To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.N...To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.Nanographite powder(NGP)has excellent properties,such as high adsorption,conductivity,and lubrication,since it has the characteristics of small size,large specific surface area,and high surface energy.However,previous studies on the improvement of expansive soil with NGP are not processed enough.To study the improvement effect of NGP on expansive soil,non-load swelling ratio tests,consolidation tests,unconfined compressive strength tests,mercury injection tests,and micro-CT tests on expansive soil mixed with different NGP contents were performed.The results show that the non-load swelling ratio,mechanical properties,and porosity of expansive soil show some increasement after adding NGP.The strength of expansive soil reaches the maximum when the NGP content is 1.450%.The cumulative mercury volume and compressive strain of expansive soil reach the maximum with the 2.0%NGP content.Finally,the modification mechanism of swelling,compressibility,microstructure,and compressive strength of expansive soil by NGP is revealed.展开更多
The results of pot and pond trials are as follows.On equal amount of nitrogen(N)applied,the wheat nitrate reduction activity(NRA)and photosynthesis strength and other phy-siological properties are stronger and yields ...The results of pot and pond trials are as follows.On equal amount of nitrogen(N)applied,the wheat nitrate reduction activity(NRA)and photosynthesis strength and other phy-siological properties are stronger and yields are higher at normal soil moisture than those atdrought.At the same soil moisture,in a certain range of N applied,these properties of wheat in-crease with the increasing of N applied,but they descend when the amount of N applied exceedsa certain range.展开更多
The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four ...The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four carboxymethylcelluloses （CMC） mixed at various rates with the sandy soil, on the water-holding capacity and hydraulic conductivity （Ks） when leached with distilled water （simulating rain）, tap water, and saline water were evaluated. The maximum water absorption of CMCs ranged between 80 and 100 kg. kg^-1 of polymer; however, the absorbent swelling capacity decreased significantly with increasing the salt concentration in the solution. The water absorption capacity of CMCs decreased significantly when incorporated in the sandy soil compared to that of the absorbent alone. Application of CMC increased significantly the available water content up to 3 ± 0.5 times. All soils treated with CMCs showed a significant lower in Ks compared to the control soil. Meanwhile, Ks was found increased with increasing the salt concentration in the leaching solution. This understanding of characteristics of the absorbents and the interactions among absorbents, soil, and irrigation water quality would be of help in water management of sandy soil展开更多
基金Project(2017TFC1503102)supported by the National Key Research and Development Project,ChinaProjects(51874065,U1903112)supported by the National Natural Science Foundation of China。
文摘To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.Nanographite powder(NGP)has excellent properties,such as high adsorption,conductivity,and lubrication,since it has the characteristics of small size,large specific surface area,and high surface energy.However,previous studies on the improvement of expansive soil with NGP are not processed enough.To study the improvement effect of NGP on expansive soil,non-load swelling ratio tests,consolidation tests,unconfined compressive strength tests,mercury injection tests,and micro-CT tests on expansive soil mixed with different NGP contents were performed.The results show that the non-load swelling ratio,mechanical properties,and porosity of expansive soil show some increasement after adding NGP.The strength of expansive soil reaches the maximum when the NGP content is 1.450%.The cumulative mercury volume and compressive strain of expansive soil reach the maximum with the 2.0%NGP content.Finally,the modification mechanism of swelling,compressibility,microstructure,and compressive strength of expansive soil by NGP is revealed.
文摘The results of pot and pond trials are as follows.On equal amount of nitrogen(N)applied,the wheat nitrate reduction activity(NRA)and photosynthesis strength and other phy-siological properties are stronger and yields are higher at normal soil moisture than those atdrought.At the same soil moisture,in a certain range of N applied,these properties of wheat in-crease with the increasing of N applied,but they descend when the amount of N applied exceedsa certain range.
文摘The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four carboxymethylcelluloses （CMC） mixed at various rates with the sandy soil, on the water-holding capacity and hydraulic conductivity （Ks） when leached with distilled water （simulating rain）, tap water, and saline water were evaluated. The maximum water absorption of CMCs ranged between 80 and 100 kg. kg^-1 of polymer; however, the absorbent swelling capacity decreased significantly with increasing the salt concentration in the solution. The water absorption capacity of CMCs decreased significantly when incorporated in the sandy soil compared to that of the absorbent alone. Application of CMC increased significantly the available water content up to 3 ± 0.5 times. All soils treated with CMCs showed a significant lower in Ks compared to the control soil. Meanwhile, Ks was found increased with increasing the salt concentration in the leaching solution. This understanding of characteristics of the absorbents and the interactions among absorbents, soil, and irrigation water quality would be of help in water management of sandy soil
