To address the challenges in resource utilization of dredged soil from the Yangtze River(high moisture content,low strength,and difficulty in forming),and the inadequacies of traditional bubble-mixed lightweight soil(insufficient tensile strength and high brittleness,rendering it unsuitable as a floating island substrate),research on lightweighting and fiber modification is conducted.Orthogonal experiments are conducted to determine the optimal mix proportion by varying the cement-sand ratio,foam volume content,and water-sand ratio.Basalt fiber(BF)and polypropylene fiber(PPF)with different parameters are then incorporated.The modification effects are investigated through mechanical property tests and microscopic analysis.Results indicate that the optimal mix proportion is a cement-to-sand ratio of 0.4,a foam volume fraction of 10%,and a water-to-sand ratio of 0.35,corresponding to a dry density of 0.77 g/cm3,a wet density of 0.84 g/cm3,the optimal 28-day compressive strength,and a water absorption rate of 12.3%.The optimal BF content is 0.5%(length:12 mm),which increases the splitting tensile strength by 18% and significantly reduces the dry shrinkage rate.The optimal PPF dosage is 0.3%(length:9 mm),which enhances the 28-day toughness by 30%,improves the saturated compressive strength,and reduces the probability of brittle failure.Both fibers improve the interfacial bonding strength to a certain extent.With a density close to that of water,this material can be used as a floating landscape carrier,providing technical support for the lightweight and ecological utilization of dredged soil from the Yangtze River.