The application of lightweight soil for changing and filling is an effective foundation treatment method for the construction of sponge cities in collapsible loess areas. In this paper, the L₂₅(5⁴) orthogonal test targeting on the strength, permeability and density characteristics was first used to optimize the mixture ratio design of proposed lightweight soil with cotton stalk fibres (LSCF). The corresponding effects of each mixed content on the performance of LSCF were analysed. The soil water characteristic curves (SWCCs) of LSCF with different cement and cotton stalk fibre contents were then measured using the quick centrifuge method. In comparison with undisturbed loess, the volumetric moisture content of LSCF (for the same matrix suction) was larger, and LSCF had a better water-holding capacity. Based on the Van Genuchten model, an improved fitting model for matrix suction SWCC of LSCF was proposed by considering the influence of cement. Qualitative agreement with the test results indicates that the proposed model could be potentially used to obtain the SWCC curve without conducting any experiments, which is especially useful for the sponge city constructions in loess areas.

利用轻质土进行换填是在湿陷性黄土地区建设海绵城市的有效基础处理方法。在本文中，L ₂₅（5 ⁴）首先针对强度，渗透性和密度特性进行正交试验，以优化拟议的轻质土壤与棉秆纤维（LSCF）的混合比设计。分析了每种混合含量对LSCF性能的相应影响。然后使用快速离心法测量了不同水泥和棉秆纤维含量的LSCF的土壤水分特征曲线（SWCC）。与未扰动的黄土相比，LSCF的体积含水量（相同的基质吸力）更大，并且LSCF的保水能力更好。在Van Genuchten模型的基础上，考虑水泥的影响，提出了一种改进的LSCF基质吸力SWCC拟合模型。