In the research, secondary geological disasters of Wenchuan earthquake were defined and the consequences were illustrated based on geological disasters, such as collapse, landslide and debris flow, and threats of barr...In the research, secondary geological disasters of Wenchuan earthquake were defined and the consequences were illustrated based on geological disasters, such as collapse, landslide and debris flow, and threats of barrier lakes. In addition, the characteristics of secondary disasters were analyzed, as follows: Rupture of geological faults lays foundation in terms of geological structure; loose solids provide resources of an earthquake; abundant rainfall and large runoffs are driving forces of an earthquake; rainstorm, flood, and long-term high temperature are major inducing factors. Furthermore, suggestions on prevention of secondary disasters were proposed in terms of prevention before, at and after an earthquake. Finally, the scientific and practical significances of secondary disasters were illustrated.展开更多
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
On February 6, 2023, a series of severe earthquakes occurred in eastern Turkey and neighboring areas of Syria. It was the largest earthquake in the world in more than a year, and the largest earthquake in the history ...On February 6, 2023, a series of severe earthquakes occurred in eastern Turkey and neighboring areas of Syria. It was the largest earthquake in the world in more than a year, and the largest earthquake in the history of Turkey. Living under the fear of earthquakes, the people in Turkey and other earthquake zones have hoped again and again to change their fate, but they have to resign themselves to fate. Thus, the author analyzed the causes of large earthquakes such as Turkey earthquake, and found that some of the world’s potential seismic zones have been eroded by sea water or river water for a long time to create a series of surface faults. When the moon gets close to these faults, it will have a huge gravitational pull on them, and even cause the fault to move, resulting in strong earthquakes. Especially in some seismic zones, earthquakes are occurring more and more frequently and their intensity is getting bigger and bigger. The main reason is that the opening of the Arctic shipping route and the exploration and exploitation of oil and gas have caused the melting of the Arctic ice sheet and the loss of glaciers, which has led to the weakening of the Arctic vortex and the reduction of the compression ability of the polar vortices to the clouds, thus slowing down the rotation of the Earth and thus the revolution of the moon. So the moon gradually moves in a spiral toward the Earth;as the moon orbit close to the Earth, the moon’s gravity on the surface faults will gradually strengthen, so it is easy to cause the surface fault dislocations, resulting in frequent earthquakes or strong earthquakes. So the author puts forward some measures to prevent frequent and strong earthquakes.展开更多
Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the eff...Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.展开更多
From the advanced experiences at home and abroad,according to the requirements of emergency evacuation at earthquake disaster,then strategies and methods to disaster prevention and reduction functions of urban green l...From the advanced experiences at home and abroad,according to the requirements of emergency evacuation at earthquake disaster,then strategies and methods to disaster prevention and reduction functions of urban green land construction were put forward.展开更多
This paper introduced domestic and overseas status, the historical evolution and the development history of earthquake disaster reduction planning. The urgencies and realistic significance were analyzed to carry out e...This paper introduced domestic and overseas status, the historical evolution and the development history of earthquake disaster reduction planning. The urgencies and realistic significance were analyzed to carry out earthquake disaster reduction planning for districts or countries in the northwest. With Hongsibao District in Wuzhong City, Ningxia Province as an example, this article analyzed in detail the present situation and the special problems of earthquake disaster reduction planning in Northwest China. The relevant solving measures were put forward in order to offer a reference for the scientific establishment and effective implementation of earth- quake disaster reduction planning in Northwest China. The foundation of earthquake disaster reduction in the Hongsibao District is still very weak, there is a single earthquake monitoring means, the emergency rescue system is not complete, the working mechanism is not perfect, and the lack of funding for the work of earthquake disaster reduction.展开更多
