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
In order to understand the fundamentals of the chemical mechanical polishing（CMP） material removal mechanism,the indentation depth of a slurry particle into a wafer surface is determined using the in situ nanomechan...In order to understand the fundamentals of the chemical mechanical polishing（CMP） material removal mechanism,the indentation depth of a slurry particle into a wafer surface is determined using the in situ nanomechan-ical testing system tribo-indenter by Hysitron.It was found that the removal mechanism in CMP is most probably a molecular scale removal theory.Furthermore,a comprehensive mathematical model was modified and used to pinpoint the effects of wafer/pad relative velocity,which has not been modeled previously.The predicted results based on the current model are shown to be consistent with the published experimental data.Results and analysis may lead to further understanding of the microscopic removal mechanism at the molecular scale in addition to its underlying theoretical foundation.展开更多
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Project supported by the National Natural Science Foundation of China(No.51005102)the Natural Science Foundation of Jiangsu Province in China(No.BK2004020)the Fundamental Research Funds for the Central Universities(No.JUSRP10909)
文摘In order to understand the fundamentals of the chemical mechanical polishing（CMP） material removal mechanism,the indentation depth of a slurry particle into a wafer surface is determined using the in situ nanomechan-ical testing system tribo-indenter by Hysitron.It was found that the removal mechanism in CMP is most probably a molecular scale removal theory.Furthermore,a comprehensive mathematical model was modified and used to pinpoint the effects of wafer/pad relative velocity,which has not been modeled previously.The predicted results based on the current model are shown to be consistent with the published experimental data.Results and analysis may lead to further understanding of the microscopic removal mechanism at the molecular scale in addition to its underlying theoretical foundation.
