Short-term performance optimization of steel fiber-reinforced concrete for roadway support

Introduction Steel fiber-reinforced concrete(SFRC) is widely used to mitigate early instability during mining because of its excellent toughness and crack resistance. However, its rapid early strength development requires chemical accelerators. Short-term support performance also depends on support thickness. Methods This study investigated the effects of accelerator dosage and support thickness on short-term SFRC performance using a 1363-m-level transport roadway in an iron ore mine in Yunnan Province as a case study. The analysis focused on two critical short-term time points-4 h and 7 h after mining-to identify the optimal support parameters. Laboratory specimens were prepared with accelerator dosages of 5%, 7.5% and 10%. Mechanical properties were measured at 4 and 7 h of curing. Numerical simulations evaluated displacement, maximum principal stress,and plastic zone development for SFRC supports of 30 mm, 60 mm, and 100 mm thicknesses at 4 and 7 h. Results The results indicated that decreasing accelerator dosage and extending curing age increase compressive strength and shear resistance but reduce elastic modulus. A lower accelerator dosage and greater support thickness reduced roadway displacement, plastic zone volume, and maximum principal stress. Support thickness was the dominant factor influencing SFRC support effectiveness. The optimal SFRC configuration was 5% accelerator dosage and a 100 mm support thickness. Discussion Field measurements confirmed that sidewall displacements stabilized at approximately 25 mm. This outcome indicated satisfactory performance of the adopted support system. These findings provide a scientific for optimizing short-term mechanical parameters of SFRC roadway supports.