Over 240 debris flows occurred in hill-slopes, gullies ( indicated those with single-channel) and watersheds (indicated those with tributaries and channels) on July 10th 2013 in the Wenchuan county, and caused 29 ...Over 240 debris flows occurred in hill-slopes, gullies ( indicated those with single-channel) and watersheds (indicated those with tributaries and channels) on July 10th 2013 in the Wenchuan county, and caused 29 casualties and about 633×10^6 USD losses. This work aimed to analyze characteristics, hazards and causes of these events and explore mitigating measures based on field investigation and remote sensing images interpretation. The debris flows contained clay content of 0.1%~3.56%, having densities of 1.72-2.14 t/m^3, velocities of 5.0-m.7 m/s, discharges of 335-2353 m^3/s and sediment yields of 0.10-1.26×10^6 m^3, and also numerously occurred in large watersheds with the area over lo km^2. Large debris flows formed 3 hazard-chains in slopes, gullies, watersheds and rivers, which all evolved in dammed lakes and outburst flood, and 26 dammed lakes and lO newly ones were generated along the rivers of Min and Yuzi. The remarkable spatial difference of loose solid materials accumulation and intense rainfall, with the cumulative of about or more than 150 mm and the hourly of over 16mm, caused debris flows in the sections from Yingxiu to Miansi and Gengda. The damages on buildings, reconstructions, highways,factories and hydro power station originated from the impacting, scouring, burying of debris flows, the submerging of dammed lake and the scouring of outburst flood, and the huge losses came from the ruinous destructions of control engineering works of debris flows as well as the irrational location and low- resistant capabilities of reconstructions. For hazards mitigating of debris flows in long term, the feasible measures for short term, including risk-reassessing of foregone and potential hazard sites, regional alarming system establishing and integrated control in disastrous sites, and middle-long term, including improving reconstruction standard, rationally disposing river channel bed rise and selecting appropriate reconstruction time and plans, were strongly suggested.展开更多
Cities ability reducing earthquake disasters is a complex system involving numerous factors, moreover the re-search on evaluating cities ability reducing earthquake disasters relates to multi-subject, such as earthqua...Cities ability reducing earthquake disasters is a complex system involving numerous factors, moreover the re-search on evaluating cities ability reducing earthquake disasters relates to multi-subject, such as earthquake sci-ence, social science, economical science and so on. In this paper, firstly, the conception of cities ability reducing earthquake disasters is presented, and the ability could be evaluated with three basic elements the possible seis-mic casualty and economic loss during the future earthquakes that are likely to occur in the city and its surround-ings and time required for recovery after earthquake; based upon these three basic elements, a framework, which consists of six main components, for evaluating citys ability reducing earthquake disasters is proposed; then the statistical relations between the index system and the ratio of seismic casualty, the ratio of economic loss and re-covery time are gained utilizing the cities prediction results of earthquake disasters which were made during the ninth five-year plan; at last, the method defining the comprehensive index of cities ability reducing earthquake disasters is presented. Thus the relatively comprehensive theory frame is set up. The frame can evaluate cities ability reducing earthquake disasters absolutely and quantitatively and consequently instruct the decision-making on reducing cities earthquake disasters loss.展开更多
Over the past decade, seismically induced damage to bridges has been widely reported following major earthquakes such as the 1994 Northridge, 1995 Kobe and 1999 Chi-Chi events. Since these earthquakes, restrainers and...Over the past decade, seismically induced damage to bridges has been widely reported following major earthquakes such as the 1994 Northridge, 1995 Kobe and 1999 Chi-Chi events. Since these earthquakes, restrainers and stoppers have been installed on bridges to prevent unseating and excessive displacements, respectively. Alternatively, column jacketing has also been proven to be effective. However, the enhanced shear strength may result in extra retrofitting works on the footing. For bridges damaged in the Chi-Chi earthquake, investigations revealed that most bridge columns experienced none-to-minor damage in the longitudinal direction. The reason for this unexpected performance was the construction practice of using a rubber bearing, which is an unbolted design that may slide under large lateral forces. In this paper, parametric studies on simply-supported bridges retrofitted by a restrainer or concrete shear key along the longitudinal and transverse axes were carried out. The research focuses on finding suitable combinations of the design force and gap spacing so the restrainer and concrete shear key can be used as an unseating prevention device, with respect to the allowable column damage in terms of displacement ductility under near-fault type earthquakes. A two-lane PCI-girder bridge was selected as the benchmark model. In the longitudinal direction, a total of nine combinations considering yielding strength and gap spacing for the restrainer were analyzed; while parameters for the concrete shear key were divided into three shear force levels and three gap spacings. In the transverse direction, a similar approach was adapted, except smaller gap spacing was used. For each of the above mentioned earthquakes, seven input ground motions were selected and their PGAs were adjusted to 0.36g and 0.45g as the Design earthquake and Maximum Considerable Earthquake, respectively. Based on the results of nonlinear time history analyses, proper parameters to design the restrainers and concrete shear keys are obtained. Responses obtained from numerical simulations under the Chi-Chi earthquake leaded to new implications to design those devices. Restrainer should not exceed its breaking strain and sufficient unseating length will be needed always. Concrete Shear key was determined by considering both displacement demand of the superstructure and displacement ductility of the column at the same time. Further study is needed to provide optimal design parameters for use in performance based bridge design.展开更多
