冻融作用下硫酸盐渍土土水特性及微观机理研究OA

In order to study the soil-water characteristics and micro-mechanism of sulfate saline soil under freeze-thaw-salt coupling,the soil-water characteristic curves of saline soil with different salt content were test-ed and fitted with Gardner model,van-Genuchten model,and Fredlund-Xing model,and the microstructure and pore distribution characteristics of sulfate saline soil under freeze-thaw-salt coupling were analyzed.The results indicate that the volumetric water content of sulfate-salted soil decreases as matrix suction increases,with the re-sulting curves exhibiting a single-peak inverse'S'shape.Notably,for a given volumetric water content,higher salt concentrations correspond to increased matrix suction.Freeze-thaw cycles promote the microstructural dis-integration of the soil,leading to an increase in large pore volume and overall porosity.Following these cycles,both the matrix suction and volumetric water content of the soil samples decreased,causing the soil-water char-acteristic curve to shift leftward with an increasing number of freeze-thaw cycles.To evaluate the test results of saline soil,the G model,V-G model,and F-X model were employed.The F-X model exhibited a low fitting cor-relation coefficient,while the V-G model demonstrated poor fitting in both high and low suction phases.In con-trast,the G model provided an overall good fitting performance.The microstructural changes in soil samples re-sulting from freeze-thaw actions are critical factors contributing to the reduction of the soil's water-holding ca-pacity.The progressive development of pores and fissures in the samples,influenced by freezing,thawing,and salinity,facilitates the migration of water equilibrium.