纤维灌浆料钢筋套筒拉拔试验及承载力研究

Pull-out tests and load-bearing capacity studies of steel sleeves with fiber-reinforced grouting materials

关键词:  聚丙烯纤维灌浆料  聚乙烯醇纤维灌浆料  抗压强度  压缩韧性  单向拉伸试验  灌浆套筒力学性能

Key words:  polypropylene fiber-reinforced grouting materials  polyvinyl alcohol fiber-reinforced grouting materials  compressive strength  compressive toughness  uniaxial tensile tests  mechanical properties of reinforced grouting sleeves

摘要:

为研究纤维掺入对灌浆套筒的力学性能影响,对聚丙烯(polypropylene,PP)纤维及聚乙烯醇(polyvinyl alcohol,PVA)纤维增强灌浆料进行了材性性能及其灌浆套筒力学性能试验研究。对不同长度、掺量的PP、PVA纤维增强灌浆料进行了力学性能试验,对4d、6d、8d(d为钢筋直径)3种钢筋锚固长度的纤维增强灌浆料套筒开展了单向拉伸试验。结果表明:掺入纤维导致灌浆料的流动度和抗压强度出现一定程度的下降,对抗折强度影响不明显,且随着纤维长度及掺量的增加,灌浆料压缩韧性显著提高；4d埋深套筒试件发生钢筋拔出破坏,6d、8d埋深套筒试件发生钢筋拉断破坏,且随着灌浆料纤维长度与掺量增加,发生钢筋拔出破坏的套筒极限承载力和极限位移增加；纤维增强灌浆料的抗压强度与套筒极限承载力和极限位移之间存在显著的负相关性,纤维增强灌浆料的压缩韧性则体现出正相关关系；基于传统灌浆套筒极限承载力预测公式,引入灌浆料压缩韧性指数这一参数,提出综合考虑灌浆料抗压强度及压缩韧性的纤维增强套筒承载力预测公式。

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.