Laboratory swelling deformation tests were carried out on compacted GMZ bentonite and bentonite-sand mixtures with 30%and 50%sand contents at 20,40,60,80 and 90°C with infiltration of distilled water.Influence of...Laboratory swelling deformation tests were carried out on compacted GMZ bentonite and bentonite-sand mixtures with 30%and 50%sand contents at 20,40,60,80 and 90°C with infiltration of distilled water.Influence of temperature,initial dry density,and quartz sand content on the swelling deformation characteristic of compacted bentonite specimens was analyzed.Results indicate that the swelling deformation process is accelerated,and the maximum swelling strain increases with the increase in temperature,while the maximum swelling strain tends to be stable with increasing temperature.In the meantime,the temperature effects depend on both of the sand content and the initial dry density of the specimens,the increases of the maximum swelling strain induced by increasing temperature,are enlarged by increasing sand content or initial dry density.Adding of quartz sand to bentonite not only influences the integrality of bentonite specimen,but also increase the microfissuring in area on quartz sand,which are advantageous to the heat transfer,leading to the increase of swelling deformation capacity of the specimen.The increased dry density relatively increases the bentonite content,so the swelling property is enhanced.However,no change on mineral composition of bentonite was observed when temperature was changed from 20 to 90°C.展开更多
The effect of various dosages of dolomites on the reduction swelling property of iron ore pellets was studied. Experimental results show that the reduction swelling index(RSI) decreases from 13.35% to 4.0%, while the ...The effect of various dosages of dolomites on the reduction swelling property of iron ore pellets was studied. Experimental results show that the reduction swelling index(RSI) decreases from 13.35% to 4.0%, while the porosity of roasted pellets increases from 35% to 40% with increasing the dolomite dosage from 0 to 10.5%. Meanwhile, the content of magnesium ferrite with high melting temperature, as well as the stability of magnetite(Fe3 O4) in the roasted pellets, increases with increasing the magnesium oxide(MgO) content from dolomite. The reasons for the decrease of RSI rely on the absence of crystal transformation from Fe2 O3 to Fe3 O4, the increased porosity of roasted pellet, and the suppression of phase transition of 2CaO·SiO2 resulted from the incorporation of magnesium into calcium silicate.展开更多
It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concen...It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.展开更多
Black cotton soil in East Africa is not a stable engineering material for highway and railroad projects. Its strong swelling potential when it absorbs water causes distresses in subgrade of highway and railroad, and t...Black cotton soil in East Africa is not a stable engineering material for highway and railroad projects. Its strong swelling potential when it absorbs water causes distresses in subgrade of highway and railroad, and thus leads to failures of the projects. This paper presents study on the swelling characteristics of black cotton soil in East Africa. Lab tests were conducted to obtain its basic engineering properties, and the results show that black cotton soil contains high amount of montmorillonite and exchangeable cations and is strong expansive soil. Molecular modelling was exploited to further investigate water absorption ability of montmorillonite. Three different molecular models of montmorillonite were constructed and used for simulations, among which Types I and II montmorillonite represent the expansive soil montmorillonite in China, and Types II and III montmorillonite represent black cotton soil montmorillonite in East Africa. The results showed that the interlayer cations of Type III montmorillonite possessed the strongest water absorption ability based on analysis of radial distribution function(RDF) of cations. Interlayer compensatory cations of Na+ enhance the hydration ability of the other major cations, thus resulting in the strong swelling potential of East-Africa black cotton soil.展开更多
Many geotechnical structures,such as the subgrade of high-speed railway,are extremely sensitive to micro deformations.As one of the most commonly used indexes in China to evaluate the potential swelling level of expan...Many geotechnical structures,such as the subgrade of high-speed railway,are extremely sensitive to micro deformations.As one of the most commonly used indexes in China to evaluate the potential swelling level of expansive soils,the effectiveness and accuracy of free swelling ratio should be highly required.However,due to the deficiency of geotechnical test regulations for the free swelling ratio test,non-negligible variation difference is often observed among the test results of the same type of soil samples.Thus,a series of laboratory tests are conducted to figure out the influences of soil particle size,initial soil