The magnitude and variation of forces and shear stresses, caused by frost heaving in Fairbanks silt and the adfreeze effects of a surface ice layer and a gravel layer, were determined as a function of depth by using electric strain gauges along the upper 2.75 m of a pop pile, 30.5-cm I.D. x 0.95-cm wall, and an H-pile, 25.4-cm web x 85 kg/lineal m. The peak frost heaving forces on the H-pile for three consecutive winter seasons (1982-1985) were 752,790 and 802 kN, respectively. Peak frost heaving forces on the pipe pile of 1118 and 1115 kN were determined only for the second and third winter seasons. Maximum average shear stresses acting on the H-pile were 256,348 and 308 kPa during the three winter seasons. Maximum average shear stresses acting on the pipe pile were 627 and 972 kPa for the second and third winter seasons. Ice collars were placed around the tops of both piles during the first and third winter seasons to measure the adfreeze effects of a surface ice layer. The ice layer may have contributed 15 to 20% of the peak forces measured on the piles. A 0.6-m-thick gravel layer replaced the soil around the tops of both piles for the second and third winter seasons to measure the adfreeze effects of a gravel backfill. The gravel layer on the H-pile may have contributed about 35% of the peak forces measured. Maximum heaving forces and shear stresses occurred during periods of maximum cold and soil surface heave magnitude. These were not related to the depth of frost penetration for most of the winter since forst was present at all depths extending to the permafrost table. (mjm).

The subject of geomaterial interfaces recognizes the important influences of the interface behaviour on the performance of interfaces involving cementaceous materials such as concrete and steel, ice-structure interfaces, concrete-rock interfaces and interfaces encountered in soil reinforcement. During the past two decades, the subject of geomaterial interfaces has attracted the concerted attention of scientists and engineers both in geomechanics and applied mechanics. These efforts have been largely due to the observation that the conventional idealizations of the behaviour of interfaces between materials by frictionless contact, bonded contact, Coulomb friction or finite friction tend to omit many interesting and important influences of special relevance to geomaterials. The significant manner in which non-linear effects, dilatancy, contact degradation, hardening and softening, etc., can influence the behaviour of the interface is borne out by experimental evidence. As a result, in many instances, the response of the interface can be the governing criterion in the performance of a geomechanics problem. The primary objective of this volume is to provide a documentation of recent advances in the area of geomaterial interfaces. The volume consists of subject groupings which cover ice-structure, soil-structure and steel-concrete interfaces, mechanics of rock and concrete joints and interfaces in discrete systems.