Long-Term Thermal Regimes of Subgrade under a Drainage Channel in High-Altitudinal Permafrost Environment

Yu, Hong; Han, Hongwu; Ma, Wei; Ding, Zekun; Chen, Ling

doi:https://doi.org/10.1155/2021/6613114

Advances in Materials Science and Engineering

On this page

Abstract Introduction Results and Analysis Conclusions Data Availability Conflicts of Interest Acknowledgments References Copyright Related Articles

Special Issue

Hydraulic Engineering in Cold Regions: Materials, Structures, and Climate Impacts

View this Special Issue

Research Article | Open Access

Volume 2021 | Article ID 6613114 | https://doi.org/10.1155/2021/6613114

Long-Term Thermal Regimes of Subgrade under a Drainage Channel in High-Altitudinal Permafrost Environment

Hong Yu,^1,2,3Hongwu Han,⁴Wei Ma,^2,3Zekun Ding,^2,3and Ling Chen^2,3

Academic Editor: Ying-hao Huang

Received04 Jan 2021

Revised23 Jan 2021

Accepted02 Feb 2021

Published12 Feb 2021

Abstract

In permafrost regions, construction of a channel involves a large amount of excavation activities and changes to surface water body, which can exert great impacts on the thermal regimes of permafrost underlying. In this paper, a coupled mathematical model of heat and moisture transfer was constructed for freeze-thaw soils to investigate the long-term thermal regimes of subgrade beneath a drainage channel built on the Qinghai-Tibet Plateau. Based on the numerical simulations, the thermal regimes of the subgrade both in warm and cold seasons were analyzed within a period of 50 years, as well as the impact of the widths of the channel. The results showed that the channel excavation and flowing water within could lead to a significant underlying permafrost degradation. During the first 30 years, the permafrost beneath the channel mainly experienced a rapid downward degradation. After that, the lateral thermal erosion of the flowing water led to a rapid permafrost degradation beneath the slope of the channel. In cold seasons, the shallow ground beneath the channel would not refreeze due to the flowing water and the thaw bulb actually expanded throughout the year. For the channel with a bottom width of 15 m, the thaw bulb beneath the channel could expand laterally to the natural ground about 10 m far away from the slope shoulder of channel till the 50th year. With different widths, the long-term thermal regimes of the subgrade beneath the channels differed considerably and the maximum difference was at the slope toe of the embankment. With the numerical simulated results, it is recommended that a channel built on permafrost should be wide-and-shallow rather than narrow-and-deep if conditions permit.

1. Introduction

Permafrost is defined as ground (soil or rock including ice) with a temperature at or below 0°C for at least two consecutive years [1, 2]. A quarter of the Northern Hemisphere and 17% of the exposed land surface of earth are underlain by permafrost [3]. The distribution of permafrost on earth can be of altitudinal and latitudinal character [4]. In China, the permafrost area accounts for 22% of the total land area, which is mainly distributed on the Qinghai-Tibet Plateau (QTP), the Northeastern China, and the high mountain areas in the Northwestern China. With an average elevation of more than 4000 m, the QTP has the largest distribution of altitudinal permafrost on earth [5]. Compared with latitudinal permafrost in the Northern America and Siberia, the permafrost on the QTP is characterized with high temperatures and thermal unstable, thus being more sensitive to climatic changes and human activities [6–8].

The QTP is also known as the Asian Water Tower. It is one of the three major distribution areas of lakes in China, and its lake area accounts for more than 50% of the total in China [9, 10]. In the context of global warming, the climate warming and wetting on the QTP was significant during the past decades, which led to significant changes in lake number and area [11–14]. The recent estimations showed that, since the mid-1990s, the area, level, and volume of lakes on the QTP showed a continuous increase [15, 16]. In a study by Liu et al. [17], a rapid expansion since 2000 was observed for lakes in the endorheic basin on the QTP, particularly in the Hoh Xil region with a continuous permafrost distribution. The rapid expansion of lakes could cause flood disasters, which may exert significant threatens to the production and living of local communities, as well as major engineering infrastructures nearby [18–20].

In 2011, the Zonag Lake in the central of the Hoh Xil regions burst suddenly, which was an extreme case of lake evolution on the QTP. After the outburst, a deep and wide gully developed at the breaking point and the flood entered the downstream lakes including the Kusai Lake, Haiding Nor Lake, and Yanhu Lake. At present, the four lakes are already connected together, and the first three ones lost their storage functions, making the Yanhu Lake become a tail-end-lake [21–24]. From 2011 to 2019, the surface area of the Zonag Lake decreased from 269 to 150 km², while the surface area of Yanhu Lake increased by almost 3 times from 73 to 209 km² [5, 25]. Considering the rapid changes, some researchers conducted predictions and concluded that an overflow would occur to the Yanhu Lake in a minimum of one to two years [21]. At about 10 km downstream the Yanhu Lake, there are the Qinghai-Tibet Railway, Qinghai-Tibet Highway, Qinghai-Tibet Power Transmission Line, Golmud-Lhasa Oil Pipeline, as well as several communication cables. It is well-known that all of them are of great importance for social and economic ties between the Tibet Autonomous Region and the inner China [26–28]. If the Yanhu Lake burst in an uncontrollable condition, these major linear infrastructures would be in danger and even be destroyed by the outburst flood.

