Pub Date : 2024-09-24DOI: 10.1016/j.coldregions.2024.104334
Jun Bi , Chaozheng Shen , Guoxu Wang , Zhijian Wu , Sheng Yang , Jianguo Lu , Gaochao Lin
The soil freezing characteristic curve (SFCC) defines the relationship between unfrozen water content and temperature. It is an important soil parameter in cold regions, but it is not easy to obtain, especially in the field. This paper proposes a method to indirectly estimate the SFCC for both fine-grained and coarse-grained soils by using the one-measurement SFCC method. From regression analysis, the parameters of the van Genuchten SFCC model can be expressed as functions of an adjustable parameter x. The SFCC of a soil sample contained three different zones, and sensitivity analysis indicated that the measured point in Zone 2 provided the most reliable SFCC estimation results. The proposed model and four widely acknowledged models were compared and evaluated with 33 fine-grained soils and 9 coarse-grained soils. The results showed that the proposed model provided the best estimation of the SFCC among the five models. This result also indicated that the proposed model provided a better estimation of the SFCC for fine-grained soils. This study provides a reliable approach to develop an SFCC estimation model with the one-measurement SFCC method.
{"title":"A new method to estimate the soil freezing characteristic curve","authors":"Jun Bi , Chaozheng Shen , Guoxu Wang , Zhijian Wu , Sheng Yang , Jianguo Lu , Gaochao Lin","doi":"10.1016/j.coldregions.2024.104334","DOIUrl":"10.1016/j.coldregions.2024.104334","url":null,"abstract":"<div><div>The soil freezing characteristic curve (SFCC) defines the relationship between unfrozen water content and temperature. It is an important soil parameter in cold regions, but it is not easy to obtain, especially in the field. This paper proposes a method to indirectly estimate the SFCC for both fine-grained and coarse-grained soils by using the one-measurement SFCC method. From regression analysis, the parameters of the van Genuchten SFCC model can be expressed as functions of an adjustable parameter <em>x</em>. The SFCC of a soil sample contained three different zones, and sensitivity analysis indicated that the measured point in Zone 2 provided the most reliable SFCC estimation results. The proposed model and four widely acknowledged models were compared and evaluated with 33 fine-grained soils and 9 coarse-grained soils. The results showed that the proposed model provided the best estimation of the SFCC among the five models. This result also indicated that the proposed model provided a better estimation of the SFCC for fine-grained soils. This study provides a reliable approach to develop an SFCC estimation model with the one-measurement SFCC method.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104334"},"PeriodicalIF":3.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.coldregions.2024.104333
Wenxuan Yu , Zhihao Luo , Meiyu Fan , Liu Jin , Xiuli Du
This paper conducted comprehensive axial compressive and splitting-tensile tests to investigate the static and dynamic mechanical properties of basalt fibre reinforced lightweight-aggregate concrete (BFLAC) with fibre volume fractions of 0.0∼0.3% at the temperatures ranging from 20 °C to −90 °C, with a special focus on the microscopic mechanism analysis and quantitative discussion of low-temperature enhancement effect, strain rate effect and fibre reinforcement effect. Test results show that the splitting-tensile strength, compressive strength, and elastic modulus of lightweight-aggregate concrete (LAC) perform an apparent low-temperature enhancement effect and this enhancement effect can be strengthened by the addition of basalt fibres. More basalt fibres reach the tensile failure strength and undergo rupture failure (Mode-2), resulting in the strain rate effect of BFLAC is slightly more significant than that of LAC; but the influence of low temperature on strain rate effect is mild. The incorporation of 0.3% basalt fibres in LAC can bring at least a 20% increase in nominal strengths, showing an significant fibre reinforcement effect which can be enhanced (with maximum increase of 45.6%) as the temperature drops. Based on test results, the relationships between compressive and splitting-tensile strengths were discussed, and the empirical prediction formulas for predicting the static and dynamic mechanical properties of BFLAC at low temperatures were proposed. Research results of this paper can provide reference for mechanical performance calculation and engineering applications of BFLAC in the low-temperature environment.
