Nanjing’s determination to transform itself from a production base to a research center reflects China’s evolution toward higher-quality development.A refrigerator that thaws frozen meat in 10 minutes and then keeps...Nanjing’s determination to transform itself from a production base to a research center reflects China’s evolution toward higher-quality development.A refrigerator that thaws frozen meat in 10 minutes and then keeps it fresh,a cooker hood that remains clean even after 10 years without disassembling it for cleaning.展开更多
The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics ...The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics of frozen sodium sulfate saline sandy soil,a series of uniaxial compression tests were performed by integrating digital image correlation(DIC)technology into the testing apparatus.The evolution law of the uniaxial compression strength(UCS),the failure strain,and the formation of the shear band of the frozen sodium sulfate saline sandy soil were analyzed.The test results show that within the scope of this study,with the increase of salt content,both the UCS and the shear band angle initially decrease with increasing salt content before showing an increase.In contrast,the failure strain and the width of the shear band exhibit an initial increase followed by a decrease in the samples.In addition,to investigate the brittle failure characteristics of frozen sodium sulfate saline sandy soil,two classic brittleness evaluation methods were employed to quantitatively assess the brittleness level for the soil samples.The findings suggest that the failure characteristics under all test conditions in this study belong to the transition stage between brittle and ductile,indicating that frozen sodium sulfate saline sandy soil exhibits certain brittle behavior under uniaxial compression conditions,and the brittleness index basically decreases and then increases with the rise in salt content.展开更多
Editor-in-Chief Yuanming Lai,Academician of Chinese Academy of Sciences,director of Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,China,Associate Editor of Cold Regions Scien...Editor-in-Chief Yuanming Lai,Academician of Chinese Academy of Sciences,director of Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,China,Associate Editor of Cold Regions Science and Technology.Frozen ground accounts for 50%of the earthꞌs land area.With rapid economic development,more and more infrastructures are being constructed in the broad cold regions,resulting in disturbance to the heat balance of the cold environment.Meanwhile,climate warming impacts have been observed worldwide,with more severe effects occurring in the cold regions.展开更多
To investigate the temperature susceptibility and nonlinear memory effects of artificially frozen soil creep behavior,this study conducted uniaxial step-loading creep tests under controlled temperatures ranging from-1...To investigate the temperature susceptibility and nonlinear memory effects of artificially frozen soil creep behavior,this study conducted uniaxial step-loading creep tests under controlled temperatures ranging from-10℃to-20℃.The transient creep characteristics and steady-state creep rates of artificially frozen soils were systematically examined with respect to variations in temperature and stress.Experimental results demonstrate that decreasing temperatures lead to a decaying trend in the steady-state creep rate of silty frozen soil,confirming that low-temperature environments significantly inhibit plastic flow while enhancing material stiffness.Based on fractional calculus theory,a fractional derivative creep model was established.By incorporating temperature dependencies,the model was further improved to account for both stress and temperature effects.The model predictions align closely with experimental data,achieving over 91%agreement(standard deviation±1.8%),and effectively capture the stress-strain behavior of artificially frozen soil under varying thermal conditions.This research provides a reliable theoretical foundation for studying deformation characteristics in cold-regions engineering.展开更多
In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experi...In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experiment were conducted to explore the effects of moisture content,confining pressure,and temperature on the stress-strain characteristics and failure modes of frozen soil,as well as the changes in the internal microstructure of the sample.The experimental results show that the strength of frozen sulfate saline soil first increases and then decreases with the increase of moisture content,and the maximum strength corresponds to a moisture content of 15%.The changes in confining pressure and strength have the same trend.The lower the temperature,the greater the strength of the sample.During the entire loading process,the specimens undergo a gradual transition from volume shrinkage to volume expansion.Due to the strain harden behavior of the stress-strain curve throughout the entire loading process,the failure mode of the specimens is plastic failure.The internal microstructure of the sample gradually transitions from point-point contact and edge-point contact before shearing to edge-surface contact and edge-edge contact after shearing,and the pore size inside the sample increases after shearing,with a loose arrangement of the particle skeleton.The above research conclusions can lay a certain theoretical foun-dation for the engineering design and construction of sulfate saline soil in cold and arid areas.展开更多
Due to the high water content in warm frozen soil,the pore water pressure and pore ice pressure generated within the sample during loading significantlyinfluencethe deformation and strength of the soil skeleton.Theref...Due to the high water content in warm frozen soil,the pore water pressure and pore ice pressure generated within the sample during loading significantlyinfluencethe deformation and strength of the soil skeleton.Therefore,it is essential to develop a constitutive model for warm frozen soil that can capture the changes in ice pressure and water pressure.This study introduces a macro-meso constitutive model based on a binary-medium framework to describe the mechanical behavior of warm frozen soil.In this model,warm frozen soil is conceptualized as consisting of bonded and frictional elements from a meso perspective.The bonded elements are modeled using a macro-meso elastic constitutive approach based on poromechanics,while the frictional elements employ a macro-meso elastoplastic approach,also grounded in poromechanics.These two elements are then linked within the binarymedium model framework.By replicating the experimental curves of warm frozen soils,the theoretical results from the proposed model show excellent agreement with experimental data.This consistency indicates that the model effectively simulates the strain softening and volumetric expansion behaviors of warm frozen soil samples under various conditions.Additionally,the constitutive model predicts changes in unfrozen water pressure,frozen temperature,unfrozen water saturation,and porosity during the loading process of warm frozen soil samples.展开更多
Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformati...Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.展开更多
As a typical seasonal frozen soil region,the slopes of canal projects in Heilongjiang Province frequently experience significant landslide damage due to a high water table and freeze-thaw cycles.This study addresses t...As a typical seasonal frozen soil region,the slopes of canal projects in Heilongjiang Province frequently experience significant landslide damage due to a high water table and freeze-thaw cycles.This study addresses the limitations of existing models in analyzing the hydrothermal coupling processes of saturated soil.It is based on the principles of mass conservation,energy conservation,Darcy's law,and heat conduction theory.A hydrothermal coupling model was developed for saturated soil,incorporating temperature and porosity as variables.By comparing the model's predictions with actual engineering monitoring data,the study effectively validates the model's reliability and elucidates the dynamic changes in the temperature field,water field,and ice content of the saturated canal slopes during the freeze-thaw cycle.The findings indicate that the saturated soil is filled with water in the pore spaces,the temperature field changes gradually during freezing,the water field exhibits minimal fluctuations,and the ice content increases steadily.During the thawing process,the soil rapidly becomes re-saturated,the thawing rate accelerates,the water distribution becomes uniform,and the ice content decreases swiftly to a very low level.In spring,the shallow temperature increased to 23℃ but began to drop in the fall.The upper slope temperature fell to-10℃during winter,and the freezing depth grew as temperatures decreased.The warming in spring facilitated a rise in temperature and shallow melting.There were significant fluctuations in temperature,water,and ice content in the shallow layer of the slope(up to 1.5 m deep).At a depth of 0.5 m,the water content was 38%on day 230,dropped to1.5%on day 257,and further decreased to 0.9%on day 303.The ice content at 0.5 m depth fell from 38.9%on day303 to 24.4%on day 350,while at 1 m depth,it decreased from 36.4%on day 303 to 30%on day 350.展开更多
The warming and thawing of permafrost are the primary factors that impact the stability of embankments in cold regions.However,due to uncertainties in thermal boundaries and soil properties,the stochastic modeling of ...The warming and thawing of permafrost are the primary factors that impact the stability of embankments in cold regions.However,due to uncertainties in thermal boundaries and soil properties,the stochastic modeling of thermal regimes is challenging and computationally expensive.To address this,we propose a knowledge-integrated deep learning method for predicting the stochastic thermal regime of embankments in permafrost regions.Geotechnical knowledge is embedded in the training data through numerical modeling,while the neural network learns the mapping from the thermal boundary and soil property fields to the temperature field.The effectiveness of our method is verified in comparison with monitoring data and numerical analysis results.Experimental results show that the proposed method achieves good accuracy with small coefficient of variation.It still provides satisfactory accuracy as the coefficient of variation increases.The proposed knowledge-integrated deep learning method provides an efficient approach to predict the stochastic thermal regime of heterogeneous embankments.It can also be used in other permafrost engineering investigations that require stochastic numerical modeling.展开更多
According to the announcement of General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,the risk of microbial items in frozen drinks is very high,and it is diffic...According to the announcement of General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,the risk of microbial items in frozen drinks is very high,and it is difficult to improve.For example,a recent spot check showed that 42 kinds of frozen drinks had microbial indicators exceeding the standard.Part of the reason is that the design of the production workshop is not conducive to the rapid removal of production water,resulting in continuous moisture throughout the workshop,which provides a breeding bed for microorganisms to breed and then contaminates the product.Therefore,research is carried out from the design point of view to fundamentally reduce the moisture in the workshop and build a dry workshop for frozen drinks production,so as to effectively reduce the risk of microbial contamination of frozen drinks.展开更多
Here,a seismic-response analysis model was proposed for evaluating the nonlinear seismic response of a pile-supported bridge pier under frozen and thawed soil conditions.The effect of a seasonally frozen soil layer on...Here,a seismic-response analysis model was proposed for evaluating the nonlinear seismic response of a pile-supported bridge pier under frozen and thawed soil conditions.The effect of a seasonally frozen soil layer on the seismic vulnerability of a pile-supported bridge pier was evaluated based on reliability theory.Although the frozen soil layer inhibited the seismic response of the ground surface to a certain extent,it exacerbated the acceleration response at the bridge pier top owing to the low radiation damping effect of the frozen soil layer.Furthermore,the frozen soil layer reduced the lateral displacement of the bridge pier top relative to the ground surface by approximately 80%,thereby preventing damage caused by earthquakes,such as falling girders.Compared to the thawed state of the ground surface,the bending moment of the bridge pier in frozen ground increases.However,the bending moment of the pile foundation in frozen ground decreases,thereby lessening the seismic vulnerability of the bridge pile foundation.The results of this can provide a reference for the seismic response analysis and seismic risk assessment of pile-supported bridges in seasonally frozen regions.展开更多
