Ground temperature and deformation analysis for an expressway embankment in warm permafrost regions of the Tibet plateau

2019 ◽  
Vol 30 (3) ◽  
pp. 208-221 ◽  
Author(s):  
Jiankun Liu ◽  
Bowen Tai ◽  
Jianhong Fang
Keyword(s):  
Ground Temperature ◽  
Tibet Plateau ◽  
Deformation Analysis ◽  
Warm Permafrost ◽  
Permafrost Regions ◽  
The Tibet Plateau

scholarly journals A New Mitigation Measure to Counter Thermal Instability of Air-Cooled Embankment in Sandy Permafrost Zones of Tibet Plateau

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Minghao Liu ◽  
Jing Luo ◽  
Liang Zhang ◽  
Xin Ju
Keyword(s):  
Cooling Capacity ◽  
Ground Temperature ◽  
Tibet Plateau ◽  
Crushed Rock ◽  
Transfer Model ◽  
Rock Layer ◽  
Cooling Performance ◽  
Permafrost Warming ◽  
Warm Permafrost

A crushed-rock revetment (CRR) with high permeability that can be paved on embankment slopes is widely used to cool and protect the subgrade permafrost. In this study, a traditional CRR over warm permafrost was selected to investigate its cooling characteristics based on the ground temperature observed from 2003 to 2014. A new mitigation structure (NMS) was designed to improve the cooling capacity of the CRR and to counter the pore-filling of the rock layer. Numerical simulations were conducted to evaluate the cooling performance and reinforcing capacity of the NMS based on a developed heat and mass transfer model. The results indicate that the traditional CRR can improve the symmetry of the permafrost subgrade and decrease the ground temperature of shallow permafrost. However, the CRR cannot generate strong enough cooling to influence the deep (below 10 m depth) and warm permafrost with a mean annual ground temperature above −1.0°C. The wind-blown sand can further weaken the cooling of the CRR and cause significant permafrost warming and thawing beneath the slopes, posing a severe threat to the long-term safe operation of the embankment. The proposed NMS can produce a significantly superior cooling performance to the CRR. If the CRR is reinforced by the new structure, it can not only effectively cool the underlying warm permafrost but also elevate the permafrost table. The new structure can also protect the rock layer on the slopes from sand-filling. The NMS can be used as an effective method for roadbed design or maintenance over warm permafrost.

scholarly journals Extension of the Upper Yellow River into the Tibet Plateau: Review and New Data

Quaternary ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 14
Author(s):  
Zhengchen Li ◽  
Xianyan Wang ◽  
Jef Vandenberghe ◽  
Huayu Lu
Keyword(s):  
Tibetan Plateau ◽  
Yellow River ◽  
Google Earth ◽  
Tibet Plateau ◽  
The Yellow River ◽  
Published Data ◽  
The Tibetan Plateau ◽  
Large Lakes ◽  
River Terraces ◽  
The Tibet Plateau

The Wufo Basin at the margin of the northeastern Tibet Plateau connects the upstream reaches of the Yellow River with the lowland catchment downstream, and the fluvial terrace sequence in this basin provides crucial clues to understand the evolution history of the Yellow River drainage system in relation to the uplift and outgrowth of the Tibetan Plateau. Using field survey and analysis of Digital Elevation Model/Google Earth imagery, we found at least eight Yellow River terraces in this area. The overlying loess of the highest terrace was dated at 1.2 Ma based on paleomagnetic stratigraphy (two normal and two reversal polarities) and the loess-paleosol sequence (12 loess-paleosol cycles). This terrace shows the connections of drainage parts in and outside the Tibetan Plateau through its NE margin. In addition, we review the previously published data on the Yellow River terraces and ancient large lakes in the basins. Based on our new data and previous researches, we conclude that the modern Yellow River, with headwaters in the Tibet Plateau and debouching in the Bohai Sea, should date from at least 1.2 Ma. Ancient large lakes (such as the Hetao and Sanmen Lakes) developed as exorheic systems and flowed through the modern Yellow River at that time.

scholarly journals Establishment of Hydraulic Turbine Test Bench on the Tibet Plateau

2021 ◽  
Vol 627 ◽  
pp. 012026
Author(s):  
H M Li ◽  
Q L He ◽  
Y X Xiao ◽  
H Y Luo ◽  
H Zhang ◽  
...  
Keyword(s):  
Test Bench ◽  
Hydraulic Turbine ◽  
Tibet Plateau ◽  
The Tibet Plateau

scholarly journals Analysis of Raindrop Size Distribution Characteristics in Permafrost Regions of the Qinghai–Tibet Plateau Based on New Quality Control Scheme