{"title":"Experimental study and mechanism analysis on static and dynamic mechanical properties of BFLAC at low temperatures","authors":"Wenxuan Yu , Zhihao Luo , Meiyu Fan , Liu Jin , Xiuli Du","doi":"10.1016/j.coldregions.2024.104333","DOIUrl":"10.1016/j.coldregions.2024.104333","url":null,"abstract":"<div><div>This paper conducted comprehensive axial compressive and splitting-tensile tests to investigate the static and dynamic mechanical properties of basalt fibre reinforced lightweight-aggregate concrete (BFLAC) with fibre volume fractions <span><math><msub><mi>V</mi><mi>f</mi></msub></math></span> of 0.0∼0.3% at the temperatures ranging from 20 °C to −90 °C, with a special focus on the microscopic mechanism analysis and quantitative discussion of low-temperature enhancement effect, strain rate effect and fibre reinforcement effect. Test results show that the splitting-tensile strength, compressive strength, and elastic modulus of lightweight-aggregate concrete (LAC) perform an apparent low-temperature enhancement effect and this enhancement effect can be strengthened by the addition of basalt fibres. More basalt fibres reach the tensile failure strength and undergo rupture failure (Mode-2), resulting in the strain rate effect of BFLAC is slightly more significant than that of LAC; but the influence of low temperature on strain rate effect is mild. The incorporation of 0.3%<span><math><msub><mi>V</mi><mi>f</mi></msub></math></span> basalt fibres in LAC can bring at least a 20% increase in nominal strengths, showing an significant fibre reinforcement effect which can be enhanced (with maximum increase of 45.6%) as the temperature drops. Based on test results, the relationships between compressive and splitting-tensile strengths were discussed, and the empirical prediction formulas for predicting the static and dynamic mechanical properties of BFLAC at low temperatures were proposed. Research results of this paper can provide reference for mechanical performance calculation and engineering applications of BFLAC in the low-temperature environment.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104333"},"PeriodicalIF":3.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.coldregions.2024.104329
Shuai Bai , Lingbo Yu , Yankui Jian , Mingchao Ren , Xinchun Guan , Hui Li , Jinping Ou
The loss of strength and durability caused by early frost attack is the macro performance of internal microstructure deterioration. Understanding the influence mechanism of early frost attack at the micro level is necessary to avoid or minimize the early frost attack to macro performance. In this study, the influence of early frost attack on the strength, water sorptivity, chloride permeability, and microstructure of cement mortar was investigated. The fresh mortars were pre-cured for 10, 12, 14, and 16 h and then frozen at −10 °C for 7 days to simulate an early frost attack. After freezing, the standard curing (20 °C) was carried out until the testing. It is found that after standard curing of 28 days, the strength of early-frozen mortar can reach more than 95 % of the 28-day strength of unfrozen mortar. Interestingly, the sorptivity coefficient and total charge passed of early-frozen mortar are much higher than the level of unfrozen mortar, and the loss of resistance to water penetration and chloride ion penetration exceeds 20 %, indicating that early frost attack causes more severe damage to the durability than to the strength of mortar. Mercury intrusion porosimetry (MIP) results show that early frost attack can increase the pore volume of >50 nm and coarsen the pores within 10–50 nm. Correspondingly, key pore parameters (critical pore diameter, threshold pore diameter, and tortuosity) that affect the durability of mortar are also negatively affected. Energy dispersive spectroscopy (EDS) analysis also shows that after suffering early frost attack, the interfacial transition zone (ITZ) thickness of mortar is increased from 4 to 10 μm to 8–13 μm, and the probability of high Ca/Si ratios (4–10) in the ITZ is also increased. Finally, it is concluded that the coupling effect of pore structure coarsening and ITZ degradation leads to more severe durability loss.
