The permafrost with the highest altitude and largest area in the mid and low latitude is located in the Qing-hai-Tibet Plateau. As most frozen soils contain ice particles which are very sensitive to temperature and ot...The permafrost with the highest altitude and largest area in the mid and low latitude is located in the Qing-hai-Tibet Plateau. As most frozen soils contain ice particles which are very sensitive to temperature and other externalparameters, thus influencing the stability of the embankment in permafrost regions, it is very important todevelop techniques to prevent damages to railway embankments due to thaw settlement. In this paper, the electricalcapacitance sensors are designed to study the freezing front movement in a vessel and ice movement in water,which is the first step to apply the ECT system to the study of frozen soil. Two sensor arrangements are put intouse. First, the traditional closed electrode sensors are put into use. In this arrangement, the electrodes are attachedto the outside of the pipe or vessel, and the cross-sectional distribution of ice and water could be reconstructedfrom the capacitances measured. Also, the ice moving track at the cross section could be reflected thoroughly.Since the traditional closed electrode sensors can not meet the needs of measuring the ice freezing front movement,a new electrode sensors structure, that is, the unclosed electrode sensors are designed to satisfy the specifictest of frozen soil. In this arrangement, several pairs of electrodes are arranged along the height of the vessel. Asudden decrease in the measured capacitance is observed when the freezing front advances past the electrodes.Therefore, according to the capacitance variation, the ice movement can be reflected. In summary, electrical capacitancetomography has the advantages of being non-intrusive. With different electrode sensor arrangement, icemovement and ice freezing front can be obtained. The electrical capacitance sensor system can be applied to investigatethe complicated phenomena in frozen soil.展开更多
基金supported by a grant of the Knowledge Innovation Program of the Chinese Academy of Sciences (grant no. KZCX1-SW-04)the National Natural Science Fund (grant no. 40501017).
文摘The permafrost with the highest altitude and largest area in the mid and low latitude is located in the Qing-hai-Tibet Plateau. As most frozen soils contain ice particles which are very sensitive to temperature and other externalparameters, thus influencing the stability of the embankment in permafrost regions, it is very important todevelop techniques to prevent damages to railway embankments due to thaw settlement. In this paper, the electricalcapacitance sensors are designed to study the freezing front movement in a vessel and ice movement in water,which is the first step to apply the ECT system to the study of frozen soil. Two sensor arrangements are put intouse. First, the traditional closed electrode sensors are put into use. In this arrangement, the electrodes are attachedto the outside of the pipe or vessel, and the cross-sectional distribution of ice and water could be reconstructedfrom the capacitances measured. Also, the ice moving track at the cross section could be reflected thoroughly.Since the traditional closed electrode sensors can not meet the needs of measuring the ice freezing front movement,a new electrode sensors structure, that is, the unclosed electrode sensors are designed to satisfy the specifictest of frozen soil. In this arrangement, several pairs of electrodes are arranged along the height of the vessel. Asudden decrease in the measured capacitance is observed when the freezing front advances past the electrodes.Therefore, according to the capacitance variation, the ice movement can be reflected. In summary, electrical capacitancetomography has the advantages of being non-intrusive. With different electrode sensor arrangement, icemovement and ice freezing front can be obtained. The electrical capacitance sensor system can be applied to investigatethe complicated phenomena in frozen soil.
