The study of flow behaviour of water-sand mixtures in fractured rocks is of great necessity to understand the producing mechanism and prevention of water inrush and sand gushing accidents.A self-developed seepage test...The study of flow behaviour of water-sand mixtures in fractured rocks is of great necessity to understand the producing mechanism and prevention of water inrush and sand gushing accidents.A self-developed seepage test system is used in this paper to conduct laboratory experiments in order to study the influence of the particle size distribution,the void ratio,and the initial mass of Aeolian sand on the flow behavior.It is concluded that the water flow velocity is insensitive to the initial mass of the Aeolian sand but increases with the power exponent in the Talbot formula and the specimen height.The outflow of the Aeolian sand increases with the power exponent in the Talbot formula,the specimen height,and the initial mass of the Aeolian sand.Besides,the outflow of the Aeolian sand changes exponentially with the water flow velocity.Finally,it is found that the fractured specimen has a maximum sand filtration capacity beyond which the outflow of the Aeolian sand significantly increases with the initial mass of the Aeolian sand.展开更多
A knowledge of soil permeability is essential to evaluate hydrologic characteristics of soil, such as water storage and water movement, and soil permeability coefficient is an important parameter that reflects soil pe...A knowledge of soil permeability is essential to evaluate hydrologic characteristics of soil, such as water storage and water movement, and soil permeability coefficient is an important parameter that reflects soil permeability. In order to confirm the acceptability of the one-dimensional horizontal infiltration method(one-D method) for simultaneously determining both the saturated and unsaturated permeability coefficients of loamy sand, we first measured the cumulative infiltration and the wetting front distance under various infiltration heads through a series of one-dimensional horizontal infiltration experiments, and then analyzed the relationships of the cumulative horizontal infiltration with the wetting front distance and the square root of infiltration time. We finally compared the permeability results from Gardner model based on the one-D method with the results from other two commonly-used methods(i.e., constant head method and van Genuchten model) to evaluate the acceptability and applicability of the one-D method. The results showed that there was a robust linear relationship between the cumulative horizontal infiltration and the wetting front distance, suggesting that it is more appropriate to take the soil moisture content after infiltration in the entire wetted zone as the average soil moisture content than as the saturated soil moisture content. The results also showed that there was a robust linear relationship between the cumulative horizontal infiltration and the square root of infiltration time, suggesting that the Philip infiltration formula can better reflect the characteristics of cumulative horizontal infiltration under different infiltration heads. The following two facts indicate that it is feasible to use the one-D method for simultaneously determining the saturated and unsaturated permeability coefficients of loamy sand. First, the saturated permeability coefficient(prescribed in the Gardner model) of loamy sand obtained from the one-D method well agreed with the value obtained from the constant head method. Second, the relationship of unsaturated permeability coefficient with soil water suction for loamy sand calculated using Gardner model based on the one-D method was nearly identical with the same relationship calculated using van Genuchten model.展开更多
Muddy water irrigation,an effective water-saving irrigation method,has been widely used in the Yellow River Basin in China.To investigate the effect of sand content on water infiltration and dense layer formation unde...Muddy water irrigation,an effective water-saving irrigation method,has been widely used in the Yellow River Basin in China.To investigate the effect of sand content on water infiltration and dense layer formation under one-dimensional vertical infiltration of muddy water,muddy water infiltration experiments were performed in the laboratory,and five sand contents of muddy water(S=0%,3%,6%,9%,and 12%)were used.Models were established to describe the relationship between the cumulative infiltration amount[I(t)]and the infiltration duration(t);the relationship among the migration distance of the wetting front(Z),S,and t;the thickness of the sedimentary layer[H(t)];and the relationship between S and t.The results revealed that I(t)and Z decreased significantly with the increase of sand contents,while H(t)increased significantly with the increase of sand contents.I(t)and Z were in the range of 7 cm and 20 cm for each treatment,respectively.The variation in I(t)with t fitted Kostiakov and Philip models,and the coefficients of determination were all greater than 0.99.With the increase in S,the infiltration coefficient gradually decreased,the infiltration index gradually increased,and the sorptivity gradually decreased.The particle composition of the sedimentary layer was similar to that of the argillaceous sediment,and the content of particles with a size of less than 2 mm in the sedimentary layer was lower than that of the argillaceous sediment.Compared with the original soil,the content of particles with a size of less than 0.05 mm and physical clay particles(diameter less than 0.01 mm)in the soil with an infiltration depth of 0-2 cm increased.The retention layer was from the topsoil to the infiltration depth of approximately 2 cm.This study can provide a scientific basis for further research on soil infiltration mechanisms under muddy water.展开更多
文摘利用改进的渗透装置试验研究了细颗粒(0.075~1 mm)含量相同时骨架颗粒组成含量不同对散粒土的管涌发生临界条件以及颗粒侵蚀流失规律的影响,结果表明:不同颗粒级配的试样在管涌发生前,水力梯度与渗流速度呈线性关系,基本符合达西定律;骨架颗粒1~2、2~3、3~5 mm 3个粒径段对管涌发展起到了阻碍作用,其中1~2 mm粒径段颗粒对管涌孔隙的堵塞作用强于另外两个粒径段颗粒;对于不同级配的骨架颗粒,其不均匀系数越大,试样的下限临界水力梯度值就越大,细颗粒越不易起动,发生管涌的时间越晚,而不同级配的骨架颗粒对试样的上限临界水力梯度影响较小。