The potential of high-intensity lasers to influence nuclear decay processes has attracted considerable interest.This study quantitatively evaluated the effects of high-intensity lasers on α decay and cluster radioact...The potential of high-intensity lasers to influence nuclear decay processes has attracted considerable interest.This study quantitatively evaluated the effects of high-intensity lasers on α decay and cluster radioactivity.Our calculations revealed that,among the parent nuclei investigated,^(144)Nd is the most susceptible to laser-induced alterations,primarily because of its relatively low decay energy.Additionally,circularly polarized lasers exhibit a greater impact on decay modifications than linearly polarized lasers.Given the limited time resolution of current detectors,it is essential to account for the timeaveraging effect of the laser.By incorporating the effects of circular polarization,time averaging,and angular averaging,our theoretical predictions indicated that the modification of^(144)Nd decay could reach 0.1%at an intensity of 10^(27)W/cm^(2).However,this intensity significantly exceeds the current laser capability of 10^(23)W/cm^(2),and the predicted modification of 0.1%remains below the detection threshold of contemporary measurement techniques.Observing laser-assistedαdecay and^(14)C cluster radioactivity will likely remain unfeasible until both ultrahigh laser intensities and significant advancements in experimental resolution are achieved.展开更多
Objective:This study aims to develop a deep multiscale image learning system(DMILS)to differentiate malignant from benign thyroid follicular neoplasms on multiscale whole-slide images(WSIs)of intraoperative frozen pat...Objective:This study aims to develop a deep multiscale image learning system(DMILS)to differentiate malignant from benign thyroid follicular neoplasms on multiscale whole-slide images(WSIs)of intraoperative frozen pathological images.Methods:A total of 1,213 patients were divided into training and validation sets,an internal test set,a pooled external test set,and a pooled prospective test set at three centers.DMILS was constructed using a deep learningbased weakly supervised method based on multiscale WSIs at 10×,20×,and 40×magnifications.The performance of the DMILS was compared with that of a single magnification and validated in two pathologist-unidentified subsets.Results:The DMILS yielded good performance,with areas under the receiver operating characteristic curves(AUCs)of 0.848,0.857,0.810,and 0.787 in the training and validation sets,internal test set,pooled external test set,and pooled prospective test set,respectively.The AUC of the DMILS was higher than that of a single magnification,with 0.788 of 10×,0.824 of 20×,and 0.775 of 40×in the internal test set.Moreover,DMILS yielded satisfactory performance on the two pathologist-unidentified subsets.Furthermore,the most indicative region predicted by DMILS is the follicular epithelium.Conclusions:DMILS has good performance in differentiating thyroid follicular neoplasms on multiscale WSIs of intraoperative frozen pathological images.展开更多
The freeze-thaw cycles of frozen soil could significantly affect its thermo-hydro-mechanical-chemical(THMC)properties,causing the frost heaving and thawing settlement.The microscale essence is the water-ice phase tran...The freeze-thaw cycles of frozen soil could significantly affect its thermo-hydro-mechanical-chemical(THMC)properties,causing the frost heaving and thawing settlement.The microscale essence is the water-ice phase transition,but the microscale details are still poorly understood,especially at ultra-low temperatures.Nuclear magnetic resonance(NMR)technology and molecular dynamics(MD)simulation method were performed to explore the freeze-thaw behaviors of montmorillonite clay under temperature of 210e293 K.Then,the water-ice phase transition,freeze-thaw hysteresis,ice nucleation mechanism,and surface effect of clay at an atomistic level were discussed.A classification method of different types of unfrozen water through NMR experiment was proposed,including bulk,capillary,and bound water.Here,it is found that:(1)the freeze-thaw process of frozen soil at the macroscale was essentially the occurrence of ice-water phase transition at the microscale.(2)The freeze-thaw hysteresis was caused by different growth and melting rates of ice crystals,where the ice growth/nucleation on clay surface(i.e.freeze process)was more difficult to develop.(3)The surface effect of clay was essential for the ice nucleation and the existence of bound water.For example,little unfrozen water still existed in unfrozen soil even at 213 K.(4)For unsaturated frozen soil,the quasi-liquid water was an essential component of unfrozen water that cannot be ignored.This work could provide an atomistic insight to unravel the atomistic origin of the freeze-thaw mechanism of montmorillonite clay and complement relevant experimental evidence.展开更多
The artificial ground-freezing method is the main technical means for the excavation of mines and tunnels through the water-rich sand layer,and the comprehensive understanding of the mechanical properties of frozen sa...The artificial ground-freezing method is the main technical means for the excavation of mines and tunnels through the water-rich sand layer,and the comprehensive understanding of the mechanical properties of frozen saturated sand and the stress-strain relationship under complex stress can provide important guidance.In this study,a series of true triaxial tests of frozen saturated sand samples were conducted.Combined with the test data,the effects of temperature and medium principal stress ratio(b)on the strength and deformation characteristics of frozen saturated sand are discussed.In addition,a cohesion tensor is introduced to the Wu-Lin hypoplastic model.A scalar value is used to characterize the effect of temperature on the strength of frozen soil.The defect that the original model cannot describe the tensile capacity of frozen soil under low stress conditions is clearly solved.In addition,the cumulative deformation state variable is introduced to improve the response performance of the model in triaxial compression tests.The hypoplastic model of frozen soil has shown good performance in simulating triaxial compression tests at different temperatures and medium principal stress ratios.展开更多
