The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucke...The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.展开更多
A numerical case study on identifying the optimum number of buckets for a Pelton turbine is presented. Three parameters： number of buckets, bucket radial position and bucket angular position are grouped since they ar...A numerical case study on identifying the optimum number of buckets for a Pelton turbine is presented. Three parameters： number of buckets, bucket radial position and bucket angular position are grouped since they are found to be interrelated. By identifying the best combination of the radial and angular position for each number of buckets it is shown that reduction in the number of buckets beyond the limit suggested by the available literature can improve the efficiency and be beneficial with regard to the manufacturing complexity and cost perspective. The effect of this reduction in the number of buckets was confirmed experimentally.展开更多
A scheme with two superconducting RF cavities is designed to upgrade electron storage rings with odd buckets to multi-length bunches. In this paper, the Hefei Light Source（HLS） is given as an example for odd buckets...A scheme with two superconducting RF cavities is designed to upgrade electron storage rings with odd buckets to multi-length bunches. In this paper, the Hefei Light Source（HLS） is given as an example for odd buckets. As it is designed for 45 buckets, which is a multiple of 3, simultaneous generation of three different lengths of bunches is proposed with the presently applied user optics. The final result, without low-α optics, is to fill HLS with long bunches of length 50 ps, medium bunches of 23 ps and short bunches of 6 ps. Every third bucket can be filled with short bunches, of which the current limit is up to 6.6 m A, more than 60 times the limit for low-α mode.Moreover, particle tracking simulations to examine the beam dynamics, performed by ELEGANT, and calculations of the beam instabilities are presented in this paper.展开更多
With the popularity of smart meters and the growing availability of high-resolution load data, the research on the dynamics of electricity consumption at finely resolved timescales has become increasingly popular. Man...With the popularity of smart meters and the growing availability of high-resolution load data, the research on the dynamics of electricity consumption at finely resolved timescales has become increasingly popular. Many existing algorithms underperform when clustering load profiles contain a large number of feature points. In addition, it is difficult to accurately describe the similarity of profile shapes when load sequences have large fluctuations, leading to inaccurate clustering results. To this end, this paper proposes a high-resolution load profile clustering approach based on dynamic largest triangle three buckets(LTTBs) and multiscale dynamic time warping under limited warping path length(LDTW). Dynamic LTTB is a novel dimensionality reduction algorithm based on LTTB. New sequences are constructed by dynamically dividing the intervals of significant feature points. The extraction of fluctuation characteristics is optimized. New curves with more concentrated features will be applied to the subsequent clustering. The proposed multiscale LDTW is used to generate a similarity matrix for spectral clustering, providing a more comprehensive and flexible matching method to characterize the similarity of load profiles. Thus, the clustering effect of a high-resolution load profile is improved. The proposed approach has been applied to multiple datasets. Experiment results demonstrate that the proposed approach significantly improves the Davies-Bouldin indicator(DBI) and validity index(VI). Therefore, better similarity and accuracy can be achieved using high-resolution load profile clustering.展开更多
Installing internal bulkheads in a composite bucket foundation alters the rotational symmetry characteristic of a single-compartment bucket foundation,consequently influencing the stress distribution within the bucket...Installing internal bulkheads in a composite bucket foundation alters the rotational symmetry characteristic of a single-compartment bucket foundation,consequently influencing the stress distribution within the bucket and surrounding soil.During the seabed penetration of a spudcan from a jack-up wind turbine installation vessel,an angle may form between the spudcan’s axis and the axis of symmetry of the adjacent composite bucket foundation in the horizontal plane.Such a misalignment may affect load distribution and the non-uniform interaction between the foundation,soil,and spudcan,ultimately influencing the foundation’s stability.This study employs physical model tests to ascertain the trends in end resistance during spudcan penetration in sand,the extent of soil disturbance,and the backflow condition.The finite element coupled Eulerian-Lagrangian method is validated and utilized to determine the range of penetration angles that induce alterations in the maximum vertical displacement and tilt rate of the composite bucket foundation in sand.The differential contact stress distribution at the base of the bucket is analyzed,with qualitative criteria for sand backflow provided.Findings demonstrate that the maximum vertical displacement and tilt rate of the composite bucket foundation display a“wave-like”variation with the increasing spudcan penetration angle,peaking when the angle between the spudcan and bulkhead is the smallest.Stress distribution is predominantly concentrated at the base and apex of the bucket,becoming increasingly uneven as the penetration angle deviates from the foundation’s symmetry axis.The maximum stress gradually shifts to the junction of the bulkhead and bucket bottom on the side with the shortest net distance from the spudcan.Considering the in-place stability and stress state of the composite bucket foundation is therefore imperative,and particular attention should be paid to the foundation’s state when the angle between the spudcan and bulkhead is small.展开更多