To prevent this projected flood disaster, a large-scale drainage project was conducted in 2019 between the potential breaking point of the Yanhu Lake and the Qingshui River at the downstream [9, 29]. When serving as subgrade of man-made infrastructure, the physical and mechanical properties of permafrost are closely related to its thermal regimes [30–33]. Meanwhile, along with seasonal freezing and thawing in the active layer, significant (differential) frost heave and thaw subsidence would occur at the ground surface, which can cause series of damages to structures built upon [34]. Thus, the thermal regime of permafrost is a key variable that determines the bearing capacity and deformation of foundations and the long-term stability and integrity of the structures upon [35–38]. With regard to evolution of permafrost thermal regimes beneath hydraulic structures, the related research studies were scarce as there has been almost no large-scale hydraulic engineering conducted in continuous permafrost regions. In related fields, research studies on thermal interactions between thermokarst lake and underlying permafrost were conducted both in latitudinal and altitudinal permafrost environments. In 1978, a large tundra lake was drained to study the aggradation of permafrost into newly exposed lake-bottom sediments, and the active-layer thickness, snow depth, minimum soil temperatures, near-surface ground ice, soil heave, and permafrost temperatures had been measured for over 20 years [39]. Lin et al. [40] conducted filed observations on water and ground temperatures beneath and around a 2 m deep thermokarst lake on the QTP and found that the mean annual ground temperatures beneath the thermokarst lake were more 5°C higher than those in the surrounding terrain at the same depths. In a study by Niu et al. [41], characteristics of about 250 thermokarst lakes on the QTP were investigated and their influences on permafrost were evaluated based on field measurements in ground temperatures around a lake in the Beiluhe Basin. Through using numerical methods, Wen et al. [42] and Ling and Zhang [43] simulated the temporal and spatial variation of ground temperature and talik thickness beneath an expanding thermokarst lake on the QTP and the Alakan Arctic, respectively. In a study by Wen et al. [42], the lake was assumed to expand linearly with time both in radius and depth, while in a study by Ling and Zhang [43], the lake was assumed to expand linearly with time only in radius. Li et al. [44] conducted a moisture-heat coupled numerical simulation to investigate the permafrost degradation beneath a thermokarst pond with consideration of climate warming. Compared with thermokarst lakes, however, the thermal impact of a drainage channel to underlying permafrost may be more significant and complex due to the excavation of the channel and the running water within the channel. With regard to channels built in cold regions, Li et al. [45] established a moisture-heat-mechanic couple mathematic model and investigated the freeze-thaw influence on the channel using numerical simulations. Considering the effects of the seepage water, Zhang et al. [46, 47] investigated the thermal regimes of the permafrost beneath the dike with various antiseepage measures.

In this paper, the drainage channel of the Yanhu Lake was taken as an example and the thermal interactions among the drainage channel, the drainage water body, and the underlying permafrost subgrade were investigated through field observations and numerical simulations. With the Harlan model and Richard equation, a coupled mathematic model for heat and moisture transfer in freezing-thawing soils was established. Then, a numerical model was constructed based on the engineering geotechnical investigation conducted in the field and the dimensions of the drainage channel. The numerical model was validated with field observations carried out at the drainage channel. Then, the long-term evolution of thermal regimes of permafrost beneath the drainage with three bottom widths was investigated after a validation through using numerical simulations. It is hoped that the results of this study can provide scientific references for predicting and warning of the safe operation of the drainage channel.

2. Mathematical Model and Governing Equations

2.1. Liquid Water Flows

Without considering the effects of water vapor, the equivalent volume of water content θ in freeze-thaw soil based on the law of mass conservation can be expressed as follows:where θ is the equivalent volume of water content (m³·m⁻³); θ_u is the volume of unfrozen water content (m³·m⁻³); θ_i is the volume of ice content (m³·m⁻³); ρ_i is the density of ice (kg·m⁻³); is the density of water (kg·m⁻³); t is the time; and q_lh is the liquid water flux density which can represent liquid flows due to a pressure head gradient (m·s⁻¹).

The migration of liquid water under potential gradient in frozen soil is similar to that in unfrozen unsaturated soil based on the Harlan model and can be described by Richard equation [48, 49]. Then, it is mainly influenced by the factors including water potential gradient and hydraulic conductivity of soils. The values of water potential gradient and hydraulic conductivity in unfrozen and frozen soils differ considerably, while the regulation of water migration can still be assumed to Darcy’s law [50]. Only considering the potential gradient, the flux density of liquid water can be expressed as follows [51, 52]:where y is the vertical coordinate (m); h is the pressure head (m); and K_lh is the water conductivity coefficient of liquid water under the action of soil-water potential gradient (m·s⁻¹). Then, considering the equivalent volume water content θ as a dependent variable, the mass conservation equation of liquid water in unfrozen and frozen soils can be written as follows [53]:

The relationship between the amount of water and energy in the soil can be reflected by soil-water characteristic curve (SWCC). Then, SWCC also can represent the relationship between matric, volume water content, and saturation in frozen and unfrozen soils [52]. In this study, the van Genuchten model and Mualem model are adopted to describe the hydraulic properties of unsaturated freeze-thaw soil [53, 54]. The hydraulic properties can be written as follows:where S_e is the effective saturation; K_s is the saturation water conductivity coefficient (m·s⁻¹); θ_l, θ_s, and θ_r are liquid water content, saturated liquid water content, and residual water content (m³·m⁻³); α is the derivative of the soil intake value (m⁻¹); m = 1–1/n; and n and l are experience parameters, and Mualem suggested that l could be determined as 0.5 [54].