The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in...The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in frozen regions remains underexplored.In seasonally frozen areas,F-T(freeze-thaw)cycles threaten subgrade stability,necessitating research on pile-plate structure’s behavior under such conditions.To address this challenge,a scaled model experiment was conducted on a silty sand foundation,simulating F-T cycles using temperature control devices.Key parameters,including soil temperature,frozen depth,and displacement,were systematically monitored.Results indicate that the bearing plate functions as an effective insulation layer,significantly reducing sub-zero temperature penetration.Additionally,the anchoring action of the piles mitigates frost heave in the foundation soil,while the plate middle restrains soil deformation more effectively due to increased constraint.The thermal insulation provided by the plate maintains higher soil temperatures,delaying the onset of freezing.By the end of each freezing stage,the vertical displacement in the natural subgrade is approximately 4 times greater than that beneath the pile-plate structure.Furthermore,the frost depth is about 1.3-1.4 times and 1.6-4.9 times greater than that measured below the plate edge and middle,respectively.These insights contribute to the development of more resilient designs for high-speed railway subgrades in seasonally frozen regions,offering engineers a robust,scientifically-backed foundation for future infrastructure projects.展开更多
With global warming and the intensification of human activities, frozen soils continue to melt, leading to the formation of thermokarst collapses and thermokarst lakes. The thawing of permafrost results in the microbi...With global warming and the intensification of human activities, frozen soils continue to melt, leading to the formation of thermokarst collapses and thermokarst lakes. The thawing of permafrost results in the microbial decomposition of large amounts of frozen organic carbon (C), releasing greenhouse gases such as carbon dioxide (CO_(2)) and methane (CH4). However, little research has been done on the thermo-water-vapor-carbon coupling process in permafrost, and the interactions among hydrothermal transport, organic matter decomposition, and CO_(2) transport processes in permafrost remain unclear. We considered the decomposition and release of organic C and established a coupled thermo-water-vapor-carbon model for permafrost based on the study area located in the Beiluhe region of the Qingzang Plateau, China. The model established accurately reflected changes in permafrost temperature, moisture, and C fluxes. Dramatic changes in temperature and precipitation in the warm season led to significant soil water and heat transport, CO_(2) transport, and organic matter decomposition. During the cold season, however, the soil froze, which weakened organic matter decomposition and CO_(2) transport. The sensitivity of soil layers to changes in the external environment varied with depth. Fluctuations in energy, water, and CO_(2) fluxes were greater in shallow soil layers than in deeper ones. The latent heat of water-vapor and water-ice phase changes played a crucial role in regulating the temperature of frozen soil. The low content of soil organic matter in the study area resulted in a smaller influence of the decomposition heat of soil organic matter on soil temperature, compared to the high organic matter content in other soil types (such as peatlands).展开更多
Determination of the unfrozen water and ice contents in frozen soils is a critical issue in cold region geotechnics.The electrical conductivity method has been adopted in both laboratory and in-situ applications,but t...Determination of the unfrozen water and ice contents in frozen soils is a critical issue in cold region geotechnics.The electrical conductivity method has been adopted in both laboratory and in-situ applications,but the exact correlation of unfrozen water content as a function of the electrical conductivity remains an unanswered question.This research conducts a series of lab experiments on the unfrozen water content and electrical conductivity of frozen soils using a temperature-controlled apparatus.The test results indicate that the electrical conductivitytemperature relationship determined at positive temperatures cannot be directly applicable at negative temperatures.The electrical conductivity variation with the temperature of frozen soils is clarified based on the measured data.By quantifying the soil surface and bulk conductivities,a new physically-based model for soils is then developed that can be applicable at positive and negative temperatures.A simplified electrical conductivity model involving the unfrozen water content is developed by analyzing the impact of bulk and surface conductivities on overall electrical conductivity.The accuracy of this simplified model is verified against the experimental data and those obtained with the previous method in the literature.It is found that the results obtained with the new model agree with the measured data,and the new model exhibits a simple form and is easy to apply.展开更多
To ensure the safe operation of trains in seasonally frozen regions, achieving accurate and interpretable displacement prediction of tunnel portal slopes is a fundamental requirement. In this paper, we developed a hyb...To ensure the safe operation of trains in seasonally frozen regions, achieving accurate and interpretable displacement prediction of tunnel portal slopes is a fundamental requirement. In this paper, we developed a hybrid prediction model that integrates dual signal decomposition with an interpretable deep neural network. The Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN) first decomposes the original signals, then performs mode selection and reconstruction based on sample entropy and clustering to suppress redundancy. The high-frequency components are further analyzed using VMD and optimized via DLABC, thereby enhancing multi-scale dynamic feature extraction. On this basis, a Convolutional Neural Network(CNN)-Long Short-Term Memory(LSTM)-Attention model, tuned by the Dung Beetle Optimizer(DBO), is constructed to jointly capture local features, temporal dependencies, and key time-specific responses. Results show the proposed model achieves R^(2)>0.99 and MSE<0.07 across multiple monitoring points, significantly outperforming single-decomposition models(e.g., VMD-BP, R^(2)=0.896, MSE=1.700). The dual decomposition strategy proves effective in noise suppression and feature enhancement. Additionally, the SHapley Additive ex Planations(SHAP) analysis visualizes the model's decision process, quantifying the contribution of key factors to slope deformation, thus improving transparency and reliability. The model demonstrates specific adaptability to freeze-thaw environments, providing a robust framework for forecasting slope deformation and issuing early warnings in seasonally frozen regions.展开更多
文摘Nanjing’s determination to transform itself from a production base to a research center reflects China’s evolution toward higher-quality development.A refrigerator that thaws frozen meat in 10 minutes and then keeps it fresh,a cooker hood that remains clean even after 10 years without disassembling it for cleaning.
