为探究玄武岩纤维对花岗岩-混凝土组合体高温损伤的改善作用，以花岗岩、混凝土和4种纤维掺量（0%、0.1%、0.2%、0.3%）的花岗岩-玄武岩纤维混凝土组合体为研究对象，对其在常温和高温（200、400、600 ℃）后的抗压强度、抗拉强度、破坏形态、损伤因子和微观结构进行研究。结果表明：组合体表现出连续介质的力学特性，抗压和抗拉强度均介于花岗岩和混凝土之间；掺入玄武岩纤维可以提高组合体的抗压和抗拉强度，改善破坏形态，0.2%为较优掺量；在600 ℃高温处理后花岗岩-混凝土组合体（G-PC）的损伤因子为0.702 7，600 ℃的高温对组合体造成了严重的损伤；组合体在压缩破坏时以混凝土破坏为主，交界面和花岗岩的破坏相对较小；玄武岩纤维在混凝土内部起到了连接和阻裂作用，能够有效减少裂纹的产生和扩展。

[Objective] While the mechanical properties of rock-concrete composites and basalt fiber-reinforced concrete have been widely studied， research on their combined performance after high-temperature exposure remains limited. This study investigates the use of basalt fibers to enhance the high-temperature performance of granite-concrete composites， aiming to evaluate their efficacy in mitigating thermal damage. [Method] Granite， plain concrete， and granite-basalt fiber concrete （GBFC） composites with four fiber volume fractions （0%， 0.1%， 0.2%， and 0.3%） were tested. Following high-temperature treatments at ambient temperature and 200 ℃， 400 ℃， and 600 ℃， static uniaxial compression and splitting tensile tests were conducted to evaluate compressive strength， tensile strength， failure modes， and damage factors. Scanning electron microscopy （SEM） was also employed to analyze microstructural evolution. [Result] （1） The composites exhibited continuous medium mechanical behavior， characterized by plastic failure under uniaxial compression and brittle failure during splitting. Their compressive and tensile strengths fell between those of pure granite and concrete， trending closer toward the concrete values. （2） Basalt fiber incorporation improved both strength metrics and failure modes at elevated temperatures， with a 0.2% fiber content identified as optimal. （3） The damage factor increased progressively with temperature； specifically， the GBFC damage factors were 0.103 5 at 200 ℃， 0.339 1 at 400 ℃， and 0.702 7 at 600 ℃， indicating severe structural degradation at the highest temperature. （4） SEM analysis revealed that uniaxial compression primarily damaged the concrete matrix， while the interface and granite remained relatively intact. High-temperature treatment exacerbated concrete deterioration but had minimal impact on the interface and granite. Basalt fibers acted as bridging and crack-arresting agents within the concrete matrix， effectively mitigating crack initiation and propagation when added in appropriate amounts. [Conclusion] These findings provide valuable references for understanding composite mechanical properties， optimizing tunnel construction， and guiding post-fire evaluation and repair strategies for tunnel infrastructure.