1 Background Located in the middle reaches, Yunyang is the only fullrelocated county town of the Three Gorges Reservoir area. The new town conducted the first master plan in 1988 and started its construction in 1992. ...1 Background Located in the middle reaches, Yunyang is the only fullrelocated county town of the Three Gorges Reservoir area. The new town conducted the first master plan in 1988 and started its construction in 1992. Later the plan was adjusted several times.According to Yunyang Urban Master Plan (2005-2020), the townhas 23.29 hectares of urban construction land, and the population is expected to reach 300,000 by 2020.The new county town is located in the confluence of the rivers of Yangtze and Pengxi. Centering on the Dragon Ridge where lies the historical sites of the Panshi fort, the ecological layout of the town is arranged dendritically with two rivers, four ridges and twelve green corridors. This planning has fully respected the natural conditions and the cultural context of Yunyang, and has highlighted the features of the mountainous town (Fig.1).展开更多
Water projects’ sediment deposition problems always cause widespread concerns. The gravity of them varies in accordance not only with reservoirs’ natural and socio-economic characteristics but also with their modes ...Water projects’ sediment deposition problems always cause widespread concerns. The gravity of them varies in accordance not only with reservoirs’ natural and socio-economic characteristics but also with their modes of operation. The unique characteristics, configuration and mode of operation of Three Gorges Project (TGP) reservoir are compared with those of several existing large reservoirs in this paper. As many reservoirs are troubling environment by gradually extending coarse sediment deposition at the uppermost end of fluctuating backwater region toward upstream, Gezhouba reservoir on Yangtze and Danjiangkou reservoir on Hanjiang have shown no trace of such upstream extension of sediment deposition in relevant prototype observation data for the past 20 and more years. TGP reservoir’s in-coming flow sediment conditions and configuration in plane are almost the same as those of Gezhouba reservoir, and TGP reservoir’s mode of operation(usually keeping a very low pool level for flood control in flood season and storing up in-coming flow only thenceafter) is similar to that of Danjiangkou reservoir. New findings of sediment research and prototype flow sediment investigations as well as new agenda of large hydro projects’ construction on Jinshajiang in nearest future assure the prospects of TGP sediment handling.展开更多
The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the st...The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.展开更多
Calcretes occur in a number of locations across the Yangtze Three Gorges in Yichang,central China. They represent the phase of Quaternary calcium carbonate cementation affected by the East Asian monsoon region.Calcret...Calcretes occur in a number of locations across the Yangtze Three Gorges in Yichang,central China. They represent the phase of Quaternary calcium carbonate cementation affected by the East Asian monsoon region.Calcretes are situated at the relict fluvial terrace that were deposited within confined bedrock and limestone soil.Eight samples from separate terrace were singled out and dated by ESR.展开更多
A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients...A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients in the formula have been obtained.The formula has been verified with prototype observation data, flumes data of both nature and lightweight sand.The computed results fully reflect the characteristics of thresh- old motion of non-uniform sediment.The result have been used in some physical mo...展开更多
With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference...With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference due to crossover working procedures, tight time schedule, high quality of reinforced concrete and showcase appearance requirements, hidden troubles affecting construction safety. With above-mentioned factors in consideration, a single-side-separated sliding formwork technology advanced from past sliding formwork experiences has been developed and applied successfully. This new technology is beneficial in quick and safe operation, capable to assure best quality and appearance of shiplock concrete works, and has filled up the gap in terms of construction sliding formwork in our country.展开更多
1. INTRODUCTION The proposed Three Gorges Project, one of the biggest hydroelectric projects in the world, will dam the middle reaches of the Changjiang (Yangtze) River, the third longest river in the world, and form ...1. INTRODUCTION The proposed Three Gorges Project, one of the biggest hydroelectric projects in the world, will dam the middle reaches of the Changjiang (Yangtze) River, the third longest river in the world, and form a large reservoir. Its impacts on environment have attracted wide attention. Entrusted by National Scientific-Technical Commission, the Chinese Academy of Sciences (CAS) was in charge of a research project on this issuse from 1984 to 1989. Tho use of remote sensing played an important role in the project considering the study area is mountainous and not convenientlv located, which makes it difficult to conduct the research onlv using conventional means.展开更多