During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in t...During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.展开更多
In view of disaster-prevention and evacuation functions of urban green spaces, data collection, field investigation and questionnaire survey were integrated to analyze current situation and functions of green spaces i...In view of disaster-prevention and evacuation functions of urban green spaces, data collection, field investigation and questionnaire survey were integrated to analyze current situation and functions of green spaces in Dujiangyan City. Suggestions for enhancing disaster-prevention and evacuation functions of urban green spaces were proposed on the basis of analyzing and summarizing investigation results.展开更多
As an earthquake-prone country, China has made sustained efforts in the study of earthquakes and disaster mitigation during the past several decades, with China Seismological Bureau (CSB) as the backbone of these effo...As an earthquake-prone country, China has made sustained efforts in the study of earthquakes and disaster mitigation during the past several decades, with China Seismological Bureau (CSB) as the backbone of these efforts. Working towards this purpose, a series of key projects were implemented in the “Ninth Five-Year Plan” (1995-2000) to upgrade earthquake monitoring systems and to improve the supporting infrastructure, significant results in earthquake science were achieved. In the new century, we have worked out a blueprint for earthquake preparedness and disaster mitigation in the “Tenth Five-Year Plan”, which emphases 3 systems (i.e. Seismic Monitoring & Prediction, Seismic Hazards Prevention, Emergency Response), and 10 key projects in earthquake science and technology.展开更多
China's earthquake emergency management policies have experienced a total of four types of paradigms:the paradigm focusing on disaster relief from 1949−1966,the paradigm focusing on earthquake prevention from 1966...China's earthquake emergency management policies have experienced a total of four types of paradigms:the paradigm focusing on disaster relief from 1949−1966,the paradigm focusing on earthquake prevention from 1966−1989,the paradigm focusing on earthquake mitigation from 1989−2016,and the paradigm integrating disaster prevention,mitigation,and relief from 2016 to present.Path dependence can be found in China’s earthquake emergency management policies,which have accumulated to implement comprehensive disaster mitigation based on a pure focus on disaster relief.In addition,earthquake emergency management policies also have a change logic in which subjects are increasingly diversified,policy tools are continuously developed and influenced by the economic system,and policy paradigm changes are influenced by the international environment,national strategies,and emergencies.In the future,earthquake emergency management policies should start from organizational change,digital change and rule of law construction to promote the modernization of China's earthquake emergency governance system and capacity.展开更多
Aim:Based on the experience of the 5.12 Wenchuan Earthquake and the 8.8 Jiuzhaigou Earthquake,the emergency management strategies for nosocomial infections were compared between the two earthquakes.The experience shar...Aim:Based on the experience of the 5.12 Wenchuan Earthquake and the 8.8 Jiuzhaigou Earthquake,the emergency management strategies for nosocomial infections were compared between the two earthquakes.The experience shared in the present study provides a guideline for the emergency medical rescue of future earthquake.Methods:The patients involved in this study were those injured in the earthquake and admitted to the hospital for treatment.As an earthquake relief center,the hospital participated in the emergency rescue work of the two recent major earthquakes in western China.Review analysis was carried out in the hospital's infection control experience adopted in the two major earthquakes.It was emphasized that,targeting the characteristics and difficulties in the prevention and control of nosocomial infection,different innovative infection control emergency strategies were adopted by the frontline disaster relief hospitals,under the special circumstances and medical conditions in an earthquake disaster.Results:According to the different focus of infection control in the two earthquakes,different hospital infection control strategies were adopted,and the incidence of nosocomial infections was effectively controlled.展开更多
基金Supported by National Natural Science Foundation(40921062)China Geological Survey(1212011121261)~~
文摘In the research, secondary geological disasters of Wenchuan earthquake were defined and the consequences were illustrated based on geological disasters, such as collapse, landslide and debris flow, and threats of barrier lakes. In addition, the characteristics of secondary disasters were analyzed, as follows: Rupture of geological faults lays foundation in terms of geological structure; loose solids provide resources of an earthquake; abundant rainfall and large runoffs are driving forces of an earthquake; rainstorm, flood, and long-term high temperature are major inducing factors. Furthermore, suggestions on prevention of secondary disasters were proposed in terms of prevention before, at and after an earthquake. Finally, the scientific and practical significances of secondary disasters were illustrated.
