Problem And Solutions In Design Of Problem And Solutions In Design Of

Roadway And Railway Network In Permafrost RegionRoadway And Railway Network In Permafrost Region

A Seminar on

By

Ashish PariharRoll no. 141701

M.Tech. (Transportation Engineering)

Overview• What is Permafrost?• Where Permafrost?• Why does permafrost thaw?• What happens when permafrost thaws?• Key Terms and Landforms• Case Study• Engineered Solutions• Summary• References 02/18/15 1

What is Permafrost?

Soil or rock that remains below 0°C throughout the year, or may be for two

or more years.

Ice is not always present, frequently occurs

Moisture in the form of either water or ice may or may not be present.

Permafrost may therefore be unfrozen, partially frozen, or frozen

depending on the state of the ice/water content.02/18/15 2

What is Permafrost?

PermafrostPermafrost

Source: http://wiki.fis-ski.com/index.php/Permafrost

02/18/15 3

Where Permafrost? North America

Scandinavia

Russia

China

Some Estimated Depth:

• 440 m in Barrow, Alaska

• 600 m in the Canadian Arctic Islands

• 1493 m in the northern Lena and Yana

River basins in Siberia02/18/15 4

Why Does Permafrost Thaws?

Changes occur due to:

oSoil compression,

oChanging drainage of soil,

oClimatic changes,

oTemperature changes

Solar heating of the surface,

Temperature of pavement

surface,

Source: http://www.scienceinschool.org/2012/issue22/permafrost02/18/15 5

“No ground to stand on”

Travel Problems Increasing road hazards & damage Shorter travel season Railways shift and bend Airport runways crack

More Geohazards Landslides, Debris & mud flows Subsidence

Source: http://wiki.fis-ski.com/thawingeffects.php02/18/15 6

• Permafrost:

• Continuous Permafrost:

• Discontinuous Permafrost:

Permanently frozen ground

Temperatures have remained below 0 °C for at least 2 years

Mean annual air temperatures of below -5 °C all year,

as low as -50 °C.

Slightly warmer areas

Islands of permanently frozen ground separated by small pockets of unfrozen less cold areas.

Mean annual temps of between -1 °C and -5 °C

Key Terms And LandformsKey Terms And Landforms

02/18/15 7

Source: http://www.scienceinschool.org/2012/issue22/permafrost

Key Terms And LandformsKey Terms And Landforms

02/18/15 8

Summer temperatures sufficient to melt

This layer can be very mobile

It varies in thickness depending on latitude and vegetation cover.

Any unfrozen material within the permafrost zone.

• Active layer:

• Talik:

Key Terms And LandformsKey Terms And Landforms

02/18/15 9

Case Study

Source: http://www.chinatibettrain.com/aboutus.htm02/18/15 10

China Railway Line

QINGZANG ( Qinghai - Tibet) Railway nearly 1200 mile

Stations name :- Xining to Lhasa

Approximately 1300 miles of the new railway in between Golmud to Lhasa was having

Continuous

Discontinuous Permafrost

02/18/15 11

Engineered Solutions

1) Active method : To destroy

permafrost section completely.

2) Passive method : It Functions to

reduce heat absorption.

02/18/15 12

• Thermo-Syphon• Ventiduct Embankments• Air-Cooled Stone Embankment• Awning/ Shading Boards• Expanded Polystyrene Insulation• Dry Bridges

Engineered Solutions

02/18/15 13

Thermo-Syphons Pressurized Cylindrical tube and

Filled of low boiling point.

Dissipation of heat by:

Evaporation

Condensation of liquid.

These are best utilized for high risk sides

Unstable permafrost.Source: http://info.tibet.cn/en/news/phn/pnt/t20060605_120583.htm

02/18/15 14

Thermo-Syphons

Source: https://www.thermalfluidscentral.org/encyclopedia/index.php/Two-Phase_Closed_Thermosyphon

02/18/15 15

Ventiduct Embankments

Inclusion of pipes serving as air culverts .

Can increase heat absorption with in the embankment.

Requires natural wind current to remove heat from the

embankment.

Source: http://info.tibet.cn/en/news/phn/pnt/t20060605_120583.htm

02/18/15 16

Air Cooled Stone Embankments

Poorly graded aggregates are used to create pore spaces.

Rock layer act as thermal insulating barrier

Block stone embankments utilize large aggregates

Roughly 8-12 inches in diameter

Crushed rock embankments use smaller aggregates

3-4 inches in diameter.

Source: http://wiki.fis-ski.com/index.php/heat_transfer

17

Rock Embankment Configurations

Air Cooled Stone Embankments

Source: http://info.tibet.cn/en/news/embkmnt/pnt/t20060605_120583.htm

02/18/15 18

Awnings And Shading Boards

Primary function Is to reduce solar radiations.

Water infiltration and snow accumulation are minimized.