{"title":"Study on the influence of early frost attack on the performance of cement mortar","authors":"Shuai Bai , Lingbo Yu , Yankui Jian , Mingchao Ren , Xinchun Guan , Hui Li , Jinping Ou","doi":"10.1016/j.coldregions.2024.104329","DOIUrl":"10.1016/j.coldregions.2024.104329","url":null,"abstract":"<div><div>The loss of strength and durability caused by early frost attack is the macro performance of internal microstructure deterioration. Understanding the influence mechanism of early frost attack at the micro level is necessary to avoid or minimize the early frost attack to macro performance. In this study, the influence of early frost attack on the strength, water sorptivity, chloride permeability, and microstructure of cement mortar was investigated. The fresh mortars were pre-cured for 10, 12, 14, and 16 h and then frozen at −10 °C for 7 days to simulate an early frost attack. After freezing, the standard curing (20 °C) was carried out until the testing. It is found that after standard curing of 28 days, the strength of early-frozen mortar can reach more than 95 % of the 28-day strength of unfrozen mortar. Interestingly, the sorptivity coefficient and total charge passed of early-frozen mortar are much higher than the level of unfrozen mortar, and the loss of resistance to water penetration and chloride ion penetration exceeds 20 %, indicating that early frost attack causes more severe damage to the durability than to the strength of mortar. Mercury intrusion porosimetry (MIP) results show that early frost attack can increase the pore volume of >50 nm and coarsen the pores within 10–50 nm. Correspondingly, key pore parameters (critical pore diameter, threshold pore diameter, and tortuosity) that affect the durability of mortar are also negatively affected. Energy dispersive spectroscopy (EDS) analysis also shows that after suffering early frost attack, the interfacial transition zone (ITZ) thickness of mortar is increased from 4 to 10 μm to 8–13 μm, and the probability of high Ca/Si ratios (4–10) in the ITZ is also increased. Finally, it is concluded that the coupling effect of pore structure coarsening and ITZ degradation leads to more severe durability loss.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104329"},"PeriodicalIF":3.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.coldregions.2024.104327
Hao Zheng , Ningyu Yang , Junling Si , Chongqian Ma , Shunji Kanie
The formation of multi-layer horizontal ice lenses in frozen soil significantly alters its internal structure, leading to changes in its mechanical properties. To quantitatively analyze the effects of multi-layer ice lenses on mechanical properties, a series of freezing tests were conducted with frost-susceptible clay materials at varied freezing ratios. Then, the uniaxial compression tests were conducted to investigate the deformation and strength properties of frozen soil at different freezing ratios and temperatures. The experimental results indicate that the unique ice skeleton structure formed by horizontal ice lenses and inclined ice wedges can significantly improve the strength of the samples, leading to the peak stress and secant modulus increase with the freezing ratio, and the presence of an ice skeleton makes the strength more sensitive to temperature changes. The frozen soil samples exhibit two failure modes (bulging failure and shearing failure), which significantly affect the mechanical parameters of the soil. Based on the test results, a frost heave-induced damage coefficient is introduced into the strain softening model to account for the initial stiffness reduction caused by microcracks generated during the ice skeleton growth. This modified model effectively predicts the stress-strain relationship of soils with varying ice skeleton structures. These findings have practical implications for predicting the properties of frozen soil constructed using artificial freezing methods.
