Liquefaction Criteria for Trans-Alaska Pipeline

The Trans-Alaska Pipeline traverses a wide range of climatic, topographic, geologic, and seismic regions. Liquefaction was a potential hazard along much of the route. Many potentially liquefiable soils which will become thawed are presently frozen, so field tests such as standard penetration could not be used. As the conventional liquefaction studies were not possible, alternate procedures were developed. A field decision manual was prepared for use when unusual conditions were found during construction. This enabled ready identification by field geologists and engineers of potentially liquefiable soils by simple tests and a means by which alternate designs should be considered. Only in special cases would project design engineers be involved. In some cases detailed studies were necessary. A detailed liquefaction study in Port Valdez is described. Laboratory testing of silts showed direct evidence that the time under which soil sustains load increases the resistance to liquefaction.