The acuurate prediction of the time-dependent mechanical behavior and deformation mechanisms of second-phase reinforced alloys under size effects is critical for the development of high-strength ductile metals and all...The acuurate prediction of the time-dependent mechanical behavior and deformation mechanisms of second-phase reinforced alloys under size effects is critical for the development of high-strength ductile metals and alloys for dynamic applications.However,solving their responses using high-fidelity numerical methods is computationally expensive and,in many cases,impractical.To address this issue,a dual-scale incremental variational formulation is proposed that incorporates the influence of plastic gradients on plastic evolution characteristics,integrating a strain-rate-dependent strain gradient plasticity model and including plastic gradients in the inelastic dissipation potential.Subsequently,two minimization problems based on the energy dissipation mechanisms of strain gradient plasticity,corresponding to the macroscopic and microscopic structures,are solved,leading to the development of a homogenization-based dual-scale solution algorithm.Finally,the effectiveness of the variational model and tangent algorithm is validated through a series of numerical simulations.The contributions of this work are as follows:first,it advances the theory of self-consistent computational homogenization modeling based on the energy dissipation mechanisms of plastic strain rates and their gradients,along with the development of a rigorous multi-level finite element method(FE2)solution procedure;second,the proposed algorithm provides an efficient and accurate method for evaluating the time-dependent mechanical behavior of second-phase reinforced alloys under strain gradient effects,exploring how these effects vary with the strain rate,and investigating their potential interactions.展开更多
This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temp...This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the alloy.To this end,partially homogenized(PH)and fully homogenized(FH)billets are extruded at temperatures of250 and 450°C.The PH billet contains fine and coarse undissolved Mg_(2) Sn particles in the interdendritic region and along the grain boundaries,respectively.The fine particles(<1μm in size)retard DRX during extrusion at 250°C via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized(DRXed)grains of the extruded alloy.In addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce regions.In contrast,in the FH billet,numerous nanosized Mg_(2) Sn precipitates are formed throughout the material during extrusion at 250°C,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the precipitates.When the PH billet is extruded at the high temperature of 450°C,the retardation effect of the fine particles on DRX is weakened by their dissolution in theα-Mg matrix and the increased extent of thermally activated grain-boundary migration.In contrast,the coarse Mg_(2) Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed grains.At both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase particles.This lower strength of the former is attributed mainly to the larger grains and/or absence of nanosized M2 Sn precipitates in it.展开更多
Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical b...Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical boilers,nuclear reactors,superheaters,and other new materials applications.To effectively enhance the comprehensive performance of heat-resistant alloys,second-phase particle strengthening has been widely studied,and in the face of different service envi-ronments of advanced heat-resistant steels,the selection of suitable second-phase particles is essential to maximize the performance of these alloys.To this end,three major types of reinforcing phases in heat-resistant alloys such as carbides,rare earth oxides,and intermetallic compounds are summarized.A comparative analysis of the precipitation behavior of the reinforcing phases with different types as well as the risks and means of controlling their use in service,is presented.Key parameters for the application of various types of second-phase particles in heat-resistant alloys are provided to support the design and preparation of new ultrahigh-performance heat-resistant alloys.展开更多
In this study, the microstructure and second-phase particles in yttrium （0.05 wt.%and 0.8 wt.%） bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy co...In this study, the microstructure and second-phase particles in yttrium （0.05 wt.%and 0.8 wt.%） bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of （Fe, Ni, Mn）17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y （wt.%） alloy. Lattice parameters of these precipitates were calculated as follows：a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.展开更多
