Low temperature cracking(LTC)distress on pavement seriously affects road life.This paper finished a literature review of the research on the mechanism of LTC of asphalt composites(asphalt composites refers to asphalt ...Low temperature cracking(LTC)distress on pavement seriously affects road life.This paper finished a literature review of the research on the mechanism of LTC of asphalt composites(asphalt composites refers to asphalt binder and asphalt mixture in this article),test methods,factors contributing to LTC,measures to prevent and control the distress,and prediction of LTC in asphalt pavements.The following conclusions were obtained:the cracking mechanism of asphalt mixtures needs to be further revealed by means of simulation at the micro level,the BBR and 4 mm plate test(by DSR)methods are currently optimal,and a correlation between asphalt and asphalt mixture evaluation indexes needs to be established.Sensitivity analyses are needed for the factors affecting LTC of asphalt mixtures.It is necessary to calculate the contribution of each factor to the LTC of asphalt mixtures.The aim is to propose targeted improvement measures for the most unfavourable factors,as well as to carry out research and development of key materials for anti-cracking.Measures for the prevention and control of LTC of asphalt pavement are analyzed and discussed.Existing researches on the prediction of LTC of asphalt pavements is discussed.It is necessary to analyse the mechanical response of asphalt pavement,the damage process and the sensitivity of anti-cracking parameters on the basis of considering the complex geometrical characteristics and material properties of asphalt pavement materials.Finally,the mechanism of LTC,evaluation methods,factors influencing LTC,and remedial measures for asphalt composites were summarized,and future research prospects were suggested.This paper provides theoretical support for the further solution of LTC distress of asphalt pavement,which is effective on the improvement of pavement life.展开更多
A typical single-layer raw soil structure in villages and towns in China is taken as the research object.In the probabilistic seismic demand analysis,the seismic demand model is obtained by the incremental dynamic tim...A typical single-layer raw soil structure in villages and towns in China is taken as the research object.In the probabilistic seismic demand analysis,the seismic demand model is obtained by the incremental dynamic time history analysis method.The seismic vulnerability analysis is carried out for the raw soil structure of nonfoundation,strip foundation,and spiral anchor composite foundation,respectively.The spiral anchor composite foundation can reduce the seismic response and failure state of raw soil structure,and the performance level of the structure is significantly improved.Structural requirements sample data with the same ground motion intensity are analyzed by linear regression statistics.Compared with the probabilistic seismic demand model under various working conditions,the seismic demand increases gradually with the increase of intensity.The seismic vulnerability curve is summarized for comparative analysis.With the gradual deepening of the limit state,the reduction effect of spiral anchor composite foundation on the exceedance probability becomes more and more obvious,which can reduce the probability of structural failure to a certain extent.展开更多
The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen ...The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds.This article presents a study of the Shuo-Huang Heavy Duty Railway.Initially,on-site monitoring tests were conducted to analyze the roadbed temperature,water content and deformations due to freezing.Through these tests,the pattern of development of the roadbed freezing and swelling was understood,and the effect of this on the vibration response of the roadbed was investigated.Subsequently,load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed.Through on-site monitoring,it has been determined that the seasonal freezing layer is approximately 0.5 m deep.The depth of the frozen expansion on both sides of the road shows clear differences.The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed,with a tendency towards low-frequency and high-amplitude vibrations.Through indoor testing,we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels.We find that the initial moisture content has a greater impact on specimen freezing and expansion.The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.展开更多
The dynamic spalling characteristics of rock are important for stability analysis in rock engineering.This paper presented an experimental investigation on the dynamic spalling characteristics of granite with differen...The dynamic spalling characteristics of rock are important for stability analysis in rock engineering.This paper presented an experimental investigation on the dynamic spalling characteristics of granite with different temperatures and strain rates.A series of dynamic spalling tests with different impact velocities were conducted on thermally treated granite at different temperatures.The dynamic spalling strengths of granite with different temperatures and strain rates were determined.A model was proposed to correlate the dynamic spalling strength of granite,high temperature and strain rate.The results show that the spalling strength of granite decreases with increasing temperature.Moreover,the spalling strength of granite with a higher strain rate is larger than that with a lower strain rate.The proposed model can describe the relationship among dynamic spalling strength of granite,high temperature and strain rate.展开更多
基金financially supported by National Key R&D Program of China(2022YFE0137300)National Natural Science Foundation of China(52078018).
