The paper introduces the tectonic background, focal mechanism and distribution of aftershock of the Wenchuan earthquake on May 12,2008. The earthquake is considered to be the result of long-term interaction between th...The paper introduces the tectonic background, focal mechanism and distribution of aftershock of the Wenchuan earthquake on May 12,2008. The earthquake is considered to be the result of long-term interaction between the eastward movement of the Bayan Har Block and the Sichuan Basin. Most of the earthquake energy was released in an area （the seismic source body） 330kin long,52km wide and 20km deep over 100s. Energy release in the source body was extremely uneven, and strong ground motion in the epicenter area shows obvious asymmetrical character in the time and space scale. The high-intensity area is distributed along the source body, and the intensity distribution bears an obvious anomalous characteristic. The investigation results indicate that more than 90 percent of casualties caused by this earthquake were in the areas of intensity IX or above. Houses, schools and hospitals etc. suffered serious damage. Lifelines such as transportation, water conservation etc. also suffered significant damage. Besides, earthquake-triggered avalanches, landslides, mud-rock flows and so on were extremely serious. The tremendous earthquake disaster highlighted the deficiencies in disaster prevention and mitigation management, scientific earthquake research, technology and application of earthquake disaster prevention, and publicity of earthquake preparedness and disaster reduction.展开更多
It is considered thai the damage of the underground structures caused by earthquakes is minor for a long time. However, the catastrophic damages induced by several recent earthquakes （e. g. Kobe earthquake in 1995 ）...It is considered thai the damage of the underground structures caused by earthquakes is minor for a long time. However, the catastrophic damages induced by several recent earthquakes （e. g. Kobe earthquake in 1995 ） revealed that the study on the dynamic properties of the underground structures is indispensable. The dynamic behavior and damage mechanism of underground structure are analyzed by using shaking table tests （ both shallow-and deep-buried） and numerical simulation （3D FEM） including horizontal and vertical input motions, individually and simultaneously. From the results, the underground structure collapsed due to strong horizontal forces although vertical deformation is not negligible. The vertical excitation increases the response of structure, especially the stress and shear stress at the upper section; the soil influenced the property of soilstructure system. In the same excitation, the response in shallow-buried test is larger than deep case. Both overburden and vertical earthquake play important roles in the response of structure and those are two critical aspects in the design of the large-span underground structures, such as subway stations.展开更多
This paper describes the dynamic characteristics of a damaged nine story building in Sendal during the 2011 Tohoku Earthquake. Dynamic hysteresis characteristic is investigated. The system identification using the ext...This paper describes the dynamic characteristics of a damaged nine story building in Sendal during the 2011 Tohoku Earthquake. Dynamic hysteresis characteristic is investigated. The system identification using the extended Kalman filter determined the amplitude dependency of natural frequency and damping factor, which are consistent with damage feature. Occurrence of partial uplifting in the transverse direction is suggested by the induced higher harmonics based on the wavelet analysis. Historical change of the amplitude dependent dynamic characteristics is also discussed based on the long-term monitoring data from microtremor level to strong motion level.展开更多
Seismic safety of underground structures is one of the main concerns in underground space exploitation. As the first step for dynamic seismic response analysis, the free vibration of long large cross-section undergrou...Seismic safety of underground structures is one of the main concerns in underground space exploitation. As the first step for dynamic seismic response analysis, the free vibration of long large cross-section underground structures is studied in the present paper. The general free transverse vibration motion equation of long large cross-section underground structure is derived with the comprehensive consideration of internal and external damping, effects of shear, cross-sectional rotational inertia and axial force, and a twoparameter soil model. In this way, Timoshenko＇s beam theory is extended. Two limit cases of free transverse vibration of underground structures are discussed. Parameter study shows that in general wave propagation velocities in structures increase with soil elastic parameters. However the influence of Winkler＇s parameter k is significant while the effect of the second soil elastic parameter gp is insignificant. The free vibration frequency of underground structures increases with relative wave number and soil elastic parameters. Unlike the influence of soil elastic parameters on wave propagation velocities, the influence of soil elastic parameters k and gp on the vibration frequency of underground structures have the same order; therefore the influence of the second soil parameter gp on the free vibration of underground structures should not be neglected in dynamic seismic analysis of underground structures展开更多
An approach is described that has been developed for auxiliary monitoring of technical condition of hydropower plant dams. It is based on analysis of changes in dynamic characteristics of dams obtained by an automated...An approach is described that has been developed for auxiliary monitoring of technical condition of hydropower plant dams. It is based on analysis of changes in dynamic characteristics of dams obtained by an automated monitoring and earthquake registration system that records microseismic vibrations of structures. The configuration of the system as well as the results of seismometric monitoring of the dam of Krasnoyarsk hydroelectric power plant are described. To study behavior of the dam under normal and extreme loads it was proposed to develop a model of the dam with the use of the finite element method.展开更多
