Glijgraad

Glijgraad is a Dutch term that translates roughly as the degree or propensity of sliding. In practical use it denotes a measure of how readily two contacting surfaces slip past each other under a given load. The concept is applied across disciplines to describe sliding behavior in frictional contact, wear, and stability analyses.

In geotechnics and slope stability, glijgraad often refers to the inclination or steepness of a potential slip surface within a soil or rock mass. The higher the glijgraad, the greater the driving shear stress along the plane relative to the resisting strength, which can influence the assessment of landslide risk and the factor of safety. It is related to, but distinct from, the soil’s friction angle and cohesion, and it is used as part of stability calculations for embankments, slopes, and excavations.

In tribology and mechanical engineering, glijgraad describes how readily surfaces slide under a given loading, contributing to the overall frictional behavior of a joint or bearing. It is affected by lubrication conditions, surface roughness, temperature, and material pairings. Understanding glijgraad helps in identifying regimes from stick-slip to smooth sliding and in predicting wear and energy losses in moving components.

Measurement and reporting of glijgraad vary by field, and it is not tied to a single SI unit. It may be expressed as an angle, a dimensionless ratio, or inferred from observed slip velocity under known shear forces. See also glijvlak, wrijving, frictie, and landslide stability.