The region around the Three Gorges project on the Yangtze River has an area of 62552 square kilometres and population of 20.14 million. It limits a range hetween the sorth-north watersheds and from Yichang of Hubei Pr...The region around the Three Gorges project on the Yangtze River has an area of 62552 square kilometres and population of 20.14 million. It limits a range hetween the sorth-north watersheds and from Yichang of Hubei Province to Jiangjin of Sichuan, including 24 cities and counties-Chongjing, Yichang and Wanxian etc. In this region, relief are mainly hills and middle-low mountains. Remote censing investigation and appraisal of land use and capacity which are two of the major restrict factors for the Three Gorges project have provided related scientific bases for macro-dicision-making of the project.展开更多
The satellite-based vegetation condition index(VCI) and temperature condition index(TCI) have been used extensively for drought detection and tracking, the assessment of weather impacts on vegetation and evaluation of...The satellite-based vegetation condition index(VCI) and temperature condition index(TCI) have been used extensively for drought detection and tracking, the assessment of weather impacts on vegetation and evaluation of the health and productivity of vegetation. In this study, in order to detect and monitor the growth condition of vegetation, we have collected data on vegetation indices and land surface temperature derived from MODIS(2001-2012) and defined a vegetation health index(VHI) based on VCI and TCI for assessing vegetation health condition in the Three Gorges Area, China(TGA). The results of the study show that temporal and spatial characteristics of vegetation health condition can be detected, tracked and mapped by the VHI index. In most parts of the TGA, the vegetation health condition showed an overall increasing trend during the study period, especially in Wulong, Fengdu, Shizhu and other regions located in the midstream sections of the Three Gorges Reservoir. In addition, the four studied vegetation types all showed clear increasing trends during the study period. The increasing trend in the vegetation health condition shows a strong positive correlation with topographical slope and altitude(below 500 m). Over the seasons, this trend is strongest in autumn, followed by spring. However, the correlations between vegetation health condition and climatic factors are more frequently significant in summer and winter than in autumn and spring. The vegetation health condition has been low in 2006 and 2011. This finding is consistent with the extreme weather conditions in those two years. However, only in the summer is vegetation health condition significantly correlated with three climatic factors in most of the study area. This result implies that vegetation growth may show a lagged response to climatic factors and may also be affected by human activities, including agricultural activities, industrial activities and other economic activities.展开更多
文摘1 Background Located in the middle reaches, Yunyang is the only fullrelocated county town of the Three Gorges Reservoir area. The new town conducted the first master plan in 1988 and started its construction in 1992. Later the plan was adjusted several times.According to Yunyang Urban Master Plan (2005-2020), the townhas 23.29 hectares of urban construction land, and the population is expected to reach 300,000 by 2020.The new county town is located in the confluence of the rivers of Yangtze and Pengxi. Centering on the Dragon Ridge where lies the historical sites of the Panshi fort, the ecological layout of the town is arranged dendritically with two rivers, four ridges and twelve green corridors. This planning has fully respected the natural conditions and the cultural context of Yunyang, and has highlighted the features of the mountainous town (Fig.1).
文摘Water projects’ sediment deposition problems always cause widespread concerns. The gravity of them varies in accordance not only with reservoirs’ natural and socio-economic characteristics but also with their modes of operation. The unique characteristics, configuration and mode of operation of Three Gorges Project (TGP) reservoir are compared with those of several existing large reservoirs in this paper. As many reservoirs are troubling environment by gradually extending coarse sediment deposition at the uppermost end of fluctuating backwater region toward upstream, Gezhouba reservoir on Yangtze and Danjiangkou reservoir on Hanjiang have shown no trace of such upstream extension of sediment deposition in relevant prototype observation data for the past 20 and more years. TGP reservoir’s in-coming flow sediment conditions and configuration in plane are almost the same as those of Gezhouba reservoir, and TGP reservoir’s mode of operation(usually keeping a very low pool level for flood control in flood season and storing up in-coming flow only thenceafter) is similar to that of Danjiangkou reservoir. New findings of sediment research and prototype flow sediment investigations as well as new agenda of large hydro projects’ construction on Jinshajiang in nearest future assure the prospects of TGP sediment handling.
