Study on thermal-state variation of high-grade highway embankment under different pavement conditions

The research shows that the selection of pavement type is very important for the thermal stability of high-grade highway embankment in permafrost regions because of the different solar absorption rates between asphalt concrete and asphalt concrete pavement.In this paper,the common embankment of high-grade highway in permafrost regions is selected as the research object to study the influence of asphalt concrete and cement concrete pavement on the embankment temperature,freeze-thaw cycle process and the change law of the permafrost table,which provides a basis for the use of reasonable pavement materials in permafrost regions.

Lessons from construction and health condition evaluation of high-grade highway in permafrost regions

Located in the eastern margin of the Tibetan Plateau,the Gonghe-Yushu high-grade highway was the first of its kind in plateau permafrost regions.Most of the road sections along the high-grade highway are unstable or extremely unstable warm permafrost with an average annual ground temperature above −1℃,which is vulnerable to global warming and human engineering activities.This paper describes permafrost characteristics,roadbed design,and operation of the Gonghe-Yushu high-grade highway in detail.It is found that thaw settlement of warm and ice-rich permafrost is the main cause of subgrade subsidence in permafrost sections of this highway due to insufficient permafrost survey and drainage design.It is recommended that the interception and drainage system's design be optimized,and the permafrost upper limit and the variation of ground temperature be further investigated to provide essential data for the treatment of highway distress.It should be emphasized that protecting permafrost soil environment and optimized engineering design are crucial to successful high-grade highway engineering in permafrost regions.

Projections of corrosion and deterioration of infrastructure in United States coasts under a changing climate

Climate change can accelerate infrastructure deterioration in coastal areas because increased temperature and humidity can promote steel corrosion.This study(1)projects corrosion rate changes for reinforced concrete and steel structures in 223 coastal counties,(2)assesses the impact of corrosion rate changes on the useful life of structures,and(3)evaluates direct economic losses due to shortened useful life of highway bridges over the period 2000-2100.The results show that the useful life of concrete structures may decrease by 1.7-2.7%under the representative concentration pathway(RCP)8.5 and decrease by 0.7-1.1%under RCP 4.5 by the end of the 21st century.The useful life of steel structures may decrease by 7.9-15.9%under RCP 8.5 and 3.3-6.7%under RCP 4.5.Concrete bridges may suffer an average loss of$6.5-11.7/m 2 under RCP 8.5 and$3.3-16.5/m 2 under RCP 4.5 due to shortened useful life.Steel bridges may suffer an average loss of$73.4-111.3/m 2 under RCP 8.5 and$46.9-81.2/m 2 under RCP 4.5.In both climate scenarios,10%of counties may have negative losses and 10%of counties may have losses greater than$20 million due to corrosion rate changes for concrete and steel bridges.The results reveal the spatial difference of climate change impacts on infrastructural deterioration and suggest the importance of developing regional specific adaptation strategies.