文摘Low temperature cracking(LTC)distress on pavement seriously affects road life.This paper finished a literature review of the research on the mechanism of LTC of asphalt composites(asphalt composites refers to asphalt binder and asphalt mixture in this article),test methods,factors contributing to LTC,measures to prevent and control the distress,and prediction of LTC in asphalt pavements.The following conclusions were obtained:the cracking mechanism of asphalt mixtures needs to be further revealed by means of simulation at the micro level,the BBR and 4 mm plate test(by DSR)methods are currently optimal,and a correlation between asphalt and asphalt mixture evaluation indexes needs to be established.Sensitivity analyses are needed for the factors affecting LTC of asphalt mixtures.It is necessary to calculate the contribution of each factor to the LTC of asphalt mixtures.The aim is to propose targeted improvement measures for the most unfavourable factors,as well as to carry out research and development of key materials for anti-cracking.Measures for the prevention and control of LTC of asphalt pavement are analyzed and discussed.Existing researches on the prediction of LTC of asphalt pavements is discussed.It is necessary to analyse the mechanical response of asphalt pavement,the damage process and the sensitivity of anti-cracking parameters on the basis of considering the complex geometrical characteristics and material properties of asphalt pavement materials.Finally,the mechanism of LTC,evaluation methods,factors influencing LTC,and remedial measures for asphalt composites were summarized,and future research prospects were suggested.This paper provides theoretical support for the further solution of LTC distress of asphalt pavement,which is effective on the improvement of pavement life.
基金the financial supports from the National Key R&D Program of China(2018YFD1100404)the Program of Liaoning Provincial Department of Education(LJKZ0564)The supports from the Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology(2022B08)。
文摘A typical single-layer raw soil structure in villages and towns in China is taken as the research object.In the probabilistic seismic demand analysis,the seismic demand model is obtained by the incremental dynamic time history analysis method.The seismic vulnerability analysis is carried out for the raw soil structure of nonfoundation,strip foundation,and spiral anchor composite foundation,respectively.The spiral anchor composite foundation can reduce the seismic response and failure state of raw soil structure,and the performance level of the structure is significantly improved.Structural requirements sample data with the same ground motion intensity are analyzed by linear regression statistics.Compared with the probabilistic seismic demand model under various working conditions,the seismic demand increases gradually with the increase of intensity.The seismic vulnerability curve is summarized for comparative analysis.With the gradual deepening of the limit state,the reduction effect of spiral anchor composite foundation on the exceedance probability becomes more and more obvious,which can reduce the probability of structural failure to a certain extent.
基金funded by the National Natural Science Foundation of China(NSFC)(grant number:52078312).
文摘The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds.This article presents a study of the Shuo-Huang Heavy Duty Railway.Initially,on-site monitoring tests were conducted to analyze the roadbed temperature,water content and deformations due to freezing.Through these tests,the pattern of development of the roadbed freezing and swelling was understood,and the effect of this on the vibration response of the roadbed was investigated.Subsequently,load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed.Through on-site monitoring,it has been determined that the seasonal freezing layer is approximately 0.5 m deep.The depth of the frozen expansion on both sides of the road shows clear differences.The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed,with a tendency towards low-frequency and high-amplitude vibrations.Through indoor testing,we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels.We find that the initial moisture content has a greater impact on specimen freezing and expansion.The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.
基金supported by the Beijing Natural Science Foundation,China(Grant No.JQ20039)National Natural Science Foundation of China(Grant No.12172019).
文摘The dynamic spalling characteristics of rock are important for stability analysis in rock engineering.This paper presented an experimental investigation on the dynamic spalling characteristics of granite with different temperatures and strain rates.A series of dynamic spalling tests with different impact velocities were conducted on thermally treated granite at different temperatures.The dynamic spalling strengths of granite with different temperatures and strain rates were determined.A model was proposed to correlate the dynamic spalling strength of granite,high temperature and strain rate.The results show that the spalling strength of granite decreases with increasing temperature.Moreover,the spalling strength of granite with a higher strain rate is larger than that with a lower strain rate.The proposed model can describe the relationship among dynamic spalling strength of granite,high temperature and strain rate.
