The penetration depth of torpedo anchor in two-layered soil bed was experimentally investigated. A total of 177 experimental data were obtained in laboratory by varying the undrained shear strength of the two-layered ...The penetration depth of torpedo anchor in two-layered soil bed was experimentally investigated. A total of 177 experimental data were obtained in laboratory by varying the undrained shear strength of the two-layered soil and the thickness of the top soil layer. The geometric parameters of the anchor and the soil properties(the liquid limit, plastic limit, specific gravity, undrained shear strength, density, and water content) were measured. Based on the energy analysis and present test data, an empirical formula to predict the penetration depth of torpedo anchor in two-layered soil bed was proposed. The proposed formula was extensively validated by laboratory and field data of previous researchers. The results were in good agreement with those obtained for two-layered and single-layered soil bed.Finally, a sensitivity analysis on the parameters in the formula was performed.展开更多
[Objective] The aim was to study variation of soil moisture under different irrigation quota.[Method] By using Trime-TDR apparatus,soil moisture with different irrigation quota infiltration was measured;combining the ...[Objective] The aim was to study variation of soil moisture under different irrigation quota.[Method] By using Trime-TDR apparatus,soil moisture with different irrigation quota infiltration was measured;combining the characteristics of soil texture,curve characteristics of soil moisture variation with soil depth under different irrigation quota were analyzed.[Result] Different irrigation quota has resulted in variation of soil moisture in different layer depth.Soil moisture is 9.88%,17%,25% and 24.45% in so...展开更多
Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost ...Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost region and the soil freeze depth(SFD)in the seasonally frozen ground region across the Three Rivers Source Region(TRSR)from 1980 to 2014 using the Stefan equation,and differentiated the effects of these variations on alpine vegetation in these two regions.The results showed that the average ALT from 1980 to 2014 increased by23.01 cm/10 a,while the average SFD decreased by 3.41 cm/10 a,and both changed intensively in the transitional zone between the seasonally frozen ground and permafrost.From 1982-2014,the increase in the normalized difference vegetation index(NDVI)and the advancement of the start of the vegetation growing season(SOS)in the seasonally frozen ground region(0.0078/10 a,1.83 d/10 a)were greater than those in the permafrost region(0.0057/10 a,0.39 d/10 a).The results of the correlation analysis indicated that increases in the ALT and decreases in the SFD in the TRSR could lead to increases in the NDVI and advancement of the SOS.Surface soil moisture played a critical role in vegetation growth in association with the increasing ALT and decreasing SFD.The NDVI for all vegetation types in the TRSR except for alpine vegetation showed an increasing trend that was significantly related to the SFD and ALT.During the study period,the general frozen ground conditions were favorable to vegetation growth,while the average contributions of ALT and SFD to the interannual variation in the NDVI were greater than that of precipitation but less than that of temperature.展开更多
Soil water is a key factor limiting plant growth in water-limited regions. Without limit of soil water used by plants, soil degradation in the form of soil desiccation is easy to take place in the perennial forestland...Soil water is a key factor limiting plant growth in water-limited regions. Without limit of soil water used by plants, soil degradation in the form of soil desiccation is easy to take place in the perennial forestland and grassland with too higher density or productivity. Soil water resources use limit (SWRUL) is the lowest control limit of soil water resources which is used by plants in those regions. It can be defined as soil water storage within the maximum infiltration depth in which all of soil layers belong to dried soil layers. In this paper, after detailed discussion of characteristics of water resources and the relationship between soil water and plant growth in the Loess Plateau, the definition, quantitative method, and practical applications of SWRUL are introduced. Henceforth, we should strengthen the study of SWRUL and have a better understanding of soil water resources. All those are of great importance for designing effective restoration project and sustainable management of soil water resources in water- limited regions in the future.展开更多
基金financially supported by the Ministry of Education of China(Grant No.6141A02022337)
文摘The penetration depth of torpedo anchor in two-layered soil bed was experimentally investigated. A total of 177 experimental data were obtained in laboratory by varying the undrained shear strength of the two-layered soil and the thickness of the top soil layer. The geometric parameters of the anchor and the soil properties(the liquid limit, plastic limit, specific gravity, undrained shear strength, density, and water content) were measured. Based on the energy analysis and present test data, an empirical formula to predict the penetration depth of torpedo anchor in two-layered soil bed was proposed. The proposed formula was extensively validated by laboratory and field data of previous researchers. The results were in good agreement with those obtained for two-layered and single-layered soil bed.Finally, a sensitivity analysis on the parameters in the formula was performed.
基金Supported by State Administration of Foreign Experts Affairs,Ministry of Education,High School Discipline Innovation Indraught Program(B08039)~~
文摘[Objective] The aim was to study variation of soil moisture under different irrigation quota.[Method] By using Trime-TDR apparatus,soil moisture with different irrigation quota infiltration was measured;combining the characteristics of soil texture,curve characteristics of soil moisture variation with soil depth under different irrigation quota were analyzed.[Result] Different irrigation quota has resulted in variation of soil moisture in different layer depth.Soil moisture is 9.88%,17%,25% and 24.45% in so...
基金funded by the National Natural Science Foundation of China (41807061)Postdoctoral Science Foundation of China (2018M633454)+2 种基金Fundamental Research Funds for the Central Universities of China (GK201803046)National Science Foundation of China (41930641)National Key Research and Development Plan of China (2017YFC0504702)
文摘Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost region and the soil freeze depth(SFD)in the seasonally frozen ground region across the Three Rivers Source Region(TRSR)from 1980 to 2014 using the Stefan equation,and differentiated the effects of these variations on alpine vegetation in these two regions.The results showed that the average ALT from 1980 to 2014 increased by23.01 cm/10 a,while the average SFD decreased by 3.41 cm/10 a,and both changed intensively in the transitional zone between the seasonally frozen ground and permafrost.From 1982-2014,the increase in the normalized difference vegetation index(NDVI)and the advancement of the start of the vegetation growing season(SOS)in the seasonally frozen ground region(0.0078/10 a,1.83 d/10 a)were greater than those in the permafrost region(0.0057/10 a,0.39 d/10 a).The results of the correlation analysis indicated that increases in the ALT and decreases in the SFD in the TRSR could lead to increases in the NDVI and advancement of the SOS.Surface soil moisture played a critical role in vegetation growth in association with the increasing ALT and decreasing SFD.The NDVI for all vegetation types in the TRSR except for alpine vegetation showed an increasing trend that was significantly related to the SFD and ALT.During the study period,the general frozen ground conditions were favorable to vegetation growth,while the average contributions of ALT and SFD to the interannual variation in the NDVI were greater than that of precipitation but less than that of temperature.
文摘Soil water is a key factor limiting plant growth in water-limited regions. Without limit of soil water used by plants, soil degradation in the form of soil desiccation is easy to take place in the perennial forestland and grassland with too higher density or productivity. Soil water resources use limit (SWRUL) is the lowest control limit of soil water resources which is used by plants in those regions. It can be defined as soil water storage within the maximum infiltration depth in which all of soil layers belong to dried soil layers. In this paper, after detailed discussion of characteristics of water resources and the relationship between soil water and plant growth in the Loess Plateau, the definition, quantitative method, and practical applications of SWRUL are introduced. Henceforth, we should strengthen the study of SWRUL and have a better understanding of soil water resources. All those are of great importance for designing effective restoration project and sustainable management of soil water resources in water- limited regions in the future.
