Thermal accumulation mechanism of asphalt pavement in permafrost regions of the Qinghai–Tibet Plateau

Zhang, Zhongqiong; Wu, Qingbai; Liu, Yongzhi; Zhang, Ze; Wu, Guoqing

doi:10.1016/j.applthermaleng.2017.10.065

Cited by 41 publications

(27 citation statements)

References 15 publications

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“…The direction of water movement was perpendicular to the water contour line and to the center of the roadbed. 8 However, heat accumulation occurred below the depth of 3 m at the center of the roadbed and displayed a disk-shaped isotherm ( Figure 9C). Water content under the shoulder was higher than that under the central section of the roadbed.…”

Section: Liquid Water Migration and Vapor Condensationmentioning

confidence: 99%

“…According to the heat conduction theory, when the G and the transfer depth (distance) are constant, the λ is inversely proportional to the amount of temperature change that occurs within a given depth range, 29 meaning that the G decreases with an increase in depth. 8 During TP, the ice in pore phase to liquid water, which absorbs a large amount of heat, and the λ will be abrupt, and under these circumstances, the thawing time is extended. According to the observed data, the thawing date of the asphalt pavement (AC-13 layer) above 5 cm depth was approximately 35 days later than that of the underlying structure.…”

Section: Thermal Properties and Thawingfreezing Processesmentioning

confidence: 99%

“…8 Changes in water and temperature have also been shown to be coupled. Embankment materials and soil in cold regions undergo FP-TP, which aggravates damage to pavement.…”

mentioning

confidence: 99%

“…Numerous findings on heat absorption and temperature variation in asphalt pavement have been obtained and demonstrate that asphalt pavement experiences thermal accumulation. 8 Changes in water and temperature have also been shown to be coupled. The formation of thawing corridors in the bottoms of roadbeds was first observed in the 1980s, and the role of water in heat accumulation was first noticed in cold regions.…”

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confidence: 99%

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Hydrothermal accumulation under asphalt pavement in cold regions

Zhang

et al. 2019

Energy Science & Engineering

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Water and heat changes are the main problems that plague the stability and service performance of roadbeds in cold regions. Though hydrothermal transfer and accumulation directly affect roadbed properties, these processes remain poorly understood as monitoring data are often collected over short time periods and large spacing in depth. This research compares water and temperature data collected from 2012 to 2015 to elucidate the physical mechanisms of hydrothermal accumulation under both asphalt pavement and original pavement. These thermal and physical mechanisms include differences in the freezing process (FP) and the thawing process (TP), water transport, condensation, and hydrothermal accumulation. For instance, when compared to the underlying layer, the thawing of the surface layer of asphalt pavement was delayed by 35 days because of differences in hydrothermal properties. During TP, liquid water content changes from 3.31%‐13.2% to 15%‐37.67%, and the unfrozen water content of the soil layers under the asphalt pavement was approximately 6.85%‐12.34% higher than that of the soil layers under the original pavement. A layer with high water content and heat formed under the surface layer of asphalt pavement and provided the appropriate conditions for vapor transport and condensation. Soil layers thawed early in the preceding year, and this hydrothermal accumulation occurred on an annual basis. The annual minimum monthly average temperature was thus found to be increasing at the rate of 0.34°C/y. As water content also accounts for heat accumulation and was found to be more sensitive to change than temperature, the results of this study can provide theoretical and technical data useful for highway construction and design in permafrost regions.

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Section: Liquid Water Migration and Vapor Condensationmentioning

confidence: 99%

Section: Thermal Properties and Thawingfreezing Processesmentioning

confidence: 99%

“…8 Changes in water and temperature have also been shown to be coupled. Embankment materials and soil in cold regions undergo FP-TP, which aggravates damage to pavement.…”

mentioning

confidence: 99%

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confidence: 99%

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Hydrothermal accumulation under asphalt pavement in cold regions

Zhang

et al. 2019

Energy Science & Engineering

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“…Existing studies show that linear engineering projects (road pavement and operation) are the dominant factor responsible for such degradation [7,8]. Road pavement and operation disturb the water-heat balance between natural ground and atmosphere, thereby leading to temperature rise and permafrost degradation [9]. Consequently, permafrost degradation strongly affects the geohydrological cycle, which can cause unexpected environmental and engineering disasters.…”

Section: Introductionmentioning

confidence: 99%

Understanding Thermal Impact of Roads on Permafrost Using Normalized Spectral Entropy

Zhang

Zhao

et al. 2019

Sustainability

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Permafrost is characterized by low temperature, and its thermal stability is key to geohydrological cycles, energy exchange, and climate regulation. Increasing engineering activities, i.e., road construction and operations, are affecting the thermal stability in permafrost regions and have already led to the degradation of permafrost and caused environmental problems. To understand the spatiotemporal influence of road construction and operations on the thermal dynamics in permafrost regions, we conducted a study in the Ela Mountain Pass where multiple roads intersect on the Qinghai–Tibet Plateau (QTP) and calculated the thermal dynamics from 2000 to 2017 using normalized spectral entropy (measuring the disorderliness of time-series data). Our results indicate that road level is a significant influencing factor, where high-level roads (expressways) exhibit stronger thermal impacts than low-level roads (province- and county-level roads). Our results also indicate that duration of operation is the most significant factor that determines the thermal impacts of roads on permafrost: the thermal impacts of the newly paved expressway are positively related to elevation, while the thermal impacts of the old expressway are positively related to less vegetated areas. The study provides an excellent method for understanding the spatiotemporal impacts of engineering activities on the temperature dynamics in permafrost regions, thereby helping policymakers in China and other countries to better plan their infrastructure projects to avoid environmentally vulnerable regions. The study also calls for advanced techniques in road maintenance, which can reduce the accumulated disturbance of road operations on permafrost regions.

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Permafrost research in China related to express highway construction

Wang¹,

Niu

Chen³

et al. 2020

Permafrost & Periglacial

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Express highways are roads of high speed, large capacity, and transportation flexibility. The network of express highways in China has been developed over the last 30 years to accommodate the needs of a growing population and to facilitate economic development. Part of the network is in permafrost regions, where the construction and maintenance of these roads present significant engineering challenges due to permafrost degradation induced by climate warming and by construction. This paper summarizes the engineering problems encountered in the construction and maintenance of these express highways, and the mitigation techniques used to overcome them on new transportation projects in permafrost regions. Ten types of engineering problems along the Qinghai‐Tibet Highway, the oldest and longest highway in the permafrost regions of China are identified. Their main cause is related to permafrost degradation in the subgrade beneath the road subbase. Settlement of the highway embankment due to thaw consolidation of degrading permafrost is the dominant mechanical distress observed. Mitigation techniques, mainly for enhancing heat convection beneath express highways, are discussed along with their effects. Research in China related to transportation projects may provide a reference for future express highway design and construction in permafrost regions around the world.

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Thermal accumulation mechanism of asphalt pavement in permafrost regions of the Qinghai–Tibet Plateau

Cited by 41 publications

References 15 publications

Hydrothermal accumulation under asphalt pavement in cold regions

Hydrothermal accumulation under asphalt pavement in cold regions

Understanding Thermal Impact of Roads on Permafrost Using Normalized Spectral Entropy

Permafrost research in China related to express highway construction

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