temperature,and wet-dry circulation on the free swelling ratio of expansive soils.The results show that the initial soil temperature exerts an obvious influence on free swelling ratio and a relative weak influence on soil mass of expansive soil with the micro soil particle size(d<0.075 mm),and the correlation becomes unclear when soil particle size is within the range of 0.075 mm≤d<0.500 mm.A larger particle size of expansive soils induces a larger free swelling ratio and soil mass in the soil measuring cup regardless of initial soil temperature.However,the enlarging amplitude decreases as the particle size of expansive soils increases.There is a progressive enlargement of free swelling ratio at the first two wet-dry cycles and then it attenuates gradually when the number of wetdry cycles further increases.展开更多
Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle ti...Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.展开更多
A series of porous intelligent hydrogels, which exhibited appropriate lower critical solution temperature (LCST) and fast response behavior, were synthesized by radiation method. The structure and surface morphology o...A series of porous intelligent hydrogels, which exhibited appropriate lower critical solution temperature (LCST) and fast response behavior, were synthesized by radiation method. The structure and surface morphology of hydrogels were examined by the infrared radiation and the scanning electron microscopy, respectively. The influences of the content of crosslinking agent and relative molecular mass of polyethylene glycol (PEG) on the swelling properties of hydrogels were discussed. The molecular mechanics simulations were performed to investigate the phase transformation mechanism of poly(N-isopropyl acrylamide) (PNIPA) hydrogel. The results show that macropores are observed in hydrogels, whereas hydrogels prepared without using PEG have a dense surface. LCST of hydrogels increases with the increase of relative molecular mass of PEG. The swelling mechanism of PNIPA porous hydrogels follows non-Fickian diffusion model. The theoretical maximum water absorption S∞ is approximately consistent with experimental value according to the second-order kinetics model established by Schott. The molecule chains of PNIPA hydrogel begin folding and curling, resulting in volume shrinkage at 305 K. There are much intramolecular nonbonding interactions in molecule chains of hydrogels. The porous hydrogels are expected to be applied in the field of artificial intelligence material.展开更多
A laboratory one-dimensional consolidation apparatus was employed to research the swelling stress and volume of the sand-bentonite mixture under immersed conditions. The stress-strain characteristics of mixtures under...A laboratory one-dimensional consolidation apparatus was employed to research the swelling stress and volume of the sand-bentonite mixture under immersed conditions. The stress-strain characteristics of mixtures under varied mixing ratios and loading statuses were analyzed. Based on the results of tests, the mechanism of mixture swelling and collapsing was further discussed. The results show that mixtures with low sand ratios are suitable as hydraulic barrier or containment barriers of general landfills, geological repository and other hydraulic infrastructure works.展开更多
One kind of facile coal-based direct reduction process is using hot preheated pellets for reduction in grate kiln. In this work, effects of reduction parameters on swelling index of hot preheated pellets were investig...One kind of facile coal-based direct reduction process is using hot preheated pellets for reduction in grate kiln. In this work, effects of reduction parameters on swelling index of hot preheated pellets were investigated by photographic technique under isothermal conditions. Experimental results show that swelling index of pellets is firstly increased then gradually decreased with increasing reduction time, while that is found to be an obvious decrease from 175 % to 30% with the variation of temperature from 900℃ to 1100℃. Results of XRD combined with SEM reveal that swelling behavior of pellets is decided by structure of newly formed metal iron grains. The formation and growth of fibers iron grains promote the increase in volume. Low temperature and low CO content are favored to the formation and orientated growth of metal iron grains in the one step process.展开更多
The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Pl...The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.展开更多
The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability an...The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability analysis method for geogrid reinforced expansive soil slopes.The additional pullout force of the free zone due to the lateral swelling and the anti-pullout safety factor of each geogrid layer were obtained by ensuring the overall stability of the reinforced slope.The optimum design was carried out to treat an expansive soil cut slope in Hubei Province,China,by changing the spacing and length of geogrid reinforcement.Calculation results show that the additional pullout force caused by lateral swelling has a great influence on the anti-pullout stability of geogrids,and the local stability of the reinforced slope will be overestimated if the swelling effect of soil in the free zone is not considered.展开更多
