Use of the static penetration test in frozen soils

Abstract

Within the scope of a study on the use in frozen soils of some geotechnical field investigation methods, a series of deep, static and quasi-static, penetration tests was carried out in July 1974 at a permafrost site near Thompson, Manitoba. The field study included stress – and penetration rate – controlled tests, performed with an electric penetrometer, as well as several short-term and stage-loaded pressuremeter tests. The study shows that a static penetration test can furnish valuable information on the time-dependent strength of frozen soil, provided the test is conducted either with a very accurate control of the penetration rate, or as a stage-loaded test. It is considered that a comparison of frozen soil strengths deduced from such a test, with those determined by pressuremeter tests or triaxial compression tests, can only be made at comparable strain rates. An attempt was, therefore, made in the paper to find a relationship between the penetration rate and an equivalent time to failure for the soil surrounding the penetrometer tip, which enabled this comparison to be carried out.