Monocolumn composite bucket foundation is a new type of offshore wind energy foundation.Its bearing characteristics under shallow bedrock conditions and complex geological conditions have not been extensively studied....Monocolumn composite bucket foundation is a new type of offshore wind energy foundation.Its bearing characteristics under shallow bedrock conditions and complex geological conditions have not been extensively studied.Therefore,to analyze its bearing characteristics under complex conditions-such as silty soil,chalky soil,and shallow bedrock-this paper employs finite element software to establish various soil combination scenarios.The load-displacement curves of the foundations under these scenarios are calculated to subsequently evaluate the horizontal ultimate bearing capacity.This study investigates the effects of shallow bedrock depth,the type of soil above the bedrock,the thickness of layered soil,and the quality of layered soil on the bearing characteristics of the monocolumn composite bucket foundation.Based on the principle of single-variable control,the ultimate bearing capacity characteristics of the foundation under different conditions are compared.The distribution of soil pressure inside and outside the bucket wall on the compressed side of the foundation,along with the plastic strain of the soil at the base of the foundation,is also analyzed.In conclusion,shallow bedrock somewhat reduces foundation bearing capacity.Under shallow bedrock conditions,the degree of influence on foundation bearing capacity characteristics can considerably vary on different upper soils.The thickness of each soil layer and the depth to bedrock in stratified soils also affect the bearing capacity of the foundation.The findings of this paper provide a theoretical reference for related foundation design and construction.In practice,the bearing performance of the foundation can be enhanced by improvingthe soil quality in the bucket,adjusting the penetration depth,adjusting the percentage of different types of soil layers in the bucket,and applying other technical construction methods.展开更多
The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by...The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by the method of estimating the energy dissipation.The theoretical analysis shows that,in order to have the energy dissipation,it is necessary to determine the sequent flow depth h1 and the flow speed V1 at the corresponding position through the flow depth h2 after the hydraulic jump.The relative flow depth h2/ho is a function of the approach flow Froude numberFro,the relative slot widthb/Bo,and the relative slot angleθ/β.The expression for estimating the energy dissipation is developed,and the maximum error is not larger than 9.21%.展开更多
The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Frou...The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.展开更多
In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or sl...In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or slot-type flip bucket buckets,the present SFS-type flip bucket has better flow regime and larger energy dissipation since the three branches of the flows are separated through the outlet of the flip bucket.Meanwhile,the energy dissipation for this flip bucket is estimated.展开更多
For the development of an integrated rounded rectangular wellhead platform with a bucket foundation,a model test was conducted to study the towing motion response of such a structure under still water and wave conditi...For the development of an integrated rounded rectangular wellhead platform with a bucket foundation,a model test was conducted to study the towing motion response of such a structure under still water and wave conditions.The influence of various factors on the floating stability of the structure was investigated through alterations of the towing conditions(draft,towing point position,and wave conditions),and the related influencing mechanism was analyzed.Comparison and analysis were performed to determine the changes in the structure motion pattern and various effects of towing conditions on the structure during towing in still water and regular waves.Moreover,the influence of each factor on the structure’s motion response during towing was analyzed using the Apriori algorithm.In addition,for the simulation of the towing process under actual sea conditions,a towing test was performed under irregular waves,and the stability of towing in irregular waves was compared with that in regular waves.展开更多
Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during constru...Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during construction, certain suction bucket jacket foundation projects implement grouting techniques to ensure adequate bearing capacity. This study conducted a large-scale suction bucket foundation grouting model experiment to examine grout flow characteristics and specific phenomena under various grouting pipeline configurations. Comparative analyses of grouting efficiency and quality across different pipeline layouts identified critical influencing factors and their impact on grouting performance. The results demonstrate that the number of grout outlets should be maintained within an optimal range:insufficient outlets enhance the indentation effect and decrease fill efficiency, while excessive outlets necessitate precise spacing for effective distribution. Additionally, grout outlets should be uniformly arranged to reduce segregation and enhance overall grouting quality. This study's findings provide a scientific foundation for optimizing grouting design in suction bucket jacket foundations, with substantial implications for engineering applications.展开更多
The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local ...The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local scour patterns around a novel mono-column composite bucket foundation(MCCBF) under unidirectional flows. The experiments reveal that under weak-flow conditions, no significant scour pits develop at the front or lateral sides of the MCCBF,while two distinct scour pits form behind the lateral sides. Under strong-flow conditions, substantial scour pits emerge at both frontal and lateral sides of the bucket foundation, with two scour pits extending downstream on either side. The research demonstrates that both the range and depth of local scour increase with higher flow velocity and decreasing water depth, though the mechanisms influencing local scour around the MCCBF prove more complex than those affecting monopiles. The distinctive structural features of the MCCBF necessitate particular consideration of effects related to bucket foundation exposure. The study concludes by proposing an empirical formula for predicting maximum scour depth around the MCCBF.展开更多
The concept of sustainable agricultural village was proposed in this study,and its major economic pattern was summarized as:with the sustainable agriculture,grain production and processing as core contents,to enhance ...The concept of sustainable agricultural village was proposed in this study,and its major economic pattern was summarized as:with the sustainable agriculture,grain production and processing as core contents,to enhance the attraction of agricultural regions and establish more effective connections between rural and urban areas by properly developing eco-agricultural sightseeing and organizing satellite sustainable agricultural villages into an urban peripheral network.Dajidian Sustainable Agricultural Village in Baoding City,Hebei Province was taken for an example to elaborate the overall design concepts,and analyze the strategies for planning the village as an integrated system,including social,ecological and economic dimensions,which are specifically demonstrated as:the development of sustainable agriculture,the establishment of diversified circulation system,the independence of energy utilization,the soundness of public service system,the improvement of agricultural villages as communities.Through studying the planning of sustainable agricultural villages,this research aimed at realizing the sustainable development of overall environment system in both cities and rural areas,and guiding the improvement of the new countryside construction.展开更多
In order to study the towing dynamic properties of the large-scale composite bucket foundation the hydrodynamic software MOSES is used to simulate the dynamic motion of the foundation towed to the construction site.Th...In order to study the towing dynamic properties of the large-scale composite bucket foundation the hydrodynamic software MOSES is used to simulate the dynamic motion of the foundation towed to the construction site.The MOSES model with the prototype size is established as the water draft of 5 and 6 m under the environmental conditions on site.The related factors such as towing force displacement towing accelerations in six degrees of freedom of the bucket foundation and air pressures inside the bucket are analyzed in detail.In addition the towing point and wave conditions are set as the critical factors to simulate the limit conditions of the stable dynamic characteristics.The results show that the large-scale composite bucket foundation with reasonable subdivisions inside the bucket has the satisfying floating stability.During the towing process the air pressures inside the bucket obviously change little and it is found that the towing point at the waterline is the most optimal choice.The characteristics of the foundation with the self-floating towing technique are competitive for saving lots of cost with few of the expensive types of equipment required during the towing transportation.展开更多
基金Project(51475478)supported by the National Natural Science Foundation of ChinaProject(2012AA041801)supported by the National High Technology Research and Development Program of China+1 种基金Project(2014FJ1002)supported by the Science and Technology Major Project of Hunan Province,ChinaProject(2013CB035401)supported by the National Basic Research Program of China。
文摘The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.
