In unsaturated soil mechanics, the liquid bridge force is a significant source of soil cohesion and tensile strength. However, the classical Young-Laplace equation, which neglects the stratified nature of water at the nanoscale, fails to accurately capture the physical and mechanical behaviour of nanoscale liquid bridges. This study utilizes molecular dynamics simulations to investigate the wetting behaviour and mechanical mechanisms of liquid bridges between particles at the nanoscale. The study proposes dividing the liquid bridge force into three components: surface tension, matric suction, and adsorption force, to explain the mechanics of nanoscale liquid bridges more comprehensively. The results demonstrate that water layers within liquid bridges exhibit discrete stratified structures at the nanoscale. Moreover, the mechanical behaviour of liquid bridges is highly dependent on pore water volume and pore spacing. Specifically, the contact angle is positively correlated with the pore spacing, while the liquid bridge force increases with the pore water volume and is inversely proportional to the pore spacing. As the separation distance increases, the liquid bridge force gradually diminishes until rupture occurs. This research expands the applicability of the classical Young-Laplace equation and offers new insights into the mechanical properties of unsaturated soils, particularly clays.