Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soi...Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soil displacement reached about 90% of the total displacement,which means that P-Δ effect of axial load can be neglected.The maximum moment of pile decreased from 159 kN·m to 133 kN·m in the case of surcharge load when the axial load increased from 0 to the ultimate load.When deformation of pile caused by soil displacement is large,axial load applied on pile-head plays the role of reducing the maximum bending moment in concrete pile to some extent.When pile is on one side of the tunnel,soil displacements around the pile are all alike,which means that the soil pressures around the pile do not decrease during tunneling.Therefore,Q-s curve of the pile affected by tunneling is very close to that of pile in static loading test.Bearing capacities of piles influenced by surcharge load and uniform soil movement are 2480 kN and 2630 kN,respectively,which are a little greater than that of the pile in static loading test(2400 kN).Soil pressures along pile increase due to surcharge load and uniform soil movement,and so do the shaft resistances along pile,as a result,when rebars in concrete piles are enough,bearing capacity of pile affected by soil displacement increases compared with that of pile in static loading test.展开更多
Biochar addition can improve the physical and hydraulic characteristics of sandy soil.This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation.By ...Biochar addition can improve the physical and hydraulic characteristics of sandy soil.This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation.By indoor simulation experiments,the effects of biochar application at five levels(0%,1%,2%,4%and 6%)on the soil water retention curve,infiltration characteristics of drip irrigation and water distribution were tested and analyzed.The results showed that biochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water.Within the same infiltration time,with an increasing amount of added biochar,the diffusion distance of the horizontal wetting front(HWF)tended to decrease,while the infiltration distance of vertical wetting front(VWF)initially declined and then rose.The features of wetted bodies changed from"broad-shallow"to"narrow-deep"type.The relationship between the transport distances of HWF and VWF and the infiltration time was described by a power function.At the same distance from the point source,the larger the amount of added biochar,the higher the soil water content.Biochar had a great influence on the water content of the layer with biochar(0–200 mm)and had some effects at 200–250 mm without biochar;but it had less influence on the soil water content deeper than 250 mm.For the application rate of biochar of 4%,most water was retained within 0–250 mm soil layer.However,when biochar application amount was high(6%),it would be helpful for water infiltration.During the improvement of sandy soil,biochar application rate of 4%in the plow layer had the best effect.展开更多
As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit f...As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit facilities including stairs and elevators, escalators usually have large transit capacity. It is expected to reduce pedestrian traveling time and thus improve the quality of pedestrian’s experiences especially in jamming conditions. However, it is noticed that pedestrians may present different movement patterns, e.g., queuing on each step of the escalator, walking on the left-side and meanwhile standing on the right-side of the escalator. These different patterns affect the actual escalator traffic volume and finally the passenger spatiotemporal distribution in different built environments. Thus, in the present study, a microscopic cellular automaton(CA) simulation model considering pedestrian movement behavior on escalators is built. Simulations are performed considering different pedestrian movement speeds, queuing modes, and segregation on escalators with different escalator speeds.The actual escalator capacities under different pedestrian movement patterns are investigated. It is found that walking on escalators will not always benefit escalator transit volume improvement, especially in jamming conditions.展开更多
