为了研究玄武岩纤维和粉煤灰的联合作用对水泥土抗拉性能的提升效果和作用机理，以山区软弱土为研究对象，配制不同纤维掺量、长度和不同粉煤灰掺量的水泥土试样，通过劈裂抗拉试验和电镜扫描试验对其强度、变形、韧性和微观作用机制进行了研究。结果表明：当纤维掺量0.6%、纤维长度6 mm、粉煤灰掺量12%时，提升水泥土抗拉性能和韧性的效果最佳，与素水泥土相比，其抗拉强度、残余强度、峰值应变、拉伸吸收能分别提升了40.55%、134.68%、40.81%、132.22%；掺入18 mm的纤维会劣化水泥土的抗拉性能；二者联合作用机制是：纤维加筋了水泥土内部的薄弱面，承受和传递了拉应力，使水泥土内部受力更加均匀，粉煤灰珍珠颗粒可填充水泥土内部的孔隙，使水泥土颗粒与纤维充分黏结，增强了试样的整体性。

To investigate the improvement effect and mechanism of the combined of basalt fiber and fly ash on the tensile performance of cementitious soil, basalt fibers of various contents, lengths and fly ash of different contents were selected and incorporated into the cement soil consisting of weak soil in mountainous areas. A series of splitting tensile tests and electron microscopy scanning tests were conducted to study the strength, deformation, toughness, and microscopic mechanism of action. The results indicate that basalt fiber length 6 mm and doping amount 0.6%, and fly ash content 12% are the combined effect of the two has the best effect on improving the tensile performance and toughness of cement-soil. Compared with ordinary cement-soil, its tensile strength, residual strength, peak strain, and tensile absorption energy have increased by 40.55%, 134.68%, 40.81%, and 132.22%, respectively. The 18 mm fibers deteriorate the tensile properties of cementitious soil. The mechanism is that fibers reinforce the weak surface inside the cement soil, bear and transmit tensile stress, making the internal stress of the cement soil more uniform. Fly ash pearl particles can fill the pores inside the cement soil, making the cement soil particles fully bond with fibers, and enhancing the integrity of the sample.