Usama Ayub

This study investigates the influence of vegetation growth period on the drained mechanical behaviour of loess reinforced with Medicago sativa L (Alfalfa). Loess specimens were cultivated for 30, 60, and 90 days and tested using consolidated drained triaxial compression under effective confining pressures of 50, 75, and 100 kPa. Results show that progressive root development significantly enhances shear strength and reduces volumetric contraction. At = 50 kPa, peak deviatoric stress increased from 103.29 kPa (unreinforced) to 164.57 kPa at 90 days, corresponding to a strength gain of approximately 60%, while volumetric contraction decreased by about 31%. The results demonstrate that vegetation-induced stabilization of loess evolves progressively with root development and must be incorporated into engineering evaluations as a growth-period- and stress-dependent reinforcement mechanism.

loess; root reinforcement; triaxial test; vegetation growth period; soil-root interaction

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