Unidirectional freezing experiments under overburden pressure were carried out, in order to study the driving force of mois- ture migration of remodeled clay during freezing, through improving the indoor moisture migr...Unidirectional freezing experiments under overburden pressure were carried out, in order to study the driving force of mois- ture migration of remodeled clay during freezing, through improving the indoor moisture migration test device. Overburden pressure and cooling temperature with the same circumstance were changed to determine the influence on water migration of a single factor. Results show that water content increases above the location of the final ice lenses and decreases below the loca- tion. When the overburden pressure increases, water intake gradually decreases and the time starting to absorb water is delayed. The location of the final ice lens is not sensitive to overburden pressure but influenced by the temperature boundary. The im- pact of overburden pressure and maximum temperature is not obvious. Freezing rate is not sensitive to overburden pressure but influenced by temperature, and it increases when the cold temperature decreases. Frost heave and water intake flow in- creases with increasing time and rises up to a peak value, and then decreases. During the freezing process, water intake flow increases when freezing rate decreases. Water intake flow decreases when the overburden pressure increases when the cold temperature decreases. Finally, we expanded the segregation theory, and proposed a model to describe the relationship between water intake flow and freezing rate.展开更多
In the present study,indoor experiments were carried out to investigate the effects of rainfall on subsequent wind erosion processes on the simulated Gobi surface,with soils and gravels collected from the Alax Gobi in...In the present study,indoor experiments were carried out to investigate the effects of rainfall on subsequent wind erosion processes on the simulated Gobi surface,with soils and gravels collected from the Alax Gobi in northwestern China.The results showed that the wind erosion rate(WR)ranged from 0.4 to 1931.2 g m^((-2)min^((-1)and that the sediment transportation rate(STR)ranged from 0.00 to 51.47 g m^((-2)s^((-1)under different gravel coverage conditions(0%,20%,40%and 60%)when the wind velocity changed from 6 m s^((-1)to 18 m s^((-1).Both WR and STR increased with increasing wind velocity as a power function and decreased with increasing gravel coverage.The rainfall event had significant inhibitory effects on WR and STR,and the complex effects of soil crust formation and the changing soil surface roughness(SSR)by rainfall event played significant roles in reducing these rates during subsequent wind erosion.In this study,a valuable exploration of the effects of rainfall events on subsequent wind erosion processes in the Gobi area was conducted.The findings are of great significance for a better understanding and effective prediction of dust emissions in this region.展开更多
With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as proces...With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca^2＋ and H^＋ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca^2＋ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.展开更多
To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the g...To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the geological model of the geothermal reinjection demonstration project in Dezhou City. The biological process of porous media clogging was investigated by analyzing the variation of permeability within the medium, the main indexes of nutrient salts, and the content of extracellular polymeric substances (EPS). High-throughput sequencing, based on 16S rRNA, was used to analyze the characteristics and succession of microbial communities during the reinjection of geothermal water. The results of the study show that significant bio-clogging occurs during the reinjection of geothermal water, with an increase in the heterogeneity of the thermal reservoir medium, and a decrease in permeability. The extent of clogging gradually reduces with an increase in seepage path. Thus, thermal reservoir clogging is more serious closer to the water inlet. With an increase in the duration of reinjection, the permeability of the porous medium undergoes three stages: “rapid”, “decline-slow”, and “decrease-stable”. The results show that the richness and diversity of the bacterial community increase and decrease, respectively, during the reinjection process. Bacterial community succession occurs, and the bacterial communities mainly include the Proteobacteria and Bacteroidetes phyla. <em>Pseudomonas</em> and <em>Devosia</em> are respectively the dominant bacteria in the early and late stages of geothermal water reinjection.展开更多
The main research purpose of this paper is to study the mechanical properties of the sand gravel packing of the retaining wall under the creep condition of reinforced materials, in order to figure it out, Indoor physi...The main research purpose of this paper is to study the mechanical properties of the sand gravel packing of the retaining wall under the creep condition of reinforced materials, in order to figure it out, Indoor physical experiments were carried out.展开更多
