Effective landslide risk management requires knowledge of the landslide risks. This paper presents a risk assessment methodology for semiregional scale. The landslide probability is assessed taking into account expect...Effective landslide risk management requires knowledge of the landslide risks. This paper presents a risk assessment methodology for semiregional scale. The landslide probability is assessed taking into account expected climatechange in the case study area (the G?ta river valley). Climate change is expected to result in increased erosion and water fluctuations. There are large areas with marine clays, often quick clay, in the area and the landslide process can be rapid with extensive damages and casualties. The consequence methodology includes a wide range of consequences assessed by monetary valuation. The consequences and the landslide probability are combined as pairs of values in a risk matrix and the risk is also presented on a map. The map has been used as discussion and decision bases in the municipalities in the G?ta river valley, in the county administration and on governmental level to estimate the needs of risk mitigation and to make priorities.展开更多
High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based cal...High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based calibration of the partial factors to a reasonable safety level taking into account the specific design situations and uncertainties relevant to railway embankments. A reliability-based design has been investigated, resulting in an optimal partial factor for the considered subsoil. With a stochastic soil model to simulate the undrained shear strength of soft soil deposits, the partial factor is calibrated using asymptotic sampling for the reliability assessment. The calibration shows that the partial factor can be reduced significantly compared to the value specified in the Danish National Annex to DS/EN 1997-1 （2007）, Eurocode 7.展开更多
There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analys...There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analysis methods in which the floater is assumed as a rigid body or multiple rigid bodies and the stress distributions in the floater cannot be directly obtained.As part of the COWI Fonden funded EMULF project,a summary about the methodology,the numerical modeling procedure and the verification for stress response analysis of a semi-submersible floater for a 15MW wind turbine is presented.This analy-sis procedure includes the regeneration of the hydrodynamic pressure loads on the external wet surface of the floater due to wave diffraction,radiation and hydrostatic pressure change,and the application of these pressure loads,together with the time-varying gravity due motions,the inertial loads and the forces/moments at the boundaries(i.e.tower bottom and mooring line fairleads)of the floater to obtain the deformation and the stresses of the floater in the time domain.The analysis procedure is imple-mented in a developed MATLAB code and the DNV software package.The importance of the different hydrodynamic pressure components was discussed considering representative sea states.A verification of the obtained stress time series and statistics using this method against the regeneration from a linear frequency-domain approach was made considering irregular wave actions only,and a very good agree-ment was obtained.The developed methodology can provide an efficient solution for structural design analysis of floating wind turbines.展开更多
The tunnel industry has considered that tunnels,especially tunnels in rock,are naturally resistant to earthquake action,including faulting,shaking,deflection and ground failure.As the number of case histories of tunne...The tunnel industry has considered that tunnels,especially tunnels in rock,are naturally resistant to earthquake action,including faulting,shaking,deflection and ground failure.As the number of case histories of tunnels subject to earthquake action has increased,the industry has started to recognize that,although tunnels in rock have good resistance against earthquakes generating peak ground accelerations(PGA)lower than 0.5 g,it is important to include the dynamic forces and displacements generated by seismic ground motions in the design process to obtain a more reliable design.These additional earthquake forces impact the final design,potentially requiring changes to the ground support and additional reinforcement of the concrete lining,as illustrated by case histories presented in this paper.展开更多
Modern bridge building is much more than concrete,steel and money.The overall socioeconomic impact,influence on people migration,traffic,use of primary materials,safety of construction impact on the environment,energy...Modern bridge building is much more than concrete,steel and money.The overall socioeconomic impact,influence on people migration,traffic,use of primary materials,safety of construction impact on the environment,energy,risk scenarios,health,and most relevant now:climate and CO_(2) emissions,are among the parameters which enter into the decision process at the overall holistic conceptual level,the more detailed level of selection of bridge sites,and selection of bridge types as well as construction methods and selection of materials and products.The paper illustrates these dilemmas and illustrates by specific examples how this complicated decision process can be managed and structured in order to arrive at an overall satisfactory solution for design,construction and maintenance throughout the lifetime(life cycle)to these sometimes contradictory parameters and requirements.展开更多
文摘Effective landslide risk management requires knowledge of the landslide risks. This paper presents a risk assessment methodology for semiregional scale. The landslide probability is assessed taking into account expected climatechange in the case study area (the G?ta river valley). Climate change is expected to result in increased erosion and water fluctuations. There are large areas with marine clays, often quick clay, in the area and the landslide process can be rapid with extensive damages and casualties. The consequence methodology includes a wide range of consequences assessed by monetary valuation. The consequences and the landslide probability are combined as pairs of values in a risk matrix and the risk is also presented on a map. The map has been used as discussion and decision bases in the municipalities in the G?ta river valley, in the county administration and on governmental level to estimate the needs of risk mitigation and to make priorities.
