Permafrost

Experimental and numerical simulation study on the relation between
the freezing mode and frost heave
Xiang-yu Shang, Guo-qing Zhou, Jin-sheng Zhou
(School of Architecture and Civil Engineering,China University of Ming & Technology)
Abstract: Since frost heave in frozen soil is depended directly on the freezing mode, it can be
controlled in a relative small range by adjusting freezing modes. This paper aims at revealing
the relation between freezing mode and frost heave and finding out an efficient freezing mode,
which gets a light frost heave after reaching the same design frost depth as other modes. The
variable characteristics of the frost depth, the frost heave and the temperature field of the
Tibetan Clay under the different freezing modes including continuous mode, stepwise mode and
continuous-intermissive mode were studied by means of experiment and numerical simulation.
The continuous mode and stepwise mode’s test results show that when the frost heave is
happened, the temperature field of soil is basically stable and the distribution of the temperature
field is almost linear. The stepwise and continuous-intermissive mode’s test result show that, as
the distance away from the cooling end is increasing, the hysteresis of the response to the
temperature changing of the cooling end is more and more prominent. According to the
aforementioned conclusions, the continuous-intermissive mode may be an efficient freezing
mode because it can easily destroy the linear temperature distribution and make it unstable. The
test results have proved this point, that is to say, continuous-intermissive mode can control frost
heave effectively. This paper exposed that continuous-intermissive freezing mode of high
frequency, the number of cooling end’s temperature change cycles of a periodic process
occurring per unit time, is more efficient than that of low frequency to restrain the development
of the frost heave, and the extent of the cooling end’s temperature change has some effect on
the frost heave. Based on the improved algorithm of heat and moisture coupled model, a
self-made finite difference program was made to simulate the frost heave. On the whole, the
result of simulation is quite consistent with the test result, which indicates that the conclusions
obtained in the article are credible. Two test not be done in practice were then simulated, which
concludes that if continuous-intermissive mode’s variable frequency of cold end is too high,
effectiveness of the mode’s restraining frost heave can be decreased.
Key words: frozen soil; frost heave; freezing mode; experiment; numerical simulation
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