摘要
预应力混凝土轨枕在氯化物环境或极端气候条件作用下,会产生质量和弹性模量损失,导致轨枕寿命下降,限制了其在极端气候线路的长期应用。研究一种基于钢纤维混凝土(SFRC)无预应力轨枕材料,其具有高抗裂能力、高耐久性。首先,提出一种SFRC的配合比,制作并测试SFRC抗拉、抗压、抗折能力和扩展度;然后,制作无预应力、预应力SFRC轨枕,进行三点抗弯试验,研究SFRC轨枕的抗弯能力;最后,使用图像相关分析技术(DIC)研究SFRC轨枕抗裂能力和裂缝扩展形式。SFRC材料试验结果表明,SFRC抗拉强度为10.5 MPa,是C60混凝土的5倍以上;抗压强度119.5 MPa,是C60混凝土的2倍;抗折强度24.6 MPa,扩展度530.2 mm;试验结果表明,SFRC轨枕在裂缝宽度达到2 mm时有更高的荷载和位移;预应力SFRC轨枕具有最大的抗弯刚度,无预应力SFRC轨枕与普通混凝土轨枕抗弯刚度相近。裂缝扩展分析结果表明,预应力SFRC轨枕开裂荷载为85 kN,无预应力SFRC轨枕开裂荷载为75 kN,相较普通混凝土轨枕分别提升54.5%和36.4%,并且产生的裂缝在破坏早期表现出数量多、宽度小的特点,在结构达到极限强度时,主裂缝宽度会迅速扩展,钢纤维不断拔出,直到彻底发生破坏。无预应力SFRC轨枕和预应力SFRC轨枕的性能均高于普通轨枕,可以满足正线铁路性能需求,在极端气候环境中具有广阔的应用前景。
Prestressed concrete sleepers experience loss of mass and a reduction in elastic modulus under the influence of chloride exposure or extreme climatic conditions,which shortens their service lives and limits their long-term application on lines subject to extreme weather.Consequently,this paper aims to investigate a non-prestressed sleeper material based on steel fiber reinforced concrete(SFRC)that exhibits high crack resistance and durability without the use of prestressing.First,this study proposed a mix proportion for SFRC,followed by the fabrication and testing of its tensile,compressive,flexural strengths,and ductility.Then,both non-prestressed and prestressed SFRC sleepers were produced and subjected to three-point bending tests to evaluate their flexural capacities.Finally,digital image correlation(DIC)was employed to analyze the crack resistance and crack propagation patterns of the SFRC sleepers.Experimental results of SFRC materials demonstrated that the tensile strength of SFRC was 10.5 MPa,over five times that of C60 concrete.The compressive strength was 119.5 MPa,twice that of C60 concrete,and the flexural strength reached 24.6 MPa with an elongation of 530.2 mm.Experimental results of SFRC sleepers demonstrated that SFRC sleepers achieved greater loads and displacements when the crack width reached 2 mm.Prestressed SFRC sleepers showed the highest bending stiffness,while non-prestressed SFRC sleepers had similar bending stiffness to conventional concrete sleepers.Analysis of crack propagation indicated that the crack initiation load for prestressed SFRC sleepers was 85 kN and 75 kN for nonprestressed sleepers,and improvement of 54.5%and 36.4%were shown compared to conventional concrete sleepers.Furthermore,early-stage cracks were numerous and narrow,but as the structure approached its strength limit,the main crack width expanded rapidly,with steel fibers progressively pulling out until complete failure occurred.Both non-prestressed and prestressed SFRC sleepers outperform conventional sleepers,meeting the performance requirements of mainline railways and offering broad prospects for use in extreme climatic environments.
作者
曲玉福
韩笑东
郭恩懿
井国庆
QU Yufu;HAN Xiaodong;GUO Enyi;JING Guoqing(Wuhan Railway Vocational College of Technology,Wuhan 430205,China;University of Groningen,Groningen 9747AA,Netherlands;School of Traffic and Transportation,Beijing Jiaotong University,Beijing 100044,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)
出处
《铁道标准设计》
北大核心
2025年第7期74-78,129,共6页
Railway Standard Design
基金
国家自然科学基金重大科研仪器研制项目(5202780093)。
关键词
轨枕
钢纤维混凝土(SFRC)
力学性能
三点抗弯试验
裂缝扩展分析
静载抗裂性能
sleepers
steel fiber reinforced concrete(SFRC)
mechanical performance
three-point bending test
crack propagation analysis
static load crack resistance