2.2. Heat Transfer

Compared with the heat conduction with phase change of ice to water, the energy released by the heat convection was very small and could be neglected during the heat transfer analysis of freeze-thaw soil [55–57]. Then, the governing equations of heat transfer in freeze-thaw soil can be written as follows [49]:where C_m is the equivalent volume heat capacity and λ_m is the equivalent thermal conductivity. According to the method of sensible heat capacity, equivalent volume heat capacity C_m and equivalent thermal conductivity λ_m in freeze-thaw soils can be written as follows [55, 58]:where T_f ± ∆T is the temperature range of phase change; C_u and λ_u are the volume heat capacity and thermal conductivity of unfrozen soil; C_f and λ_f are the volume heat capacity and thermal conductivity of frozen soil; and L_s is the latent heat of phase change in per unit volume. While the temperature ranges of phase change in different soil are difficult to gain, the heat transfer equation adopted in this study is written as follows [49]:where is the volume heat capacity; is the thermal conductivity; and is the latent heat of freezing of liquid water (approximately 3.34 × 10⁵ J·kg⁻¹).

After soil freezing, not all liquid water can be transferred to solid ice. The rest of liquid water is called as unfrozen water. Then, the unfrozen water content is related to factors including the temperature, pressure, water salinity, mineralogy, soil specific surface area, and soil surface chemistry [59–62]. Based on previous work and related theories, the empirical expression as follows is used to determine the maximum unfrozen water content in the freezing process [49, 50, 52]:where a and b are parameters related to the soil properties. The volume liquid water content can be determined by temperature and equivalent volume [50, 52]:where T_f is the freezing point of saturated soil (0°C). Previous studies showed that the freezing point of soil is not a fixed value, and the ice grows only when the water content exceeds θ_umax [63].

3. A Drainage Channel Built in High-Altitude Permafrost Environment

3.1. Study Area and Drainage Channel

In this study, the drainage channel built for Yanhu Lake, in the Hoh Xil region on the QTP, was taken as an example. In the area, the elevation ranges from 4460 to 4500 m a.s.l. The meteorological data were collected from the Wu Daoliang weather station, which is about 70 km far away from the channel. The collected data showed that, in the period from 1965 to 2019, the main annual air temperature ranged from −6.5 to 3.7°C and the main annual precipitation ranged from 136 to 480 mm. Since the 1980s, the climate warming and wetting at the region was significant.

A standard whether station was set up at the channel in 2020. Figure 1 shows the observed air temperatures during the monitoring period from 24 May to 10 November in 2020. In the period, the maximum air temperature reached to 12°C, which appeared in mid-August. Combined with the collected air temperatures from the Wu Daoliang weather station, the air temperature at the projected area can be fitted using a sinusoidal function as follows:where t is the time (d).

3.2. Ground Temperature Observation at the Channel

To observe thermal regimes of permafrost subgrade beneath the channel, three ground temperature boreholes including natural ground (NG), slope shoulder (SS), and slope toe (ST) of the channel were drilled after excavation of the channel (Figure 2). The three boreholes were 20 m in depth. Considering the symmetry of the channel, the three boreholes were all arranged at one side of the channel. Within each borehole, 32 ground temperature sensors were installed with a spacing of 0.5 m between 0–10 m depth and of 1 m below 10 m depth. The measurement range of the sensor is from −40 to 40°C, with an accuracy of ±0.05°C. All the sensors were connected to a CR6 data collector, and the observation frequency of ground temperatures was 6 hours.

4. Numerical Simulations and Results Analysis

4.1. Computational Model

Previous studies showed that the boundary error would be less than 10% when the computational domain is 3–5 times of the equivalent diameter of the model [64]. In this study, the computational model was constructed based on the actual dimension of the channel. The depth of the channel was 4.7 m, and the bottom width was set as 25 m. The slope of the channel was released by 1 : 3. At present, the water depth within the channel was determined as 1 m throughout one year based on the field survey. The computation on thermal regimes of subgrade under the channel can be simplified as a 2D unsteady heat transfer problem.

According to the geological survey conducted before the drainage excavation, the soil strata can be simplified as sandy gravel, silty clay, and weathered mudstone from the surface down. The thermal and hydraulic parameters of the three soil layers are listed in Table 1, which were gained based on the borehole drillings and related laboratory tests [34, 49, 50, 52, 65].

4.2. Boundary Conditions

According to the meteorological data from the Wu Daoliang weather station, the long-term air temperatures in the study area showed a linear increase with the rate of 0.33°C/10a. Then, based on the adherent layer theory [62], the upper boundaries of GF and FE were set as temperature boundary:where t is the time (d).

As an alternative to heat budget models, linear correlations between air and water temperatures during open water periods were studied widely in previous studies [66]. Based on the analysis of a stream’s heat transport/budget equation, the air temperature shows a good linear relationship with water temperature. The relationship between the water temperature in the lake and the air temperature can be linearly fitted as follows:where and T_a(t) are the water temperature and the air temperature in the same time scale; A and B are constants; and t is the time (d).

According to the observed water temperatures (equation (15)) in lakes near the study area [40] and the air temperature showed as equation (16), the two constants of A and B in equation (14) used in this study were determined as follows:where t is the time (d).

