A Ms 8.0 large earthquake occurred in Sichuan,China on May 12,2008（hereafter called 5.12 Earthquake）,and then a large debris flow happened in the quake-hit Qingping Township of Mianzhu county on August 13,2008（here...A Ms 8.0 large earthquake occurred in Sichuan,China on May 12,2008（hereafter called 5.12 Earthquake）,and then a large debris flow happened in the quake-hit Qingping Township of Mianzhu county on August 13,2008（hereafter called 8.13 Debris Flow）.The influence of two disasters on the changes in land use were analyzed by using highresolution aerial photos and satellite remote sensing images taken before and after the 5.12 Earthquake and 8.13 Debris Flow,the selection of suitable construction land were studied by learning experiences and lessons from the selection of resettlement areas and through field surveys and with land use transfer model and analytical model in combination with RS and GIS.The results showed that the influence of the 5.12 Earthquake on ecological environment was far greater than that of the 8.13 Debris Flow;there were more salient conflicts between population and land after the earthquake.Sites for post-disaster reconstruction should not be in disaster-prone areas or in gully-facing areas.Suitable land for settlement construction in I-1~I-5 low-hazard zones is optimal settlement areas for post-disaster reconstruction.展开更多
Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the ass...Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the assumption of linear small deformation,a mathematical model of the relationship between ground deformation and construction parameters is set up.The principle and method of optimization for estimating ground deformation is studied.The actual measured data are compared with the results of theoretical analysis in a case.Considering different ground formations in different construction sites with different adverse effects on surface and underground structures,the ground surface deformations caused by shield tunneling is an aimed topic in this paper.The contributions and research implications are the revealed relationships between the ground deformation and the shield tunneling parameters during construction.展开更多
The world has experienced a rapid expansion of human settlements in both urban and rural areas in recent decades,yet the unequal impacts of this construction on global food security remain unclear.In this study,we del...The world has experienced a rapid expansion of human settlements in both urban and rural areas in recent decades,yet the unequal impacts of this construction on global food security remain unclear.In this study,we delineated the global-scale expansion of urban–rural settlements at a fine resolution from1985 to 2020 and quantified their uneven impacts on food security,focusing on the relationships between settlement types,cropland categories,and disparities in crop production.Our results showed that despite dramatic urbanization,rural settlements still constituted the majority of human settlement areas in 2020.Globally,cropland loss due to the expansion of rural settlements was 1.2 times greater than that caused by urbanization,while the associated yield loss was 1.5 times higher.Notably,urban–rural settlement expansion in Asia accounted for 61%of cropland loss and 64%of yield loss.Moreover,future scenarios predicted that Asia's urban–rural settlement expansion will continue to have the most significant impacts on the loss of cropland and yield throughout the 2030s.These results provide systematic evidence of the unequal impacts of urban–rural settlement construction on global cropland and food security.展开更多
The spatial and temporal deformation patterns and deformation control indicators of highfill foundations directly affect the design,construction and operational safety of high-fill projects.In situ monitoring can comp...The spatial and temporal deformation patterns and deformation control indicators of highfill foundations directly affect the design,construction and operational safety of high-fill projects.In situ monitoring can comprehensively reflect the deformation of high-fill during and after construction.In this paper,we have first designed and installed an integrated wireless remote monitoring system for high-fill to achieve real-time dynamic monitoring of settlement,pore water pressure and soil pressure of the fill foundation.Based on the monitoring results of nearly one year of the construction period and two years after construction,it was found that the deformation amount and deformation rate of the high-fill foundation showed a non-linear growth relationship with the filling rate and filling height.The settlement deformation of the high-fill foundation during the loading period was mainly dominated by the original foundation soil,accounting for 54.4%of the total settlement on average;the settlement deformation during the post-construction period was mainly dominated by the filling body,accounting for 77.04%of the total settlement on average,and the settlement deformation during the post-construction period mainly occurred in the first year after construction.The analysis of the deformation mechanism suggests that the deformation of the filling body is dominated by exhaust consolidation during the loading period and drainage consolidation during the post-construction period;the deformation of the original foundation soil is dominated by drainage consolidation during the loading period and drainage consolidation develops slowly during the post-construction period.It is recommended that the original foundation should be reinforced before the large area filling construction,and that the filling rate should be strictly controlled during construction.The research results can provide a scientific basis for deformation calculation and stability assessment of high-fill foundations.展开更多
基金supported by the Directional Project (Grant No. KZCX2-EW-317)Western Light Project (Grant No. 09R2340340) of Chinese Academy of SciencesNational Natural Science Funds (Grant No. 41071350,41101552)
文摘A Ms 8.0 large earthquake occurred in Sichuan,China on May 12,2008（hereafter called 5.12 Earthquake）,and then a large debris flow happened in the quake-hit Qingping Township of Mianzhu county on August 13,2008（hereafter called 8.13 Debris Flow）.The influence of two disasters on the changes in land use were analyzed by using highresolution aerial photos and satellite remote sensing images taken before and after the 5.12 Earthquake and 8.13 Debris Flow,the selection of suitable construction land were studied by learning experiences and lessons from the selection of resettlement areas and through field surveys and with land use transfer model and analytical model in combination with RS and GIS.The results showed that the influence of the 5.12 Earthquake on ecological environment was far greater than that of the 8.13 Debris Flow;there were more salient conflicts between population and land after the earthquake.Sites for post-disaster reconstruction should not be in disaster-prone areas or in gully-facing areas.Suitable land for settlement construction in I-1~I-5 low-hazard zones is optimal settlement areas for post-disaster reconstruction.
