A novel high-permeability counterfort retaining wall (HPRW) was proposed for improved control of rainfall-induced landslides, and its working performance and mechanism were studied by thorough numerical simulations. The numerical simulations revealed that the retaining effect of the HPRW was significantly better than that of the conventional counterfort retaining wall (CRW) under the effect of rainfall. Relative to the CRW, the pore water pressure and groundwater table decreased owing to the excellent drainage capacity of the HPRW, in turn leading to the decreases in the hydrodynamic pressure and earth pressure. Consequently, the slope deformation decreased and stability of the slope increased with the application of the HPRW. Furthermore, the stress and displacement of the HPRW and the earth pressure acting on the HPRW were lower than those of the CRW under identical working conditions. Parametric analysis indicated that the rainfall intensity, property of the sliding mass and gravel filling in the catchment tank affected the retaining effect of the HPRW and the stability of the slope to varying degrees. The results of this study can provide a significant basis for the design, application and subsequent research on the HPRW.

Fluidized solidified soil ( FSS ) is a cement-based engineering matergood working performance and mechanical properties. Based on fi xed cement and desulphurisation gypsum ( DG ) , fl y ash ( FA ) and ground granulated blast furnace slag ( GGBS ) were added as admixtures to the construction slurry to prepare three types of FSS: namely cement-GGBS-DG FSS ( CGD-FSS ) , cement-FA-GGBS-DG FSS ( CFGD-FSS ) , and cement-FA-DG FSS ( CFD-FSS ) . Considering 7 d, 14 d, and 28 d three curing times, compressive, fl exural, scanning electron microscopy ( SEM ) , and x-ray diffraction ( XRD ) analyses were conducted to explore the time-dependent mechanical properties and microscopic characterisation of FSS. The mechanical test showed that CFGD-FSS doped with FA and GGBS had better fl uidity, compressive strength, and fl exural strength than CGD-FSS doped with FA alone and CFD-FSS doped with GGBS. The CFGD-FSS specimen with a cement:FA:GGBS:DG ratio of 30: 10:40:20 in the curing agent had the best mechanical properties, i.e., the CFGD01 specimens. It has fl uidity of 189 mm, compressive strength of 671 kPa, and fl exural strength of 221 kPa with a 28d curing time, which can meet the working requirements of FSS for fi lling narrow engineering spaces. And compared with other specimens, it has the shortest setting time, which can effectively shorten the construction period. Microscopic analysis showed that a large number of hydration products, such as calcium silicate hydrate, calcium aluminate hydrate, and ettringite ( Aft ) , were well-formed in the FSS, resulting in good mechanical properties, especially for the CFGD-01 specimens. Finally, two empirical models were established to describe the compressive strength-porosity and fl exural strength-porosity relationships. Moreover, the investigated data agreed well with the modelling results.

To address the challenges posed by the significant quantity of ammonia-alkali white mud, this study explores the preparation of fluid solidified soil using ammonia-alkali white mud, mineral powder, and fly ash. The findings reveal that ammonia-alkali white mud primarily comprises sulfate, carbonate, and soluble chloride salt, with an alkaline solution and a well-developed pore structure. Optimal fluid solidified soil formulation, comprising 30% white mud, 30% salt mud, 25% mineral powder, 10% fly ash, and 5% calcium oxide, yields a slurry fluidity of 176 mm and a compressive strength of 3.98 MPa at 28 days. Microscopic analysis highlights AFt and C-S-H gel as the principal hydration products of fluid solidified soil. The fine particles of calcium carbonate in ammonia-alkali white mud fill the structural pores and intertwine with the hydration products, facilitating the formation of a dense structure, which constitutes the primary source of strength in fluid solidified soil. Furthermore, the heavy metal content of the solidified soil aligns with the first type of land use requirements outlined in the GB 36600-2018 standard, and the toxicity of the leaching solution adheres to the emission concentration limit stipulated by GB 8978-1996.