Macro-micro Evolution Characteristic Function of Solidified Loess under the Effects of Dry-wet Cycles

[Objective] To reveal the durability of solidified loess slope protection in long-term service. [Methods] Under the condition of dry-wet cycles, direct shear, permeability mechanical tests of solidified loess were carried out to study the evolution law of the macro-properties of stabilized loess, and the damage law of dry-wet cycles on the morphology of the microstructure was analyzed by using scanning electron microscopy and image processing technology. The micro-mechanism of improvement of the dry-wet cycle durability of the macro-properties of loess by biological glue was discussed, and the macro-micro-evolution feature function was established based on the macro-performance index and the micro-structure view parameters to describe the numerical response relationship between the macro-properties and the micro-structure under the dry-wet cycle conditions. [Results] The biological glue inhibited the deterioration of mechanical properties of solidified loess, and the inhibitive effect was positively correlated with the content of biological glue; the change of permeability of solidified loess was increased by biological glue, and the change amplitude was negatively correlated with the content of biological glue. The dry-wet cycles resulted in the failure of loess cementation, particle damage and pore increase. The biological glue enhanced the loess cementation, slowed down the particle damage and changed the pore development pattern. More than 95% of the predicted points fell within the mean square error line. The addition of biological glue could improve the durability of the macroscopic properties of loess under dry-wet cycles. The sensitivity analysis of the characteristic function showed that the porosity had the greatest influence on the mechanical properties, and the large porosity with pore size > 32 μm had the greatest influence on the permeability. [Conclusion] The research findings can provide a theoretical basis for the engineering application of biological glue for the technology of soil solidification and slope protection and subsequent improvement of the technology.