Land-atmosphere coupling is a key process of the climate system, and various coupling mechanisms have been proposed before based on observational and numerical analyses. The impact of soil moisture（SM） on evapotrans...Land-atmosphere coupling is a key process of the climate system, and various coupling mechanisms have been proposed before based on observational and numerical analyses. The impact of soil moisture（SM） on evapotranspiration（ET） and further surface temperature（ST） is an important aspect of such coupling. Using ERA-Interim data and CLM4.0 offline simulation results, this study further explores the relationships between SM/ST and ET to better understand the complex nature of the land-atmosphere coupling（i.e., spatial and seasonal variations） in eastern China, a typical monsoon area. It is found that two diagnostics of land-atmosphere coupling（i.e., SM-ET correlation and ST-ET correlation） are highly dependent on the climatology of SM and ST. By combining the SM-ET and ST-ET relationships, two ＂hot spots＂ of land-atmosphere coupling over eastern China are identified： Southwest China and North China. In Southwest China, ST is relatively high throughout the year, but SM is lowest in spring, resulting in a strong coupling in spring. However, in North China, SM is relatively low throughout the year, but ST is highest in summer, which leads to the strongest coupling in summer. Our results emphasize the dependence of land-atmosphere coupling on the seasonal evolution of climatic conditions and have implications for future studies related to land surface feedbacks.展开更多
Background:Afforestation is a common and effective approach used for the restoration of degraded ecosystems worldwide.In China,Robinia pseudoacacia(RP)is among the main non-native tree species and has been widely plan...Background:Afforestation is a common and effective approach used for the restoration of degraded ecosystems worldwide.In China,Robinia pseudoacacia(RP)is among the main non-native tree species and has been widely planted in revegetation of the Loess Plateau.However,owing to uncertainties regarding soil water consumption and carbon sequestration,it is necessary to assess the suitability and sustainability of R.pseudoacacia in restoration.In this study,we aimed to analyse the dynamic effects of R.pseudoacacia forest on soil carbon storage(SCS)and soil water storage(SWS).Specifically,we investigated the association between soil water content(SWC)and soil organic carbon(SOC)and underlying factors in the 0-500-cm profile of a 10-to 50-year-old chronosequence.Results:The results obtained indicated that the dynamics of SWS and SCS on this time scale could be divided into an initial reduction phase(the initial 20 years after afforestation)and subsequent recovery(20-50 years after afforestation).Compared with in the abandoned land(AL),the net accumulation of SCS in R.pseudoacacia forest was 2.51 Mg·ha^(-1)at 50 years after afforestation,whereas there was a 398.76-mm deficit in SWS.Additionally,the natural succession of R.pseudoacacia forest has contributed to the continuous change in stand structure(e.g.vegetation cover(VC),understory vegetation coverage(UVC),and litter biomass(LB)).Conclusions:These findings indicate that vegetation restoration increases carbon sequestration while causing soil water deficit.Furthermore,stand density(SD)was established to make a predominant contribution to the dynamics of SWS and SCS via its effects in altering vegetation,soil,and litter characteristics.Therefore,high-density plantation forests in the Loess Plateau area should be appropriately thinned to reduce the density of forest stands on the basis of soil erosion control and wind and sand fixation,so as to increase carbon sink with lower water consumption,thus realizing the synergistic development of soil carbon sequestration and water connotation.展开更多
In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The...In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The major of this paper is concerned with the Boundary Element Method for the pile-soil interaction, including general methods and calculating formulation of static and dynamic analysis of the pile and pile groups. Some results of analysis are also given.展开更多
This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations....This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations.Three-dimensional large deformation finite element(LDFE)analyses were conducted to retrospectively analyze the incidents,considering the remoulding of seabed soil and degradation of the pile-soil interface in the LDFE modeling.By comparing the field observations with the LDFE analysis,the mechanism of pile running was discussed,with a focus on investigating the pile penetration resistance in each layer.The study revealed that pile running in layered soils primarily resulted from a significant reduction in pile base resistance when transitioning from a strong layer to an adjacent weak layer.To further investigate the pile running mechanism in layered soils,a parametric study on the strength variation of adjacent soil layers and its influence on pile base resistance was conducted.Lastly,a simplified prediction model of pile base resistance,suitable for assessing the risk of pile running in layered soils,was proposed.展开更多
The paper set up 3D solid overall superstructure model of Foundation and Box foundation on Rock Slope Subgrade base using the ABAQUS, and the establish the infinite element boundary, superstructure displacement of Box...The paper set up 3D solid overall superstructure model of Foundation and Box foundation on Rock Slope Subgrade base using the ABAQUS, and the establish the infinite element boundary, superstructure displacement of Box foundation and foundation at Rock Slope Subgrade was studied by inputting different direction of earthquake response. The results show that, for the mountain frame structure, influence on the horizontal displacement of the vertical under the action of alone big earthquake, and vertical seismic action on horizontal displacement effect is smaller by mutual function of horizontal and vertical seismic, basically is same as response under the action of horizontal earthquake alone; for step shaped box foundation, the change trend of mutual function of horizontal and vertical earthquake was the complete opposite of the maximum story drift each layer under the one-way horizontal earthquake, which indicate the presence of vertical earthquake wave effect on the box foundation displacement cannot be ignored.