Experimental Study on the Compressive Strength of Improved Loess with Nano Silica-Cement-Basalt Fiber

黄土因其湿陷性强、水敏性高等特性易引发工程病害，亟需高效改良方法。本文提出一种纳米二氧化硅(Nano-SiO2)–水泥–玄武岩纤维协同改良技术，通过无侧限抗压强度试验系统研究三种材料的单因素影响规律及协同作用机制。结果表明，单因素影响下，材料最优掺量区间为Nano-SiO2占水泥质量10%~20%、水泥掺量2.5%~7.5%、玄武岩纤维掺量0.2%~0.6%。水泥掺量5%、Nano-SiO2占比10%、玄武岩纤维0.4%时无侧限抗压强度达1.059 MPa，较未改良黄土提升约12%，其中水泥对强度贡献最为突出。Nano-SiO2和玄武岩纤维过量添加因团聚效应导致强度降低。改良土体呈应变软化特征，软化程度受材料配比调控。研究表明，多材料协同配比可显著改善黄土力学性能，为黄土工程病害防治提供新思路。Loess is prone to engineering diseases due to its strong collapsibility and high water sensitivity, and efficient improvement methods are urgently needed. This paper proposes a synergistic improvement technology of nano-silica (Nano-SiO2)-cement-basalt fiber. The single-factor influence laws and synergistic action mechanisms of the three materials are studied through an unconfined compressive strength test system. The results show that under the influence of a single factor, the optimal dosage range of the materials is as follows: Nano-SiO2 accounts for 10%~20% of the cement mass, the cement dosage is 2.5%~7.5%, and the basalt fiber dosage is 0.2%~0.6%. When the cement content is 5%, the proportion of Nano-SiO2 is 10%, and the basalt fiber is 0.4%, the unbounded compressive strength reaches 1.059 MPa, which is approximately 12% higher than that of the unimproved loess. Among them, the contribution of cement to the strength is the most prominent. Excessive addition of Nano-SiO2 and basalt fibers leads to a decrease in strength due to the agglomeration effect. The improved soil shows the characteristics of strain softening, and the degree of softening is regulated by the material ratio. Studies show that the coordinated proportioning of multiple materials can significantly improve the mechanical properties of loess, providing a new idea for the prevention and control of engineering diseases in loess.