基金supported by the National Natural Science Foundation of China(Grant Nos.42372312,and 42172299)the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(Grant No.JDYC20220807).
文摘The progressive failure characteristics of geomaterial are a remarkable and challenging topic in geotechnical engineering.To study the effect of salt content and temperature on the progressive failure characteristics of frozen sodium sulfate saline sandy soil,a series of uniaxial compression tests were performed by integrating digital image correlation(DIC)technology into the testing apparatus.The evolution law of the uniaxial compression strength(UCS),the failure strain,and the formation of the shear band of the frozen sodium sulfate saline sandy soil were analyzed.The test results show that within the scope of this study,with the increase of salt content,both the UCS and the shear band angle initially decrease with increasing salt content before showing an increase.In contrast,the failure strain and the width of the shear band exhibit an initial increase followed by a decrease in the samples.In addition,to investigate the brittle failure characteristics of frozen sodium sulfate saline sandy soil,two classic brittleness evaluation methods were employed to quantitatively assess the brittleness level for the soil samples.The findings suggest that the failure characteristics under all test conditions in this study belong to the transition stage between brittle and ductile,indicating that frozen sodium sulfate saline sandy soil exhibits certain brittle behavior under uniaxial compression conditions,and the brittleness index basically decreases and then increases with the rise in salt content.
文摘Editor-in-Chief Yuanming Lai,Academician of Chinese Academy of Sciences,director of Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,China,Associate Editor of Cold Regions Science and Technology.Frozen ground accounts for 50%of the earthꞌs land area.With rapid economic development,more and more infrastructures are being constructed in the broad cold regions,resulting in disturbance to the heat balance of the cold environment.Meanwhile,climate warming impacts have been observed worldwide,with more severe effects occurring in the cold regions.
基金National Key Research and Development Program of China“Structural Stability Assessment Techniques and Demonstration for Masonry Ancient Pagodas”(2023YFF0906005)。
文摘To investigate the temperature susceptibility and nonlinear memory effects of artificially frozen soil creep behavior,this study conducted uniaxial step-loading creep tests under controlled temperatures ranging from-10℃to-20℃.The transient creep characteristics and steady-state creep rates of artificially frozen soils were systematically examined with respect to variations in temperature and stress.Experimental results demonstrate that decreasing temperatures lead to a decaying trend in the steady-state creep rate of silty frozen soil,confirming that low-temperature environments significantly inhibit plastic flow while enhancing material stiffness.Based on fractional calculus theory,a fractional derivative creep model was established.By incorporating temperature dependencies,the model was further improved to account for both stress and temperature effects.The model predictions align closely with experimental data,achieving over 91%agreement(standard deviation±1.8%),and effectively capture the stress-strain behavior of artificially frozen soil under varying thermal conditions.This research provides a reliable theoretical foundation for studying deformation characteristics in cold-regions engineering.
基金supported by the National Natural Science Foun-dation of China(12362032)the Key Research and Development Pro-gram of Gansu Province-Social Development(23YFFA0063).
文摘In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experiment were conducted to explore the effects of moisture content,confining pressure,and temperature on the stress-strain characteristics and failure modes of frozen soil,as well as the changes in the internal microstructure of the sample.The experimental results show that the strength of frozen sulfate saline soil first increases and then decreases with the increase of moisture content,and the maximum strength corresponds to a moisture content of 15%.The changes in confining pressure and strength have the same trend.The lower the temperature,the greater the strength of the sample.During the entire loading process,the specimens undergo a gradual transition from volume shrinkage to volume expansion.Due to the strain harden behavior of the stress-strain curve throughout the entire loading process,the failure mode of the specimens is plastic failure.The internal microstructure of the sample gradually transitions from point-point contact and edge-point contact before shearing to edge-surface contact and edge-edge contact after shearing,and the pore size inside the sample increases after shearing,with a loose arrangement of the particle skeleton.The above research conclusions can lay a certain theoretical foun-dation for the engineering design and construction of sulfate saline soil in cold and arid areas.
基金the financial support from the funding of the National Natural Science Foundation of China(NSFC)(Grant Nos.42401160 and U22A20596)the Science and Technology Plan Project of Linzhi(Grant No.SYQ2024-13).
文摘Due to the high water content in warm frozen soil,the pore water pressure and pore ice pressure generated within the sample during loading significantlyinfluencethe deformation and strength of the soil skeleton.Therefore,it is essential to develop a constitutive model for warm frozen soil that can capture the changes in ice pressure and water pressure.This study introduces a macro-meso constitutive model based on a binary-medium framework to describe the mechanical behavior of warm frozen soil.In this model,warm frozen soil is conceptualized as consisting of bonded and frictional elements from a meso perspective.The bonded elements are modeled using a macro-meso elastic constitutive approach based on poromechanics,while the frictional elements employ a macro-meso elastoplastic approach,also grounded in poromechanics.These two elements are then linked within the binarymedium model framework.By replicating the experimental curves of warm frozen soils,the theoretical results from the proposed model show excellent agreement with experimental data.This consistency indicates that the model effectively simulates the strain softening and volumetric expansion behaviors of warm frozen soil samples under various conditions.Additionally,the constitutive model predicts changes in unfrozen water pressure,frozen temperature,unfrozen water saturation,and porosity during the loading process of warm frozen soil samples.
