A two-lift gradient design for airport pavements has been proposed to mitigate the functional degradation, especially the salt-frost (S-F) damage induced by deicing slat fluids. Herein, this study focuses on elucidating the mechanism and improvement of incorporating mineral admixtures in the development of a novel S-F resistant surface concrete material, which is of great significance for delaying the functional deterioration of pavement surface in northern China. The results indicated that the filling effect and secondary hydration reaction between the fly ash (FA) and silica fume (SF) and cement hydration products results in a dense spatial network structure, effectively reducing porosity and optimizing pore structure. It was found that SF can effectively improve the frost resistance and salt corrosion resistance of cement mortar, while the influence of FA depends on its content and environmental conditions. The incorporation of FA and SF significantly enhanced the structural density of cement concrete and reduced chloride ion permeability. The improvement in impermeability is most pronounced when both FA and SF are used in combination. In addition, a fitting equation between the admixture content and chloride ion permeability has been established, demonstrating good fitting results. In non-frozen saline soil areas, a large amount of FA or SF could be incorporated; in seasonally frozen areas, the priority should be given to SF to ensure salt corrosion resistance and frost resistance. The findings of this study provide a scientific basis for sustainable airport pavement construction in northern China.

This paper presents a case study for soil improvement using a combined vacuum and fill sur-charge preloading method for the 3rd runway of the Suvarnabhumi International Airport in Bangkok, Thailand. Prefabricated vertical drains of 10 m long was used. The preloading consisted of an average of 86 kPa of vacuum pressure plus a 22 kPa of fill sur-charge due to the granular fill and drainage layer. The vacuum preloading system adopted is described. Monitored settlements and pore water pressures are presented. The average ground settled monitored is around 70 cm and the average degree of consolidation as estimated using settlement data is higher than 90%. Degree of consolidation is also calculated using pores water pressure distribution monitored along the depth which gave a good verification of the degree of consolidation achieved.

Substantial degradation can occur to warm permafrost due to changes in surface conditions resulting from infrastructure development and climate warming. The associated geohazards, including differential settlement, slope instability, and liquefaction of degraded, unconsolidated materials in seismically active warm permafrost regions, pose substantial threats to the built infrastructure. Among them, seismic hazards of degraded permafrost have received little attention. This paper aims to provide a case study of an airport built on warm permafrost about 80 years ago, focusing on climate changes, permafrost degradation, and observed seismic hazards during a strong earthquake. The study site, that is, the Northway Airport, is located in a discontinuous permafrost area in Interior Alaska. Geotechnical data from 1973, 1991, and 2005 were compiled and analyzed to reveal permafrost degradation at various surface conditions, and are compared with the well-known degradation data from a site in Fairbanks. Furthermore, the responses of the airport runway during the 2002 Denali earthquake (Mw = 7.9), including liquefaction and lateral spreading displacements, are described and analyzed. And the seismic hazards of civilian airports built on permafrost across Alaska are surveyed. Distinct trends are revealed in two periods, namely, from 1943 to 1975 and from 1976 to 2021, for air temperature, precipitation, and wind speed. Permafrost tables were observed to drop with time at various rates for different surface conditions. Liquefaction and lateral spreading were observed extensively during the earthquake. The locations of observed liquefaction at the airport are mapped, and the lateral spreading displacements are estimated based on available photos. The standard penetration test data collected during geotechnical investigations are analyzed, and a liquefiable layer is identified at the talik between the active layer and the permafrost table. Moreover, 55% of Alaska's civilian airports are in permafrost areas. Among them, two-thirds fall within seismic zones with a risk level of 3 or above. This study demonstrates the high seismic risks of degraded permafrost and its potential impact on the built infrastructure.

Kerosene is widely used in various types of anthropogenic activities. Its environmental safety is mainly discussed in the context of aerospace activities. At all stages of its life cycle, aerospace activity impacts the environment. In aviation, the pollution of atmospheric air and terrestrial ecosystems is caused, first of all, by jet fuel and the products of its incomplete combustion and is technologically specified for a number of models in the case of fuel leak during an emergency landing. In the rocket and space activities, jet fuel enters terrestrial ecosystems as a result of fuel spills from engines and fuel tanks at the crash sites of the first stages of launch vehicles. The jet fuel from the second and third stages of launch vehicles does not enter terrestrial ecosystems. The fuel components have been studied in sufficient detail. However, the papers with representative data sets and their statistical processing not only for the kerosene content, but also for the total petroleum hydrocarbons in the soils affected by aerospace activity are almost absent. Nevertheless, the available data and results of mathematical modeling allow us to assert that an acceptable level of hydrocarbons, not exceeding the assimilation potential, enters terrestrial ecosystems during a regular aerospace activity. Thus, the incoming amount of jet fuel disappears rapidly enough without causing any irreversible damage.

