in deep shaft passing through outburst coal seam group

Aiming at the support problems when the coal mine deep vertical shaft passes over the outburst coal seam group, the use of steel fiber concrete shaft lining structure is proposed. Firstly, the benchmark mix ratio of high-performance concrete for shaft lining is obtained through orthogonal design configuration, and the mechanical properties of concrete under different steel fiber mixing rates are investigated. Then, the support project at the coal uncovering of the second return shaft of Dingji Coal Mine is taken as the background, and based on the similarity criterion, the model tests of the shaft lining under uneven loads are carried out. The test results show that the high-performance steel fiber concrete has good mechanical properties, and the compressive strength, tensile strength and flexural strength of the high-performance steel fiber concrete are about 5.3%, 37.5% and 52.5% higher than those of the ordinary concrete when the steel fiber mixing amount is 0.4%, respectively. Under the action of uneven load, the bearing capacity of high-performance steel fiber concrete shaft lining structure is about 13.2%-15.6% higher than that of plain concrete shaft lining. The circumferential compressive strain of the optimized high-performance steel fiber concrete shaft lining is from −230.0×10⁻⁶ to −587.2×10⁻⁶, which is much smaller than its ultimate compressive strain value, indicating that this new type of shaft lining structure is safe and reliable.