Abstract:To investigate the influence of fiber incorporation on the mechanical properties of reinforced grouting sleeves, experimental studies were conducted on the material properties of polypropylene (PP) fiber-reinforced and polyvinyl alcohol (PVA) fiber-reinforced grouting materials. Mechanical property tests were performed on PP and PVA fiber-reinforced grouting materials with varying lengths and volume fractions. Uniaxial tensile tests were carried out on fiber-reinforced grouting sleeves with three different reinforcement anchorage lengths of 4d, 6d, and 8d (where d represents the diameter of the reinforcement bar). The results indicate that the addition of fibers leads to a certain degree of reduction in the fluidity and compressive strength of the grouting material, with insignificant impact on flexural strength. Moreover, as the fiber length and volume fraction increase, the compressive toughness of the grouting material improves significantly. For sleeve specimens with a 4d embedment depth, reinforcement pull-out failure occurred, while reinforcement rupture occurred in specimens with 6d and 8d embedment depths. Additionally, as the fiber length and volume fraction in the grouting material increase, the ultimate bearing capacity and ultimate displacement of the sleeves undergoing reinforcement pull-out failure also increase. There was a significant negative correlation between the compressive strength of the fiber-reinforced grouting material and the ultimate bearing capacity and ultimate displacement of the sleeves, whereas a positive correlation was observed with the compressive toughness of the material. Based on the traditional prediction formula for the ultimate bearing capacity of grouting sleeves, a new prediction formula that comprehensively considers both the compressive strength and compressive toughness of the grouting material is proposed by introducing the compressive toughness index as a parameter.