Soda residue (SR), a waste by-product of sodium carbonate production, occupies land resources and pollutes the environment seriously. To promote the resource reusing of waste SR, this paper studies the feasibility of utilizing SR for the preparation of soda residue soil (SRS) through laboratory and field tests. The SR and fly ash (FA) were mixed with six different proportions (SR:FA is 1:0, 10:1, 8:1, 6:1, 3:1, 1:1) to prepare SRS, and the optimum water content, maximum dry density, shear strength, and unconfined compression strength of the SRS were measured. The representative SRS (SR:FA is 10:1) was selected to investigate the compression performance and collapsibility. The preparation and filling method of SRS in the field was proposed, and the effects of gravel, sand, and lime on the mechanical properties of SRS were studied through field tests. The results show that the addition of FA contributed to the strength development of SR, and the addition of lime, sand and rubble have a significant effect on the subgrade bearing capacity of SRS. The subgrade bearing capacity and deformation modulus of SRS in field tests is more than 210 kPa and 34.48 MPa, respectively. The results provide experimental basis and reference for the preparation of SRS, the scientific application of SRS in geotechnical engineering to promote sustainable development.

In order to reuse waste soda residue, the feasibility of utilizing liquid soda residue and liquid fly ash to prepare soda residue soil was investigated. The mechanical properties of the soda residue soil were studied and analyzed through laboratory tests and field tests. The raw materials preparation process and liquid-liquid mixing method in the field were determined, and the optimal mixing proportion of the soda residue soil was investigated by compaction test and micro penetration test. And the filling quality of the liquid-liquid mixing and solid-liquid soda residue soil was measured by micro penetration test, light dynamic penetration test, and variable energy dynamic penetration test. The test results showed that the optimal mass ratio of soda residue to fly ash is 7:3. The optimal water content and maximum dry density of the soda residue soil with the optimal mix ratio are 63.5% and 0.88 g/cm³, respectively. After 5 months of natural drying, the soda residue soil filled by liquid soda residue and liquid fly ash has higher strength and better uniformity of hardness. The water content of the soda residue soil is between 160% to 180%, and drainage consolidation is the effective method to reduce the water content and improve the strength of the soda residue soil. Compared with the method of preparing the soda residue soil by solid mixing, the method used in this experiment is simple, efficient and feasible.