The leakage and diffusion characteristics of natural gas were investigated in the condition of the leakage of liquefied natural gas(LNG) in the storage tank.Fluent was adopted to simulate the process in a series of th...The leakage and diffusion characteristics of natural gas were investigated in the condition of the leakage of liquefied natural gas(LNG) in the storage tank.Fluent was adopted to simulate the process in a series of three-dimension unsteady state calculations.The effects of different heights of the cofferdam(1.0 m, 2.0 m and 3.0 m),wind directions,ambient temperature,leakage location,leakage volume on the diffusion process of natural gas were investigated.The diffusion characteristics of the natural gas clouds over cofferdam were found.Under windless condition,when the gas clouds met,the gas clouds rose due to the collision,which made them easier to cross the cofferdam and spread out.The higher the ambient temperature was,the higher the gas concentration around the cofferdam was,and the smaller the gas concentration difference was.When the leakage occurred,the higher coffe rdam was more beneficial to delay the outward diffusion of gas clouds.However,when the leaka ge stopped,the higher cofferdam went against the dissipation of gas clouds.Under windy condition,the time to form stable leakage flow field was faster than that of windless,and the lower cofferdam further reduced this time.Therefore,considering the effect of barrier and dissipation,it was suggested that the rational height of cofferdam should be designed in the range of 1.0 m to 2.0 m.In case of emergency,the leakage of gas should be deduced reasonably by combining the measurement of gas concentration with the rolling of gas clouds.When windless,the leakage area should be entered between the overflows of gas clouds.展开更多
Suaeda salsa is an important local species in the intertidal beach of the Western Pacific coast. However,under the artificial cofferdam and Spartina alterniflora expansion,Suaeda marsh has degraded seriously. Therefor...Suaeda salsa is an important local species in the intertidal beach of the Western Pacific coast. However,under the artificial cofferdam and Spartina alterniflora expansion,Suaeda marsh has degraded seriously. Therefore,using Yancheng Nature Reserve as a case study area,taking ETM+images in 2000,2006 and 2011 as the basic data sources,we revealed the evolution characteristics of Salsa marsh which was impacted. The research results are as follows. From 2000 to 2011,Salsa marsh area in the artificial area tempestuously degraded,decreasing by 87. 158%,more than 22% than those in the natural area. The landscape was fragmentized. Landscape polymerization degree index dropped from 95. 780 to 65. 455,more than 16% than those in the natural area. The mean patch area fell down to 21. 429 ha from 389. 333 ha,more than 11% that in the natural area. Compared to the steady change in natural conditions,the area was reduced by 118. 167 ha/a from 2000 to 2006,while during 2006-2011,it was only 51. 500 ha/a in artificial area. As for spatial change of landscape,in artificial area,the Salsa marsh centroid moved forward to the southeast with 666. 350 m,but that in natural area moved forward to the north with 1 042. 710 m from 2000 to 2006. From 2006 to 2011,the centroid moved forward to east and north respectively. Artificial cofferdam transformed the area into freshwater ecosystem,and meanwhile the freshwater was beneficial to Reed marsh. During 2000 to 2006,in the artificial area,539 ha Salsa marsh controlled by cofferdam transferred into reed marsh and aquaculture ponds,of which the transformation rate was nearly 4% higher than that in natural area. From 2006 to 2011,178 ha Salsa marsh was transferred into reed marsh,the transformation rate was 20% higher than that in natural area. With rapid spreading and strong competition of Spartina species,the coastal wetland has formed the pattern of " Salsa – Spartina marshes". From 2000 to 2006,in artificial area,15. 24% of Salsa marsh was transferred into Spartina marsh,of which the transformation rate was13% higher than that in natural area. And from 2006 to 2011,30. 07% Salsa marsh was replaced by the Spartina marsh in artificial area,the rate was almost 10% higher than that in the natural area.展开更多
This study presented a novel circular cofferdam for offshore bridges consisting of ring segments and investigated its structural behaviors using ANSYS Mechanical. Because the bottom segment of the cofferdam which has ...This study presented a novel circular cofferdam for offshore bridges consisting of ring segments and investigated its structural behaviors using ANSYS Mechanical. Because the bottom segment of the cofferdam which has a double sleeve cross-section was installed by suction, contact behaviors of the cofferdam wall and the lid plate during installation are important for design and the behaviors were also analyzed. Prior to numerical investigation of the bottom segment and complete cofferdam after dewatering, a suction modeling for structural analysis was proposed and evaluate by seepage analysis. Hydrodynamic loads applied to the cofferdam were also evaluated using panel method based on the potential flow theory. Through numerical analyses, structural behaviors of the cofferdam during installation were then investigated. First, contact behaviors between the lid plate and the wall were analyzed using different contact conditions imposed on the interface. Sharp stress increases were shown while the stress jumps were limited to contact area. Next, structural behaviors were investigated by considering seepage pressure. Using an axisymmetric seepage model, the total water pressure considering seepage was estimated and applied to structural analysis. The analysis results showed that strong effects of seepage on the stress change in cofferdam occurred and the seepage effects are necessary to be considered in design of the cofferdam induced by suction.展开更多