{"title":"Influence of ice skeleton on the mechanical behavior of frozen soil under uniaxial compression","authors":"Hao Zheng , Ningyu Yang , Junling Si , Chongqian Ma , Shunji Kanie","doi":"10.1016/j.coldregions.2024.104327","DOIUrl":"10.1016/j.coldregions.2024.104327","url":null,"abstract":"<div><div>The formation of multi-layer horizontal ice lenses in frozen soil significantly alters its internal structure, leading to changes in its mechanical properties. To quantitatively analyze the effects of multi-layer ice lenses on mechanical properties, a series of freezing tests were conducted with frost-susceptible clay materials at varied freezing ratios. Then, the uniaxial compression tests were conducted to investigate the deformation and strength properties of frozen soil at different freezing ratios and temperatures. The experimental results indicate that the unique ice skeleton structure formed by horizontal ice lenses and inclined ice wedges can significantly improve the strength of the samples, leading to the peak stress and secant modulus <span><math><msub><mi>E</mi><mn>50</mn></msub></math></span> increase with the freezing ratio, and the presence of an ice skeleton makes the strength more sensitive to temperature changes. The frozen soil samples exhibit two failure modes (bulging failure and shearing failure), which significantly affect the mechanical parameters of the soil. Based on the test results, a frost heave-induced damage coefficient is introduced into the strain softening model to account for the initial stiffness reduction caused by microcracks generated during the ice skeleton growth. This modified model effectively predicts the stress-strain relationship of soils with varying ice skeleton structures. These findings have practical implications for predicting the properties of frozen soil constructed using artificial freezing methods.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104327"},"PeriodicalIF":3.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The variations of shear strength parameters against the freeze-thaw cycles are not well understood in the previous study. This research mainly investigated the influence of freeze-thaw treatment on the shear strength parameters and their relationship with the freeze-thaw damage variable for sandstones. The fraction dimensions of sandstone surfaces and basic friction angles display an increasing trend under freeze-thaw cycles. It implies that the sandstone surface becomes rougher due to the freeze-thaw loss of cementation minerals and thus induces the increase in the basic friction angle. Another interesting finding is that although the cohesion of sandstone reduces, the internal friction angle also increases with increasing freeze-thaw cycles. Thus, the reduction in the shear strength under freeze-thaw actions should be attributed to the loss of cohesion. Moreover, the change of shear strength parameters is also related with the freeze-thaw damage degree. As the number of freeze-thaw cycles increases, the increase in porosity and reduction in P-wave velocity are much larger for the YY and YR sandstones with higher porosities, thus, they suffer much more serious freeze-thaw damage, and they have a much larger variation in shear strength parameters. The novel finding is that the growth in basic friction angle is positively correlated with the increase of freeze-thaw damage, and the internal friction angle exponentially increases with the increase of freeze-thaw damage. This study provides a much better understanding of the change of the shear strength parameters under freeze-thaw cycles.
在以往的研究中，剪切强度参数随冻融循环的变化并不十分清楚。本研究主要探讨了冻融处理对砂岩剪切强度参数的影响及其与冻融破坏变量的关系。在冻融循环下，砂岩表面的分数尺寸和基本摩擦角呈上升趋势。这意味着，由于冻融损失了胶结矿物，砂岩表面变得更加粗糙，从而导致基本摩擦角增大。另一个有趣的发现是，虽然砂岩的内聚力降低了，但内摩擦角也随着冻融循环的增加而增大。因此，冻融作用下剪切强度的降低应归因于内聚力的丧失。此外，抗剪强度参数的变化还与冻融破坏程度有关。随着冻融循环次数的增加，孔隙度较高的 YY 和 YR 砂岩的孔隙度增加和 P 波速度降低的幅度更大，因此其遭受的冻融破坏更为严重，剪切强度参数的变化也更大。新发现是基本摩擦角的增长与冻融破坏的增加呈正相关，内摩擦角随着冻融破坏的增加呈指数增长。这项研究有助于更好地理解冻融循环下剪切强度参数的变化。
{"title":"Study on the freeze-thaw damage degree and its influence on the shear strength parameters of sandstones","authors":"Shibing Huang , Lizhen Duan , Luobin Zhen , Shilin Yu , Chunyang Zhang","doi":"10.1016/j.coldregions.2024.104328","DOIUrl":"10.1016/j.coldregions.2024.104328","url":null,"abstract":"<div><div>The variations of shear strength parameters against the freeze-thaw cycles are not well understood in the previous study. This research mainly investigated the influence of freeze-thaw treatment on the shear strength parameters and their relationship with the freeze-thaw damage variable for sandstones. The fraction dimensions of sandstone surfaces and basic friction angles display an increasing trend under freeze-thaw cycles. It implies that the sandstone surface becomes rougher due to the freeze-thaw loss of cementation minerals and thus induces the increase in the basic friction angle. Another interesting finding is that although the cohesion of sandstone reduces, the internal friction angle also increases with increasing freeze-thaw cycles. Thus, the reduction in the shear strength under freeze-thaw actions should be attributed to the loss of cohesion. Moreover, the change of shear strength parameters is also related with the freeze-thaw damage degree. As the number of freeze-thaw cycles increases, the increase in porosity and reduction in P-wave velocity are much larger for the YY and YR sandstones with higher porosities, thus, they suffer much more serious freeze-thaw damage, and they have a much larger variation in shear strength parameters. The novel finding is that the growth in basic friction angle is positively correlated with the increase of freeze-thaw damage, and the internal friction angle exponentially increases with the increase of freeze-thaw damage. This study provides a much better understanding of the change of the shear strength parameters under freeze-thaw cycles.