Permafrost

element method to eliminate the oscillation of thermal gradient in the frozen fringe reported by
Shen and Konrad (1993).
Third, the one-dimensional model will be validated and verified using the field data on
pipe movement in the deep permafrost section of the Fairbanks pipeline test facility. Finally the
model will also be used to predict pipe movement for a life period when the major portion of
the total heave occurs.
Key words: Numerical analysis, predict, buried chilled gas pipeline
38
Test Research on Frost-Heave Amount by Artificial Ground Freezing
with Different Freezing Directions
Lin-lin Yu, Xue-yan Xu, Ming-guo Qiu
(School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China)
Abstract: As following merits, more flexible adaptability to complicated hydro-geologic
condition, high intensity, well water-resisting property, non-contamination to environment and
so on, artificial ground freezing is more and more recognized in subterranean works recent
years. As for present technology, there are certain environmental hazards, frost heave and thaw
collapse. Though excessive either of them will result in surficial inhomogeneous deformation,
destruction of structures, even grave engineering accidents, which and the influence on the
surrounding buildings, those problems don’t receive systemic research all along.
The paper studies the frost-heave amount generated by artificial ground freezing with
different freezing directions through combination of indoor test and finite-element numerical
simulation; estimating and analyzing by test, engineering certificating by numerical simulation,
analyzing and summarizing both results through correlated theories. To begin with, according to
Standard for Soil Test Method of frost-heave amount, adopt standard frost-heave-amount test
apparatus, ST5405 type high-low temperature freezing and thawing cycle testing box and
DT615 data taker system; carry out the frost-heave test on the samples of disturbed clay soil
under the condition of different moisture content, density, soil temperature, ambient
temperature; by varying the upside, downside, surrounding temperature, separately test and
research on the change features of frost heave, frost depth, temperature field with distinct
freezing modes as follows: from top to bottom, from bottom to top, from lateral to center
simulating the freezing course of construction program with artificial ground freezing method.
Test results reveal, under the same test conditions, the minimal frost-heave amount occurs in the
from-bottom-to-top freezing mode, the maximal in the from-top-to-bottom freezing mode,
consequently the from-bottom-to-top freezing mode can effectively reduce the frost-heave
amount in the practical engineering; when the frost heave happens, both the temperature filed
and the frost-heave factor of frozen soil are nearly stable, furthermore, the distribution of the
temperature field approximately linear. As the distance increasing between the freezing end and
each part of the samples, the alteration of the temperature field shows the rules of gradual decay.
According as the initial and boundary conditions, which on the basis of test research, apply
giant F. E. M. program to analyzing the practical engineering. The outcome indicates the results