The Thawed Strength of Soil Compacted While Frozen: An Introductory Study

Abstract

Abstract In the northern United States and in Canada, expensive earthmoving equipment usually stands idle during winter months. Considerable overall economies would result if soil could be excavated, transported, and recompacted while frozen. If engineers are to accept winter operations with frozen soil, the soil after thawing should have a strength that approaches that of the same soil worked while unfrozen. This paper examines the strength of soil that is compacted while frozen and then thawed before shearing and compares it with the strength of the same soil compacted in an unfrozen state and never frozen. The thawed strength of frozen-while-compacted soil depends on its density, and therefore on the size, shape, and strength of the lumps of frozen soil and on the compactive effort. The influence of density (and indirectly the influence of compactive effort) on a thawed sand, a thawed silt, and a thawed clay are clearly outlined here. Work remains to be done to find the optimum frozen lump size and shape for each soil type and temperature, and then to develop the machinery needed to produce the optimum lumps in the field in winter.