Hydro-mechanical degradation of strength in saline soils under moisture infiltration and leaching

Rising groundwater and recurrent flooding in Uzbekistan accelerate moisture infiltration and salt leaching in saline foundation soils, which may significantly reduce stiffness and shear strength. This study investigates coupled effects of moisture, salinity, and filtration on the strength parameters of saline loam and sandy loam using a controlled laboratory program. The methodology includes baseline geotechnical and chemical characterization, one-dimensional filtration and diffusion leaching, and repeated mechanical testing to obtain cohesion ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>c</mml:mi> </mml:math> ), internal friction angle ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>φ</mml:mi> </mml:math> ), and deformability indicators. The results demonstrate a monotonic decrease in soluble salt content with increasing leaching degree ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> ) and a pronounced reduction of cohesion after leaching (e.g., from 25 to 1.5 kPa for a representative gypsum-bearing loam case), while <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>φ</mml:mi> </mml:math> exhibits a soil-dependent trend under extended exposure. Empirical relationships and observed trends are used to characterize strength degradation under groundwater-rise scenarios. The novelty of the study lies in quantifying the hydro-chemical degradation of strength parameters and providing engineering-relevant trends applicable to foundation assessment in saline areas.