Permafrost

several tenfold KPa to several tenfold MPa according to different constraint condition. The
design of tunnel lining structure should be in accordance with different frost force for the sake
of being both safe and economical. By FEM numerical simulation, the partition standard of
frost force rank of tunnel in frozen earth could be found.
Key words: tunnel; frost force rank; FEM numerical simulation; frozen earth
28
Heat transfer characteristics of Qinghai-Tibet railway embankment
with crushed-stone side slope in permafrost regions
Guoyu Li 1 , Ning Li 1,2 , Jiamei Kang 2
(1. State Key Laboratory of Frozen Soil Engineering, CAREERI, Chinese Academy of Science, Lanzhou,
Gansu 730000, China;
2. Institute of Geotechnical Engineering, Xi’an University of Technology, Xi’an, Shanxi 710048, China)
Abstract:The embankment with crushed-stone side slope in permafrost regions is an effective
measure cooling subgrade and protecting permafrost. Considering the influence of the nocturnal
cold air on the embankment with crushed-stone side slope in summer seasons in Plateau, the
numerical analyses for the temperature field and thermal flow of the embankment at Beiluhe
Test Base along Qinghai-Tibet railway were conducted on a full day in the present paper. The
results show that the embankment with crushed-stone side slope releases less heat from the
embankment in nighttime than that absorbed in daytime. This suggests that the embankment
with crushed-stone side slope has cooling effect in nighttime. In addition, the present paper
considered the difference of the heat transfer of the embankment between cold seasons and
warm seasons and studied the change characters of the temperature field and thermal flow of
the embankment. The results show that the embankment with crushed-stone side slope released
more heat in cold seasons that that absorbed in warm seasons from the change of the thermal
flow monitored. This is useful for protecting permafrost underlying railway embankment.
Key words: Qinghai-Tibet railway, embankment with crushed-stone side slope,
thermal diode effect, thermal flow, cooling effect
Management and incident Analysis of Underground Gas Pipeline of
Cities in Cold Area
Hong-sheng Li, Zeng-li Liu, Xiao-peng Zhang
(Department of Engineering Mechanics, Dalian University of Technology,116024, Dalian, P.R. China)
Abstract: Crack incidents of municipal underground gas pipeline occur quite frequently in cold
regions in northern part of China, which could be attributed to the following causes: defective
design, unregulated construction and lack of stringent management. With respect to design,
there exists insufficient buried depth as well as effect of frost heaving force caused by freezing
soil has not been taken into account while temperature shock happens. Crack of pipeline due to