<p>Stability assessment of vertical trenches excavated in sands within a small range of capillarity has been under-represented in the literature. This paper, therefore, studied the hydro-mechanical characterisation of a vertical excavation in sand on a basis of experimental and numerical modelling. A series of column sample tests within a small range of suction profile (<i>s</i> = 0–2&#xa0;kPa) were conducted to quantify the hydraulic and mechanical behaviour of an unsaturated sand. The experimental results revealed a zone of collapse at high degrees of saturation. After this threshold, a rise in shear strength was observed, a zone where suction is slightly before and beyond the air entry value (<i>AEV</i>). Scatter in shear strength was observed at different suction profiles, attributed to variations in water content (WC) and therefore in soil fabrics. Post-failure measurement of WC taken at different heights of the specimens demonstrated variations in WC, attributed to different in suction along the specimen’s height and water migration (WM) during load application. The WC variations caused changes in strength along the specimen’s height. The experimental results were, then, quantified on the basis of an extended upper bound discretisation scheme, UNSAT-DLO. Changes in soil fabrics, variations in suction along the specimen’s height and the WM phenomenon were modelled in the UNSAT-DLO approach. The numerical comparison exhibited reasonable agreement against the experimental data.</p>