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104328"},"PeriodicalIF":3.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.coldregions.2024.104330
Jun Zhang , Wenjun Nie , Mintae Kim , Xianghong He , Dahu Rui , Weidong Pan
The low permeability of clayey soil and the pressure of liquid extraction and injection tend to form preferential flow paths in the soil, diminishing the remediation efficiency of shaft washing. Therefore, a new in-situ repair method combining artificial freezing and shaft washing is proposed. Using Pb and Cd contaminated clayey soil as the research object, in-situ model tests of different eluent types, concentrations, and suction modes were conducted to investigate the removal rate of heavy metals and the distribution of temperature and water field. The results demonstrated that the artificial freezing method can effectively induce the water (eluent) migration from the unfrozen zone to the freezing front. Besides, it effectively resolved the issue of poor washing efficiency caused by preferential flow between the extraction and injection wells during the extraction process. After five freeze-thaw cycles, the removal rate of Pb and Cd reached 46.16 % and 59.04 %, respectively. The combination of artificial freezing and plastic drainage plate technology merges artificial freezing and shaft washing methods to achieve the remediation of heavy metal-contaminated soil, providing a reference for the in-situ remediation of heavy metal-contaminated clayey soil.
{"title":"Model test of in-situ remediation for heavy metal-contaminated clayey soil by artificial freezing and shaft washing","authors":"Jun Zhang , Wenjun Nie , Mintae Kim , Xianghong He , Dahu Rui , Weidong Pan","doi":"10.1016/j.coldregions.2024.104330","DOIUrl":"10.1016/j.coldregions.2024.104330","url":null,"abstract":"<div><div>The low permeability of clayey soil and the pressure of liquid extraction and injection tend to form preferential flow paths in the soil, diminishing the remediation efficiency of shaft washing. Therefore, a new in-situ repair method combining artificial freezing and shaft washing is proposed. Using Pb and Cd contaminated clayey soil as the research object, in-situ model tests of different eluent types, concentrations, and suction modes were conducted to investigate the removal rate of heavy metals and the distribution of temperature and water field. The results demonstrated that the artificial freezing method can effectively induce the water (eluent) migration from the unfrozen zone to the freezing front. Besides, it effectively resolved the issue of poor washing efficiency caused by preferential flow between the extraction and injection wells during the extraction process. After five freeze-thaw cycles, the removal rate of Pb and Cd reached 46.16 % and 59.04 %, respectively. The combination of artificial freezing and plastic drainage plate technology merges artificial freezing and shaft washing methods to achieve the remediation of heavy metal-contaminated soil, providing a reference for the in-situ remediation of heavy metal-contaminated clayey soil.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104330"},"PeriodicalIF":3.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As part of the pantograph-catenary system, a catenary covered with ice can affect the current collected by pantograph sliding, posing a threat to the normal operation of the train. At the icing conditions, the speed reduction method is usually adopted in practical engineering to ensure the stable energy transfer quality of the pantograph-catenary system, while its reduction ranges remain unclear. To aim at providing speed recommendations for safe train operation under various ice conditions in practical engineering, the model of the ice-covered pantograph-catenary system is established in this work and the effect of ice covering on both the static characteristics of the catenary and the dynamic interaction of the system are investigated. The results indicate ice increases the stiffness and sag of the contact wire, resulting in a significant increase in elastic inhomogeneity across the span of the contact wire. As ice thickness and train speed increase, there is an increase in the vibration amplitude of support point and an increase in the fluctuation range of the contact force. It is suggested that the operational speeds of trains should be less than 350 km/h, 330 km/h, 280 km/h, and 260 km/h, corresponding to the ice thicknesses of 4 mm, 8 mm, 12 mm, and 16 mm, respectively.
