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Temperature and moisture variations were experimentally investigated for the subgrade of the Astana-Burabai Highway, located in the northern region of Kazakhstan.Temperature and moisture were measured by means of specially manufactured sensors,including an element for temperature measurement based on the effect of thermal resistance and an element for moisture measurement through diamagnetic permeability.It was determined that the long-term average depth of frost penetration was 237 cm.In the upper part of the subgrade with 1 m of thickness,the average duration of a frozen condition decreases toward the bottom from 131 days to 117 days,with an average rate of 0.133 day/cm.The unfrozen water content decreases with the negative temperature reduction.In the case of high values of initial moisture (12%~22%),the unfrozen water content does not depend on the initial moisture;and it decreases under the power law,with reduction of negative temperature.In the case of the lowest values of moisture (9%~12%),the unfrozen water content depends also on negative temperature;but its values are considerably lower. 相似文献
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The thawing-melting of the permafrost damages the subground of highways on the Qinghai-Tibet Plateau. With the application of ground-penetrating-radar (GPR) technology, the maximum permafrost melting interface can be effectively distinctly differentiated and imaged. A hierarchical feature of the permafrost region is shown clearly on the imaging profile of GPR data. The complete ablation zone or part of it is displayed distinctly. In addition, the details of subsurface layers can be effectively characterized by GPR attribute-analysis technology. With the attribute calculation and filter, the instantaneous amplitude, instantaneous frequency, and relative wave impedance can be applied in a more efficient way to divide the complete ablation zone, part of the ablation and non-ablation interface. The relative distribution of water content in a seasonally thawing permafrost region can be obtained through a comprehensive GPR attribute analysis. 相似文献
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