Water conveyance tunnels usually experience high internal water pressures and complex soil conditions.Therefore,shield tunnels with double-lining structure have been adopted because of their high bearing capacity.The ...Water conveyance tunnels usually experience high internal water pressures and complex soil conditions.Therefore,shield tunnels with double-lining structure have been adopted because of their high bearing capacity.The effect of the interface between the segmental and inner linings on the bearing capacity has been widely investigated;however,the effect of soil on the internal water pressure bearing capacity has not been emphasized enough.Therefore,in this study,model tests and an analytical solution are presented to elucidate the effect of soil on the internal water pressure bearing capacity.First,model tests are conducted on double-lining models under sandy soil and highly weathered argillaceous siltstone conditions.The internal force and earth pressure under these different soil conditions are then compared to reveal the contribution of soil to the internal water pressure bearing capacity.Following this,an analytical solution,considering the soil–double-lining interaction,is proposed to further investigate the contribution of the soil.The analytical solution is verified with model tests.The analytical solution is in good agreement with the model test results and can be used to evaluate the mechanical behavior of the double-lining and soil contribution.The effect of soil on the bearing capacity is found to be related with the elastic modulus of the soil and the deformation state of the double-lining.Before the double-lining cracks,the sandy soil contributes 3.7%of the internal water pressure but the contribution of the soil rises to 10.4%when it is the highly weathered argillaceous siltstone.After the double-lining cracks,the soil plays an important role in bearing internal water pressure.The soil contributions of sandy soil and highly weathered argillaceous siltstones are 10.5%and 27.8%,respectively.The effect of soil should be considered in tunnel design with the internal water pressure.展开更多
According to the structural characteristics of hazardous waste landfill, a new model based on the finite element method （FEM） is developed. The detection layer is considered as a sealed space and it is assumed that ...According to the structural characteristics of hazardous waste landfill, a new model based on the finite element method （FEM） is developed. The detection layer is considered as a sealed space and it is assumed that total current flows through the leak for the high resistivity of geomembrane liner. The leak current is regarded as a positive point current ＋I and the other current source is -I. Electrical potential of an arbitrary point in detection layer satisfies Poisson equation. Experiments for detecting leaks in liner were carried out. Excellent agreement between experimental data and simulated model data validates the new model. Parametric curves for a single leak show that with optimum selection of field survey parameters leaks can be detected effectively. For multiple leaks, the simulated results indicate that they are detectable when leak separation is larger than measurement spacing.展开更多
Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused ...Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused on the deep double-line Sejila Mountain tunnel to systematically analyze the spatial response of blasting-induced vibration and to develop a prediction model through field tests and numerical simulations.The results revealed that the presence of a cross passage significantly altered propagation paths and the spatial distribution of blasting-induced vibration velocity.The peak particle velocity(PPV)at the cross-passage corner was amplified by approximately 1.92 times due to wave reflection and geometric focusing.Blasting-induced vibration waves attenuated non-uniformly across the tunnel cross-section,where PPV on the blast-face side was 1.54–6.56 times higher than that on the opposite side.We propose an improved PPV attenuation model that accounts for the propagation path effect.This model significantly improved fitting accuracy and resolved anomalous parameter(k and a)estimates in traditional equations,thereby improving prediction reliability.Furthermore,based on the observed spatial distribution of blasting-induced vibration,optimal monitoring point placement and targeted vibration control measures for tunnel blasting were discussed.These findings provide a scientific basis for designing blasting schemes and vibration mitigation strategies in deep tunnels.展开更多
