Fatigue,corrosion,and bolt loosening are the main causes of structural performance degradation and collapse in steel bridges.Accurate monitoring of steel bridge diseases is a basic premise for ensuring high-quality op...Fatigue,corrosion,and bolt loosening are the main causes of structural performance degradation and collapse in steel bridges.Accurate monitoring of steel bridge diseases is a basic premise for ensuring high-quality operation and maintenance of steel bridges.In this regard,a summary and analysis were conducted on the classification of steel bridge diseases,monitoring and detection methods,application statuses,and major difficulties.The main causes,research status,and development trends of steel bridge diseases are discussed.The results showed that,for fatigue crack problems,fatigue crack initiation has a small scale,high difficulty in monitoring and detection,few methods,and low accuracy.As the cracks grow,the difficulty of monitoring and detection decreases,the number of methods increases,and the accuracy improves.Fatigue crack monitoring and detection are affected by the environmental and vehicular loads.Superficial corrosion features are evident in steel bridges,and corrosion identification methods and technologies are rapidly developing.Monitoring and detecting corrosion in concealed areas is difficult and requires further improvements in monitoring and detection technologies and their accuracy.Monitoring and detection methods and supporting equipment for bolt loosening in steel bridges are rapidly developing.The development of intelligent monitoring and detection technologies and supporting equipment is an important research topic that urgently needs to be addressed for the full-lifecycle operation and maintenance of steel bridges and the sustainable development of bridge engineering.Developing new intelligent sensing components based on high-performance materials and sensing element design theory to improve the monitoring and detection perception ability is an important development direction for steel bridge monitoring and detection.Research on intelligent monitoring and detection technologies,standardized indicators,and related topics based on intelligent operations and maintenance provide great support for the development of steel-bridge disease monitoring and detection.展开更多
The confined aquifer dewatering for long-deep excavations usually encounters challenges due to complicated geotechnical conditions,large excavation sizes,and high hydraulic pressures.To propose the most efficient sche...The confined aquifer dewatering for long-deep excavations usually encounters challenges due to complicated geotechnical conditions,large excavation sizes,and high hydraulic pressures.To propose the most efficient scheme of confined aquifer dewatering for long-deep excavations,dewatering optimizations were performed using the simulation–optimization method.An open cut tunnel of the Jiangyin-Jingjiang Yangtze River Tunnel Project was taken as an example.The methods of finite element and linear programming(LP)were combined to optimize the dewatering process.A three-dimensional finite element model was developed.After simulating the pumping tests,hydraulic conductivity was inverted.Then,necessary parameters in the LP method were determined by simulating dewatering with each pumping well,and various LP models were developed based on some important influence factors such as dewatering sequence,considered pumping wells,and pumping rate limitation.Finally,the optimal pumping rates were solved and applied to the numerical model,with induced drawdown and ground settlement computed for comparison.The results indicate that the optimization can significantly reduce the required wells in the original design.Dewatering in the deepest zone exhibits the highest efficiency for long-deep excavations with gradually varying depths.For the dewatering sequence from the shallowest to the deepest zone,more pumping wells are required but less energy is consumed.Higher quantity and more advantageous locations of pumping wells in the LP model usually result in lower total pumping rate,drawdown,and ground settlement.If more pumping wells are considered in the deepest zone,pumping rate limitation of single well will only slightly increase the total pumping rate,number of required pumping wells,drawdown,and ground settlement.展开更多
基金funded by the National Key Research and Development Program of China(grant No.2022YFB3706405)National Natural Science Foundation of China(grant Nos.52378316,52278318 and 52108176)+1 种基金National Key Research and Development Program of China(grant No.2021YFB1600300)List of Scientific and Technological Key Projects in Transportation Industry(grant No.2019-MS1-011)。
文摘Fatigue,corrosion,and bolt loosening are the main causes of structural performance degradation and collapse in steel bridges.Accurate monitoring of steel bridge diseases is a basic premise for ensuring high-quality operation and maintenance of steel bridges.In this regard,a summary and analysis were conducted on the classification of steel bridge diseases,monitoring and detection methods,application statuses,and major difficulties.The main causes,research status,and development trends of steel bridge diseases are discussed.The results showed that,for fatigue crack problems,fatigue crack initiation has a small scale,high difficulty in monitoring and detection,few methods,and low accuracy.As the cracks grow,the difficulty of monitoring and detection decreases,the number of methods increases,and the accuracy improves.Fatigue crack monitoring and detection are affected by the environmental and vehicular loads.Superficial corrosion features are evident in steel bridges,and corrosion identification methods and technologies are rapidly developing.Monitoring and detecting corrosion in concealed areas is difficult and requires further improvements in monitoring and detection technologies and their accuracy.Monitoring and detection methods and supporting equipment for bolt loosening in steel bridges are rapidly developing.The development of intelligent monitoring and detection technologies and supporting equipment is an important research topic that urgently needs to be addressed for the full-lifecycle operation and maintenance of steel bridges and the sustainable development of bridge engineering.Developing new intelligent sensing components based on high-performance materials and sensing element design theory to improve the monitoring and detection perception ability is an important development direction for steel bridge monitoring and detection.Research on intelligent monitoring and detection technologies,standardized indicators,and related topics based on intelligent operations and maintenance provide great support for the development of steel-bridge disease monitoring and detection.
基金supported by the National Natural Science Foundation of China(Grant Nos.41972269 and 52178384)the Project of Jiangsu Provincial Transportation Construction Bureau,China(Grant No.2021QD05).
文摘The confined aquifer dewatering for long-deep excavations usually encounters challenges due to complicated geotechnical conditions,large excavation sizes,and high hydraulic pressures.To propose the most efficient scheme of confined aquifer dewatering for long-deep excavations,dewatering optimizations were performed using the simulation–optimization method.An open cut tunnel of the Jiangyin-Jingjiang Yangtze River Tunnel Project was taken as an example.The methods of finite element and linear programming(LP)were combined to optimize the dewatering process.A three-dimensional finite element model was developed.After simulating the pumping tests,hydraulic conductivity was inverted.Then,necessary parameters in the LP method were determined by simulating dewatering with each pumping well,and various LP models were developed based on some important influence factors such as dewatering sequence,considered pumping wells,and pumping rate limitation.Finally,the optimal pumping rates were solved and applied to the numerical model,with induced drawdown and ground settlement computed for comparison.The results indicate that the optimization can significantly reduce the required wells in the original design.Dewatering in the deepest zone exhibits the highest efficiency for long-deep excavations with gradually varying depths.For the dewatering sequence from the shallowest to the deepest zone,more pumping wells are required but less energy is consumed.Higher quantity and more advantageous locations of pumping wells in the LP model usually result in lower total pumping rate,drawdown,and ground settlement.If more pumping wells are considered in the deepest zone,pumping rate limitation of single well will only slightly increase the total pumping rate,number of required pumping wells,drawdown,and ground settlement.