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.41625019 and 41605042)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20151525)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Land-atmosphere coupling is a key process of the climate system, and various coupling mechanisms have been proposed before based on observational and numerical analyses. The impact of soil moisture（SM） on evapotranspiration（ET） and further surface temperature（ST） is an important aspect of such coupling. Using ERA-Interim data and CLM4.0 offline simulation results, this study further explores the relationships between SM/ST and ET to better understand the complex nature of the land-atmosphere coupling（i.e., spatial and seasonal variations） in eastern China, a typical monsoon area. It is found that two diagnostics of land-atmosphere coupling（i.e., SM-ET correlation and ST-ET correlation） are highly dependent on the climatology of SM and ST. By combining the SM-ET and ST-ET relationships, two ＂hot spots＂ of land-atmosphere coupling over eastern China are identified： Southwest China and North China. In Southwest China, ST is relatively high throughout the year, but SM is lowest in spring, resulting in a strong coupling in spring. However, in North China, SM is relatively low throughout the year, but ST is highest in summer, which leads to the strongest coupling in summer. Our results emphasize the dependence of land-atmosphere coupling on the seasonal evolution of climatic conditions and have implications for future studies related to land surface feedbacks.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB40020000)the National Natural Science Foundation of China(No.41807011)。
文摘Background:Afforestation is a common and effective approach used for the restoration of degraded ecosystems worldwide.In China,Robinia pseudoacacia(RP)is among the main non-native tree species and has been widely planted in revegetation of the Loess Plateau.However,owing to uncertainties regarding soil water consumption and carbon sequestration,it is necessary to assess the suitability and sustainability of R.pseudoacacia in restoration.In this study,we aimed to analyse the dynamic effects of R.pseudoacacia forest on soil carbon storage(SCS)and soil water storage(SWS).Specifically,we investigated the association between soil water content(SWC)and soil organic carbon(SOC)and underlying factors in the 0-500-cm profile of a 10-to 50-year-old chronosequence.Results:The results obtained indicated that the dynamics of SWS and SCS on this time scale could be divided into an initial reduction phase(the initial 20 years after afforestation)and subsequent recovery(20-50 years after afforestation).Compared with in the abandoned land(AL),the net accumulation of SCS in R.pseudoacacia forest was 2.51 Mg·ha^(-1)at 50 years after afforestation,whereas there was a 398.76-mm deficit in SWS.Additionally,the natural succession of R.pseudoacacia forest has contributed to the continuous change in stand structure(e.g.vegetation cover(VC),understory vegetation coverage(UVC),and litter biomass(LB)).Conclusions:These findings indicate that vegetation restoration increases carbon sequestration while causing soil water deficit.Furthermore,stand density(SD)was established to make a predominant contribution to the dynamics of SWS and SCS via its effects in altering vegetation,soil,and litter characteristics.Therefore,high-density plantation forests in the Loess Plateau area should be appropriately thinned to reduce the density of forest stands on the basis of soil erosion control and wind and sand fixation,so as to increase carbon sink with lower water consumption,thus realizing the synergistic development of soil carbon sequestration and water connotation.
文摘In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The major of this paper is concerned with the Boundary Element Method for the pile-soil interaction, including general methods and calculating formulation of static and dynamic analysis of the pile and pile groups. Some results of analysis are also given.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51879183,51890913)Sino-German Mobility Programme(Grant No.M-0045)。
文摘This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations.Three-dimensional large deformation finite element(LDFE)analyses were conducted to retrospectively analyze the incidents,considering the remoulding of seabed soil and degradation of the pile-soil interface in the LDFE modeling.By comparing the field observations with the LDFE analysis,the mechanism of pile running was discussed,with a focus on investigating the pile penetration resistance in each layer.The study revealed that pile running in layered soils primarily resulted from a significant reduction in pile base resistance when transitioning from a strong layer to an adjacent weak layer.To further investigate the pile running mechanism in layered soils,a parametric study on the strength variation of adjacent soil layers and its influence on pile base resistance was conducted.Lastly,a simplified prediction model of pile base resistance,suitable for assessing the risk of pile running in layered soils,was proposed.
文摘The paper set up 3D solid overall superstructure model of Foundation and Box foundation on Rock Slope Subgrade base using the ABAQUS, and the establish the infinite element boundary, superstructure displacement of Box foundation and foundation at Rock Slope Subgrade was studied by inputting different direction of earthquake response. The results show that, for the mountain frame structure, influence on the horizontal displacement of the vertical under the action of alone big earthquake, and vertical seismic action on horizontal displacement effect is smaller by mutual function of horizontal and vertical seismic, basically is same as response under the action of horizontal earthquake alone; for step shaped box foundation, the change trend of mutual function of horizontal and vertical earthquake was the complete opposite of the maximum story drift each layer under the one-way horizontal earthquake, which indicate the presence of vertical earthquake wave effect on the box foundation displacement cannot be ignored.