{"title":"Effect of ice-covered catenary on dynamic interactions of pantograph-catenary system and limited speed of trains","authors":"Zefeng Yang, Ziqian Yang, Guizao Huang, Xing Chen, Tongxin Ma, Huan Zhang, Wenfu Wei, Guangning Wu","doi":"10.1016/j.coldregions.2024.104331","DOIUrl":"10.1016/j.coldregions.2024.104331","url":null,"abstract":"<div><div>As part of the pantograph-catenary system, a catenary covered with ice can affect the current collected by pantograph sliding, posing a threat to the normal operation of the train. At the icing conditions, the speed reduction method is usually adopted in practical engineering to ensure the stable energy transfer quality of the pantograph-catenary system, while its reduction ranges remain unclear. To aim at providing speed recommendations for safe train operation under various ice conditions in practical engineering, the model of the ice-covered pantograph-catenary system is established in this work and the effect of ice covering on both the static characteristics of the catenary and the dynamic interaction of the system are investigated. The results indicate ice increases the stiffness and sag of the contact wire, resulting in a significant increase in elastic inhomogeneity across the span of the contact wire. As ice thickness and train speed increase, there is an increase in the vibration amplitude of support point and an increase in the fluctuation range of the contact force. It is suggested that the operational speeds of trains should be less than 350 km/h, 330 km/h, 280 km/h, and 260 km/h, corresponding to the ice thicknesses of 4 mm, 8 mm, 12 mm, and 16 mm, respectively.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104331"},"PeriodicalIF":3.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1016/j.coldregions.2024.104326
Haifeng Huo , Qingwei Chen , Enzhao Xiao , Haichao Li , Hui Xu , Tao Li , Xueyuan Tang
Compacted snow is a primary construction material in polar regions and experiences persistent deformation during loading, which considerably affects the safety of snow structures. This study conducts a series of one-dimensional compression tests to investigate the effect of initial densities and stress levels on the long-term deformation of compacted snow samples over 90 days. The compression curve of compacted snow can be divided into three stages: instantaneous, primary, and secondary compressions. Instantaneous compression occurs at pressurization; primary compression occurs within 10 to 40 min of loading; secondary compression occurs when snow remains unstable for 90 days. Secondary compression is the main cause of long-term deformation of the samples and the secondary compression coefficient tends to decrease with a higher initial density and lower normal pressure. A fractional creep model is developed to describe the experimental data and a good agreement was obtained. The proposed model adopts the fractional deviation approach to modify the classic Burgers model, and the density-dependent parameters are calibrated using the experimental data. The proposed model is verified as a useful tool in describing the creep behavior of snow, and the results of this study contribute to the safe operation of building structures on snow foundations.