Phase Ⅲ Rolled Compacted Concrete(RCC) cofferdam construction belongs to Phase Ⅲ diversion works. It is a key item to ensure an achievement in the reservoir impoundment, navigation and power generation in 2003 and a...Phase Ⅲ Rolled Compacted Concrete(RCC) cofferdam construction belongs to Phase Ⅲ diversion works. It is a key item to ensure an achievement in the reservoir impoundment, navigation and power generation in 2003 and a guarantee to the safety construction of the follow up right bank intake dam section and the powerhouse. Restrained by conditions for construction, navigation, the worksite and the duration, both the concreting intensity and the height of Phase Ⅲ RCC cofferdam exceed the current construction level. In view of these difficulties, a great deal of research work performed by relevant departments is described in the paper.展开更多
With the continuous development and progress of the times, water conservancy engineering has become the cornerstone of national economic development. It is of great significance to explore the application and developm...With the continuous development and progress of the times, water conservancy engineering has become the cornerstone of national economic development. It is of great significance to explore the application and development of water conservancy engineering technology. As an important technology in the construction of water conservancy projects, the application of cofferdam technology plays a very important role in the economic, social and environmental benefits of water conservancy projects, which is more worthy of our research and discussion. From the perspective of case engineering, this paper explores the application method of cofferdam construction technology in hydraulic engineering construction.展开更多
In order to ensure the stable water supply in cities and villages, many water conservancy projects for water storage, transportation and transportation need to be built. During the construction of water conservancy pr...In order to ensure the stable water supply in cities and villages, many water conservancy projects for water storage, transportation and transportation need to be built. During the construction of water conservancy projects, various scientific and advanced construction technologies need to be adopted. On this basis, the construction quality of water conservancy projects will be continuously improved to better meet the needs of economic and social development and people's life and production. Therefore, in the process of water conservancy project construction, the diversion construction technology should be reasonably applied and the appropriate diversion method should be selected to ensure the orderly development of water conservancy project construction. This paper analyzes the application of different types of diversion technology, hoping to give full play to the role of diversion technology and lay a solid foundation for future water conservancy construction.展开更多
As a frequently used technical type in water conservancy projects at the present stage, cofferdam technology plays a very important role in technical support. It has a great impact on both hydropower industry and the ...As a frequently used technical type in water conservancy projects at the present stage, cofferdam technology plays a very important role in technical support. It has a great impact on both hydropower industry and the whole project. However, it should be noted that although most enterprises have selectively integrated some cofferdam technology into water conservancy project construction in recent years, cofferdam technology can not give full play to its application advantages due to the careless construction process and the neglect of water conservancy construction principles. Therefore, it is of great practical value to clarify the application principles of cofferdam technology and make an in-depth analysis of the main cofferdam technology from multiple angles.展开更多
With the continuous development of China's social economy, water conservancy and hydropower infrastructure is particularly important, and cofferdam diversion technology is an important technical measure in the con...With the continuous development of China's social economy, water conservancy and hydropower infrastructure is particularly important, and cofferdam diversion technology is an important technical measure in the construction of water conservancy projects. cofferdam diversion technology has the characteristics of fast flow rate and large flow, which slows down the impact of water flow on construction projects and plays a guiding role in water flow. As the most common and used construction method of water conservancy and hydropower engineering, in order to improve the stability and impact resistance, each construction process should be accurately coordinated. During the construction of the construction of water conservancy engineering, the comprehensive analysis of cofferdam diversion technology is conducted to facilitate the development of water conservancy and hydropower engineering in China.展开更多
In the construction of long-span sea crossing bridge, it is often necessary to build huge pier foundation in deep water, which often uses steel cofferdam to block water, forming dry construction conditions. Under the ...In the construction of long-span sea crossing bridge, it is often necessary to build huge pier foundation in deep water, which often uses steel cofferdam to block water, forming dry construction conditions. Under the condition of silt layer exceeding 40m and deep water, the construction technology of double wall steel cofferdams is adopted for the steel cofferdams of bridge caps. Baiteng river section of Jinhai super large bridge between Zhuhai and Jinan is adjacent to Jinhai highway bridge (Baitenghe bridge). The left and right sections of the highway are located on both sides of the railway. The main pier 129 # - 130 # (corresponding to the left and right sections of the highway) crosses the main channel of Baitenghe river with a span of 180m, and the stratum is mainly composed of two layers. The average thickness of the muddy layer is about 45m, and the highway and railway are adjacent to each other, so it is difficult to construct the cofferdam. According to the construction characteristics of this project, this paper studies the construction technology of steel sheet pile combined cofferdam and underwater concrete bottom sealing.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11922206,11702089,12272132)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20240388)。