基金supported by the National Basic Research Program("973") of China (2012CB026102)the National Natural Science Foundation of China (No.41271080 and No.41230630)the open fund of Qinghai Research and Observation Base, Key Laboratory of Highway Construction and Maintenance Technology in Permafrost Region Ministry of Transport, PRC(2012-12-4)
文摘Unidirectional freezing experiments under overburden pressure were carried out, in order to study the driving force of mois- ture migration of remodeled clay during freezing, through improving the indoor moisture migration test device. Overburden pressure and cooling temperature with the same circumstance were changed to determine the influence on water migration of a single factor. Results show that water content increases above the location of the final ice lenses and decreases below the loca- tion. When the overburden pressure increases, water intake gradually decreases and the time starting to absorb water is delayed. The location of the final ice lens is not sensitive to overburden pressure but influenced by the temperature boundary. The im- pact of overburden pressure and maximum temperature is not obvious. Freezing rate is not sensitive to overburden pressure but influenced by temperature, and it increases when the cold temperature decreases. Frost heave and water intake flow in- creases with increasing time and rises up to a peak value, and then decreases. During the freezing process, water intake flow increases when freezing rate decreases. Water intake flow decreases when the overburden pressure increases when the cold temperature decreases. Finally, we expanded the segregation theory, and proposed a model to describe the relationship between water intake flow and freezing rate.
基金National Natural Science Foundation of China,No.41930640,No.41977069。
文摘In the present study,indoor experiments were carried out to investigate the effects of rainfall on subsequent wind erosion processes on the simulated Gobi surface,with soils and gravels collected from the Alax Gobi in northwestern China.The results showed that the wind erosion rate(WR)ranged from 0.4 to 1931.2 g m^((-2)min^((-1)and that the sediment transportation rate(STR)ranged from 0.00 to 51.47 g m^((-2)s^((-1)under different gravel coverage conditions(0%,20%,40%and 60%)when the wind velocity changed from 6 m s^((-1)to 18 m s^((-1).Both WR and STR increased with increasing wind velocity as a power function and decreased with increasing gravel coverage.The rainfall event had significant inhibitory effects on WR and STR,and the complex effects of soil crust formation and the changing soil surface roughness(SSR)by rainfall event played significant roles in reducing these rates during subsequent wind erosion.In this study,a valuable exploration of the effects of rainfall events on subsequent wind erosion processes in the Gobi area was conducted.The findings are of great significance for a better understanding and effective prediction of dust emissions in this region.
基金supported by the National Natural Science Foundation of China(Grant No.51209014)the Fundamental Research Funds for the Changjiang River Scientific Research Institute(Grant No.CKSF2013012/TB)
文摘With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca^2＋ and H^＋ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca^2＋ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.
文摘To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the geological model of the geothermal reinjection demonstration project in Dezhou City. The biological process of porous media clogging was investigated by analyzing the variation of permeability within the medium, the main indexes of nutrient salts, and the content of extracellular polymeric substances (EPS). High-throughput sequencing, based on 16S rRNA, was used to analyze the characteristics and succession of microbial communities during the reinjection of geothermal water. The results of the study show that significant bio-clogging occurs during the reinjection of geothermal water, with an increase in the heterogeneity of the thermal reservoir medium, and a decrease in permeability. The extent of clogging gradually reduces with an increase in seepage path. Thus, thermal reservoir clogging is more serious closer to the water inlet. With an increase in the duration of reinjection, the permeability of the porous medium undergoes three stages: “rapid”, “decline-slow”, and “decrease-stable”. The results show that the richness and diversity of the bacterial community increase and decrease, respectively, during the reinjection process. Bacterial community succession occurs, and the bacterial communities mainly include the Proteobacteria and Bacteroidetes phyla. <em>Pseudomonas</em> and <em>Devosia</em> are respectively the dominant bacteria in the early and late stages of geothermal water reinjection.
文摘The main research purpose of this paper is to study the mechanical properties of the sand gravel packing of the retaining wall under the creep condition of reinforced materials, in order to figure it out, Indoor physical experiments were carried out.