基金the support of Lancaster University Renewable Energy Group and Fluid Machinery Group
文摘A numerical case study on identifying the optimum number of buckets for a Pelton turbine is presented. Three parameters： number of buckets, bucket radial position and bucket angular position are grouped since they are found to be interrelated. By identifying the best combination of the radial and angular position for each number of buckets it is shown that reduction in the number of buckets beyond the limit suggested by the available literature can improve the efficiency and be beneficial with regard to the manufacturing complexity and cost perspective. The effect of this reduction in the number of buckets was confirmed experimentally.
基金Supported by National Natural Science Foundation of China(11327902,11175180,11175182)U.S.DOE(DE-AC02-76SF00515)
文摘A scheme with two superconducting RF cavities is designed to upgrade electron storage rings with odd buckets to multi-length bunches. In this paper, the Hefei Light Source（HLS） is given as an example for odd buckets. As it is designed for 45 buckets, which is a multiple of 3, simultaneous generation of three different lengths of bunches is proposed with the presently applied user optics. The final result, without low-α optics, is to fill HLS with long bunches of length 50 ps, medium bunches of 23 ps and short bunches of 6 ps. Every third bucket can be filled with short bunches, of which the current limit is up to 6.6 m A, more than 60 times the limit for low-α mode.Moreover, particle tracking simulations to examine the beam dynamics, performed by ELEGANT, and calculations of the beam instabilities are presented in this paper.
基金supported by the Joint Fund of National Natural Science Foundation of China (No. U1936213)National Natural Science Foundation of China (No. 61872230)+1 种基金Program of Shanghai Academic Research Leader (No. 21XD1421500)Shanghai Science and Technology Commission Project (No. 20020500600)。
文摘With the popularity of smart meters and the growing availability of high-resolution load data, the research on the dynamics of electricity consumption at finely resolved timescales has become increasingly popular. Many existing algorithms underperform when clustering load profiles contain a large number of feature points. In addition, it is difficult to accurately describe the similarity of profile shapes when load sequences have large fluctuations, leading to inaccurate clustering results. To this end, this paper proposes a high-resolution load profile clustering approach based on dynamic largest triangle three buckets(LTTBs) and multiscale dynamic time warping under limited warping path length(LDTW). Dynamic LTTB is a novel dimensionality reduction algorithm based on LTTB. New sequences are constructed by dynamically dividing the intervals of significant feature points. The extraction of fluctuation characteristics is optimized. New curves with more concentrated features will be applied to the subsequent clustering. The proposed multiscale LDTW is used to generate a similarity matrix for spectral clustering, providing a more comprehensive and flexible matching method to characterize the similarity of load profiles. Thus, the clustering effect of a high-resolution load profile is improved. The proposed approach has been applied to multiple datasets. Experiment results demonstrate that the proposed approach significantly improves the Davies-Bouldin indicator(DBI) and validity index(VI). Therefore, better similarity and accuracy can be achieved using high-resolution load profile clustering.
文摘Installing internal bulkheads in a composite bucket foundation alters the rotational symmetry characteristic of a single-compartment bucket foundation,consequently influencing the stress distribution within the bucket and surrounding soil.During the seabed penetration of a spudcan from a jack-up wind turbine installation vessel,an angle may form between the spudcan’s axis and the axis of symmetry of the adjacent composite bucket foundation in the horizontal plane.Such a misalignment may affect load distribution and the non-uniform interaction between the foundation,soil,and spudcan,ultimately influencing the foundation’s stability.This study employs physical model tests to ascertain the trends in end resistance during spudcan penetration in sand,the extent of soil disturbance,and the backflow condition.The finite element coupled Eulerian-Lagrangian method is validated and utilized to determine the range of penetration angles that induce alterations in the maximum vertical displacement and tilt rate of the composite bucket foundation in sand.The differential contact stress distribution at the base of the bucket is analyzed,with qualitative criteria for sand backflow provided.Findings demonstrate that the maximum vertical displacement and tilt rate of the composite bucket foundation display a“wave-like”variation with the increasing spudcan penetration angle,peaking when the angle between the spudcan and bulkhead is the smallest.Stress distribution is predominantly concentrated at the base and apex of the bucket,becoming increasingly uneven as the penetration angle deviates from the foundation’s symmetry axis.The maximum stress gradually shifts to the junction of the bulkhead and bucket bottom on the side with the shortest net distance from the spudcan.Considering the in-place stability and stress state of the composite bucket foundation is therefore imperative,and particular attention should be paid to the foundation’s state when the angle between the spudcan and bulkhead is small.