Objective： To analyze the epidemiological features of patients with head injuries in the 2008 Wenchuan earthquake. Methods： Medical records of patients with head injuries who were admitted to 14 hospitals in Deyang...Objective： To analyze the epidemiological features of patients with head injuries in the 2008 Wenchuan earthquake. Methods： Medical records of patients with head injuries who were admitted to 14 hospitals in Deyang, Mianyang and Chengdu cities after the earthquake were retrospectively analyzed. The patients＇ age, gender, cause of injury, diagnosis, and outcome were analyzed retrospectively. Results： A total of 1 281 patients with 807 males and 474 females were included. According to Glasgow Coma Scale score at admission, 1 029 patients presented with mild injury, 161 moderate injury and 91 severe injury. The major cause of injuries （83%） was bruise by collapsed buildings.Open head injuries accounted for 60.8%. A total of 720 patients underwent surgical treatment. Good recovery was achieved in 1 056 patients, moderate disability in 106, se- vere disability in 71, coma in 29 and death in 19. Conclusions： In this series, male patients were more than female patients. The main cause of injury was hit by falling objects due to building collapse. Minor and open craniocerebral injuries were most common. The epidemiological features of head injuries in Wenchuan earthquake may be helpful to preparation for future rescue.展开更多
3D city models associate a database of a city to a rigorous geospatial representation that is close to the visible reality by combining appearance, geometry, and semantics. As such, these models may include tools that...3D city models associate a database of a city to a rigorous geospatial representation that is close to the visible reality by combining appearance, geometry, and semantics. As such, these models may include tools that convey attribute analysis, not only at the statistical level but also in terms of visual appearance of the objects, thus allowing the generation of new knowledge about a phenomenon or its effects. Lisbon is a city with a moderate level of seismic risk, and has been hit in the past by strong earthquakes. Several seismic vulnerability studies of buildings have been carried out in Lisbon. These studies generate different scenarios that consider the magnitude and source location of potential earthquakes. The results of these studies were presented as maps obtained from crossing information contained in 2D layers and presented in a GIS environment. In the present study a seismic vulnerability assessment of Lisbon's buildings held in 2D is extended to the third dimension, which refines the resolution and the set of parameters and explores the gains of spatial analysis in 3D representations. The numerous parameters that contribute to assess seismic vulnerability of buildings may be analyzed individually or simultaneously as well as in multiple seismic scenarios. Although covering all residential buildings in Lisbon, the application of the 3Dcity model is demonstrated with more detail in three pilot areas.展开更多
基金sponsored by the National Key Technology R&D Program(2006BAC13B01),China
文摘The paper introduces the tectonic background, focal mechanism and distribution of aftershock of the Wenchuan earthquake on May 12,2008. The earthquake is considered to be the result of long-term interaction between the eastward movement of the Bayan Har Block and the Sichuan Basin. Most of the earthquake energy was released in an area （the seismic source body） 330kin long,52km wide and 20km deep over 100s. Energy release in the source body was extremely uneven, and strong ground motion in the epicenter area shows obvious asymmetrical character in the time and space scale. The high-intensity area is distributed along the source body, and the intensity distribution bears an obvious anomalous characteristic. The investigation results indicate that more than 90 percent of casualties caused by this earthquake were in the areas of intensity IX or above. Houses, schools and hospitals etc. suffered serious damage. Lifelines such as transportation, water conservation etc. also suffered significant damage. Besides, earthquake-triggered avalanches, landslides, mud-rock flows and so on were extremely serious. The tremendous earthquake disaster highlighted the deficiencies in disaster prevention and mitigation management, scientific earthquake research, technology and application of earthquake disaster prevention, and publicity of earthquake preparedness and disaster reduction.
文摘It is considered thai the damage of the underground structures caused by earthquakes is minor for a long time. However, the catastrophic damages induced by several recent earthquakes （e. g. Kobe earthquake in 1995 ） revealed that the study on the dynamic properties of the underground structures is indispensable. The dynamic behavior and damage mechanism of underground structure are analyzed by using shaking table tests （ both shallow-and deep-buried） and numerical simulation （3D FEM） including horizontal and vertical input motions, individually and simultaneously. From the results, the underground structure collapsed due to strong horizontal forces although vertical deformation is not negligible. The vertical excitation increases the response of structure, especially the stress and shear stress at the upper section; the soil influenced the property of soilstructure system. In the same excitation, the response in shallow-buried test is larger than deep case. Both overburden and vertical earthquake play important roles in the response of structure and those are two critical aspects in the design of the large-span underground structures, such as subway stations.