基金the National Key Research and Development Program of China(Grant No.2023YFF1303501)the National Science Fund for Distinguished Young Scholars of China(Grant No.42225702)the Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE201814).
文摘Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.
基金financial support from the National Natural Science Foundation of China(42401175)Heilongjiang Provincial Key Research and Development Program Project(JD2023SJ46)+2 种基金Heilongjiang Provincial Research Institutes Scientific Research Business Fund Project(CZKYF2025-1-B008)Open Fund for Key Laboratory of Heilongjiang Province Hydraulic Research Institute(DT2024A01)Heilongjiang Province Postdoctoral Special Grant(LBH-TZ2418)。
文摘As a typical seasonal frozen soil region,the slopes of canal projects in Heilongjiang Province frequently experience significant landslide damage due to a high water table and freeze-thaw cycles.This study addresses the limitations of existing models in analyzing the hydrothermal coupling processes of saturated soil.It is based on the principles of mass conservation,energy conservation,Darcy's law,and heat conduction theory.A hydrothermal coupling model was developed for saturated soil,incorporating temperature and porosity as variables.By comparing the model's predictions with actual engineering monitoring data,the study effectively validates the model's reliability and elucidates the dynamic changes in the temperature field,water field,and ice content of the saturated canal slopes during the freeze-thaw cycle.The findings indicate that the saturated soil is filled with water in the pore spaces,the temperature field changes gradually during freezing,the water field exhibits minimal fluctuations,and the ice content increases steadily.During the thawing process,the soil rapidly becomes re-saturated,the thawing rate accelerates,the water distribution becomes uniform,and the ice content decreases swiftly to a very low level.In spring,the shallow temperature increased to 23℃ but began to drop in the fall.The upper slope temperature fell to-10℃during winter,and the freezing depth grew as temperatures decreased.The warming in spring facilitated a rise in temperature and shallow melting.There were significant fluctuations in temperature,water,and ice content in the shallow layer of the slope(up to 1.5 m deep).At a depth of 0.5 m,the water content was 38%on day 230,dropped to1.5%on day 257,and further decreased to 0.9%on day 303.The ice content at 0.5 m depth fell from 38.9%on day303 to 24.4%on day 350,while at 1 m depth,it decreased from 36.4%on day 303 to 30%on day 350.
基金funding support from the National Natural Science Foundation of China(Grant Nos.42277161,42230709).
文摘The warming and thawing of permafrost are the primary factors that impact the stability of embankments in cold regions.However,due to uncertainties in thermal boundaries and soil properties,the stochastic modeling of thermal regimes is challenging and computationally expensive.To address this,we propose a knowledge-integrated deep learning method for predicting the stochastic thermal regime of embankments in permafrost regions.Geotechnical knowledge is embedded in the training data through numerical modeling,while the neural network learns the mapping from the thermal boundary and soil property fields to the temperature field.The effectiveness of our method is verified in comparison with monitoring data and numerical analysis results.Experimental results show that the proposed method achieves good accuracy with small coefficient of variation.It still provides satisfactory accuracy as the coefficient of variation increases.The proposed knowledge-integrated deep learning method provides an efficient approach to predict the stochastic thermal regime of heterogeneous embankments.It can also be used in other permafrost engineering investigations that require stochastic numerical modeling.
文摘According to the announcement of General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,the risk of microbial items in frozen drinks is very high,and it is difficult to improve.For example,a recent spot check showed that 42 kinds of frozen drinks had microbial indicators exceeding the standard.Part of the reason is that the design of the production workshop is not conducive to the rapid removal of production water,resulting in continuous moisture throughout the workshop,which provides a breeding bed for microorganisms to breed and then contaminates the product.Therefore,research is carried out from the design point of view to fundamentally reduce the moisture in the workshop and build a dry workshop for frozen drinks production,so as to effectively reduce the risk of microbial contamination of frozen drinks.
基金National Natural Science Foundation of China under Grant Nos.52068045,U21A2012 and 41825015。
文摘Here,a seismic-response analysis model was proposed for evaluating the nonlinear seismic response of a pile-supported bridge pier under frozen and thawed soil conditions.The effect of a seasonally frozen soil layer on the seismic vulnerability of a pile-supported bridge pier was evaluated based on reliability theory.Although the frozen soil layer inhibited the seismic response of the ground surface to a certain extent,it exacerbated the acceleration response at the bridge pier top owing to the low radiation damping effect of the frozen soil layer.Furthermore,the frozen soil layer reduced the lateral displacement of the bridge pier top relative to the ground surface by approximately 80%,thereby preventing damage caused by earthquakes,such as falling girders.Compared to the thawed state of the ground surface,the bending moment of the bridge pier in frozen ground increases.However,the bending moment of the pile foundation in frozen ground decreases,thereby lessening the seismic vulnerability of the bridge pile foundation.The results of this can provide a reference for the seismic response analysis and seismic risk assessment of pile-supported bridges in seasonally frozen regions.