文摘Monocolumn composite bucket foundation is a new type of offshore wind energy foundation.Its bearing characteristics under shallow bedrock conditions and complex geological conditions have not been extensively studied.Therefore,to analyze its bearing characteristics under complex conditions-such as silty soil,chalky soil,and shallow bedrock-this paper employs finite element software to establish various soil combination scenarios.The load-displacement curves of the foundations under these scenarios are calculated to subsequently evaluate the horizontal ultimate bearing capacity.This study investigates the effects of shallow bedrock depth,the type of soil above the bedrock,the thickness of layered soil,and the quality of layered soil on the bearing characteristics of the monocolumn composite bucket foundation.Based on the principle of single-variable control,the ultimate bearing capacity characteristics of the foundation under different conditions are compared.The distribution of soil pressure inside and outside the bucket wall on the compressed side of the foundation,along with the plastic strain of the soil at the base of the foundation,is also analyzed.In conclusion,shallow bedrock somewhat reduces foundation bearing capacity.Under shallow bedrock conditions,the degree of influence on foundation bearing capacity characteristics can considerably vary on different upper soils.The thickness of each soil layer and the depth to bedrock in stratified soils also affect the bearing capacity of the foundation.The findings of this paper provide a theoretical reference for related foundation design and construction.In practice,the bearing performance of the foundation can be enhanced by improvingthe soil quality in the bucket,adjusting the penetration depth,adjusting the percentage of different types of soil layers in the bucket,and applying other technical construction methods.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51579076,51479057)
文摘The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by the method of estimating the energy dissipation.The theoretical analysis shows that,in order to have the energy dissipation,it is necessary to determine the sequent flow depth h1 and the flow speed V1 at the corresponding position through the flow depth h2 after the hydraulic jump.The relative flow depth h2/ho is a function of the approach flow Froude numberFro,the relative slot widthb/Bo,and the relative slot angleθ/β.The expression for estimating the energy dissipation is developed,and the maximum error is not larger than 9.21%.
基金Project supported by the National Natural Science Foundation of China(Grant No.51179056)the PAPD(Grant No.3014-SYS1401)the Fundamental Research Funds for the Central Universities of China(Grant No.2014B03114)
文摘The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.
基金Project supported by the National Natural Science Foundation of China(Grant No.51579076).
文摘In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or slot-type flip bucket buckets,the present SFS-type flip bucket has better flow regime and larger energy dissipation since the three branches of the flows are separated through the outlet of the flip bucket.Meanwhile,the energy dissipation for this flip bucket is estimated.
基金support from the National Natural Science Foundation of China(No.52171274)。
文摘For the development of an integrated rounded rectangular wellhead platform with a bucket foundation,a model test was conducted to study the towing motion response of such a structure under still water and wave conditions.The influence of various factors on the floating stability of the structure was investigated through alterations of the towing conditions(draft,towing point position,and wave conditions),and the related influencing mechanism was analyzed.Comparison and analysis were performed to determine the changes in the structure motion pattern and various effects of towing conditions on the structure during towing in still water and regular waves.Moreover,the influence of each factor on the structure’s motion response during towing was analyzed using the Apriori algorithm.In addition,for the simulation of the towing process under actual sea conditions,a towing test was performed under irregular waves,and the stability of towing in irregular waves was compared with that in regular waves.
