Basic physical properties of red sandstone soil.

To enhance the suitability of red sandstone as a railway roadbed fill, basalt fiber (BF) was utilized to modify cement cured red sandstone soil. The study commenced with the determination of the optimal cement admixture in improved red sandstone soil through disintegration testing. Following this, unconfined compressive strength (UCS) tests, undrained and unconsolidated shear (UU) tests were conducted to assess the impact of BF on the strength and deformation characteristics of the cement cured red sandstone soil. Finally, the intrinsic and damage mechanisms through which BF improves the mechanical properties of cement cured red sandstone soil were elucidated in conjunction with scanning electron microscopy (SEM) testing. The results of the study indicate that cement significantly enhances the water stability of red sandstone soil. The disintegration of the specimens effectively ceased once the cement dosage exceeded 4%. The addition of BF significantly enhances the strength of cement cured red sandstone soil. As the BF content increases, the UCS and peak deviatoric stress exhibit an initial increase followed by a decrease. At the optimal BF dosage of 6‰, the UCS improved 24.48% ~ 25.40%, while the peak deviatoric stress improved 31.13% ~ 39.48%. The incorporation of BF also enhanced the deformation and stability properties of the cement cured red sandstone soil, resulting in increased elastic modulus and failure strain. However, the soil brittleness index exhibited varying degrees of reduction, while ductility was improved. The SEM test results indicate that cement primarily provides cohesion between soil particle. BF effectively inhibits the generation and propagation of cracks through the adhesive properties of cement and its interfacial friction with soil particle, as well as by forming a three-dimensional reinforcing network. The research result demonstrates that the use of BF to enhance cement-cured red sandstone soil significantly improves its mechanical properties, offering a sustainable method for strengthening railway foundations and contributing to advancements in civil engineering applications.为提升红砂岩作为铁路路基填料的适配性，本研究采用玄武岩纤维（basalt fiber, BF）对水泥固化红砂岩土进行改性。本研究首先通过崩解试验确定水泥固化红砂岩土的最优水泥掺量；随后开展无侧限抗压强度（unconfined compressive strength, UCS）试验、不固结不排水剪切（undrained and unconsolidated shear, UU）试验，以评估玄武岩纤维对水泥固化红砂岩土的强度与变形特性的影响；最后结合扫描电子显微镜（scanning electron microscopy, SEM）试验，阐明玄武岩纤维改善水泥固化红砂岩土力学性能的内在机理与损伤机制。 研究结果显示，水泥可显著改善红砂岩土的水稳定性能；当水泥掺量超过4%时，试样的崩解现象即可得到有效遏制。掺入玄武岩纤维可显著提升水泥固化红砂岩土的强度，随着玄武岩纤维掺量的增加，无侧限抗压强度与偏应力峰值均呈现先升后降的变化趋势。在最优玄武岩纤维掺量6‰时，无侧限抗压强度提升了24.48%~25.40%，偏应力峰值提升了31.13%~39.48%。 掺入玄武岩纤维还可改善水泥固化红砂岩土的变形与稳定性能，使弹性模量与破坏应变均有所提升，但土体脆性指数出现不同程度的降低，延性得到改善。扫描电子显微镜试验结果表明，水泥主要通过粘结作用为土颗粒提供粘结力；玄武岩纤维可借助水泥的粘结特性及其与土颗粒间的界面摩擦作用，以及形成的三维增强网络，有效抑制裂缝的产生与扩展。 本研究结果证实，采用玄武岩纤维增强水泥固化红砂岩土可显著提升其力学性能，为铁路路基加固提供了可持续的技术路径，同时也为土木工程应用的发展提供了技术支撑。