{"title":"Long-Term One-Dimensional Compression Tests and Fractional Creep Model of Compacted Snow","authors":"Haifeng Huo , Qingwei Chen , Enzhao Xiao , Haichao Li , Hui Xu , Tao Li , Xueyuan Tang","doi":"10.1016/j.coldregions.2024.104326","DOIUrl":"10.1016/j.coldregions.2024.104326","url":null,"abstract":"<div><div>Compacted snow is a primary construction material in polar regions and experiences persistent deformation during loading, which considerably affects the safety of snow structures. This study conducts a series of one-dimensional compression tests to investigate the effect of initial densities and stress levels on the long-term deformation of compacted snow samples over 90 days. The compression curve of compacted snow can be divided into three stages: instantaneous, primary, and secondary compressions. Instantaneous compression occurs at pressurization; primary compression occurs within 10 to 40 min of loading; secondary compression occurs when snow remains unstable for 90 days. Secondary compression is the main cause of long-term deformation of the samples and the secondary compression coefficient tends to decrease with a higher initial density and lower normal pressure. A fractional creep model is developed to describe the experimental data and a good agreement was obtained. The proposed model adopts the fractional deviation approach to modify the classic Burgers model, and the density-dependent parameters are calibrated using the experimental data. The proposed model is verified as a useful tool in describing the creep behavior of snow, and the results of this study contribute to the safe operation of building structures on snow foundations.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104326"},"PeriodicalIF":3.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1016/j.coldregions.2024.104325
Anna J. Crawford , Greg Crocker , Jesse Smith , Derek Mueller , Till J.W. Wagner
The drift and deterioration of large and tabular icebergs, also known as “ice islands” in the Arctic, are modeled for both operational (e.g., offshore risk mitigation) and research (e.g., oceanographic impact of melt water input) purposes. In this paper, we build a theoretical argument to show that the lateral deterioration of ice islands is controlled by the rate of sidewall notch growth at the waterline, with this growth leading to the development of underwater rams and buoyancy-induced calving via the ‘footloose’ mechanism. This dominance of footloose-type lateral deterioration allows for the majority of ice island deterioration to be simulated with only three oceanic variables: wave height, wave period, and sea-surface temperature. Information regarding the size and lineage of ice islands tracked in the Canadian Ice Island Drift, Deterioration and Detection (CI2D3) Database provides opportunity to assess our theoretical work, as the database serves as a validation dataset for simulations of ice island length and area change. When simulating the length reduction over time of ice islands tracked in the CI2D3 Database, the footloose model reduced the mean error over 80 d to +277 m, compared to −1545 and −1403 m with no-melt and thermal-melt models, respectively. We also demonstrate a new approach to simulating the areal deterioration of ice islands resulting from discrete footloose calving events. The approach utilizes two parameters: the length-to-width ratio of the ice island (r) and the width of a footloose calving event relative to the ice island's length (K). With r = 1.6 and K= 0.8, the mean error in modeled area was close to zero after 20 d of simulation. A comparison of stresses associated with footloose events from a 1D-beam model and those simulated with 3D finite-element modeling showed that the 1D and 3D simulations produce broadly similar results. This supports our approaches and parameter assignments for simulating ice island length and area reduction from footloose calving. These approaches can now be incorporated into ice island deterioration models. The benefit of this incorporation will be greatest for those interested in research of longer-term impacts of ice island deterioration on ocean properties given the greater improvements to model error over periods of time that are longer than those that usually concern offshore ice management operations.
{"title":"Evaluating the importance of footloose-type failure in ice island deterioration modeling","authors":"Anna J. Crawford , Greg Crocker , Jesse Smith , Derek Mueller , Till J.W. Wagner","doi":"10.1016/j.coldregions.2024.104325","DOIUrl":"10.1016/j.coldregions.2024.104325","url":null,"abstract":"<div><div>The drift and deterioration of large and tabular icebergs, also known as “ice islands” in the Arctic, are modeled for both operational (e.g., offshore risk mitigation) and research (e.g., oceanographic impact of melt water input) purposes. In this paper, we build a theoretical argument to show that the lateral deterioration of ice islands is controlled by the rate of sidewall notch growth at the waterline, with this growth leading to the development of underwater rams and buoyancy-induced calving via the ‘footloose’ mechanism. This dominance of footloose-type lateral deterioration allows for the majority of ice island deterioration to be simulated with only three oceanic variables: wave height, wave period, and sea-surface temperature. Information regarding the size and lineage of ice islands tracked in the Canadian Ice Island Drift, Deterioration and Detection (CI2D3) Database provides opportunity to assess our theoretical work, as the database serves as a validation dataset for simulations