文摘The acuurate prediction of the time-dependent mechanical behavior and deformation mechanisms of second-phase reinforced alloys under size effects is critical for the development of high-strength ductile metals and alloys for dynamic applications.However,solving their responses using high-fidelity numerical methods is computationally expensive and,in many cases,impractical.To address this issue,a dual-scale incremental variational formulation is proposed that incorporates the influence of plastic gradients on plastic evolution characteristics,integrating a strain-rate-dependent strain gradient plasticity model and including plastic gradients in the inelastic dissipation potential.Subsequently,two minimization problems based on the energy dissipation mechanisms of strain gradient plasticity,corresponding to the macroscopic and microscopic structures,are solved,leading to the development of a homogenization-based dual-scale solution algorithm.Finally,the effectiveness of the variational model and tangent algorithm is validated through a series of numerical simulations.The contributions of this work are as follows:first,it advances the theory of self-consistent computational homogenization modeling based on the energy dissipation mechanisms of plastic strain rates and their gradients,along with the development of a rigorous multi-level finite element method(FE2)solution procedure;second,the proposed algorithm provides an efficient and accurate method for evaluating the time-dependent mechanical behavior of second-phase reinforced alloys under strain gradient effects,exploring how these effects vary with the strain rate,and investigating their potential interactions.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of ScienceICT and Future Planning(MSIP,South Korea)(No.2019R1A2C1085272)+1 种基金by the Materials and Components Technology Development Program of the Ministry of TradeIndustry and Energy(MOTIE,South Korea)(No.20011091)。
文摘This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the alloy.To this end,partially homogenized(PH)and fully homogenized(FH)billets are extruded at temperatures of250 and 450°C.The PH billet contains fine and coarse undissolved Mg_(2) Sn particles in the interdendritic region and along the grain boundaries,respectively.The fine particles(<1μm in size)retard DRX during extrusion at 250°C via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized(DRXed)grains of the extruded alloy.In addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce regions.In contrast,in the FH billet,numerous nanosized Mg_(2) Sn precipitates are formed throughout the material during extrusion at 250°C,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the precipitates.When the PH billet is extruded at the high temperature of 450°C,the retardation effect of the fine particles on DRX is weakened by their dissolution in theα-Mg matrix and the increased extent of thermally activated grain-boundary migration.In contrast,the coarse Mg_(2) Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed grains.At both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase particles.This lower strength of the former is attributed mainly to the larger grains and/or absence of nanosized M2 Sn precipitates in it.
基金The authors express their gratitude to the National Science Foundation for Young Scientists of China(51704021)Key Research and Development Projects of Shandong Province(2021CXGC010)+1 种基金Key Research and Development Projects of Sichuan Province(021YFG0114)Fundamental Research Funds for the Central Universities(FRF-IDRY-20-015,FRF-TP-20-004A3,FRF-TP-19-030A2,and FRF-TP-16-079A1)for their kind financial support.
文摘Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical boilers,nuclear reactors,superheaters,and other new materials applications.To effectively enhance the comprehensive performance of heat-resistant alloys,second-phase particle strengthening has been widely studied,and in the face of different service envi-ronments of advanced heat-resistant steels,the selection of suitable second-phase particles is essential to maximize the performance of these alloys.To this end,three major types of reinforcing phases in heat-resistant alloys such as carbides,rare earth oxides,and intermetallic compounds are summarized.A comparative analysis of the precipitation behavior of the reinforcing phases with different types as well as the risks and means of controlling their use in service,is presented.Key parameters for the application of various types of second-phase particles in heat-resistant alloys are provided to support the design and preparation of new ultrahigh-performance heat-resistant alloys.
文摘In this study, the microstructure and second-phase particles in yttrium （0.05 wt.%and 0.8 wt.%） bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of （Fe, Ni, Mn）17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y （wt.%） alloy. Lattice parameters of these precipitates were calculated as follows：a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.
