针对淮河流域蚌埠段高液限黏土堤防出现纵向裂缝问题，采用水泥和纤维对高液限黏土进行改性，通过对不同水泥掺量和纤维掺量改性高液限黏土平面应变试验研究，得到改性土应力-应变曲线、中主应力、弹性模量随水泥纤维掺量的变化关系，结合微观结构测试，揭示水泥纤维改性高液限黏土的机理。结果表明：在平面应变状态下，水泥和纤维的加入明显改善了高液限黏土的强度；对于改性高液限黏土，水泥掺量逐渐增加后，中主应力对土体破坏影响逐渐减小；水泥掺量较低情况下，应力-应变曲线呈现硬化型或弱软化型，试样脆性指数低，试样破坏时无明显剪切带，纤维掺量对试样破坏形态影响程度低；当水泥掺量较高时，应力-应变曲线呈现强软化型，试样脆性指数随着纤维掺量增加而减小，试样破坏有明显剪切带且随着纤维掺量增加而逐渐弱化；从微观结构可知水泥改善土颗粒间有效应力的传递，纤维破坏有效应力的传递，二者相互作用，引起试样剪切带痕迹和滑动面形式发生改变。

In order to solve the problem of longitudinal cracks in the high liquid limit clay embankment in the Bengbu section of the Huaihe River Basin, the high liquid limit clay was modified by using cement and fibers. Through the research on the plane strain tests of the modified high liquid limit clay with different contents of cement and fibers, the variation relationships of the stress-strain curve, the intermediate principal stress and the elastic modulus of the modified soil with the contents of cement and fibers were obtained. Combined with the microstructure test, the mechanism of the modification of high liquid limit clay by cement and fibers was revealed. The results show under the plane strain state, the addition of cement and fibers significantly improve the strength of high liquid limit clay. For the modified high liquid limit clay, the influence of the intermediate principle stress on the destruction of the soil gradually decreases as the cement content increases. Under low cement content conditions, the stress-strain curve shows hardening type or weak softening type, the brittleness index of the sample is low, and no obvious shear band is observed during sample failure, the influence of fiber content on the failure morphology of the sample is low. When the cement content is high, the stress-strain curve shows a strong softening type, the brittleness index of the sample decreases as the fiber content increases, and obvious shear band is observed during sample failure, which is weakened gradually as the fiber content increases. From the microstructure analysis, cement improves the effective stress transmission between soil particles, while fibers disrupt the effective stress transmission, and the interaction between the two causes the trace of the shear band and the form of the sliding plane to change.