文摘Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the assumption of linear small deformation,a mathematical model of the relationship between ground deformation and construction parameters is set up.The principle and method of optimization for estimating ground deformation is studied.The actual measured data are compared with the results of theoretical analysis in a case.Considering different ground formations in different construction sites with different adverse effects on surface and underground structures,the ground surface deformations caused by shield tunneling is an aimed topic in this paper.The contributions and research implications are the revealed relationships between the ground deformation and the shield tunneling parameters during construction.
基金supported by the National Natural Science Foundation of China(42293271)。
文摘The world has experienced a rapid expansion of human settlements in both urban and rural areas in recent decades,yet the unequal impacts of this construction on global food security remain unclear.In this study,we delineated the global-scale expansion of urban–rural settlements at a fine resolution from1985 to 2020 and quantified their uneven impacts on food security,focusing on the relationships between settlement types,cropland categories,and disparities in crop production.Our results showed that despite dramatic urbanization,rural settlements still constituted the majority of human settlement areas in 2020.Globally,cropland loss due to the expansion of rural settlements was 1.2 times greater than that caused by urbanization,while the associated yield loss was 1.5 times higher.Notably,urban–rural settlement expansion in Asia accounted for 61%of cropland loss and 64%of yield loss.Moreover,future scenarios predicted that Asia's urban–rural settlement expansion will continue to have the most significant impacts on the loss of cropland and yield throughout the 2030s.These results provide systematic evidence of the unequal impacts of urban–rural settlement construction on global cropland and food security.
基金supported by the Youth Science and Technology Fund Program in Gansu Province(20JR5RA434 and 20JR10RA200)National Natural Science Foundation of China(52168051)+1 种基金Gansu Province University Innovation Fund Project(2020A031)Gansu Provincial Science and Technology Plan Fund Project(22CX8GA112)。
文摘The spatial and temporal deformation patterns and deformation control indicators of highfill foundations directly affect the design,construction and operational safety of high-fill projects.In situ monitoring can comprehensively reflect the deformation of high-fill during and after construction.In this paper,we have first designed and installed an integrated wireless remote monitoring system for high-fill to achieve real-time dynamic monitoring of settlement,pore water pressure and soil pressure of the fill foundation.Based on the monitoring results of nearly one year of the construction period and two years after construction,it was found that the deformation amount and deformation rate of the high-fill foundation showed a non-linear growth relationship with the filling rate and filling height.The settlement deformation of the high-fill foundation during the loading period was mainly dominated by the original foundation soil,accounting for 54.4%of the total settlement on average;the settlement deformation during the post-construction period was mainly dominated by the filling body,accounting for 77.04%of the total settlement on average,and the settlement deformation during the post-construction period mainly occurred in the first year after construction.The analysis of the deformation mechanism suggests that the deformation of the filling body is dominated by exhaust consolidation during the loading period and drainage consolidation during the post-construction period;the deformation of the original foundation soil is dominated by drainage consolidation during the loading period and drainage consolidation develops slowly during the post-construction period.It is recommended that the original foundation should be reinforced before the large area filling construction,and that the filling rate should be strictly controlled during construction.The research results can provide a scientific basis for deformation calculation and stability assessment of high-fill foundations.