Two lines of research on eye movements in reading are summarized. One line of research examines how adult readers identify compound words during reading. The other line of research deals with how a specific reading go...Two lines of research on eye movements in reading are summarized. One line of research examines how adult readers identify compound words during reading. The other line of research deals with how a specific reading goal influences the way long expository texts are read. Both lines of research are conducted using Finnish as the source language. With respect to the first research question, it is demonstrated that compound words are recognized either holistically or via their components, depending on the length of the compound word. Readers begin to process whatever information is readily available in the foveal vision(i.e., either the whole-word form or the initial component). The second line of research demonstrates that(1)a specific reading goal is capable of exerting an early effect on readers’ eye fixation patterns,(2)time course analyses based on eye movement patterns can reveal interesting individual differences, and(3)working memory capacity is linked to the efficiency to strategically allocate attention as well as to encode information to and retrieve it from the long-term memory. It is concluded that the eye-tracking technique is an excellent research tool to tap into the workings of the human mind during the comprehension of written texts.展开更多
目的:探索睡眠剥夺对大鼠运动能力及谷氨酰胺含量变化的影响,为睡眠剥夺后的运动训练等提供一定的实验依据。方法:将30只雄性SD大鼠按体重随机分安静对照组、0 h睡眠剥夺力竭运动组(SDE)、24 h SDE、48 h SDE和72 h SDE组(n=6),采用轻...目的:探索睡眠剥夺对大鼠运动能力及谷氨酰胺含量变化的影响,为睡眠剥夺后的运动训练等提供一定的实验依据。方法:将30只雄性SD大鼠按体重随机分安静对照组、0 h睡眠剥夺力竭运动组(SDE)、24 h SDE、48 h SDE和72 h SDE组(n=6),采用轻柔刺激法建立睡眠剥夺模型和依据Bedford建立的大鼠运动模型。结果:24 h SDE睡眠剥夺组与0 h SDE组比较,大鼠后蹬跑时间明显长(P<0.05),48 h SDE睡眠剥夺组和72 h SDE睡眠剥夺与0h SDE睡眠剥夺组比较,后蹬跑时间显著性减少(P<0.01);24 h SDE睡眠剥夺组与C组比较大鼠胸腺谷氨酰胺含量显著升高(P<0.05),48 h SDE睡眠剥夺组和72 h SDE睡眠剥夺组与C组比较大鼠胸腺谷氨酰胺含量降低(P<0.01);睡眠剥夺组与C组比较,血清谷氨酰胺含量的变化均具有高度显著性差异(P<0.01),睡眠剥夺24 h后血清谷氨酰胺含量显著增多,却在睡眠剥夺48 h、72 h后血清谷氨酰胺含量明显下降。结论:①睡眠剥夺24 h能提高大鼠运动能力,睡眠剥夺48 h甚至是72 h后大鼠运动能力开始降低。②睡眠剥夺24 h后大鼠胸腺谷氨酰胺含量和血清谷氨酰胺含量升高,而睡眠剥夺48 h后大鼠胸腺和血清的谷氨酰胺含量下降明显,睡眠剥夺72 h后胸腺和血清谷氨酰胺含量显著性降低。展开更多
临近桩基受到基坑开挖引起的土体水平位移作用,导致桩身产生附加弯矩、应力和位移,可能降低临近桩基的安全度,这已成为工程界关注的一个重要问题。基于非线性荷载传递的p-y曲线法,采用LPILE Plus 5.0软件对基坑开挖引起的土体位移与临...临近桩基受到基坑开挖引起的土体水平位移作用,导致桩身产生附加弯矩、应力和位移,可能降低临近桩基的安全度,这已成为工程界关注的一个重要问题。基于非线性荷载传递的p-y曲线法,采用LPILE Plus 5.0软件对基坑开挖引起的土体位移与临近桩基的相互作用进行分析,讨论了桩侧土体抗力特性、桩头约束条件和土体位移分布模式等对桩基弯矩、内力和位移等的影响,并根据分析结果,提出一些建议,可供工程设计参考。展开更多
基金Project(51208071)supported by the National Natural Science Foundation of ChinaProject(2010CB732106)supported by the National Basic Research Program of China
文摘Effect of soil displacement on friction single pile in the cases of tunneling,surcharge load and uniform soil movement was discussed in details with finite element method.Lateral displacement of the pile caused by soil displacement reached about 90% of the total displacement,which means that P-Δ effect of axial load can be neglected.The maximum moment of pile decreased from 159 kN·m to 133 kN·m in the case of surcharge load when the axial load increased from 0 to the ultimate load.When deformation of pile caused by soil displacement is large,axial load applied on pile-head plays the role of reducing the maximum bending moment in concrete pile to some extent.When pile is on one side of the tunnel,soil displacements around the pile are all alike,which means that the soil pressures around the pile do not decrease during tunneling.Therefore,Q-s curve of the pile affected by tunneling is very close to that of pile in static loading test.Bearing capacities of piles influenced by surcharge load and uniform soil movement are 2480 kN and 2630 kN,respectively,which are a little greater than that of the pile in static loading test(2400 kN).Soil pressures along pile increase due to surcharge load and uniform soil movement,and so do the shaft resistances along pile,as a result,when rebars in concrete piles are enough,bearing capacity of pile affected by soil displacement increases compared with that of pile in static loading test.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest(20130313006,201503136)the National Natural Science Foundation of China(31660073)+1 种基金the National Key Research and Development Program of China(2017YFD0200803-04,2018YFD0800804,2017YFD0201900)the Youth Foundation of Xinjiang Academy of Agricultural Sciences(xjnkq-2015002)
