The warming and melting of permafrost due to climate warming pose a considerable threat to the integrity of the Pan Arctic building, thus jeopardizing sustainable development. The increase in ambient temperature in permafrost areas will cause deterioration in the bearing capacity of building pile foundations. Considering the continuous deepening of the active layer (za), the present paper used small-scale physical modeling to investigate the potential variation of bearing capacity and load transfer mechanism of pile foundations under the scenario of continuous degradation of permafrost. The ultimate bearing capacity of a single pile and the undrained shear strength of the ground under different za are estimated by cone penetration tests. In the static load test of single piles, the axial load-settlement, axial force of pile shaft, and earth pressure at the pile tip are measured. The results show that the rise in ground temperature and the deepening of the za shorten the elastic and elastic-plastic stages of the load-displacement curve, resulting in a gradual decline in the bearing capacity of a single pile. The pile-soil interface temperature is always higher than the adjacent ground temperature at the same depth. Adfreezing force of the pile-soil interface decreases due to the increase in ground temperature and water content. With the deepening of za, the peak point of the shaft resistance decreases from -30 cm to -60 cm under the ultimate state. Meanwhile, with more axial load transfer along the pile shaft to the pile tip, the share ratio of pile tip resistance to ultimate stress gradually increases. In addition, the temperature rise of frozen soil at the pile tip accelerates the settling rate of the pile, which eventually causes the pile foundation failure.

The current water environment carrying capacity assessment method has a single assessment index and does not constrain the scope of assessment. It is not possible to adaptively assess the water environment carrying capacity layer by layer. In order to solve this problem, in this paper. we propose an adaptive assessment method of urban water environment carrying capacity based on water quality target constraints. This method constructs a new evaluation index system for water environment carrying capacity, which takes water resources and environment, water pollution control, and economic carrying capacity as the criteria, and takes water quality status, pollution discharge, technology management. economic development, and social development as the constraint target layer, and takes the total wastewater discharge, industrial water consumption, and urbanization level as the constraint index layer. Two methods of structural entropy weight and mean square error decision are introduced to realize the adaptive joint weight assignment evaluation of the reference layer and the target layer. Through experimental analysis, the assessed area has a good water environment carrying capacity and foundation, and the overall water environment carrying capacity of the study area from 2016 to 2019 was on the rise.

The object of the research is the behavior of axial compressed piles in the foundations on continuous permafrost soils under global warming. There is a degradation of permafrost soils at present. The permafrost layer is vertically divided into two parts: 1) the top, the active layer; 2) the bottom, the frozen mass. The active layer of soil thaws in summer and freezes in winter. Frozen soil behaves as a rock in winter and as a liquid mass on some soil thickness in summer. Accordingly, the surface forces acting on the pile surface in winter time disappear in the entire melted liquid soil layer in summer time. We considered the design of a pile by the condition of the first kind buckling (form) under axial compression. We took into account the conditions when the depth of the base thawing soil increases in the upper part of the pile at the stages of operation (in the summertime of the pile operation). In addition, we considered the calculation of the pile length under the same conditions at a given load on the pile at the stage of its design. To forecast the piles operating time in pile foundations or individual piles during global warming on the Earth, an algorithm for calculating pile length at the design stage is proposed. The paper provides a numerical example of calculating the pile operational life in the solid frozen soil of the foundation in an oil pipeline support.

Most residential buildings and capital structures in the permafrost zone are constructed on the principle of maintaining the frozen state of the foundation soils. The changing climate and the increasing anthropogenic impact on the environment lead to changes in the boundaries of permafrost. These changes are especially relevant in the areas of piling foundations of residential buildings and other engineering structures located in the northern regions since they can lead to serious accidents caused by the degradation of permafrost and decrease the bearing capacity of the soil in such areas. Therefore, organization of temperature monitoring and forecasting of temperature changes in the soil under the buildings is an actual problem. To solve this problem, we use computer simulation methods of three-dimensional nonstationary thermal fields in the soil in combination with real-time monitoring of the temperature of the soil in thermometric wells. The developed approach is verified by using the temperature monitoring data for a specific residential building in the city of Salekhard. Comparison of the results of numerical calculations with experimental data showed good agreement. Using the developed computer software, nonstationary temperature fields under this building are obtained and, on this basis, the bearing capacities of all piles are calculated and a forecast of their changes in the future is given. To avoid decreasing the bearing capacity of piles it is necessary to prevent the degradation of permafrost and to supply the thermal stabilization of the soil. The proposed approach, based on a combination of the soil temperature monitoring and computer modeling methods, can be used to improve geotechnical monitoring methods.