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2265 ◽  
Author(s):  
Ma ◽  
Zhao ◽  
Yang ◽  
Xiao ◽  
Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Quality Control ◽  
Rain Rate ◽  
Tibet Plateau ◽  
Frozen Ground ◽  
Fall Velocity ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Raindrop size distribution (DSD) can reflect the fundamental microphysics of precipitation and provide an accurate estimation of its amount and characteristics; however, there are few observations and investigations of DSD in cold, mountainous regions. We used the second-generation particle size and velocity disdrometer Parsivel2 to establish a quality control scheme for raindrop spectral data obtained for the Qinghai–Tibet Plateau in 2015. This scheme included the elimination of particles in the lowest two size classes, particles >10 mm in diameter and rain rates <0.01 mm∙h−1. We analyzed the DSD characteristics for different types of precipitation and rain rates in both permafrost regions and regions with seasonally frozen ground. The precipitation in the permafrost regions during the summer were mainly solid with a large particle size and slow fall velocity, whereas the precipitation in the regions with seasonally frozen ground were mainly liquid. The DSD of snow had a broader drop spectrum, the largest particle size, the slowest fall velocity, and the largest number of particles, followed by hail. Rain and sleet shared similar DSD characteristics, with a smaller particle size, slower velocity, and smaller number of particles. The particle concentration for different classes of rain rate decreased with an increase in particle size and decreased gradually with an increase in rain rate. Precipitation with a rain rate >2 mm∙h−1 was the main contributor to the annual precipitation. The dewpoint thresholds for snow and rain in permafrost regions were 0 and 1.5 °C, respectively. The dewpoint range 0–1.5 °C was characterized by mixed precipitation with a large proportion of hail. This study provides valuable DSD information on the Qinghai–Tibet Plateau and can be used as an important reference for the quality control of raindrop spectral data in regions dominated by solid precipitation.

The generation and reworking of continental crust during early Paleozoic in Gondwanan affinity terranes from the Tibet Plateau

2019 ◽  
Vol 190 ◽  
pp. 486-497 ◽  
Author(s):  
Yiming Liu ◽  
Sanzhong Li ◽  
M. Santosh ◽  
Huahua Cao ◽  
Shengyao Yu ◽  
...  
Keyword(s):  
Continental Crust ◽  
Tibet Plateau ◽  
Early Paleozoic ◽  
The Tibet Plateau

Impact process and mechanism of summertime rainfall on thermal–moisture regime of active layer in permafrost regions of central Qinghai–Tibet Plateau

2021 ◽  
pp. 148970
Author(s):  
Zhang Mingli ◽  
Wen Zhi ◽  
Li Desheng ◽  
Chou Yaling ◽  
Zhou Zhixiong ◽  
...  
Keyword(s):  
Active Layer ◽  
Tibet Plateau ◽  
Moisture Regime ◽  
Impact Process ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Comparison of cloud cover between satellite and ground observation over the Tibet Plateau

2021 ◽  
Author(s):  
Yisheng Zhang ◽  
Zengliang Zhao ◽  
Fei Niu
Keyword(s):  
Cloud Cover ◽  
Tibet Plateau ◽  
Ground Observation ◽  
The Tibet Plateau

Equilibrium Spin-up of Cold and Warm Permafrost Models

2021 ◽  
Author(s):  
Cameron Ross ◽  
Ryley Beddoe ◽  
Greg Siemens
Keyword(s):  
Climate Change ◽  
Temperature Response ◽  
Ground Temperature ◽  
Future Climate Change ◽  
Climate Projections ◽  
Multiple Model ◽  
Climate Data ◽  
Ground Temperatures ◽  
C Cycle ◽  
Warm Permafrost

&lt;p&gt;Initialization (spin-up) of a numerical ground temperature model is a critical but often neglected step for solving heat transfer problems in permafrost. Improper initialization can lead to significant underlying model drift in subsequent transient simulations, distorting the effects on ground temperature from future climate change or applied infrastructure. &amp;#160;In a typical spin-up simulation, a year or more of climate data are applied at the surface and cycled repeatedly until ground temperatures are declared to be at equilibrium with the imposed boundary conditions, and independent of the starting conditions.&lt;/p&gt;&lt;p&gt;Spin-up equilibrium is often simply declared after a specified number of spin-up cycles. In few studies, equilibrium is visually confirmed by plotting ground temperatures vs spin-up cycles until temperatures stabilize; or is declared when a certain inter-cycle-temperature-change threshold is met simultaneously at all depths, such as &amp;#8710;T &amp;#8804; 0.01&lt;sup&gt;o&lt;/sup&gt;C per cycle. In this study, we investigate the effectiveness of these methods for determining an equilibrium state in a variety of permafrost models, including shallow and deep (10 &amp;#8211; 200 m), high and low saturation soils (S = 100 and S = 20), and cold and warm permafrost (MAGT = ~-10 &lt;sup&gt;o&lt;/sup&gt;C and &gt;-1 &lt;sup&gt;o&lt;/sup&gt;C). The efficacy of equilibrium criteria 0.01&lt;sup&gt;o&lt;/sup&gt;C/cycle and 0.0001&lt;sup&gt;o&lt;/sup&gt;C/cycle are compared. Both methods are shown to prematurely indicate equilibrium in multiple model scenarios. &amp;#160;Results show that no single criterion can programmatically detect equilibrium in all tested models, and in some scenarios can result in up to 10&lt;sup&gt;o&lt;/sup&gt;C temperature error or 80% less permafrost than at true equilibrium. &amp;#160;A combination of equilibrium criteria and visual confirmation plots is recommended for evaluating and declaring equilibrium in a spin-up simulation.&lt;/p&gt;&lt;p&gt;Long-duration spin-up is particularly important for deep (10+&amp;#160;m) ground models where thermal inertia of underlying permafrost slows the ground temperature response to surface forcing, often requiring hundreds or even thousands of spin-up cycles to establish equilibrium. Subsequent transient analyses also show that use of a properly initialized 100 m permafrost model can reduce the effect of climate change on mean annual ground temperature of cold permafrost by more than 1 &lt;sup&gt;o&lt;/sup&gt;C and 3 &lt;sup&gt;o&lt;/sup&gt;C under RCP2.6 and RCP8.5 climate projections, respectively, when compared to an identical 25 m model. These results have important implications for scientists, engineers and policy makers that rely on model projections of long-term permafrost conditions.&lt;/p&gt;

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