Without considering the impacts of artificial heat inputs, ground water inputs, stream shading, and wind sheltering, the values of A and B in equation (14) in the same area have very slight differences [66]. Then, the water temperature in the channel can be written as equation (17). Thus, the boundary BH and BG were set as follows:where t is the time (d).

The boundary condition at CD was set as heat flux with the value of 0.03 W/m², which was gained from the geothermal gradient within the ground temperature boreholes. The boundary of DE was thermal insulation boundary, and that of BC was the symmetry boundary. With the governing equations and boundary conditions above, the problem was solved numerically using the commercial software of COMSOL Multiphysics. The spatial and temporal discretization of governing equations was carried out by using the finite method. The simulation was conducted over a time period of 50 years before the drainage channel excavation to gain the initial temperature field. After the excavation, the boundary conditions were set as the ones described above.

4.3. Model Validation

A comparison between field observed and numerical simulated ground temperatures at ST on October 15 in the first year after the channel excavation was conducted to validate the numerical model and its parameterization (Figure 3). It can be found that the numerical simulated results agreed with the field observed well within the permafrost layer, including the depth of the permafrost table and the permafrost temperatures below. While in the active layer, there were some slight discrepancies between the numerical simulated and field observed ground temperatures. The discrepancies may relate to the simplification of the soil strata in the numerical simulation and the depth of the temperature sensors installed within the borehole. Overall, the numerical model and its parameterization in this study can be used to simulate the permafrost thermal regimes beneath the channel.

5. Results and Analysis

5.1. Long-Term Permafrost Thermal Regimes beneath the Channel in Warm Seasons

In the permafrost regions on the QTP, the maximum seasonal thaw depth generally occurs in mid-October. In the following analysis, the time point was chose to investigate the long-term permafrost thermal regimes beneath the channel. For brevity, we only took the channel with the width of 15 m as an example.

Figure 4 shows the thermal regimes of subgrade beneath the channel on October 15 within the 50 years after the channel excavation. It can be seen that, due to combined thermal effects of the flowing water and climate warming, the permafrost beneath the channel degraded rapidly with time went on. While in the natural ground far away from the channel, the permafrost degraded slowly due to the climate warming effect. In the 5^th year, the maximum seasonal thaw depth at NG, ST, and centerline of the channel (CC) was 2.4, 9.2, and 10.5 m, respectively. A thaw bulb developed beneath the channel due to the thermal effect of flow water. The permafrost temperatures beneath the channel also increased considerably comparing with those beneath the natural ground at the same depths. For example, at the depth of 10 m, the permafrost temperatures under CC and NG were 0.14°C and −0.45°C, respectively, with a difference up to 0.6°C. With increase in the operation time, the thaw bulb beneath the channel expanded rapidly in the vertical direction. In 10^th year after the channel excavation, the maximum seasonal thawing depth at CC and ST reached to 16.7 and 14.4 m, respectively. Till the 30^th year, the permafrost beneath the channel degraded almost totally within the depth of 30 m. After that, the later thermal erosion of the channel became considerable, and the permafrost beneath the channel slope degraded with the depth of 30 m.

(a)

(b)

(c)

(d)

(e)

(f)

The above results showed that, during the first 30 years of the channel operation, the permafrost beneath the channel experienced a rapid downward degradation because of the significant thermal effect of the flowing water. Along with the rapid downward degradation of permafrost beneath the channel, a large lateral thermal gradient developed beneath the slope of the channel. This significant thermal gradient would cause uneven deformations of the slope and even slumps or collapse because of the temperature dependence of mechanical properties of frozen soils. Thus, how to ensure the slope stability of the channel is a great challenge in permafrost environment.

5.2. Long-Term Permafrost Thermal Regimes beneath the Channel in Cold Seasons

In mid-April, the active layer on the QTP generally refreezes completely. In order to investigate the thermal regimes of subgrade beneath the channel in cold seasons, ground temperature distributions within the subgrade on April 15 within the 50 years after the channel excavation were analyzed in this section.

Figure 5 shows the thermal regimes of subgrade beneath the channel on April 15 within the 50 years after the channel excavation. The shallow ground far away from the slope shoulder of the channel refrozen totally in cold seasons. While, beneath the channel, the thaw bulb beneath the channel did not freeze due to the flowing water. Compared with the last warm season in the same year (Figure 4), the thaw bulb still expanded in the following cold seasons. In the 5^th year, the thaw bulb mainly exited vertically beneath the bottom of the channel and the water body within the channel. With the time went on, the thaw bulb developed rapidly both in vertical and lateral directions. Special attention should be paid to ground thermal regimes beneath the slope of the channel. The shallow ground on the slope was frozen but the deep ground was thawed in the cold season due to the lateral thermal erosion of the flowing water. Till the 50^th year, the thaw bulb in the cold season reached to the natural ground about 10 m far away from the slope shoulder of the channel. This meant that, all the deep ground beneath the slope of the channel was thawed throughout the year.

(a)

(b)

(c)

(d)

(e)

(f)

5.3. Impacts of Channel Width on Long-Term Thermal Regimes of Permafrost Subgrade

The width of the channel is not only related to the slope stability of the channel but also the permafrost degradation beneath the channel. To investigate the impacts of the channel width, a series of numerical simulations with different widths of the channel (15, 25, and 35 m) were carried out in this study. The flow of water was determined as a constant, and then the water depths were different for the channels with different widths. With the channel widths of 15, 25, and 35 m, the water depths were set as 1.53, 1.0, and 0.74 m, respectively.

