A new concept of frost-heave characteristics of soils

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science and Technology, 16, 3, pp. 271-279, 1989-07-01 A new concept of frost-heave characteristics of soils Svec, O. J. Cold Regions INTRODUCTIONThe classification of soils according to their frostsusceptibility has been used in the design of roads and airfields to minimize damage occurring due to frost action. To determine the frost-susceptibility index to a satisfactory level of confidence, additional freezing tests are often required.Problems with commercial tests stem from requirements that the tests must be simple, of short duration and inexpensive. On the other hand, it is very difficult to handle a complex problem by simple means. In fact, such an approach could often lead to erroneous and misleading results. BACKGROUNDA comprehensive survey of transportation departments throughout the world by Chamberlain ( 198 1 ) revealed that most agencies are using their own unique frost-susceptibility criteria. In addition, freezing tests employed for this purpose are poorly designed and executed; only frost heave or thaw weakening, rather than both, are considered. As a result, the frost-susceptibility index does not represent the actual heaving or thaw-weakening potential, particularly for marginally frost-susceptible soils. Recognizing this problem, Chamberlain (1987), of the Cold Regions Research and Engineering Laboratory (CRREL), developed and proposed a new five-day freezing test. Its main feature, other than improved equipment and data acquisition and control, is that it requires two freeze-thaw cycles and the California Bearing Ratio (CBR) test. The frost-susceptibility index is then defined as the heave rate at the end of the first eight hours of each two-day freeze-thaw cycle. The repetition of the freeze-thaw cycle accounts for the changes in susceptibility to frost heave in frost virgin material. The CBR test, which is performed after the second thaw, yields the thaw-weakening index. The important feature of this new test is that the results of both tests are then used to determine the frost-heave potential. NEEDS AND OBJECTIVESThe drawback of all tests used today is that the thermal boundary conditions are chosen not because they reflect the freezing conditions in the ground as they occur in nature, but rather to provide a convenient testing procedure. For example, the temperature gradient used in the newest CRREL freezing tests is 0.4 "C cm-'. Such high gradients do not occur in nature frequently and, moreover, ...

Effect of freeze–thaw on the hydraulic conductivity and morphology of compacted clay

“…Consequently, more cracks are available for flow and the hydraulic conductivity increases. However, under a very high rate of freezing, ice lenses may not form or may not be visible (Konrad and Morgenstern 1980;Svec 1989). Hydraulic conductivity under these conditions is still unknown.…”

Frost Heave Induced Mechanics of Buried Pipelines

“…The presence of a chilled gas pipeline would, however, result in the freezing of unfrozen soil in shallow discontinuous permafrost. The presence of a chilled gas pipeline in a frost-susceptible zone can also result in the gradual development of a zone of frozen soil around the pipeline (Slusarchuck et al 1978;Myrich et al 1982;Konrad and Morgenstern 1984;Dallimore and Williams 1984;Bahmanyar and Harrison 1985;Nixon 1987aNixon , 1987bSvec 1989;Shen and Ladanyi 1991).…”

Effect of particle trapping on frost heaving soils

“…Comparison of ( 28), ( 27) and (11) gives K 0 = SP 0 T m g/L f . Equations ( 28) and ( 27) imply that SP is independent of the freezing rate; however, experiments by Konrad and Morgenstern [17,27], Svec [26] and Kim [59] show that during the early stages of transient frost heave experiments the measured segregation potential SP = v w /G T depends on the freezing rate and can be much smaller than predicted by (27) or (28).…”

“…Konrad and Morgenstern tabulated SP as a function of soil properties, overburden pressure and salinity for a variety of soils [16,17], and several studies by them and others have demonstrated its usefulness in the prediction of frost heave rates in field situations [18][19][20][21][22][23][24]. However, a shortcoming of frost heave models based on the SP concept is a tendency to overpredict the rate of frost heave at early times in step freezing tests, when the freezing rate is high [16,19,20,25,26]. As noted by Konrad and Morgenstern [6,27], Sego et al [25] and Svec [26], at very high freezing rates SP is no longer a unique function of soil properties but depends also on the rate of freezing.…”

“…However, a shortcoming of frost heave models based on the SP concept is a tendency to overpredict the rate of frost heave at early times in step freezing tests, when the freezing rate is high [16,19,20,25,26]. As noted by Konrad and Morgenstern [6,27], Sego et al [25] and Svec [26], at very high freezing rates SP is no longer a unique function of soil properties but depends also on the rate of freezing. This is in part because at very high freezing rates the soil water freezes in situ and the water intake rate v w approaches zero, or can even be negative (water expulsion) [17,28].…”