As a main charging burden of blast furnace(BF)ironmaking process,pellets play an important role in ironmaking process.However,compared with sinters,there are some inevitable disadvantages for traditional acid pellets,...As a main charging burden of blast furnace(BF)ironmaking process,pellets play an important role in ironmaking process.However,compared with sinters,there are some inevitable disadvantages for traditional acid pellets,e.g.,reduction swell,low melting temperature.Therefore,the fluxed-pellets have been applied in BF,especially MgO-fluxed pellets.In the present study,the effects of category and content of MgO bearing additive on the compressive strength(CS),reduction swelling index(RSI),reduction disintegration index(RDI)and melting-dripping properties of the pellets were investigated.Minerals composition,pore distribution and microstructure of MgO-flux pellets were studied by X-ray powder diffraction(XRD),mercury intrusion method and scanning electron microscopy(SEM),respectively.The results show that the light burned magnesite(LBM)is more suitable MgO bearing additive for fluxed-pellets.With increasing LBM content from 0 to 2.0%,the CS decreases from 3066 to 2689 N,RSI decreases from 16.43%to 9.97%and RDI decreases from 19.2%to 12.99%.The most appropriate MgO bearing additive content in the fluxed-pellets is 2.0%according to principal component analysis(PCA).展开更多
Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex...Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex- pression up-regulates after ischemia-reperfusion injury in rats, making the astrocytic endfeet swelling, with the con- sequence of the injury of blood-brain barrier（BBB） , increasing the permeability of BBB, render too much water in the blood flow to the brain parenchyma, which results in cytotoxic edema, disordering the stability of the central nervous system. In addintion, the increased permeability of BBB is one of the important reasons for the cerebral stroke, therefore, it is essential that research the relationship between AQP-4 with BBB further and restore the blood-brain barrier injury be a new strategy for the prevention and treatment of stroke, worthy of further research.展开更多
基金Project (41402260) supported by the National Natural Science Foundation of ChinaProject (20136101120006) supported by the Research Fund for the Doctoral Program of Higher Education,China
文摘Laboratory swelling deformation tests were carried out on compacted GMZ bentonite and bentonite-sand mixtures with 30%and 50%sand contents at 20,40,60,80 and 90°C with infiltration of distilled water.Influence of temperature,initial dry density,and quartz sand content on the swelling deformation characteristic of compacted bentonite specimens was analyzed.Results indicate that the swelling deformation process is accelerated,and the maximum swelling strain increases with the increase in temperature,while the maximum swelling strain tends to be stable with increasing temperature.In the meantime,the temperature effects depend on both of the sand content and the initial dry density of the specimens,the increases of the maximum swelling strain induced by increasing temperature,are enlarged by increasing sand content or initial dry density.Adding of quartz sand to bentonite not only influences the integrality of bentonite specimen,but also increase the microfissuring in area on quartz sand,which are advantageous to the heat transfer,leading to the increase of swelling deformation capacity of the specimen.The increased dry density relatively increases the bentonite content,so the swelling property is enhanced.However,no change on mineral composition of bentonite was observed when temperature was changed from 20 to 90°C.
基金Project(50725416) supported by the National Natural Science for Distinguished Young Scholars of China
文摘The effect of various dosages of dolomites on the reduction swelling property of iron ore pellets was studied. Experimental results show that the reduction swelling index(RSI) decreases from 13.35% to 4.0%, while the porosity of roasted pellets increases from 35% to 40% with increasing the dolomite dosage from 0 to 10.5%. Meanwhile, the content of magnesium ferrite with high melting temperature, as well as the stability of magnetite(Fe3 O4) in the roasted pellets, increases with increasing the magnesium oxide(MgO) content from dolomite. The reasons for the decrease of RSI rely on the absence of crystal transformation from Fe2 O3 to Fe3 O4, the increased porosity of roasted pellet, and the suppression of phase transition of 2CaO·SiO2 resulted from the incorporation of magnesium into calcium silicate.
基金Project(51404005)supported by the National Natural Science Foundation of China
文摘It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.