Figure 6 shows ground temperature profiles at CC, ST, mid-slope (MS), and SS of the channels with the widths of 15, 25, and 35 m on October 15 in the 15^th year after the channel excavation. It can be seen that, with different widths of the channel, the long-term thermal regimes of the subgrade differed, but the magnitudes of the difference were different at the four locations. At CC (Figure 6(a)), the ground thermal regimes for the channels with different widths were close to each other. The difference in the maximum thaw depths for the three cases was about 1 m. This means that, with different widths, the thermal erosion from the channels did not differed considerably at this location. While, at ST, the maximum thaw depths for the channels with different widths differed considerably. The smaller the width of the channel was, the grater the maximum thaw depth was at ST (Figure 6(b)). This considerable difference was related to different water depths within the channels with different widths. When the width of the channel increased from 15 to 35 m, the maximum thaw depth at ST decreased from 18.2 to 15.5 m. At MS (Figure 6(c)), the difference in maximum thaw depths for the three cases was also considerable. The wider the channel was, the smaller the maximum thaw depths were. At SS (Figure 6(d)), the ground thermal regimes were also very close to each other with three widths of the channel.

(a)

(b)

(c)

(d)

The above results showed that the thermal regimes of subgrade differed considerably for the channels with different widths. The difference mainly existed at slope toe and middle of the slope. While at the centerline and slope shoulder, the ground thermal regimes were very close to each other. For slope stability, the greater thaw depth is generally harmful. Thus, it can be concluded that a channel built on permafrost should be wide-and-shallow rather than narrow-and-deep if conditions permit.

6. Conclusions

In permafrost regions, construction of a channel involves a large amount of excavation activities and changes to surface water body, which can exert great impacts on thermal regimes of underlying permafrost. In this paper, a coupled mathematical model of heat and moisture transfer for freeze-thaw soil was constructed to investigate the long-term thermal regimes of subgrade beneath a drainage channel built for an expanding lake on the Qinghai-Tibet Plateau. Using numerical simulations, thermal regimes of the subgrade both in warm and cold seasons were analyzed during a 50-year period, as well as the impact of the channel width. The conclusions were obtained as follows:(1)In permafrost environment, excavation of the channel and the flowing water within could lead to a significant permafrost degradation. During the first 30 years of the channel operation, the permafrost beneath the channel mainly experienced a rapid downward degradation due to the thermal effect of the flowing water. After that, the lateral thermal erosion of the flowing water caused a rapid permafrost degradation beneath the slope of the channel. With a width of 15 m, the permafrost beneath the channel bottom and slope would degrade totally within a depth of 30 m in a 50-year period.(2)The ground beneath the channel would not refreeze in cold seasons due to the flowing water within the channel, and the thaw bulb developed throughout a year. During the first 10 years, the thaw bulb mainly existed vertically beneath the channel. After that, the thaw bulb expanded quickly in lateral direction. Till the 50th year after the excavation of the channel, the thaw bulb reached to the natural ground about 25∼30 m far away from the centerline of the channel with a width of 15 m.(3)In permafrost environment, the width of the channel is an important factor. With different widths, the long-term thermal regimes of the subgrade beneath the channels differed considerably. The maximum difference was at the slope toe of the channel. The narrower the channel was, the larger the maximum thaw depth was at the slope toe. Thus, it is recommended that the channels in permafrost environment should be designed as wide-and-shallow rather than narrow-and-deep if conditions permit.

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest

The authors declare that they have no conflicts of interest related to this manuscript.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (nos. 41772325 and 41630636).

