Physically Based Equation for Phase Composition Curve of Frozen Soils

2013 ◽  
Vol 2349 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Zhen Liu ◽  
Xiong (Bill) Yu
Keyword(s):  
Phase Composition ◽  
Frozen Soils ◽  
Physically Based ◽  
Composition Curve

Using molecular dynamics to unravel phase composition behavior of nano-size pores in frozen soils: Does Young–Laplace equation apply in low temperature range?

2018 ◽  
Vol 55 (8) ◽  
pp. 1144-1153 ◽  
Author(s):  
Chao Zhang ◽  
Zhen Liu ◽  
Peng Deng
Keyword(s):  
Molecular Dynamics ◽  
Phase Composition ◽  
Low Temperature ◽  
Laplace Equation ◽  
Frozen Soils ◽  
Temperature Range ◽  
Fundamental Relationship ◽  
Physically Based ◽  
Composition Curve ◽  
Nano Size

The phase composition curve of frozen soils is a fundamental relationship in understanding permafrost and seasonally frozen soils. However, due to the complex interplay between adsorption and capillarity, a clear physically based understanding of the phase composition curve in the low temperature range, i.e., <265 K, is still absent. Especially, it is unclear whether the Young–Laplace equation corresponding to capillarity still holds in nano-size pores where adsorption could dominate. In this paper, a framework based on molecular dynamics was developed to investigate the phase transition behavior of water confined in nano-size pores. A series of simulations was conducted to unravel the effects of the pore size and wettability on the freezing and melting of pore water. This is the first time that the phase composition behavior of frozen soils is analyzed using molecular dynamics. It is found that the Young–Laplace equation may not apply in the low temperature range.

scholarly journals Change in Frozen Soils and Its Effect on Regional Hydrology in the Upper Heihe Basin, on the Northeastern Qinghai-Tibetan Plateau

2017 ◽  
Author(s):  
Bing Gao ◽  
Dawen Yang ◽  
Yue Qin ◽  
Yuhan Wang ◽  
Hongyi Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
Annual Runoff ◽  
Base Flow ◽  
Permafrost Degradation ◽  
Frozen Ground ◽  
Frozen Soils ◽  
Physically Based ◽  
Hydrological Cycles

Abstract. Frozen ground has an important role in regional hydrological cycles and ecosystems, especially on the Qinghai-Tibetan Plateau, which is characterized by high elevation and a dry climate. This study modified a distributed physically based hydrological model and applied it to simulate the long-term (from 1971 to 2013) change of frozen ground and its effect on hydrology in the upper Heihe basin located in the northeastern Qinghai-Tibetan Plateau. The model was validated carefully against data obtained from multiple ground-based observations. Based on the model simulations, we analyzed the changes of frozen soils and their effects on the hydrology. The results showed that the permafrost area shrank by 9.5 % (approximately 600 km2), especially in areas with elevation between 3500 m and 3900 m. The maximum frozen depth of seasonally frozen ground decreased at a rate of approximately 5.2 cm/10 yr, and the active layer depth over the permafrost increased by about 3.5 cm/10 yr. Runoff increased significantly during cold seasons (November–March) due to the increase in liquid soil moisture caused by rising soil temperature. Areas where permafrost changed into seasonally frozen ground at high elevation showed especially large changes in runoff. Annual runoff increased due to increased precipitation, the base flow increased due to permafrost degradation, and the actual evapotranspiration increased significantly due to increased precipitation and soil warming. The groundwater storage showed an increasing trend, which indicated that the groundwater recharge was enhanced due to the degradation of permafrost in the study area.

Naturally Frozen Soils from the Field to the Laboratory

ISCORD 2013 ◽  
2013 ◽  
Author(s):  
Benjamin A. Still ◽  
Zhaohui (Joey) Yang ◽  
Xiaoxuan Ge ◽  
Anthony Paris
Keyword(s):  
Frozen Soils
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