文摘Biochar addition can improve the physical and hydraulic characteristics of sandy soil.This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation.By indoor simulation experiments,the effects of biochar application at five levels(0%,1%,2%,4%and 6%)on the soil water retention curve,infiltration characteristics of drip irrigation and water distribution were tested and analyzed.The results showed that biochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water.Within the same infiltration time,with an increasing amount of added biochar,the diffusion distance of the horizontal wetting front(HWF)tended to decrease,while the infiltration distance of vertical wetting front(VWF)initially declined and then rose.The features of wetted bodies changed from"broad-shallow"to"narrow-deep"type.The relationship between the transport distances of HWF and VWF and the infiltration time was described by a power function.At the same distance from the point source,the larger the amount of added biochar,the higher the soil water content.Biochar had a great influence on the water content of the layer with biochar(0–200 mm)and had some effects at 200–250 mm without biochar;but it had less influence on the soil water content deeper than 250 mm.For the application rate of biochar of 4%,most water was retained within 0–250 mm soil layer.However,when biochar application amount was high(6%),it would be helpful for water infiltration.During the improvement of sandy soil,biochar application rate of 4%in the plow layer had the best effect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.71473207 and 71871189)the Research Grant Council of the Hong Kong Administrative Region,China(Grant No.CityU118909)the Open Fund of Beijing Engineering and Technology Research Center of Rail Transit Line Safety and Disaster Prevention(Grant No.RRC201701)
文摘As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit facilities including stairs and elevators, escalators usually have large transit capacity. It is expected to reduce pedestrian traveling time and thus improve the quality of pedestrian’s experiences especially in jamming conditions. However, it is noticed that pedestrians may present different movement patterns, e.g., queuing on each step of the escalator, walking on the left-side and meanwhile standing on the right-side of the escalator. These different patterns affect the actual escalator traffic volume and finally the passenger spatiotemporal distribution in different built environments. Thus, in the present study, a microscopic cellular automaton(CA) simulation model considering pedestrian movement behavior on escalators is built. Simulations are performed considering different pedestrian movement speeds, queuing modes, and segregation on escalators with different escalator speeds.The actual escalator capacities under different pedestrian movement patterns are investigated. It is found that walking on escalators will not always benefit escalator transit volume improvement, especially in jamming conditions.
文摘Two lines of research on eye movements in reading are summarized. One line of research examines how adult readers identify compound words during reading. The other line of research deals with how a specific reading goal influences the way long expository texts are read. Both lines of research are conducted using Finnish as the source language. With respect to the first research question, it is demonstrated that compound words are recognized either holistically or via their components, depending on the length of the compound word. Readers begin to process whatever information is readily available in the foveal vision(i.e., either the whole-word form or the initial component). The second line of research demonstrates that(1)a specific reading goal is capable of exerting an early effect on readers’ eye fixation patterns,(2)time course analyses based on eye movement patterns can reveal interesting individual differences, and(3)working memory capacity is linked to the efficiency to strategically allocate attention as well as to encode information to and retrieve it from the long-term memory. It is concluded that the eye-tracking technique is an excellent research tool to tap into the workings of the human mind during the comprehension of written texts.
文摘目的:探索睡眠剥夺对大鼠运动能力及谷氨酰胺含量变化的影响,为睡眠剥夺后的运动训练等提供一定的实验依据。方法:将30只雄性SD大鼠按体重随机分安静对照组、0 h睡眠剥夺力竭运动组(SDE)、24 h SDE、48 h SDE和72 h SDE组(n=6),采用轻柔刺激法建立睡眠剥夺模型和依据Bedford建立的大鼠运动模型。结果:24 h SDE睡眠剥夺组与0 h SDE组比较,大鼠后蹬跑时间明显长(P<0.05),48 h SDE睡眠剥夺组和72 h SDE睡眠剥夺与0h SDE睡眠剥夺组比较,后蹬跑时间显著性减少(P<0.01);24 h SDE睡眠剥夺组与C组比较大鼠胸腺谷氨酰胺含量显著升高(P<0.05),48 h SDE睡眠剥夺组和72 h SDE睡眠剥夺组与C组比较大鼠胸腺谷氨酰胺含量降低(P<0.01);睡眠剥夺组与C组比较,血清谷氨酰胺含量的变化均具有高度显著性差异(P<0.01),睡眠剥夺24 h后血清谷氨酰胺含量显著增多,却在睡眠剥夺48 h、72 h后血清谷氨酰胺含量明显下降。结论:①睡眠剥夺24 h能提高大鼠运动能力,睡眠剥夺48 h甚至是72 h后大鼠运动能力开始降低。②睡眠剥夺24 h后大鼠胸腺谷氨酰胺含量和血清谷氨酰胺含量升高,而睡眠剥夺48 h后大鼠胸腺和血清的谷氨酰胺含量下降明显,睡眠剥夺72 h后胸腺和血清谷氨酰胺含量显著性降低。
文摘临近桩基受到基坑开挖引起的土体水平位移作用,导致桩身产生附加弯矩、应力和位移,可能降低临近桩基的安全度,这已成为工程界关注的一个重要问题。基于非线性荷载传递的p-y曲线法,采用LPILE Plus 5.0软件对基坑开挖引起的土体位移与临近桩基的相互作用进行分析,讨论了桩侧土体抗力特性、桩头约束条件和土体位移分布模式等对桩基弯矩、内力和位移等的影响,并根据分析结果,提出一些建议,可供工程设计参考。