References

S. Kozarski, L. Marks, and J. Repelewska-Pkalowa, “Multi-language glossary of permafrost and related ground-ice terms,” 1998.
View at: Google Scholar
Y. H. Mu, G. Y. Li, W. Ma, Z. M. Song, Z. W. Zhou, and W. Fei, “Rapid permafrost thaw induced by heat loss from a buried warm-oil pipeline and a new mitigation measure combining seasonal air-cooled embankment and pipe insulation,” Energy, vol. 203, Article ID 117919, 2020.
View at: Publisher Site | Google Scholar
S. Gruber, “Derivation and analysis of a high-resolution estimate of global permafrost zonation,” The Cryosphere, vol. 5, no. 1, pp. 1547–1582, 2011.
View at: Google Scholar
W. Dobinski, “Permafrost,” Earth-Science Reviews, vol. 108, no. 3-4, pp. 158–169, 2011.
View at: Publisher Site | Google Scholar
P. Lu, J. Han, Z. Li et al., “Lake outburst accelerated permafrost degradation on Qinghai-Tibet Plateau,” Remote Sensing of Environment, vol. 249, Article ID 112011, 2020.
View at: Publisher Site | Google Scholar
H. J. Jun, S. X. Li, G. D. Cheng, S. L. Wang, and X. Li, “Permafrost and climatic change in China,” Global and Planetary Change, vol. 26, no. 4, pp. 387–404, 2000.
View at: Google Scholar
H. J. Jun, Q. H. Yu, S. L. Wang, and L. Z. Lue, “Changes in permafrost environments along the Qinghai-Tibet engi1neering corridor induced by anthropogenic activities and climate warming,” Cold Regions Science and Technology, vol. 53, no. 3, pp. 317–333, 2006.
View at: Google Scholar
W. Ma, G. D. Cheng, and Q. B. Wu, “Construction on permafrost foundations: lessons learned from the Qinghai-Tibet Railroad,” Cold Regions Science and Technology, vol. 59, pp. 3–11, 2009.
View at: Google Scholar
B. Liang, S. Qi, Z. Y. Li, Y. T. Li, and J. H. Chen, “Dynamic change of Lake area over the Tibetan Plateau and its response to climate change,” Mountain Research, vol. 36, no. 2, pp. 206–216, 2018.
View at: Google Scholar
B. K. Liu, L. Lin, Y. E. Du et al., “Causes of the outburst of Zonag lake in Hoh Xil, Tibetan plateau, and its impact on surrounding environment,” Journal of Geographical Sciences, vol. 38, no. 2, pp. 305–311, 2016.
View at: Google Scholar
J. Du, “Change of temperature in Tibetan plateau from 1961–2000,” Acta Geographica Sinica, vol. 56, no. 33, pp. 232–239, 2001.
View at: Google Scholar
T. Niu, L. Chen, and Z. Zhou, “The characteristics of climate change over the Tibetan Plateau in the last 40 years and the detection of climatic jumps,” Advances in Atmospheric Sciences, vol. 21, no. 2, pp. 193–203, 2004.
View at: Publisher Site | Google Scholar
Y. F. Shi, Y. P. Shen, E. Kang et al., “Recent and future climate change in northwest China,” Climate Change, vol. 80, no. 3-4, pp. 379–393, 2007.
View at: Publisher Site | Google Scholar
Q. L. You, S. C. Kang, N. Pepin et al., “Climate warming and associated changes in atmospheric circulation in the eastern and central Tibetan Plateau from a homogenized dataset,” Global and Planetary Change, vol. 72, no. 1-2, pp. 11–24, 2010.
View at: Publisher Site | Google Scholar
G. Q. Zhang, T. D. Yao, H. J. Xie et al., “Response of Tibetan Plateau lakes to climate change: trends, patterns, and mechanisms,” Earth-Science Reviews, vol. 208, Article ID 103269, 2020.
View at: Publisher Site | Google Scholar
L. Y. Tang, X. F. Duan, F. J. Kong et al., “Influences of climate change on area variation of Qinghai lake on Qinghai-Tibetan plateau since 1980s,” Scientific Reports, vol. 8, no. 1, p. 7331, 2018.
View at: Publisher Site | Google Scholar
W. H. Liu, C. W. Xie, L. Zhao et al., “Rapid expansion of lakes in the endorheic basin on the Qinghai-Tibet Plateau since 2000 and its potential drivers,” CATENA, vol. 197, Article ID 104924, 2021.
View at: Publisher Site | Google Scholar
G. Zhang, T. Yao, W. Chen et al., “Regional differences of lake evolution across China during 1960s–2015 and its natural and anthropogenic causes,” Remote Sensing of Environment, vol. 221, pp. 386–404, 2019.
View at: Publisher Site | Google Scholar
C. Song, B. Huang, K. Richards, L. Ke, and V. Hien Phan, “Accelerated lake expansion on the Tibetan Plateau in the 2000s: induced by glacial melting or other processes?” Water Resources Research, vol. 50, no. 4, pp. 3170–3186, 2014.
View at: Publisher Site | Google Scholar
Y. Lei, K. Yang, B. Wang et al., “Response of inland lake dynamics over the Tibetan Plateau to climate change,” Climatic Change, vol. 125, no. 2, pp. 281–290, 2014.
View at: Publisher Site | Google Scholar
W.-h. Liu, C.-w. Xie, L. Zhao et al., “Dynamic changes in lakes in the Hoh Xil region before and after the 2011 outburst of Zonag lake,” Journal of Mountain Science, vol. 16, no. 5, pp. 1098–1110, 2019.
View at: Publisher Site | Google Scholar
Y. E. Du, B. K. Liu, W. G. He, S. Q. Duan, F. J. Hou, and Z. L. Wang, “Dynamic change and cause analysis of salt lake area in Hoh Xil on Qinghai-Tibet Plateau during 1976–2017,” Journal of Geographical Sciences, vol. 40, no. 1, pp. 47–54, 2018.
View at: Google Scholar