基金financially supported by the National Natural Science Foundation of China(Nos.41807209,51778215,51708185,and 51974293)the Young Teacher Foundation of HPU(No.2019XQG-19)+3 种基金the Henan Provincial Youth Talent Promotion Program(No.2020HYTP003)the Jiangsu Province Science Foundation for Youths(No.BK20180658)the Doctor Foundation of Henan Polytechnic University(Nos.B2017-51 and B2017-53)China Postdoctoral Science Foundation(No.2018M632422)。
文摘The study of flow behaviour of water-sand mixtures in fractured rocks is of great necessity to understand the producing mechanism and prevention of water inrush and sand gushing accidents.A self-developed seepage test system is used in this paper to conduct laboratory experiments in order to study the influence of the particle size distribution,the void ratio,and the initial mass of Aeolian sand on the flow behavior.It is concluded that the water flow velocity is insensitive to the initial mass of the Aeolian sand but increases with the power exponent in the Talbot formula and the specimen height.The outflow of the Aeolian sand increases with the power exponent in the Talbot formula,the specimen height,and the initial mass of the Aeolian sand.Besides,the outflow of the Aeolian sand changes exponentially with the water flow velocity.Finally,it is found that the fractured specimen has a maximum sand filtration capacity beyond which the outflow of the Aeolian sand significantly increases with the initial mass of the Aeolian sand.
基金funded by the National Basic Research Program of China (2013CB429902)the National Natural Science Foundation of China (U1303181, 41671032)
文摘A knowledge of soil permeability is essential to evaluate hydrologic characteristics of soil, such as water storage and water movement, and soil permeability coefficient is an important parameter that reflects soil permeability. In order to confirm the acceptability of the one-dimensional horizontal infiltration method(one-D method) for simultaneously determining both the saturated and unsaturated permeability coefficients of loamy sand, we first measured the cumulative infiltration and the wetting front distance under various infiltration heads through a series of one-dimensional horizontal infiltration experiments, and then analyzed the relationships of the cumulative horizontal infiltration with the wetting front distance and the square root of infiltration time. We finally compared the permeability results from Gardner model based on the one-D method with the results from other two commonly-used methods(i.e., constant head method and van Genuchten model) to evaluate the acceptability and applicability of the one-D method. The results showed that there was a robust linear relationship between the cumulative horizontal infiltration and the wetting front distance, suggesting that it is more appropriate to take the soil moisture content after infiltration in the entire wetted zone as the average soil moisture content than as the saturated soil moisture content. The results also showed that there was a robust linear relationship between the cumulative horizontal infiltration and the square root of infiltration time, suggesting that the Philip infiltration formula can better reflect the characteristics of cumulative horizontal infiltration under different infiltration heads. The following two facts indicate that it is feasible to use the one-D method for simultaneously determining the saturated and unsaturated permeability coefficients of loamy sand. First, the saturated permeability coefficient(prescribed in the Gardner model) of loamy sand obtained from the one-D method well agreed with the value obtained from the constant head method. Second, the relationship of unsaturated permeability coefficient with soil water suction for loamy sand calculated using Gardner model based on the one-D method was nearly identical with the same relationship calculated using van Genuchten model.
基金the National Natural Science Foundation of China(Grant No.52079105 and 51779205)the Doctoral Dissertations Innovation Fund of Xi’an University of Technology(Grant No.310-252072107).
文摘Muddy water irrigation,an effective water-saving irrigation method,has been widely used in the Yellow River Basin in China.To investigate the effect of sand content on water infiltration and dense layer formation under one-dimensional vertical infiltration of muddy water,muddy water infiltration experiments were performed in the laboratory,and five sand contents of muddy water(S=0%,3%,6%,9%,and 12%)were used.Models were established to describe the relationship between the cumulative infiltration amount[I(t)]and the infiltration duration(t);the relationship among the migration distance of the wetting front(Z),S,and t;the thickness of the sedimentary layer[H(t)];and the relationship between S and t.The results revealed that I(t)and Z decreased significantly with the increase of sand contents,while H(t)increased significantly with the increase of sand contents.I(t)and Z were in the range of 7 cm and 20 cm for each treatment,respectively.The variation in I(t)with t fitted Kostiakov and Philip models,and the coefficients of determination were all greater than 0.99.With the increase in S,the infiltration coefficient gradually decreased,the infiltration index gradually increased,and the sorptivity gradually decreased.The particle composition of the sedimentary layer was similar to that of the argillaceous sediment,and the content of particles with a size of less than 2 mm in the sedimentary layer was lower than that of the argillaceous sediment.Compared with the original soil,the content of particles with a size of less than 0.05 mm and physical clay particles(diameter less than 0.01 mm)in the soil with an infiltration depth of 0-2 cm increased.The retention layer was from the topsoil to the infiltration depth of approximately 2 cm.This study can provide a scientific basis for further research on soil infiltration mechanisms under muddy water.