文摘Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during construction, certain suction bucket jacket foundation projects implement grouting techniques to ensure adequate bearing capacity. This study conducted a large-scale suction bucket foundation grouting model experiment to examine grout flow characteristics and specific phenomena under various grouting pipeline configurations. Comparative analyses of grouting efficiency and quality across different pipeline layouts identified critical influencing factors and their impact on grouting performance. The results demonstrate that the number of grout outlets should be maintained within an optimal range:insufficient outlets enhance the indentation effect and decrease fill efficiency, while excessive outlets necessitate precise spacing for effective distribution. Additionally, grout outlets should be uniformly arranged to reduce segregation and enhance overall grouting quality. This study's findings provide a scientific foundation for optimizing grouting design in suction bucket jacket foundations, with substantial implications for engineering applications.
基金financially supported by the Scientific Research Foundation of China Three Gorges Corporation (Grant No. 32007095)。
文摘The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local scour patterns around a novel mono-column composite bucket foundation(MCCBF) under unidirectional flows. The experiments reveal that under weak-flow conditions, no significant scour pits develop at the front or lateral sides of the MCCBF,while two distinct scour pits form behind the lateral sides. Under strong-flow conditions, substantial scour pits emerge at both frontal and lateral sides of the bucket foundation, with two scour pits extending downstream on either side. The research demonstrates that both the range and depth of local scour increase with higher flow velocity and decreasing water depth, though the mechanisms influencing local scour around the MCCBF prove more complex than those affecting monopiles. The distinctive structural features of the MCCBF necessitate particular consideration of effects related to bucket foundation exposure. The study concludes by proposing an empirical formula for predicting maximum scour depth around the MCCBF.
基金Supported by the Key Project of National Scientific and Technological Supporting Program of the "Eleventh Five-year Plan"(2008BAJ08B04-10)Scientific and Technological Program of the Ministry of Construc-tion(2009-K5-1)Soft Science Research Program of Tianjin Municipal Construction Committee(2008Soft-36)~~
文摘The concept of sustainable agricultural village was proposed in this study,and its major economic pattern was summarized as:with the sustainable agriculture,grain production and processing as core contents,to enhance the attraction of agricultural regions and establish more effective connections between rural and urban areas by properly developing eco-agricultural sightseeing and organizing satellite sustainable agricultural villages into an urban peripheral network.Dajidian Sustainable Agricultural Village in Baoding City,Hebei Province was taken for an example to elaborate the overall design concepts,and analyze the strategies for planning the village as an integrated system,including social,ecological and economic dimensions,which are specifically demonstrated as:the development of sustainable agriculture,the establishment of diversified circulation system,the independence of energy utilization,the soundness of public service system,the improvement of agricultural villages as communities.Through studying the planning of sustainable agricultural villages,this research aimed at realizing the sustainable development of overall environment system in both cities and rural areas,and guiding the improvement of the new countryside construction.
基金The National Natural Science Foundation of China(No.51109160)the National High Technology Research and Development Program of China(863 Program)(No.2012AA051705)+1 种基金the International S&T Cooperation Program of China(No.2012DFA70490)the Natural Science Foundation of Tianjin(No.13JCQNJC06900,13JCYBJC19100)
文摘In order to study the towing dynamic properties of the large-scale composite bucket foundation the hydrodynamic software MOSES is used to simulate the dynamic motion of the foundation towed to the construction site.The MOSES model with the prototype size is established as the water draft of 5 and 6 m under the environmental conditions on site.The related factors such as towing force displacement towing accelerations in six degrees of freedom of the bucket foundation and air pressures inside the bucket are analyzed in detail.In addition the towing point and wave conditions are set as the critical factors to simulate the limit conditions of the stable dynamic characteristics.The results show that the large-scale composite bucket foundation with reasonable subdivisions inside the bucket has the satisfying floating stability.During the towing process the air pressures inside the bucket obviously change little and it is found that the towing point at the waterline is the most optimal choice.The characteristics of the foundation with the self-floating towing technique are competitive for saving lots of cost with few of the expensive types of equipment required during the towing transportation.