This is an attempt to predict the potential economic impacts on public infrastructure upon degrading permafrost which is losing its bearing capacity. Climate change-related increases in costs (economic losses or damage) are estimated for several climate futures by 2050 separately for 39 municipalities located in the Russian Arctic permafrost domain. The hypothetical changes in mean annual ground temperature are inferred from air and ground temperature trends and monitoring data, with reference to forecasts of the Climate Center of the Russian Meteorological Service (Roshydromet) and climate change scenarios (representative concentration pathways RCP2.6, RCP4.5, and RCP8.5). The calculations were performed for twelve possible cases with different air ground temperature assumptions, with regard to the difference between the ground and air mean annual temperatures. This difference, or temperature shifts, due to radiation, snow, vegetation, and atmospheric precipitation effects, was estimated either by means of calculations proceeding from possible changes of climate variables or by summation of known values reported from different Arctic areas. The economic losses were evaluated as maximum and minimum values at extreme values of permafrost parameters, separately for each case. The buildings and facilities on permafrost were assumed to have pile foundations with friction piles. The permafrost thaw impact was meant as the loss of the soil capacity to bear the support structures for the infrastructure leading to deformation and failure. The impact was considered significant if the change exceeded the safety margin according to the Russian Building Code. The greatest damage is expected to housing stock and buildings and structures of main economic sectors. The monetary value of the residential infrastructure was estimated using a specially compiled inventory database including address, age, and surface area of 23.900 houses in 39 selected Russian Arctic municipalities over a total area of 44.600 km(2). The estimation of fixed assets stemmed from the assumption that their monetary value is proportional to the gross output in the respective economic sector, which, in its turn, correlates with the payroll total corrected for mean industry coefficients for different regions of Russia. The potential damage may reach up to US$ 132 billion (total) and similar to US$ 15 billion for residential infrastructure alone, which generally agrees with other estimates.

At present, the improvement of the horizontal bearing capacity of the piles by pre-consolidation of the soft soil foundation has been well recognized by practising engineers. However, how to estimate the increment of horizontal bearing capacity of piles during the pre-engineering process is still difficult. In this article, a practical calculation method for estimating the increment of horizontal bearing capacity of piles is established based on the Bowles[1] method and by considering the impact of pre-drainage and pre-consolidation treatment of the layered soft soil foundation. This method provides an effective way to calculate the shear strength index and pre-consolidation treatment time based on the shear strength of undisturbed soft soil by laboratory test. Meanwhile, the elastoplastic solution of the horizontally loaded pile and the calculation formula of the plastic zone depth of layered soft soil foundation are analytically derived, based on the influence of elastoplastic yielding of soils surrounding the pile. In addition, the source code for computing the horizontal displacement of the pile top and the maximum bending moment of the pile body are given. Finally, the horizontal displacement, bearing capacity and the maximum bending moment of piles in the sluice pile foundation engineering case in Zhejiang Province are calculated according to the proposed method. The results of the field tests before and after the pre-consolidation treatments are compared. It is found that the estimated results are close to the test results, which may provide a good reference for similar engineering designs.

Temperature is a key factor that affects the adfreeze strength between frozen soil and a structure. Under the influence of climate change, permafrost degradation reduces the bearing capacity of bored piles in permafrost regions. Based on the monitoring results of bored piles at a site in Beiluhe and related simulations, the effect of a ventilated open structure (VOS) on the temperature at the pile-soil interface and the bearing capacity of bored piles was discussed. The results showed that climate warming can significantly reduce the bearing capacity of bored piles. The higher thermal conductivity of concrete than frozen soil had a negligible influence on thermal stability of pile. However, the temperature at the pile-soil interface decrease drastically within a year due to the lower surface boundary temperature beneath a VOS. Numerical simulation indicated that the bearing capacity of bored piles with a VOS increases during the first 25 years and then decreased. While the bearing capacity without a VOS decreases over 50 years. A VOS can improve the stability of bored piles, delay bearing capacity degradation of bored piles for at least 50 years, and significantly reduce the design pile length.

Climate change has a substantial impact on infrastructures in the permafrost on the Qinghai-Tibetan Plateau (QTP). In this study, the mean annual ground temperature (MAGT) and permafrost evolution were investigated in both the historical (1950-2005) and projected (2006-2099) periods. Then, an allowable bearing capacity model was used to discuss the allowable bearing capacity change on the QTP. Results show that the MAGT increased by 0.36 degrees C during 1950-2005. The MAGT will increase by 0.40 (RCP2.6), 0.79 (RCP4.5), 1.07 (RCP6.0), and 1.75 (RCP8.5) degrees C during 2006-2099. In addition, the permafrost area has decreased by 0.195 x 10(6) km(2) in 1950-2005. The permafrost area will decrease by 0.232 x 10 6 (RCP2.6), 0.468 x 10 6 (RCP4.5), 0.564 x 10 6 (RCP6.0), and 0.803 x 10 6 (RCP8.5) km 2 during 2006-2099. With the degradation of permafrost, the allowable bearing capacity in permafrost zones would decrease accordingly. The decreasing trend is 6 kPa per 10 years in 1950-2005, and will be 0.6 (RCP2.6), 5 (RCP4.5), 7 (RCP6.0), and 11 (RCP8.5) kPa per 10 years during 2006-2099. The most remarkable trend would be observed under RCP8.5. Meanwhile, some scientific advices for the design, construction, operation and maintenance of permafrost engineering in the context of climate change were provided.

Considering different physicographical territory under changing climate conditions, a quantitative technique is presented for estimating the changes in bearing capacity of the permafrost foundations. The results showed an increase in the permafrost temperature over 30 years (1960-1990) due to climate warming. This led to a decrease in the bearing capacity foundations in the north of Western Siberia, and in some regions the reduction was up to 45%. The predicted climate warming may lead to a further decrease in the bearing capacity of the foundations built on the principle of permafrost construction, which will lead to an increase in the number of deformations of buildings and structures and may adversely affect the development of the region's infrastructure.