The general design and layout of the double-line five-step ship-lock,the water delivery technique for high head ship-lock,the key technical problems of fully lined ship-lock and the monitoring techniques for large-sca...The general design and layout of the double-line five-step ship-lock,the water delivery technique for high head ship-lock,the key technical problems of fully lined ship-lock and the monitoring techniques for large-scale miter gates and hoisting equipment under complicated operation conditions of Three Gorges Project (TGP) are introduced.Since the operation of ship-lock in 2003,the operation practice has proved that the design techniques are advanced,rational and reliable.The design and construction of the fully lined ship-lock promotes the development of design theory and practice of ship-lock projects,which makes the construction technology of ship-lock in the world reach a new level.展开更多
Throughout Oscar Wilde’s farcical comedy,The Importance of Being Ernest,there are two story lines.The lines are both independent to each other,but are connected with each other.With the author’s thoughtful arrangeme...Throughout Oscar Wilde’s farcical comedy,The Importance of Being Ernest,there are two story lines.The lines are both independent to each other,but are connected with each other.With the author’s thoughtful arrangement and distinctive technology,the two lines push the development of plot;intensify the depth of conflict and make the structure complete.It seems the author told us a story,but indeed it gives us a lot of inspiration and education.展开更多
Flexible traction substations (FTSSs) integrating power converters, solar photovoltaics (PVs), and energy storage systems (ESSs) are beneficial for electric railways (ERs) evolving toward a sustainable and efficient s...Flexible traction substations (FTSSs) integrating power converters, solar photovoltaics (PVs), and energy storage systems (ESSs) are beneficial for electric railways (ERs) evolving toward a sustainable and efficient system. However, traction load and PV generation are uncertain and fluctuating, unfavorable to efficient PV energy consumption in ERs. Thus, this paper proposes a power flow control strategy for FTSSs. First, a real-time power flow optimization method is proposed to calculate the output power references of the back-to-back converter (BTBC) and ESS. It aims for efficient regenerative braking energy and PV energy utilization and negative sequence current suppression. Then, a model predictive power control (MPPC) scheme is designed for BTBC to track output power and DC-bus voltage references quickly and accurately. It includes a revised dynamic reference generation method and a model-based double-line frequency ripple (DLFR) filter. Meanwhile, an MPPC scheme for a bidirectional DC-DC converter is designed to regulate output power of ESS, which realizes accurate power reference tracking and smooth operational mode transition. Finally, the validity of the proposed strategy is confirmed through simulations and experiments.展开更多
基金the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-0700-07-456 E00051)the National Natural Science Foundation of China(Nos.51978517,52090082,and 52108381)the Shanghai Science and Technology Committee Program(Nos.21DZ1200601 and 20DZ1201404)。
文摘Water conveyance tunnels usually experience high internal water pressures and complex soil conditions.Therefore,shield tunnels with double-lining structure have been adopted because of their high bearing capacity.The effect of the interface between the segmental and inner linings on the bearing capacity has been widely investigated;however,the effect of soil on the internal water pressure bearing capacity has not been emphasized enough.Therefore,in this study,model tests and an analytical solution are presented to elucidate the effect of soil on the internal water pressure bearing capacity.First,model tests are conducted on double-lining models under sandy soil and highly weathered argillaceous siltstone conditions.The internal force and earth pressure under these different soil conditions are then compared to reveal the contribution of soil to the internal water pressure bearing capacity.Following this,an analytical solution,considering the soil–double-lining interaction,is proposed to further investigate the contribution of the soil.The analytical solution is verified with model tests.The analytical solution is in good agreement with the model test results and can be used to evaluate the mechanical behavior of the double-lining and soil contribution.The effect of soil on the bearing capacity is found to be related with the elastic modulus of the soil and the deformation state of the double-lining.Before the double-lining cracks,the sandy soil contributes 3.7%of the internal water pressure but the contribution of the soil rises to 10.4%when it is the highly weathered argillaceous siltstone.After the double-lining cracks,the soil plays an important role in bearing internal water pressure.The soil contributions of sandy soil and highly weathered argillaceous siltstones are 10.5%and 27.8%,respectively.The effect of soil should be considered in tunnel design with the internal water pressure.