Source: http://www.scienceinschool.org/2012/issue22/permafrost/awnings_shading.htm

02/18/15 19

Awning

Awning configurations02/18/15 20

Dry Bridges

Pile lengths of 25 to 30 m,

Pile diameters of about 1.2m,

Utilizes a negative friction force

To ensure engineering stability,

Ignoring the carrying capacity of pile

Permafrost thaw problems. Er’a’ga dry bridge on Muli Railway, China

Source: http://wiki.fis-ski.com/index.php/Permafrost

02/18/15 21

SUMMARY OF ENGINEERED SOLUTIONSEngineered

SolutionExpected Outcome Potential Drawbacks

Cost ($/100 track feet)

Thermosyphons

High risk sites, unstable permafrost, useful for transitional zones

Damage during transport or installation, obstruction of fins, maintenance potential

 

$27,500-$30,800

Ventiducts

Embankments

Minimize differential settlements, reduce internal temperature of embankment

Blockage due to snow or debris, minimized performance due to settlements, water ponding, maintenance potential

$9,800- PVC

$16,500- Concrete

$23,750- Metal

Block Stone

Embankments

Increase convection cooling of entire embankment, increased full width embankment stability

Plugging due to snow or fines, settlements risk $44,800

Crushed Rock

Revetments

Convection cooling of shoulders, stability of shoulder sections

Warming in centre of embankment with cooling of shoulders (differential settlement), plugging due to snow or fines

$12,000 22

SUMMARY OF ENGINEERED SOLUTIONS

Engineered Solution

Expected Outcome Potential DrawbacksCost ($/100 track

feet)

Awning/

Shading Board

Reduce solar radiation, minimize water infiltration, improve convection cooling

Damage due to natural or manmade occurrences, maintenance potential

No Data

Extruded

Polystyrene

Minimize heat influx into soil, reduce frost penetration depth, minimize construction depth

Water absorption, mechanical damage, decreasing insulation performance $2,300

Dry Bridge

Ensure stability during permafrost degradation, eliminates settlements and thaw consolidation

Differential settlements of columns, damages due to natural or manmade occurrences $1,040,000

23

Summary

Should be part of the planning of any engineering project in the north.

It is best to disturb the permafrost.

Thawing make soils more stable for future construction.

Costs of continual maintenance vs. initial cost of advanced

engineering solutions

How rapidly can permafrost thawing be expected to occur?

Special attention has been paid to ground temperature and ice

content.24

References

Cheng, G. D. _1984_. “Problems on zonation of high-altitude permafrost.” Acta Geogr. Sin., 39_2_, 185–193 _in Chinese; Abstract in English_.

Cheng, G. D. _2003_. “The effect of local factors on spatial distribution of permafrost and its revealing to Qinghai–Xizang Railroad design.” Sci. China (Ser. D), 33_6_, 602–607.

Cheng G. D. _2005_. “A roadbed cooling approach for the construction of Qinghai–Tibet Railway.” Cold Regions Sci. Technol., 42_2_, 169–176.

Ding, Y. J. _1998_. “Recent degradation of permafrost in China and the response to climate warming.” Proc., 7th Int. Conf. on Permafrost, Univ. of Laval, Yellowknife, Canada, 225–230.

Lai, Y. M., Zhang, L. X., and Zhang, S. J. _2003_. “The cooling effect of ripped-stone embankments on Qinghai–Tibet Railway under climatic warming.” Chin. Sci. Bull., 48_6_, 598–604.

Research Group of the Qinghai–Xizang Highway. _1983_. “Distribution regularities of high-ice-content permafrost along Qinghai–Xizang Highway.” Proc., 2nd National Conf. on Permafrost, Gansu Cultural Press, Lanzhou, China, 43–51.

02/18/15 25

References

Tong, C. J., and Wu, Q. B. _1996_. “The effect of climate warming on the Qinghai–Tibet Highway.” Cold Regions Sci. Technol., 24_1_, 101–106.

Wang, S. L., Zhao, X. F., Guo, D. X., and Huang, Y. Z. _1996_. “Response of permafrost to climate change in the Qinghai–Xizang Plateau.” J. Glaciol. Geocryol., 18 _Special Issue_, 157–165 _in Chinese_.

Wu, Q. B., Liu, Y. Z., and Tong, C. J. _2003_. “Interaction between frozen soil and engineering in cold regions.” J. Eng. Geol., 8_3_, 281–287.

Sheng, Y., et al. ~2002b! “Application of thermal-insulation treatment to roadway engineering in permafrost region.” J. Glaciol. Geocryol., 24~5!, 618–622.

Slater, A. G., Pitman, A. J., and Desborough, C. E. ~1998!. “Simulation of freeze-thaw cycles in a circulation model land surface scheme.” J. Geophys. Res., [Atmos.], 103~D10!, 11303–11312.

Smith, M. W., and Riseborough, D. W. ~1996! “Permafrost monitoring and detection of climate change.” Permafrost Periglacial Process., 7~4! 301–309.

02/18/15 26