The Mechanisms and Effects of Frost Heave Essay -- Soil Soils Agricult

The Mechanisms and Effects of Frost Heave ABSTRACT Frost heave is the increase in volume experienced by soils when they freeze. Water moves to the upper horizons from below; when it freezes it forms segregated ice lenses which push apart the soil around them as they grow, causing the observed volume increase. Frost heave has a number of effects upon the soil and upon structures supported by the soil which make it an important process to understand. INTRODUCTION During the freezing of some soils, nearly pure ice forms in segregated lenses parallel to soil isotherms (Hillel, 1980). The formation of these lenses causes frost heave, a phenomenon in which the surface of the soil is "heaved" vertically by as much as several tens of centimeters. The overall volume of the soil also increases greatly, and heave pressures of many atmospheres can build up (Mitchell, 1993). Frost heave often causes substantial soil disruption (cryoturbation) as well as damage to roads, fence posts, foundations, plants, and other structures within and on top of the soil. In this paper I will examine the mechanisms and effects of frost heave. MECHANISMS Early studies of frost heave hypothesized that the observed volume growth in the soil was entirely due to the increase in volume that occurs when soil water changes to ice. Experiments by Taber in the 1960's, however, demonstrated that frost heave occurred even in soils saturated in benzene and nitrobenzene, liquids that contract when they freeze (Hillel, 1980). This finding led to a search for the new mechanism, the particulars of which are still being resolved. Mitchell (1993) specifies three necessary conditions for ice segregation and frost heave to occur: 1. A frost susceptibl... ...in the soils of this region might be explained through frost heaving. Works Cited: Anderson, Suzanne Prestrud, 1988, The upfreezing process: Experiments with a single clast: Geological Society of America Bulletin, v. 100, p. 609-621. Clark, M.J. (Ed.), 1988, Advances in Periglacial Geomorphology: Chichester, John Wiley & Sons, 481 p. Dash, J.G., 1989, Thermonuclear Pressure in Surface Melting: Motivation for Frost Heave: Science, v. 246, p. 1591-1593. Durbin, Steve, Personal Communication on 10/12/96. Hillel, Daniel, 1980, Applications in Soil Physics: New York, Academic Press, Inc., 385 p. Mitchell, James K., 1993, Fundamentals of Soil Behavior: New York, John Wiley & Sons, 543 p. Smith, M.W., 1985, Observations of soil freezing and frost heave at Inuvik, Northwest Territories, Canada: Canadian Journal of Earth Science, v. 223, p. 283-290.