基金supported by the Funding for post-doctoral research in Foshan City。
文摘The leakage and diffusion characteristics of natural gas were investigated in the condition of the leakage of liquefied natural gas(LNG) in the storage tank.Fluent was adopted to simulate the process in a series of three-dimension unsteady state calculations.The effects of different heights of the cofferdam(1.0 m, 2.0 m and 3.0 m),wind directions,ambient temperature,leakage location,leakage volume on the diffusion process of natural gas were investigated.The diffusion characteristics of the natural gas clouds over cofferdam were found.Under windless condition,when the gas clouds met,the gas clouds rose due to the collision,which made them easier to cross the cofferdam and spread out.The higher the ambient temperature was,the higher the gas concentration around the cofferdam was,and the smaller the gas concentration difference was.When the leakage occurred,the higher coffe rdam was more beneficial to delay the outward diffusion of gas clouds.However,when the leaka ge stopped,the higher cofferdam went against the dissipation of gas clouds.Under windy condition,the time to form stable leakage flow field was faster than that of windless,and the lower cofferdam further reduced this time.Therefore,considering the effect of barrier and dissipation,it was suggested that the rational height of cofferdam should be designed in the range of 1.0 m to 2.0 m.In case of emergency,the leakage of gas should be deduced reasonably by combining the measurement of gas concentration with the rolling of gas clouds.When windless,the leakage area should be entered between the overflows of gas clouds.
基金Supported by National Natural Science Foundation of China(41771199)Basic Research Project of Jiangsu Province,China(BK20171277)
文摘Suaeda salsa is an important local species in the intertidal beach of the Western Pacific coast. However,under the artificial cofferdam and Spartina alterniflora expansion,Suaeda marsh has degraded seriously. Therefore,using Yancheng Nature Reserve as a case study area,taking ETM+images in 2000,2006 and 2011 as the basic data sources,we revealed the evolution characteristics of Salsa marsh which was impacted. The research results are as follows. From 2000 to 2011,Salsa marsh area in the artificial area tempestuously degraded,decreasing by 87. 158%,more than 22% than those in the natural area. The landscape was fragmentized. Landscape polymerization degree index dropped from 95. 780 to 65. 455,more than 16% than those in the natural area. The mean patch area fell down to 21. 429 ha from 389. 333 ha,more than 11% that in the natural area. Compared to the steady change in natural conditions,the area was reduced by 118. 167 ha/a from 2000 to 2006,while during 2006-2011,it was only 51. 500 ha/a in artificial area. As for spatial change of landscape,in artificial area,the Salsa marsh centroid moved forward to the southeast with 666. 350 m,but that in natural area moved forward to the north with 1 042. 710 m from 2000 to 2006. From 2006 to 2011,the centroid moved forward to east and north respectively. Artificial cofferdam transformed the area into freshwater ecosystem,and meanwhile the freshwater was beneficial to Reed marsh. During 2000 to 2006,in the artificial area,539 ha Salsa marsh controlled by cofferdam transferred into reed marsh and aquaculture ponds,of which the transformation rate was nearly 4% higher than that in natural area. From 2006 to 2011,178 ha Salsa marsh was transferred into reed marsh,the transformation rate was 20% higher than that in natural area. With rapid spreading and strong competition of Spartina species,the coastal wetland has formed the pattern of " Salsa – Spartina marshes". From 2000 to 2006,in artificial area,15. 24% of Salsa marsh was transferred into Spartina marsh,of which the transformation rate was13% higher than that in natural area. And from 2006 to 2011,30. 07% Salsa marsh was replaced by the Spartina marsh in artificial area,the rate was almost 10% higher than that in the natural area.