基金Project(51878164) supported by the National Natural Science Foundation of ChinaProjects(BK20180149, BK20161421) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(KFJ170106) supported by Changsha University of Science & Technology via Open Fund of National Engineering Laboratory of Highway Maintenance Technology, China。
文摘Black cotton soil in East Africa is not a stable engineering material for highway and railroad projects. Its strong swelling potential when it absorbs water causes distresses in subgrade of highway and railroad, and thus leads to failures of the projects. This paper presents study on the swelling characteristics of black cotton soil in East Africa. Lab tests were conducted to obtain its basic engineering properties, and the results show that black cotton soil contains high amount of montmorillonite and exchangeable cations and is strong expansive soil. Molecular modelling was exploited to further investigate water absorption ability of montmorillonite. Three different molecular models of montmorillonite were constructed and used for simulations, among which Types I and II montmorillonite represent the expansive soil montmorillonite in China, and Types II and III montmorillonite represent black cotton soil montmorillonite in East Africa. The results showed that the interlayer cations of Type III montmorillonite possessed the strongest water absorption ability based on analysis of radial distribution function(RDF) of cations. Interlayer compensatory cations of Na+ enhance the hydration ability of the other major cations, thus resulting in the strong swelling potential of East-Africa black cotton soil.
基金Project(2016M591957) supported by the China Postdoctoral Science FoundationProjects(51878667,51678571)supported by the National Natural Science Foundation of ChinaProject(2017XKQY050) supported by the Fundamental Research Funds for the Central Universities,China。
文摘Many geotechnical structures,such as the subgrade of high-speed railway,are extremely sensitive to micro deformations.As one of the most commonly used indexes in China to evaluate the potential swelling level of expansive soils,the effectiveness and accuracy of free swelling ratio should be highly required.However,due to the deficiency of geotechnical test regulations for the free swelling ratio test,non-negligible variation difference is often observed among the test results of the same type of soil samples.Thus,a series of laboratory tests are conducted to figure out the influences of soil particle size,initial soil temperature,and wet-dry circulation on the free swelling ratio of expansive soils.The results show that the initial soil temperature exerts an obvious influence on free swelling ratio and a relative weak influence on soil mass of expansive soil with the micro soil particle size(d<0.075 mm),and the correlation becomes unclear when soil particle size is within the range of 0.075 mm≤d<0.500 mm.A larger particle size of expansive soils induces a larger free swelling ratio and soil mass in the soil measuring cup regardless of initial soil temperature.However,the enlarging amplitude decreases as the particle size of expansive soils increases.There is a progressive enlargement of free swelling ratio at the first two wet-dry cycles and then it attenuates gradually when the number of wetdry cycles further increases.
文摘Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.
基金Project(102101210100) supported by the Key Science and Technology Project of Henan Province,ChinaProjects(2011B430023,12B430021) supported by the Natural Science Foundation of Henan Province,China
文摘A series of porous intelligent hydrogels, which exhibited appropriate lower critical solution temperature (LCST) and fast response behavior, were synthesized by radiation method. The structure and surface morphology of hydrogels were examined by the infrared radiation and the scanning electron microscopy, respectively. The influences of the content of crosslinking agent and relative molecular mass of polyethylene glycol (PEG) on the swelling properties of hydrogels were discussed. The molecular mechanics simulations were performed to investigate the phase transformation mechanism of poly(N-isopropyl acrylamide) (PNIPA) hydrogel. The results show that macropores are observed in hydrogels, whereas hydrogels prepared without using PEG have a dense surface. LCST of hydrogels increases with the increase of relative molecular mass of PEG. The swelling mechanism of PNIPA porous hydrogels follows non-Fickian diffusion model. The theoretical maximum water absorption S∞ is approximately consistent with experimental value according to the second-order kinetics model established by Schott. The molecule chains of PNIPA hydrogel begin folding and curling, resulting in volume shrinkage at 305 K. There are much intramolecular nonbonding interactions in molecule chains of hydrogels. The porous hydrogels are expected to be applied in the field of artificial intelligence material.