文摘This paper describes the dynamic characteristics of a damaged nine story building in Sendal during the 2011 Tohoku Earthquake. Dynamic hysteresis characteristic is investigated. The system identification using the extended Kalman filter determined the amplitude dependency of natural frequency and damping factor, which are consistent with damage feature. Occurrence of partial uplifting in the transverse direction is suggested by the induced higher harmonics based on the wavelet analysis. Historical change of the amplitude dependent dynamic characteristics is also discussed based on the long-term monitoring data from microtremor level to strong motion level.
基金Financial support from the Beijing Natural Science Foundation (No. KZ200810016007)the National 973 Key Program (No. 2010CB732003)the National Science Foundation of China(NSFC) (No. 50825403) is gratefully acknowledged
文摘Seismic safety of underground structures is one of the main concerns in underground space exploitation. As the first step for dynamic seismic response analysis, the free vibration of long large cross-section underground structures is studied in the present paper. The general free transverse vibration motion equation of long large cross-section underground structure is derived with the comprehensive consideration of internal and external damping, effects of shear, cross-sectional rotational inertia and axial force, and a twoparameter soil model. In this way, Timoshenko＇s beam theory is extended. Two limit cases of free transverse vibration of underground structures are discussed. Parameter study shows that in general wave propagation velocities in structures increase with soil elastic parameters. However the influence of Winkler＇s parameter k is significant while the effect of the second soil elastic parameter gp is insignificant. The free vibration frequency of underground structures increases with relative wave number and soil elastic parameters. Unlike the influence of soil elastic parameters on wave propagation velocities, the influence of soil elastic parameters k and gp on the vibration frequency of underground structures have the same order; therefore the influence of the second soil parameter gp on the free vibration of underground structures should not be neglected in dynamic seismic analysis of underground structures
文摘An approach is described that has been developed for auxiliary monitoring of technical condition of hydropower plant dams. It is based on analysis of changes in dynamic characteristics of dams obtained by an automated monitoring and earthquake registration system that records microseismic vibrations of structures. The configuration of the system as well as the results of seismometric monitoring of the dam of Krasnoyarsk hydroelectric power plant are described. To study behavior of the dam under normal and extreme loads it was proposed to develop a model of the dam with the use of the finite element method.
文摘Objective： To analyze the epidemiological features of patients with head injuries in the 2008 Wenchuan earthquake. Methods： Medical records of patients with head injuries who were admitted to 14 hospitals in Deyang, Mianyang and Chengdu cities after the earthquake were retrospectively analyzed. The patients＇ age, gender, cause of injury, diagnosis, and outcome were analyzed retrospectively. Results： A total of 1 281 patients with 807 males and 474 females were included. According to Glasgow Coma Scale score at admission, 1 029 patients presented with mild injury, 161 moderate injury and 91 severe injury. The major cause of injuries （83%） was bruise by collapsed buildings.Open head injuries accounted for 60.8%. A total of 720 patients underwent surgical treatment. Good recovery was achieved in 1 056 patients, moderate disability in 106, se- vere disability in 71, coma in 29 and death in 19. Conclusions： In this series, male patients were more than female patients. The main cause of injury was hit by falling objects due to building collapse. Minor and open craniocerebral injuries were most common. The epidemiological features of head injuries in Wenchuan earthquake may be helpful to preparation for future rescue.
基金partially supported by the Project FCT UID/GEO/50019/2013-Instituto Dom Luiz
文摘3D city models associate a database of a city to a rigorous geospatial representation that is close to the visible reality by combining appearance, geometry, and semantics. As such, these models may include tools that convey attribute analysis, not only at the statistical level but also in terms of visual appearance of the objects, thus allowing the generation of new knowledge about a phenomenon or its effects. Lisbon is a city with a moderate level of seismic risk, and has been hit in the past by strong earthquakes. Several seismic vulnerability studies of buildings have been carried out in Lisbon. These studies generate different scenarios that consider the magnitude and source location of potential earthquakes. The results of these studies were presented as maps obtained from crossing information contained in 2D layers and presented in a GIS environment. In the present study a seismic vulnerability assessment of Lisbon's buildings held in 2D is extended to the third dimension, which refines the resolution and the set of parameters and explores the gains of spatial analysis in 3D representations. The numerous parameters that contribute to assess seismic vulnerability of buildings may be analyzed individually or simultaneously as well as in multiple seismic scenarios. Although covering all residential buildings in Lisbon, the application of the 3Dcity model is demonstrated with more detail in three pilot areas.