基金Project(SPKJ016-06)supported by the Key Research Project of State Power Corporation,ChinaProject(2004AC1O1D31)supported by the Key Scientific Research Project of Hubei Province,ChinaProject(0722018)supported by the China Three Gorges Corporation
文摘The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.
文摘Calcretes occur in a number of locations across the Yangtze Three Gorges in Yichang,central China. They represent the phase of Quaternary calcium carbonate cementation affected by the East Asian monsoon region.Calcretes are situated at the relict fluvial terrace that were deposited within confined bedrock and limestone soil.Eight samples from separate terrace were singled out and dated by ESR.
基金Supported by Doctorial Fund of Ministry of Education (2002-173) and (2003-172)
文摘A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients in the formula have been obtained.The formula has been verified with prototype observation data, flumes data of both nature and lightweight sand.The computed results fully reflect the characteristics of thresh- old motion of non-uniform sediment.The result have been used in some physical mo...
文摘With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference due to crossover working procedures, tight time schedule, high quality of reinforced concrete and showcase appearance requirements, hidden troubles affecting construction safety. With above-mentioned factors in consideration, a single-side-separated sliding formwork technology advanced from past sliding formwork experiences has been developed and applied successfully. This new technology is beneficial in quick and safe operation, capable to assure best quality and appearance of shiplock concrete works, and has filled up the gap in terms of construction sliding formwork in our country.
文摘1. INTRODUCTION The proposed Three Gorges Project, one of the biggest hydroelectric projects in the world, will dam the middle reaches of the Changjiang (Yangtze) River, the third longest river in the world, and form a large reservoir. Its impacts on environment have attracted wide attention. Entrusted by National Scientific-Technical Commission, the Chinese Academy of Sciences (CAS) was in charge of a research project on this issuse from 1984 to 1989. Tho use of remote sensing played an important role in the project considering the study area is mountainous and not convenientlv located, which makes it difficult to conduct the research onlv using conventional means.
文摘The region around the Three Gorges project on the Yangtze River has an area of 62552 square kilometres and population of 20.14 million. It limits a range hetween the sorth-north watersheds and from Yichang of Hubei Province to Jiangjin of Sichuan, including 24 cities and counties-Chongjing, Yichang and Wanxian etc. In this region, relief are mainly hills and middle-low mountains. Remote censing investigation and appraisal of land use and capacity which are two of the major restrict factors for the Three Gorges project have provided related scientific bases for macro-dicision-making of the project.
基金Natural Science Foundation Project of CQ CSTC(CSTC2011jj A00025)
文摘The satellite-based vegetation condition index(VCI) and temperature condition index(TCI) have been used extensively for drought detection and tracking, the assessment of weather impacts on vegetation and evaluation of the health and productivity of vegetation. In this study, in order to detect and monitor the growth condition of vegetation, we have collected data on vegetation indices and land surface temperature derived from MODIS(2001-2012) and defined a vegetation health index(VHI) based on VCI and TCI for assessing vegetation health condition in the Three Gorges Area, China(TGA). The results of the study show that temporal and spatial characteristics of vegetation health condition can be detected, tracked and mapped by the VHI index. In most parts of the TGA, the vegetation health condition showed an overall increasing trend during the study period, especially in Wulong, Fengdu, Shizhu and other regions located in the midstream sections of the Three Gorges Reservoir. In addition, the four studied vegetation types all showed clear increasing trends during the study period. The increasing trend in the vegetation health condition shows a strong positive correlation with topographical slope and altitude(below 500 m). Over the seasons, this trend is strongest in autumn, followed by spring. However, the correlations between vegetation health condition and climatic factors are more frequently significant in summer and winter than in autumn and spring. The vegetation health condition has been low in 2006 and 2011. This finding is consistent with the extreme weather conditions in those two years. However, only in the summer is vegetation health condition significantly correlated with three climatic factors in most of the study area. This result implies that vegetation growth may show a lagged response to climatic factors and may also be affected by human activities, including agricultural activities, industrial activities and other economic activities.