文摘This study presented a novel circular cofferdam for offshore bridges consisting of ring segments and investigated its structural behaviors using ANSYS Mechanical. Because the bottom segment of the cofferdam which has a double sleeve cross-section was installed by suction, contact behaviors of the cofferdam wall and the lid plate during installation are important for design and the behaviors were also analyzed. Prior to numerical investigation of the bottom segment and complete cofferdam after dewatering, a suction modeling for structural analysis was proposed and evaluate by seepage analysis. Hydrodynamic loads applied to the cofferdam were also evaluated using panel method based on the potential flow theory. Through numerical analyses, structural behaviors of the cofferdam during installation were then investigated. First, contact behaviors between the lid plate and the wall were analyzed using different contact conditions imposed on the interface. Sharp stress increases were shown while the stress jumps were limited to contact area. Next, structural behaviors were investigated by considering seepage pressure. Using an axisymmetric seepage model, the total water pressure considering seepage was estimated and applied to structural analysis. The analysis results showed that strong effects of seepage on the stress change in cofferdam occurred and the seepage effects are necessary to be considered in design of the cofferdam induced by suction.
文摘Phase Ⅲ Rolled Compacted Concrete(RCC) cofferdam construction belongs to Phase Ⅲ diversion works. It is a key item to ensure an achievement in the reservoir impoundment, navigation and power generation in 2003 and a guarantee to the safety construction of the follow up right bank intake dam section and the powerhouse. Restrained by conditions for construction, navigation, the worksite and the duration, both the concreting intensity and the height of Phase Ⅲ RCC cofferdam exceed the current construction level. In view of these difficulties, a great deal of research work performed by relevant departments is described in the paper.
文摘With the continuous development and progress of the times, water conservancy engineering has become the cornerstone of national economic development. It is of great significance to explore the application and development of water conservancy engineering technology. As an important technology in the construction of water conservancy projects, the application of cofferdam technology plays a very important role in the economic, social and environmental benefits of water conservancy projects, which is more worthy of our research and discussion. From the perspective of case engineering, this paper explores the application method of cofferdam construction technology in hydraulic engineering construction.
文摘In order to ensure the stable water supply in cities and villages, many water conservancy projects for water storage, transportation and transportation need to be built. During the construction of water conservancy projects, various scientific and advanced construction technologies need to be adopted. On this basis, the construction quality of water conservancy projects will be continuously improved to better meet the needs of economic and social development and people's life and production. Therefore, in the process of water conservancy project construction, the diversion construction technology should be reasonably applied and the appropriate diversion method should be selected to ensure the orderly development of water conservancy project construction. This paper analyzes the application of different types of diversion technology, hoping to give full play to the role of diversion technology and lay a solid foundation for future water conservancy construction.
文摘As a frequently used technical type in water conservancy projects at the present stage, cofferdam technology plays a very important role in technical support. It has a great impact on both hydropower industry and the whole project. However, it should be noted that although most enterprises have selectively integrated some cofferdam technology into water conservancy project construction in recent years, cofferdam technology can not give full play to its application advantages due to the careless construction process and the neglect of water conservancy construction principles. Therefore, it is of great practical value to clarify the application principles of cofferdam technology and make an in-depth analysis of the main cofferdam technology from multiple angles.
文摘With the continuous development of China's social economy, water conservancy and hydropower infrastructure is particularly important, and cofferdam diversion technology is an important technical measure in the construction of water conservancy projects. cofferdam diversion technology has the characteristics of fast flow rate and large flow, which slows down the impact of water flow on construction projects and plays a guiding role in water flow. As the most common and used construction method of water conservancy and hydropower engineering, in order to improve the stability and impact resistance, each construction process should be accurately coordinated. During the construction of the construction of water conservancy engineering, the comprehensive analysis of cofferdam diversion technology is conducted to facilitate the development of water conservancy and hydropower engineering in China.
文摘In the construction of long-span sea crossing bridge, it is often necessary to build huge pier foundation in deep water, which often uses steel cofferdam to block water, forming dry construction conditions. Under the condition of silt layer exceeding 40m and deep water, the construction technology of double wall steel cofferdams is adopted for the steel cofferdams of bridge caps. Baiteng river section of Jinhai super large bridge between Zhuhai and Jinan is adjacent to Jinhai highway bridge (Baitenghe bridge). The left and right sections of the highway are located on both sides of the railway. The main pier 129 # - 130 # (corresponding to the left and right sections of the highway) crosses the main channel of Baitenghe river with a span of 180m, and the stratum is mainly composed of two layers. The average thickness of the muddy layer is about 45m, and the highway and railway are adjacent to each other, so it is difficult to construct the cofferdam. According to the construction characteristics of this project, this paper studies the construction technology of steel sheet pile combined cofferdam and underwater concrete bottom sealing.
