Byerlee's law

Byerlee's law is an empirical relation between normal stress and frictional strength in rocks. It describes laboratory-observed friction across a broad range of rock types and pressures.

Connect

Normal stress: The component of stress acting perpendicular to a surface. Byerlee's law uses normal stress to predict the frictional resistance of a rock surface.
Rock friction: Resistance to sliding between rock surfaces or within fractured rock. Byerlee's law summarizes measured rock-friction behavior across many materials.
Fault mechanics: The study of forces, deformation, and motion on geological faults. Byerlee's law provides a basic friction rule for mechanical models of faults.
Rate-and-state friction: A friction framework in which strength evolves with sliding rate and the history of contact. Unlike the simple stress relation, it models time-dependent friction and slip stability.
Shear stress: The component of stress acting parallel to a surface. Sliding begins when applied shear stress overcomes frictional strength.
Friction coefficient: A dimensionless ratio relating frictional force to normal force. The law's stress slopes correspond approximately to characteristic friction coefficients.
Earthquake nucleation: The process by which a fault patch begins unstable slip that can grow into an earthquake. Frictional strength helps determine whether loading produces stable or unstable fault motion.
Laboratory friction laws: Empirical and theoretical relations fitted to friction measured in controlled experiments. Byerlee's law is a broad empirical rule within this larger family of models.
Coulomb friction: A friction model in which resistance is proportional to normal force, often with a cohesive offset. Byerlee's relation approximates this frictional form over much of its stress range.
Direct shear test: A laboratory test that shears a specimen along a chosen plane under controlled load. Laboratory shear tests provide measurements used to characterize rock friction.