文摘A laboratory one-dimensional consolidation apparatus was employed to research the swelling stress and volume of the sand-bentonite mixture under immersed conditions. The stress-strain characteristics of mixtures under varied mixing ratios and loading statuses were analyzed. Based on the results of tests, the mechanism of mixture swelling and collapsing was further discussed. The results show that mixtures with low sand ratios are suitable as hydraulic barrier or containment barriers of general landfills, geological repository and other hydraulic infrastructure works.
基金Projects(51404213,51404214,51674225)supported by the National Natural Science Fundation of ChinaProject(1421324065)supported by the Development Fund for Outstanding Young Teachers of Zhengzhou University,China
文摘One kind of facile coal-based direct reduction process is using hot preheated pellets for reduction in grate kiln. In this work, effects of reduction parameters on swelling index of hot preheated pellets were investigated by photographic technique under isothermal conditions. Experimental results show that swelling index of pellets is firstly increased then gradually decreased with increasing reduction time, while that is found to be an obvious decrease from 175 % to 30% with the variation of temperature from 900℃ to 1100℃. Results of XRD combined with SEM reveal that swelling behavior of pellets is decided by structure of newly formed metal iron grains. The formation and growth of fibers iron grains promote the increase in volume. Low temperature and low CO content are favored to the formation and orientated growth of metal iron grains in the one step process.
基金National Natural Science Foundation of China(Grant No.22175059)to provide fund for conducting experiments.
文摘The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.
基金Project(51978085)supported by the National Natural Science Foundation of ChinaProject(201808430102)supported by the China Scholarship Council+1 种基金Project(JTG-201507)supported by the Highway Industry Standard Compilation Project of Ministry of Transportation,ChinaProject(kfj180102)supported by the Open Fund of Changsha University of Science&Technology,China。
文摘The traditional stability analysis method of geogrid reinforced slopes does not consider the effect of lateral swelling,so it is not applicable to reinforced expansive soil slopes.This paper reports a new stability analysis method for geogrid reinforced expansive soil slopes.The additional pullout force of the free zone due to the lateral swelling and the anti-pullout safety factor of each geogrid layer were obtained by ensuring the overall stability of the reinforced slope.The optimum design was carried out to treat an expansive soil cut slope in Hubei Province,China,by changing the spacing and length of geogrid reinforcement.Calculation results show that the additional pullout force caused by lateral swelling has a great influence on the anti-pullout stability of geogrids,and the local stability of the reinforced slope will be overestimated if the swelling effect of soil in the free zone is not considered.
基金Projects(51874080,51604069)supported by the National Natural Science Foundation of ChinaProject(N162504004)supported by the Fundamental Research Funds for the Central Universities,China
文摘As a main charging burden of blast furnace(BF)ironmaking process,pellets play an important role in ironmaking process.However,compared with sinters,there are some inevitable disadvantages for traditional acid pellets,e.g.,reduction swell,low melting temperature.Therefore,the fluxed-pellets have been applied in BF,especially MgO-fluxed pellets.In the present study,the effects of category and content of MgO bearing additive on the compressive strength(CS),reduction swelling index(RSI),reduction disintegration index(RDI)and melting-dripping properties of the pellets were investigated.Minerals composition,pore distribution and microstructure of MgO-flux pellets were studied by X-ray powder diffraction(XRD),mercury intrusion method and scanning electron microscopy(SEM),respectively.The results show that the light burned magnesite(LBM)is more suitable MgO bearing additive for fluxed-pellets.With increasing LBM content from 0 to 2.0%,the CS decreases from 3066 to 2689 N,RSI decreases from 16.43%to 9.97%and RDI decreases from 19.2%to 12.99%.The most appropriate MgO bearing additive content in the fluxed-pellets is 2.0%according to principal component analysis(PCA).
文摘Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex- pression up-regulates after ischemia-reperfusion injury in rats, making the astrocytic endfeet swelling, with the con- sequence of the injury of blood-brain barrier（BBB） , increasing the permeability of BBB, render too much water in the blood flow to the brain parenchyma, which results in cytotoxic edema, disordering the stability of the central nervous system. In addintion, the increased permeability of BBB is one of the important reasons for the cerebral stroke, therefore, it is essential that research the relationship between AQP-4 with BBB further and restore the blood-brain barrier injury be a new strategy for the prevention and treatment of stroke, worthy of further research.