Q. B. Wu, Y. W. Zhou, and C. J. Tong, Permafrost Survey and Mapping, Science Press, Beijing, China, 2018.
Q. Chen, D. P. Wen, X. F. Wen, and S. P. Xie, “Preliminary conception of hydrological monitoring scheme for cocoacili salt lake in Qinghai province,” Yellow River, vol. 41, no. 11, pp. 7–10, 2019.
View at: Google Scholar
X. Yao, M. Sun, P. Gong et al., “Overflow probability of the salt lake in Hoh Xil region,” Journal of Geographical Sciences, vol. 28, no. 5, pp. 647–655, 2018.
View at: Publisher Site | Google Scholar
Y. B. Lang, Y. Zheng, W. Jin, Y. H. Mu, and M. T. Chai, “Method of three-dimensional monitoring on permafrost around lake draining project on the Qinghai-Tibet Plateau,” Journal of Yangtze River Scientific Research Institute, pp. 1–8, 2020.
View at: Google Scholar
X. J. Yao, M. P. Sun, P. Gong et al., “Overflow probability of the salt lake in Hoh Xil region,” Journal of Geographical Sciences, vol. 71, no. 9, pp. 1520–1527, 2016.
View at: Google Scholar
C. W. Xie, W. H. Liu, J. C. Wu et al., “Environmental changes caused by the outburst of Zonag Lake and the possible outburst model of Yanhu Lake in the Hoh Xil region,” Journal of Glaciology and Geocryology, vol. 41, no. 6, pp. 1–16, 2019.
View at: Google Scholar
R. H. Ma, G. S. Yang, H. T. Duan et al., “Number, area, and spatial distribution of lakes in China,” Scientia Sinica (Terrae), vol. 41, no. 3, pp. 394–401, 2011.
View at: Google Scholar
Y. H. Mu, W. Ma, Y. Z. Liu, and Z. Z. Sun, “Monitoring investigation on thermal stability of air-convection crushed-rock embankment,” Cold Regions Science and Technology, vol. 62, no. 2-3, pp. 160–172, 2010.
View at: Publisher Site | Google Scholar
Y. Mu, G. Wang, Q. Yu, G. Li, W. Ma, and S. Zhao, “Thermal performance of a combined cooling method of thermosyphons and insulation boards for tower foundation soils along the Qinghai-Tibet power transmission line,” Cold Regions Science and Technology, vol. 121, pp. 226–236, 2016.
View at: Publisher Site | Google Scholar
Y. Mu, G. Li, Q. Yu, W. Ma, D. Wang, and F. Wang, “Numerical study of long-term cooling effects of thermosyphons around tower footings in permafrost regions along the Qinghai-Tibet power transmission line,” Cold Regions Science and Technology, vol. 121, pp. 237–249, 2016.
View at: Publisher Site | Google Scholar
Y. Mu, W. Ma, G. Li, F. Niu, Y. Liu, and Y. Mao, “Impacts of supra-permafrost water ponding and drainage on a railway embankment in continuous permafrost zone, the interior of the Qinghai-Tibet Plateau,” Cold Regions Science and Technology, vol. 154, pp. 23–31, 2018.
View at: Publisher Site | Google Scholar
Z. W. Wu, Y. M. Lai, and E. M. Zang, Tunnel Engineering in Cold Region, Ocean Press, Beijing, China, 2003.
Y. M. Lai, M. Y. Zhang, and S. Y. Li, Theory and Application of Cold Regions Engineering, Science Press, Beijing, China, 2009.
X. T. Xu, R. Q. Bai, Y. Lai, M. Y. Zhang, and J. G. Run, “Work conjugate stress and strain variables for unsaturated frozen soils,” Journal of Hydrology, vol. 582, Article ID 124537, 2020.
View at: Publisher Site | Google Scholar
X. T. Xu, B. X. Wang, C. X. Fan, and W. D. Zhang, “Strength and deformation characteristics of silty clay under frozen and unfrozen states,” Cold Regions Science and Technology, vol. 172, Article ID 102982, 2020.
View at: Publisher Site | Google Scholar
X. T. Xu, W. D. Zhang, C. X. Fan, Y. Lai, and J. Wu, “Effect of freeze–thaw cycles on the accumulative deformation of frozen clay under cyclic loading conditions: experimental evidence and theoretical model,” Road Materials and Pavement Design, vol. 11, 2019.
View at: Publisher Site | Google Scholar
J. R. Mackay and C. R. Burn, “The first 20 years (1978-1979 to 1998-1999) of ice-wedge growth at the Illisarvik experimental drained lake site, western Arctic coast, Canada,” Canadian Journal of Earth Sciences, vol. 39, no. 1, pp. 95–111, 2002.
View at: Publisher Site | Google Scholar
Z. J. Lin, F. J. Niu, J. Luo, M. H. Liu, and G. A. Yin, “Thermal regime at bottom of Thermokarst Lake along Qinghai-Tibet engineering corridor,” Earth Science-Journal of China University of Geosciences, vol. 40, no. 1, pp. 179–188, 2015.
View at: Google Scholar
F. J. Niu, Z. J. Lin, H. Liu, and J. H. Lu, “Characteristics of thermokarst lakes and their influence on permafrost in Qinghai–Tibet Plateau,” Geomorphology, vol. 132, no. 3-4, pp. 222–233, 2011.
View at: Publisher Site | Google Scholar
Z. Wen, Z. Yang, Q. Yu et al., “Modeling thermokarst lake expansion on the Qinghai-Tibetan Plateau and its thermal effects by the moving mesh method,” Cold Regions Science and Technology, vol. 121, pp. 84–92, 2016.
View at: Publisher Site | Google Scholar
F. Ling and T. Zhang, “Simulating heat source effect of a thermokarst lake in the first 540 years on the Alaskan Arctic using a simple lake expanding model,” Cold Regions Science and Technology, vol. 160, pp. 176–183, 2019.
View at: Publisher Site | Google Scholar
