Piled embankments have many advantages that have been applied in high-speed railway construction engineering.However,the load transfer mechanism of piled embankments,such as soil arching and tension membranes,is still...Piled embankments have many advantages that have been applied in high-speed railway construction engineering.However,the load transfer mechanism of piled embankments,such as soil arching and tension membranes,is still unclear,especially under dynamic loads.To investigate the soil arching and tension membrane under dynamic train loads on high-speed railways,a large-scale piled embankment model test with X-shaped piles as vertical reinforcement was performed,in which twenty-eight earth pressure cells were installed in the piled embankment and an M-shaped wave was adopted to simulate the high-speed railway train load.The results show that dynamic soil arching only occurs when two bogies of a carriage pass by and disappears at other times.The dynamic soil arching and membrane effect are the most significant under the concrete base.The arching height,stress concentration ratio and pile-soil load sharing ratio have a minimal value at 25 Hz.The dynamic soil arching degrades severely at 25 Hz,whose height at 25 Hz is only 0.35 times that at 5 Hz.The arching height fluctuates over a narrow range with increasing loading amplitude.The stress concentration ratio and the pile-soil load sharing ratio increase monotonically as the loading amplitude increases.展开更多
This study is focused on the effect of vibration induced by moving trains in tunnels on the surrounding ground and structures.A three-dimensional finite element model is established for a one-track railway tunnel and ...This study is focused on the effect of vibration induced by moving trains in tunnels on the surrounding ground and structures.A three-dimensional finite element model is established for a one-track railway tunnel and an adjacent twelve-storey building frame by using commercial software Midas GTS-NX(2019)and Midas Gen.This study considered the moving load effect of a complete train,which varies with space as well as with time.The effect of factors such as train speed,overburden pressure on the tunnel and variation in soil properties are studied in the time domain.As a result,the variations in horizontal and vertical acceleration for two different sites,i.e.,the free ground surface(without structure)and the area containing the structure,are compared.Also,the displacement pattern of the raft foundation is plotted for different train velocities.At lower speeds,the heaving phenomenon is negligible,but as the speed increases,both the heaving and differential settlement increase in the foundation.This study demonstrates that the effect of moving train vibrations should be considered in the design of new nearby structures and proper ground improvement should be considered for existing structures.展开更多
The effect of varying the temperature and the concentration of ammonium nitrate solution on the stress corrosion cracking (SCC) susceptibility of mild steel is studied. An increase in the temperature causes a decrease...The effect of varying the temperature and the concentration of ammonium nitrate solution on the stress corrosion cracking (SCC) susceptibility of mild steel is studied. An increase in the temperature causes a decrease in the stress corrosion life. It appears that the susceptibility in the range 368 K to 380 K was greater than at other temperatures. Near the boiling point corrosion and stress corrosion occurs, at the boiling point, the cracking was associated with a high rate of general corrosion. Microscopic examination after stress corrosion testing in 10Wt%, 20Wt%, and 52Wt% NH4NO3 solution revealed that in all cases there was severe intergranular attack, especially at the high concentration.展开更多
基金Natural Science Research Project of Anhui Educational Committee under Grant No.2022AH050844Anhui Provincial Natural Science Foundation of China under Grant No.2008085ME143+1 种基金the Doctoral Foundation of Anhui University of Science and Technology under Grant No.13190018Innovation and Entrepreneurship Training Program for College Students under Grant No.S202110361059。
文摘Piled embankments have many advantages that have been applied in high-speed railway construction engineering.However,the load transfer mechanism of piled embankments,such as soil arching and tension membranes,is still unclear,especially under dynamic loads.To investigate the soil arching and tension membrane under dynamic train loads on high-speed railways,a large-scale piled embankment model test with X-shaped piles as vertical reinforcement was performed,in which twenty-eight earth pressure cells were installed in the piled embankment and an M-shaped wave was adopted to simulate the high-speed railway train load.The results show that dynamic soil arching only occurs when two bogies of a carriage pass by and disappears at other times.The dynamic soil arching and membrane effect are the most significant under the concrete base.The arching height,stress concentration ratio and pile-soil load sharing ratio have a minimal value at 25 Hz.The dynamic soil arching degrades severely at 25 Hz,whose height at 25 Hz is only 0.35 times that at 5 Hz.The arching height fluctuates over a narrow range with increasing loading amplitude.The stress concentration ratio and the pile-soil load sharing ratio increase monotonically as the loading amplitude increases.
文摘This study is focused on the effect of vibration induced by moving trains in tunnels on the surrounding ground and structures.A three-dimensional finite element model is established for a one-track railway tunnel and an adjacent twelve-storey building frame by using commercial software Midas GTS-NX(2019)and Midas Gen.This study considered the moving load effect of a complete train,which varies with space as well as with time.The effect of factors such as train speed,overburden pressure on the tunnel and variation in soil properties are studied in the time domain.As a result,the variations in horizontal and vertical acceleration for two different sites,i.e.,the free ground surface(without structure)and the area containing the structure,are compared.Also,the displacement pattern of the raft foundation is plotted for different train velocities.At lower speeds,the heaving phenomenon is negligible,but as the speed increases,both the heaving and differential settlement increase in the foundation.This study demonstrates that the effect of moving train vibrations should be considered in the design of new nearby structures and proper ground improvement should be considered for existing structures.
文摘The effect of varying the temperature and the concentration of ammonium nitrate solution on the stress corrosion cracking (SCC) susceptibility of mild steel is studied. An increase in the temperature causes a decrease in the stress corrosion life. It appears that the susceptibility in the range 368 K to 380 K was greater than at other temperatures. Near the boiling point corrosion and stress corrosion occurs, at the boiling point, the cracking was associated with a high rate of general corrosion. Microscopic examination after stress corrosion testing in 10Wt%, 20Wt%, and 52Wt% NH4NO3 solution revealed that in all cases there was severe intergranular attack, especially at the high concentration.
基金Projects(51322403,51274254)supported by the National Natural Science Foundation of ChinaProject(2015CB060200)supported by the National Basic Research Program of China