基金supported by the National Natural Science Foundation of China(Nos.12475136 and 12075327)。
文摘The potential of high-intensity lasers to influence nuclear decay processes has attracted considerable interest.This study quantitatively evaluated the effects of high-intensity lasers on α decay and cluster radioactivity.Our calculations revealed that,among the parent nuclei investigated,^(144)Nd is the most susceptible to laser-induced alterations,primarily because of its relatively low decay energy.Additionally,circularly polarized lasers exhibit a greater impact on decay modifications than linearly polarized lasers.Given the limited time resolution of current detectors,it is essential to account for the timeaveraging effect of the laser.By incorporating the effects of circular polarization,time averaging,and angular averaging,our theoretical predictions indicated that the modification of^(144)Nd decay could reach 0.1%at an intensity of 10^(27)W/cm^(2).However,this intensity significantly exceeds the current laser capability of 10^(23)W/cm^(2),and the predicted modification of 0.1%remains below the detection threshold of contemporary measurement techniques.Observing laser-assistedαdecay and^(14)C cluster radioactivity will likely remain unfeasible until both ultrahigh laser intensities and significant advancements in experimental resolution are achieved.
基金supported by the Taishan Scholar Project(No.ts20190991,tsqn202211378)the Key R&D Project of Shandong Province(No.2022CXPT023)the General Program of National Natural Science Foundation of China(No.82371933)。
文摘Objective:This study aims to develop a deep multiscale image learning system(DMILS)to differentiate malignant from benign thyroid follicular neoplasms on multiscale whole-slide images(WSIs)of intraoperative frozen pathological images.Methods:A total of 1,213 patients were divided into training and validation sets,an internal test set,a pooled external test set,and a pooled prospective test set at three centers.DMILS was constructed using a deep learningbased weakly supervised method based on multiscale WSIs at 10×,20×,and 40×magnifications.The performance of the DMILS was compared with that of a single magnification and validated in two pathologist-unidentified subsets.Results:The DMILS yielded good performance,with areas under the receiver operating characteristic curves(AUCs)of 0.848,0.857,0.810,and 0.787 in the training and validation sets,internal test set,pooled external test set,and pooled prospective test set,respectively.The AUC of the DMILS was higher than that of a single magnification,with 0.788 of 10×,0.824 of 20×,and 0.775 of 40×in the internal test set.Moreover,DMILS yielded satisfactory performance on the two pathologist-unidentified subsets.Furthermore,the most indicative region predicted by DMILS is the follicular epithelium.Conclusions:DMILS has good performance in differentiating thyroid follicular neoplasms on multiscale WSIs of intraoperative frozen pathological images.
基金financially supported by the Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE202104)the Natural Science Foundation of GuangDong Basic and Applied Basic Research Foundation(Grant No.2024A1515011853)the Research Grants Council(RGC)of Hong Kong Special Administrative Region Government(HKSARG)of China(Grant Nos.:N_PolyU534/20).
文摘The freeze-thaw cycles of frozen soil could significantly affect its thermo-hydro-mechanical-chemical(THMC)properties,causing the frost heaving and thawing settlement.The microscale essence is the water-ice phase transition,but the microscale details are still poorly understood,especially at ultra-low temperatures.Nuclear magnetic resonance(NMR)technology and molecular dynamics(MD)simulation method were performed to explore the freeze-thaw behaviors of montmorillonite clay under temperature of 210e293 K.Then,the water-ice phase transition,freeze-thaw hysteresis,ice nucleation mechanism,and surface effect of clay at an atomistic level were discussed.A classification method of different types of unfrozen water through NMR experiment was proposed,including bulk,capillary,and bound water.Here,it is found that:(1)the freeze-thaw process of frozen soil at the macroscale was essentially the occurrence of ice-water phase transition at the microscale.(2)The freeze-thaw hysteresis was caused by different growth and melting rates of ice crystals,where the ice growth/nucleation on clay surface(i.e.freeze process)was more difficult to develop.(3)The surface effect of clay was essential for the ice nucleation and the existence of bound water.For example,little unfrozen water still existed in unfrozen soil even at 213 K.(4)For unsaturated frozen soil,the quasi-liquid water was an essential component of unfrozen water that cannot be ignored.This work could provide an atomistic insight to unravel the atomistic origin of the freeze-thaw mechanism of montmorillonite clay and complement relevant experimental evidence.
基金support provided by the Open Project Foundation for Key Laboratories of Universities in Fujian Province(KF-T18014)the Scientific Research Project of Shaanxi Coalfield Geology Group Co.,Ltd.(SMDZ-2019CX-7).
文摘The artificial ground-freezing method is the main technical means for the excavation of mines and tunnels through the water-rich sand layer,and the comprehensive understanding of the mechanical properties of frozen saturated sand and the stress-strain relationship under complex stress can provide important guidance.In this study,a series of true triaxial tests of frozen saturated sand samples were conducted.Combined with the test data,the effects of temperature and medium principal stress ratio(b)on the strength and deformation characteristics of frozen saturated sand are discussed.In addition,a cohesion tensor is introduced to the Wu-Lin hypoplastic model.A scalar value is used to characterize the effect of temperature on the strength of frozen soil.The defect that the original model cannot describe the tensile capacity of frozen soil under low stress conditions is clearly solved.In addition,the cumulative deformation state variable is introduced to improve the response performance of the model in triaxial compression tests.The hypoplastic model of frozen soil has shown good performance in simulating triaxial compression tests at different temperatures and medium principal stress ratios.
基金The authors express their gratitude to the financial support from National Key R&D Program of China(No.2023YFB2604001)National Natural Science Foundation of China(No.52478475,No.52378463 and No.52168066).