基金Project supported by the National High-Technology Research and Development Program of China(Grant No.2001AA644010)
文摘According to the structural characteristics of hazardous waste landfill, a new model based on the finite element method （FEM） is developed. The detection layer is considered as a sealed space and it is assumed that total current flows through the leak for the high resistivity of geomembrane liner. The leak current is regarded as a positive point current ＋I and the other current source is -I. Electrical potential of an arbitrary point in detection layer satisfies Poisson equation. Experiments for detecting leaks in liner were carried out. Excellent agreement between experimental data and simulated model data validates the new model. Parametric curves for a single leak show that with optimum selection of field survey parameters leaks can be detected effectively. For multiple leaks, the simulated results indicate that they are detectable when leak separation is larger than measurement spacing.
基金financially supported by the National Natural Science Foundation of China(Nos.42577209 and U22A20239)the Key R&D Program of Hunan Province(No.2024WK2004)the Key Technologies for Accurate Diagnosis and Intelligent Prevention and Control of Slope Hazards in Open pit Mines,181 Major R&D projects of Metallurgical Corporation of China Ltd。
文摘Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused on the deep double-line Sejila Mountain tunnel to systematically analyze the spatial response of blasting-induced vibration and to develop a prediction model through field tests and numerical simulations.The results revealed that the presence of a cross passage significantly altered propagation paths and the spatial distribution of blasting-induced vibration velocity.The peak particle velocity(PPV)at the cross-passage corner was amplified by approximately 1.92 times due to wave reflection and geometric focusing.Blasting-induced vibration waves attenuated non-uniformly across the tunnel cross-section,where PPV on the blast-face side was 1.54–6.56 times higher than that on the opposite side.We propose an improved PPV attenuation model that accounts for the propagation path effect.This model significantly improved fitting accuracy and resolved anomalous parameter(k and a)estimates in traditional equations,thereby improving prediction reliability.Furthermore,based on the observed spatial distribution of blasting-induced vibration,optimal monitoring point placement and targeted vibration control measures for tunnel blasting were discussed.These findings provide a scientific basis for designing blasting schemes and vibration mitigation strategies in deep tunnels.
文摘The general design and layout of the double-line five-step ship-lock,the water delivery technique for high head ship-lock,the key technical problems of fully lined ship-lock and the monitoring techniques for large-scale miter gates and hoisting equipment under complicated operation conditions of Three Gorges Project (TGP) are introduced.Since the operation of ship-lock in 2003,the operation practice has proved that the design techniques are advanced,rational and reliable.The design and construction of the fully lined ship-lock promotes the development of design theory and practice of ship-lock projects,which makes the construction technology of ship-lock in the world reach a new level.
文摘Throughout Oscar Wilde’s farcical comedy,The Importance of Being Ernest,there are two story lines.The lines are both independent to each other,but are connected with each other.With the author’s thoughtful arrangement and distinctive technology,the two lines push the development of plot;intensify the depth of conflict and make the structure complete.It seems the author told us a story,but indeed it gives us a lot of inspiration and education.
基金supported in part by the National Science Fund for Excellent Young Scholars of China 52122707in part by the National Key R&D Program of China 2021YFB2601500in part by the Sichuan Science and Technology Program 2022NSFSC1896.
文摘Flexible traction substations (FTSSs) integrating power converters, solar photovoltaics (PVs), and energy storage systems (ESSs) are beneficial for electric railways (ERs) evolving toward a sustainable and efficient system. However, traction load and PV generation are uncertain and fluctuating, unfavorable to efficient PV energy consumption in ERs. Thus, this paper proposes a power flow control strategy for FTSSs. First, a real-time power flow optimization method is proposed to calculate the output power references of the back-to-back converter (BTBC) and ESS. It aims for efficient regenerative braking energy and PV energy utilization and negative sequence current suppression. Then, a model predictive power control (MPPC) scheme is designed for BTBC to track output power and DC-bus voltage references quickly and accurately. It includes a revised dynamic reference generation method and a model-based double-line frequency ripple (DLFR) filter. Meanwhile, an MPPC scheme for a bidirectional DC-DC converter is designed to regulate output power of ESS, which realizes accurate power reference tracking and smooth operational mode transition. Finally, the validity of the proposed strategy is confirmed through simulations and experiments.
