A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral st...A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral stress and strain, then the elastic modulus of the material is determined by the linear fitting method. It is found that the modulus is positively correlated to the grain size and negatively correlated to the container size. Arching and dragging are revealed to be the mechanism of such correlations by using the digital image correlation method and the pressure film technology based on the statistical method.展开更多
The swelling behavior of red-bed rocks is a significant factor in the abnormal uplift of subgrades for high-speed railways constructed on the red stratum in the Sichuan Basin,China.The prime objective of this paper is...The swelling behavior of red-bed rocks is a significant factor in the abnormal uplift of subgrades for high-speed railways constructed on the red stratum in the Sichuan Basin,China.The prime objective of this paper is to investigate the impact of mineralogical composition,moisture content,and overburden load on the time-dependent unconfined and oedometric swelling behavior of red-bed siltstone in the context of differences in the slake durability.Twenty samples were prepared for the swelling test,with eleven used for the unconfined swelling and slake index tests and nine for the oedometric swelling test.The temporal dependency of swelling is characterized by the viscosity coefficient of water absorption in a proposed swelling model.Results indicate that the swelling deformation of red-bed rocks is due to a combination of hydration swelling within the rock matrix and crack expansion caused by air breakage.In the unconfined swelling test,the final axial swelling strain of red-bed rocks decreases linearly with increasing slake index,while the viscosity coefficient increases exponentially with the slake index.In the oedometric swelling test,red-bed rocks with lower slake durability show greater sensitivity to lateral constraint and overburden load compared to those with higher slake durability.展开更多
This study investigates the influence of date palm fibers(DPF)on the mechanical performance of bituminous mixtures using two experimental methodologies:the wet and dry processes.In the wet process,DPFs were pre-blende...This study investigates the influence of date palm fibers(DPF)on the mechanical performance of bituminous mixtures using two experimental methodologies:the wet and dry processes.In the wet process,DPFs were pre-blended with bitumen at varying contents ranging from 1%to 5%by weight,prior to mixing with aggregates.The resulting mixtures were evaluated based on several key performance indicators,including Marshall stability,creep resistance,compactness,and water sensitivity.The inclusion of fibers generally enhanced mechanical properties,with optimal improvements observed at 2%to 4%fiber content.Notably,the mixture with 3%DPF content demonstrated a 35.7%increase in Marshall stability,while the lowest compactness reduction(−1.9%)occurred at 1%fiber addition.In the dry process,the effects of both fiber length(1 cm,3 cm,and 5 cm)and fiber content(0.1%to 0.5%)were examined,focusing specifically on rutting and creep resistance.The results showed that 3 cm fibers significantly improved rutting resistance,whereas the 0.1%fiber content yielded the highest enhancement in creep resistance.However,no clear correlation was established between the two performance metrics,suggesting that the mechanical response is highly deformation-dependent.Overall,the addition of DPF contributed to improved durability,strength,and resistance to deformation in asphalt mixtures.The findings underscore the potential of date palm fibers as a sustainable,low-cost,and environmentally friendly additive in pavement engineering,particularly in regions where palm waste is readily available and underutilized.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11372038 and 11402023
文摘A simple uniaxial oedometric system is developed to test the elastic modulus of granular materials. The stress- strain relationship is first measured under conditions of uniaxial compression with additional lateral stress and strain, then the elastic modulus of the material is determined by the linear fitting method. It is found that the modulus is positively correlated to the grain size and negatively correlated to the container size. Arching and dragging are revealed to be the mechanism of such correlations by using the digital image correlation method and the pressure film technology based on the statistical method.
基金financial support received from the National Natural Science Foundation of China(No.51578230).
文摘The swelling behavior of red-bed rocks is a significant factor in the abnormal uplift of subgrades for high-speed railways constructed on the red stratum in the Sichuan Basin,China.The prime objective of this paper is to investigate the impact of mineralogical composition,moisture content,and overburden load on the time-dependent unconfined and oedometric swelling behavior of red-bed siltstone in the context of differences in the slake durability.Twenty samples were prepared for the swelling test,with eleven used for the unconfined swelling and slake index tests and nine for the oedometric swelling test.The temporal dependency of swelling is characterized by the viscosity coefficient of water absorption in a proposed swelling model.Results indicate that the swelling deformation of red-bed rocks is due to a combination of hydration swelling within the rock matrix and crack expansion caused by air breakage.In the unconfined swelling test,the final axial swelling strain of red-bed rocks decreases linearly with increasing slake index,while the viscosity coefficient increases exponentially with the slake index.In the oedometric swelling test,red-bed rocks with lower slake durability show greater sensitivity to lateral constraint and overburden load compared to those with higher slake durability.
文摘This study investigates the influence of date palm fibers(DPF)on the mechanical performance of bituminous mixtures using two experimental methodologies:the wet and dry processes.In the wet process,DPFs were pre-blended with bitumen at varying contents ranging from 1%to 5%by weight,prior to mixing with aggregates.The resulting mixtures were evaluated based on several key performance indicators,including Marshall stability,creep resistance,compactness,and water sensitivity.The inclusion of fibers generally enhanced mechanical properties,with optimal improvements observed at 2%to 4%fiber content.Notably,the mixture with 3%DPF content demonstrated a 35.7%increase in Marshall stability,while the lowest compactness reduction(−1.9%)occurred at 1%fiber addition.In the dry process,the effects of both fiber length(1 cm,3 cm,and 5 cm)and fiber content(0.1%to 0.5%)were examined,focusing specifically on rutting and creep resistance.The results showed that 3 cm fibers significantly improved rutting resistance,whereas the 0.1%fiber content yielded the highest enhancement in creep resistance.However,no clear correlation was established between the two performance metrics,suggesting that the mechanical response is highly deformation-dependent.Overall,the addition of DPF contributed to improved durability,strength,and resistance to deformation in asphalt mixtures.The findings underscore the potential of date palm fibers as a sustainable,low-cost,and environmentally friendly additive in pavement engineering,particularly in regions where palm waste is readily available and underutilized.