基金The funding initiating this work was provided by Banedanmark
文摘High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based calibration of the partial factors to a reasonable safety level taking into account the specific design situations and uncertainties relevant to railway embankments. A reliability-based design has been investigated, resulting in an optimal partial factor for the considered subsoil. With a stochastic soil model to simulate the undrained shear strength of soft soil deposits, the partial factor is calibrated using asymptotic sampling for the reliability assessment. The calibration shows that the partial factor can be reduced significantly compared to the value specified in the Danish National Annex to DS/EN 1997-1 （2007）, Eurocode 7.
文摘There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analysis methods in which the floater is assumed as a rigid body or multiple rigid bodies and the stress distributions in the floater cannot be directly obtained.As part of the COWI Fonden funded EMULF project,a summary about the methodology,the numerical modeling procedure and the verification for stress response analysis of a semi-submersible floater for a 15MW wind turbine is presented.This analy-sis procedure includes the regeneration of the hydrodynamic pressure loads on the external wet surface of the floater due to wave diffraction,radiation and hydrostatic pressure change,and the application of these pressure loads,together with the time-varying gravity due motions,the inertial loads and the forces/moments at the boundaries(i.e.tower bottom and mooring line fairleads)of the floater to obtain the deformation and the stresses of the floater in the time domain.The analysis procedure is imple-mented in a developed MATLAB code and the DNV software package.The importance of the different hydrodynamic pressure components was discussed considering representative sea states.A verification of the obtained stress time series and statistics using this method against the regeneration from a linear frequency-domain approach was made considering irregular wave actions only,and a very good agree-ment was obtained.The developed methodology can provide an efficient solution for structural design analysis of floating wind turbines.
文摘The tunnel industry has considered that tunnels,especially tunnels in rock,are naturally resistant to earthquake action,including faulting,shaking,deflection and ground failure.As the number of case histories of tunnels subject to earthquake action has increased,the industry has started to recognize that,although tunnels in rock have good resistance against earthquakes generating peak ground accelerations(PGA)lower than 0.5 g,it is important to include the dynamic forces and displacements generated by seismic ground motions in the design process to obtain a more reliable design.These additional earthquake forces impact the final design,potentially requiring changes to the ground support and additional reinforcement of the concrete lining,as illustrated by case histories presented in this paper.
文摘Modern bridge building is much more than concrete,steel and money.The overall socioeconomic impact,influence on people migration,traffic,use of primary materials,safety of construction impact on the environment,energy,risk scenarios,health,and most relevant now:climate and CO_(2) emissions,are among the parameters which enter into the decision process at the overall holistic conceptual level,the more detailed level of selection of bridge sites,and selection of bridge types as well as construction methods and selection of materials and products.The paper illustrates these dilemmas and illustrates by specific examples how this complicated decision process can be managed and structured in order to arrive at an overall satisfactory solution for design,construction and maintenance throughout the lifetime(life cycle)to these sometimes contradictory parameters and requirements.