of ice island length and area change. When simulating the length reduction over time of ice islands tracked in the CI2D3 Database, the footloose model reduced the mean error over 80 d to +277 m, compared to −1545 and −1403 m with no-melt and thermal-melt models, respectively. We also demonstrate a new approach to simulating the areal deterioration of ice islands resulting from discrete footloose calving events. The approach utilizes two parameters: the length-to-width ratio of the ice island (<em>r</em>) and the width of a footloose calving event relative to the ice island's length (<em>K</em>). With <em>r</em> = 1.6 and <em>K</em>= 0.8, the mean error in modeled area was close to zero after 20 d of simulation. A comparison of stresses associated with footloose events from a 1D-beam model and those simulated with 3D finite-element modeling showed that the 1D and 3D simulations produce broadly similar results. This supports our approaches and parameter assignments for simulating ice island length and area reduction from footloose calving. These approaches can now be incorporated into ice island deterioration models. The benefit of this incorporation will be greatest for those interested in research of longer-term impacts of ice island deterioration on ocean properties given the greater improvements to model error over periods of time that are longer than those that usually concern offshore ice management operations.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104325"},"PeriodicalIF":3.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1016/j.coldregions.2024.104324
Tantan Zhu , Huanhuan Zhu , Ang Li , Xilei Zong , Bin Zeng , Xin He
To investigate the evolution of physical properties of sandstone under unidirectional constraint during freeze-thaw cycles, an experimental device was specifically designed. Unidirectional constraint freeze-thaw tests were performed on sandstone specimens. The study analyzed variations in the dry mass, saturated mass, and longitudinal wave velocity of the sandstone both before and after undergoing freeze-thaw cycles, as well as examining the evolution of resistivity throughout the process. Results revealed that an increase in the number of freeze-thaw cycles leads to a gradual increase in the saturated mass of sandstone, while its dry mass consistently decreases, irrespective of whether it is subjected to constraint or not. The change rates of both dry mass and saturated mass were found to be significantly lower under unidirectional constraint compared to that without constraint. With more freeze-thaw cycles, a decline in longitudinal wave velocity was noted. Under unconstrained conditions, no significant direction dependence in longitudinal wave velocity was detected. However, under unidirectional constraint, there was a smaller decrease in the longitudinal wave velocity along the direction of constraint compared to other directions. This indicates that constraint mitigates frost heave damage. In the temperature rise and maintenance stages, resistivity initially dropped, then increased prior to stabilizing at a constant value. Conversely, in temperature decrease and maintenance stages, resistivity first rose, then dipped before ultimately rising again. Temperature primarily influenced resistivity by affecting the ion movement velocity within pore water and the connectivity of the conductive network.
{"title":"Physical properties and anisotropy of sandstone during freeze-thaw cycle under unidirectional constraint","authors":"Tantan Zhu , Huanhuan Zhu , Ang Li , Xilei Zong , Bin Zeng , Xin He","doi":"10.1016/j.coldregions.2024.104324","DOIUrl":"10.1016/j.coldregions.2024.104324","url":null,"abstract":"<div><p>To investigate the evolution of physical properties of sandstone under unidirectional constraint during freeze-thaw cycles, an experimental device was specifically designed. Unidirectional constraint freeze-thaw tests were performed on sandstone specimens. The study analyzed variations in the dry mass, saturated mass, and longitudinal wave velocity of the sandstone both before and after undergoing freeze-thaw cycles, as well as examining the evolution of resistivity throughout the process. Results revealed that an increase in the number of freeze-thaw cycles leads to a gradual increase in the saturated mass of sandstone, while its dry mass consistently decreases, irrespective of whether it is subjected to constraint or not. The change rates of both dry mass and saturated mass were found to be significantly lower under unidirectional constraint compared to that without constraint. With more freeze-thaw cycles, a decline in longitudinal wave velocity was noted. Under unconstrained conditions, no significant direction dependence in longitudinal wave velocity was detected. However, under unidirectional constraint, there was a smaller decrease in the longitudinal wave velocity along the direction of constraint compared to other directions. This indicates that constraint mitigates frost heave damage. In the temperature rise and maintenance stages, resistivity initially dropped, then increased prior to stabilizing at a constant value. Conversely, in temperature decrease and maintenance stages, resistivity first rose, then dipped before ultimately rising again. Temperature primarily influenced resistivity by affecting the ion movement velocity within pore water and the connectivity of the conductive network.</p></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"228 ","pages":"Article 104324"},"PeriodicalIF":3.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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