The soil arching effect is the key mechanism for load transfer in pile-supported reinforced road (runway) foundations. In order to investigated the formation and evolution process of soil arching effect in the whole process of embankment filling and soft soil foundation consolidation, a three-dimensional hydro-mechanical coupled numerical model of PHC pile reinforced soft soil runway foundation was established based on the foundation treatment project in Pudong Airport. The variation laws of soil settlement, pore water pressure, and pile soil stress were analyzed, and the influence of pile spacing was considered. These data from both numerical simulation and field test indicate the soil arching effect in the foundation reinforced by PHC piles and preliminary reveal the evolution of soil arching in the process of embankment filling and soft soil foundation consolidation. The preliminary results encourage the authors to continue this research to investigate the evolution of soil arching under aircraft dynamic loads through adding a more suitable constitutive model or subroutine in this numerical model.

Rising temperatures due to climate change can significantly impact the freeze-thaw condition of airport pavements in cold regions. This case study investigates the implications of warming temperatures on the freeze-thaw penetration and frost heave of pavements in critical airports across Canada. To this end, different methods were used in the quantification process through climate change simulations considering emission scenario RCP8.5 in 20 and 40 year time horizons. The results show that climate change would have different design implications for airport pavements, depending on their location. The predictions suggest a shallower frost penetration depth, and possibly less frost heave, for the airports not underlain by permafrost, while airports over permafrost areas might experience an increase in thickness of the active layer, ranging from 41 to 57 percent, by 2061. Among the different methods used in this study, it was observed that some methods performed better in predicting the frost depth of fine soils, while others worked better in the frost depth prediction of coarse soils. The results indicate the need for more mechanistic models to provide a more realistic prediction of freeze-thaw penetration, as compared to existing empirical models.

The thermal parameters of adherent layer are of great significance to the distribution characteristics of temperature field and foundation stability control of runway in permafrost region. This paper investigated the effects of annual range of temperature (A), annual average temperature (T-A), and other factors on the adherent layer thickness (H), temperature amplitude (A(0)), and annual average ground temperature (T-0), and further analyzed the thermal parameters of the adherent layer by using the FEM (Finite Element Model) roadbed temperature field and experimental data. The results indicate: A and average monthly total solar radiation (Q) have the most serious on H. A numerical method for determining the parameters of the adherent layer based on various conditions such as A and T-A was proposed by multiple regression. The temperature fields of the three types of pavements obtained by FEM and the experimental data were compared with the numerical calculation results for verification, and the conclusions were in close agreement, illustrating that the proposed method for calculating the parameters of the adherent layer is reasonable and effective. The research results extend the application region of adherent layer theory and provide a reference for runway construction in the permafrost region of Northeast China.

The permafrost in the Da Xing'anling Mountains Northeastern China has experienced rapid and significant degradation due to climate warming and human activities during the last few decades. In this study, the permafrost degradation and freezing/thawing characteristics of the active layer at Mo'he airport were investigated through a ground temperatures data set collected over 10 years of measurements. During the monitoring period, thawing permafrost under the airport was observed, induced by climate warming, and thermal disturbance of airport construction and operation. The permafrost table under the blast pad declined considerably and varied from - 9 m to -14 m, and from - 4.5 m to -12 m under the natural site. The maximum depth of frost penetration at this airport shows a decreasing trend. The freezing duration of soil under the blast pad is shorter comparing with the natural ground surface, while its thawing duration is longer. The warming rates of permafrost at -10 m depth under the blast pad were 0.25-0.33 degrees C/a, and those under the natural ground were 0.03 degrees C/a and 0.15 degrees C/ a. The results provide valuable data for designing, construction and operation of the airport, and a reference for other airports construction in permafrost regions.