Examining the Anisotropic Strength of Plain and Steel Fiber Reinforced Shotcrete

Shotcrete, a crucial component for initial rock support in underground mining and civil projects, significantly influences the adequacy of support systems. Evaluating the strength of shotcrete involves conducting uniaxial compressive strength (UCS) tests on the extracted core samples. Typically, shotcrete cores are obtained along the direction of application, leading to an oversight of its strength perpendicular to this direction. Consequently, the true bearing strength of shotcrete is neglected, despite higher stresses acting normal to the application direction. While the anisotropic behavior of shotcrete is documented, comprehensive studies on this scale and nature are lacking. This research addresses this gap by presenting extensive testing of shotcrete cores extracted from tunnels of a mega hydroelectric project in Pakistan. The study encompasses 7 and 28-day strength tests of shotcrete cores, shedding light on the often-overlooked perpendicular strength. Additionally, the investigation extends to the anisotropic behavior of steel fiber-reinforced shotcrete, revealing that shotcrete exhibits increased strength perpendicular to its application direction. This exploration contributes valuable insights to the understanding of shotcrete behavior, emphasizing its multifaceted strength characteristics.