文摘The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in frozen regions remains underexplored.In seasonally frozen areas,F-T(freeze-thaw)cycles threaten subgrade stability,necessitating research on pile-plate structure’s behavior under such conditions.To address this challenge,a scaled model experiment was conducted on a silty sand foundation,simulating F-T cycles using temperature control devices.Key parameters,including soil temperature,frozen depth,and displacement,were systematically monitored.Results indicate that the bearing plate functions as an effective insulation layer,significantly reducing sub-zero temperature penetration.Additionally,the anchoring action of the piles mitigates frost heave in the foundation soil,while the plate middle restrains soil deformation more effectively due to increased constraint.The thermal insulation provided by the plate maintains higher soil temperatures,delaying the onset of freezing.By the end of each freezing stage,the vertical displacement in the natural subgrade is approximately 4 times greater than that beneath the pile-plate structure.Furthermore,the frost depth is about 1.3-1.4 times and 1.6-4.9 times greater than that measured below the plate edge and middle,respectively.These insights contribute to the development of more resilient designs for high-speed railway subgrades in seasonally frozen regions,offering engineers a robust,scientifically-backed foundation for future infrastructure projects.
基金the financial support from the National Natural Science Foundation of China(No.U22A20596).
文摘With global warming and the intensification of human activities, frozen soils continue to melt, leading to the formation of thermokarst collapses and thermokarst lakes. The thawing of permafrost results in the microbial decomposition of large amounts of frozen organic carbon (C), releasing greenhouse gases such as carbon dioxide (CO_(2)) and methane (CH4). However, little research has been done on the thermo-water-vapor-carbon coupling process in permafrost, and the interactions among hydrothermal transport, organic matter decomposition, and CO_(2) transport processes in permafrost remain unclear. We considered the decomposition and release of organic C and established a coupled thermo-water-vapor-carbon model for permafrost based on the study area located in the Beiluhe region of the Qingzang Plateau, China. The model established accurately reflected changes in permafrost temperature, moisture, and C fluxes. Dramatic changes in temperature and precipitation in the warm season led to significant soil water and heat transport, CO_(2) transport, and organic matter decomposition. During the cold season, however, the soil froze, which weakened organic matter decomposition and CO_(2) transport. The sensitivity of soil layers to changes in the external environment varied with depth. Fluctuations in energy, water, and CO_(2) fluxes were greater in shallow soil layers than in deeper ones. The latent heat of water-vapor and water-ice phase changes played a crucial role in regulating the temperature of frozen soil. The low content of soil organic matter in the study area resulted in a smaller influence of the decomposition heat of soil organic matter on soil temperature, compared to the high organic matter content in other soil types (such as peatlands).
基金supported by the Science and Technology Research and Development Program of China Railway Group Limited(Grant No.2022-ZD-13)Natural Science Foundation of Hunan Province,China(Grant No.2022JJ10076)。
文摘Determination of the unfrozen water and ice contents in frozen soils is a critical issue in cold region geotechnics.The electrical conductivity method has been adopted in both laboratory and in-situ applications,but the exact correlation of unfrozen water content as a function of the electrical conductivity remains an unanswered question.This research conducts a series of lab experiments on the unfrozen water content and electrical conductivity of frozen soils using a temperature-controlled apparatus.The test results indicate that the electrical conductivitytemperature relationship determined at positive temperatures cannot be directly applicable at negative temperatures.The electrical conductivity variation with the temperature of frozen soils is clarified based on the measured data.By quantifying the soil surface and bulk conductivities,a new physically-based model for soils is then developed that can be applicable at positive and negative temperatures.A simplified electrical conductivity model involving the unfrozen water content is developed by analyzing the impact of bulk and surface conductivities on overall electrical conductivity.The accuracy of this simplified model is verified against the experimental data and those obtained with the previous method in the literature.It is found that the results obtained with the new model agree with the measured data,and the new model exhibits a simple form and is easy to apply.
基金Dalian Jiaotong University for its support during this research。
文摘To ensure the safe operation of trains in seasonally frozen regions, achieving accurate and interpretable displacement prediction of tunnel portal slopes is a fundamental requirement. In this paper, we developed a hybrid prediction model that integrates dual signal decomposition with an interpretable deep neural network. The Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN) first decomposes the original signals, then performs mode selection and reconstruction based on sample entropy and clustering to suppress redundancy. The high-frequency components are further analyzed using VMD and optimized via DLABC, thereby enhancing multi-scale dynamic feature extraction. On this basis, a Convolutional Neural Network(CNN)-Long Short-Term Memory(LSTM)-Attention model, tuned by the Dung Beetle Optimizer(DBO), is constructed to jointly capture local features, temporal dependencies, and key time-specific responses. Results show the proposed model achieves R^(2)>0.99 and MSE<0.07 across multiple monitoring points, significantly outperforming single-decomposition models(e.g., VMD-BP, R^(2)=0.896, MSE=1.700). The dual decomposition strategy proves effective in noise suppression and feature enhancement. Additionally, the SHapley Additive ex Planations(SHAP) analysis visualizes the model's decision process, quantifying the contribution of key factors to slope deformation, thus improving transparency and reliability. The model demonstrates specific adaptability to freeze-thaw environments, providing a robust framework for forecasting slope deformation and issuing early warnings in seasonally frozen regions.