S. Li, H. Zhan, Y. Lai, Z. Sun, and W. Pei, “The coupled moisture-heat process of permafrost around a thermokarst pond in Qinghai-Tibet Plateau under global warming,” Journal of Geophysical Research: Earth Surface, vol. 119, no. 4, pp. 836–853, 2014.
View at: Publisher Site | Google Scholar
S. Y. Li, Y. M. Lai, M. Y. Zhang, W. S. Pei, C. Zhang, and F. Yu, “Centrifuge and numerical modeling of the frost heave mechanism of a cold-region canal,” Acta Geotechnica, vol. 14, no. 12, pp. 1113–1128, 2018.
View at: Publisher Site | Google Scholar
H. Zhang, J. Zhang, E. Wang, Z. Zhang, W. Cao, and P. Zhou, “Thermal and settlement analyses under a riverbank over permafrost,” Computers and Geotechnics, vol. 91, pp. 48–57, 2017.
View at: Publisher Site | Google Scholar
H. Zhang, J. Zhang, E. Wang, M. Zhang, Z. Zhang, and M. Chai, “Analysis of thermal regime under riverbank in permafrost region,” Applied Thermal Engineering, vol. 123, pp. 963–972, 2017.
View at: Publisher Site | Google Scholar
R. L. Harlan, “Analysis of coupled heat-fluid transport in partially frozen soil,” Water Resources Research, vol. 9, no. 5, pp. 1314–1323, 1973.
View at: Publisher Site | Google Scholar
X. Z. Xu, J. C. Wang, and L. X. Zhang, Physics of Frozen Soil, Science Press, Beijing, China, 2010.
M. L. Zhang, Z. Wen, K. Xue, L. Z. Chen, and D. S. Li, “A coupled model for liquid water, water vapor and heat transport of saturated-unsaturated soil in cold regions: model formulation and verification,” Environmental Earth Sciences, vol. 75, no. 8, pp. 1–19, 2016.
View at: Publisher Site | Google Scholar
K. Hansson, J. Simunek, M. Mizoguchi, L.-C. Lundin, and M. T. van Genuchten, “Water flow and heat transport in frozen soil: numerical solution and freeze-thaw applications,” Vadose Zone Journal, vol. 3, no. 2, pp. 693–704, 2004.
View at: Publisher Site | Google Scholar
M. L. Zhang, “The influence of rainfall variations on the thermal-moisture dynamics of the embankment in permafrost regions of the Qinghai-Tibet Plateau,” University of Chinese Academy of Sciences, Lanzhou, China, 2016, Ph. D. dissertation.
View at: Google Scholar
M. T. van Genuchten, “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils,” Soil Science Society of America Journal, vol. 44, no. 5, pp. 892–898, 1980.
View at: Publisher Site | Google Scholar
Y. Mualem, “A new model for predicting the hydraulic conductivity of unsaturated porous media,” Water Resources Research, vol. 12, no. 3, pp. 513–522, 1976.
View at: Publisher Site | Google Scholar
Y.-W. Jame and D. I. Norum, “Heat and mass transfer in a freezing unsaturated porous medium,” Water Resources Research, vol. 16, no. 4, pp. 811–819, 1980.
View at: Publisher Site | Google Scholar
W. D. An, Z. W. Wu, and W. Ma, Interaction Among Temperature, Moisture and Stress Field in Frozen Soil, Lanzhou University Press, Lanzhou, China, 1990.
W. D. An, Z. W. Wu, and W. Ma, Temperature, Water Stress and Interaction of Frozen Soil, Lanzhou University press, Lanzhou, China, 1989.
Y. M. Lai, Z. W. Wu, S. J. Zhang, W. B. Yu, and Y. S. Deng, “In-situ observed study for effect of heat preservation in cold regions tunnels,” Journal of the China Railway Society, vol. 1, pp. 81–86, 2003.
View at: Google Scholar
H. B. Dillon and O. B. Andersland, “Predicting unfrozen water contents in frozen soils,” Canadian Geotechnical Journal, vol. 3, no. 2, pp. 53–60, 1966.
View at: Publisher Site | Google Scholar
D. M. Anderson and N. R. Morgenstern, “Physics, chemistry, and mechanics of frozen ground: a review,” in Proceedings of the Second International Conference on Permafrost, pp. 257–288, National Academy of Sciences, Washington, DC, USA, July 1973.
View at: Google Scholar
L. U. Arenson and D. C. Sego, “The effect of salinity on the freezing of coarse-grained sands,” Canadian Geotechnical Journal, vol. 43, no. 3, pp. 325–337, 2006.
View at: Publisher Site | Google Scholar
M. M. Darrow, S. L. Huang, and S. Akagawa, “Adsorbed cation effects on the frost susceptibility of natural soils,” Cold Regions Science and Technology, vol. 55, no. 3, pp. 263–277, 2009.
View at: Publisher Site | Google Scholar
H. P. Hu, S. X. Yang, and Z. D. Lei, “A numerical simulation for heat and moisture transfer during soil freezing,” Journal of Hydraulic Engineering, vol. 7, pp. 1–8, 1992.
View at: Google Scholar
Y. X. Xia and Y. D. Wang, Mechanical Calculation of Tunnel Structure, People’s Communications Press, Beijing, China, 2001.
J. M. Zhang, “Study on roadbed stability in permafrost regions on Qinghai-Tibetan plateau and classification of permafrost in Highway engineering,” University of Chinese Academy of Sciences, Lanzhou, China, 2004, Ph. D. Dissertation.
View at: Google Scholar
T. R. Erickson and H. G. Stefan, “Linear air/water temperature correlations for streams during open water periods,” Journal of Hydrologic Engineering, vol. 5, no. 3, pp. 317–321, 2000.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2021 Hong Yu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

353

Downloads

882

Citations