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On February 6, 2023, a series of severe earthquakes occurred in eastern Turkey and neighboring areas of Syria. It was the largest earthquake in the world in more than a year, and the largest earthquake in the history of Turkey. Living under the fear of earthquakes, the people in Turkey and other earthquake zones have hoped again and again to change their fate, but they have to resign themselves to fate. Thus, the author analyzed the causes of large earthquakes such as Turkey earthquake, and found that some of the world’s potential seismic zones have been eroded by sea water or river water for a long time to create a series of surface faults. When the moon gets close to these faults, it will have a huge gravitational pull on them, and even cause the fault to move, resulting in strong earthquakes. Especially in some seismic zones, earthquakes are occurring more and more frequently and their intensity is getting bigger and bigger. The main reason is that the opening of the Arctic shipping route and the exploration and exploitation of oil and gas have caused the melting of the Arctic ice sheet and the loss of glaciers, which has led to the weakening of the Arctic vortex and the reduction of the compression ability of the polar vortices to the clouds, thus slowing down the rotation of the Earth and thus the revolution of the moon. So the moon gradually moves in a spiral toward the Earth;as the moon orbit close to the Earth, the moon’s gravity on the surface faults will gradually strengthen, so it is easy to cause the surface fault dislocations, resulting in frequent earthquakes or strong earthquakes. So the author puts forward some measures to prevent frequent and strong earthquakes.
基金supported by the project of the China Geological Survey(No.DD20221746)the National Natural Science Foundation of China(Grant Nos.41101086)。
文摘Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.
文摘From the advanced experiences at home and abroad,according to the requirements of emergency evacuation at earthquake disaster,then strategies and methods to disaster prevention and reduction functions of urban green land construction were put forward.
基金Supported by State Key Laboratory of Loess and Quaternary Geology Open-end Fund(SKLLQG1426)Post-doctoral Foundation and National Natural Science Foundation of China(41102107)~~
文摘This paper introduced domestic and overseas status, the historical evolution and the development history of earthquake disaster reduction planning. The urgencies and realistic significance were analyzed to carry out earthquake disaster reduction planning for districts or countries in the northwest. With Hongsibao District in Wuzhong City, Ningxia Province as an example, this article analyzed in detail the present situation and the special problems of earthquake disaster reduction planning in Northwest China. The relevant solving measures were put forward in order to offer a reference for the scientific establishment and effective implementation of earth- quake disaster reduction planning in Northwest China. The foundation of earthquake disaster reduction in the Hongsibao District is still very weak, there is a single earthquake monitoring means, the emergency rescue system is not complete, the working mechanism is not perfect, and the lack of funding for the work of earthquake disaster reduction.
基金supported by the Key Program of National Natural Science Found of China (Grant No. 41030742)the Program of National Natural Science Found of China (Grant No. 41171012)
文摘Over 240 debris flows occurred in hill-slopes, gullies ( indicated those with single-channel) and watersheds (indicated those with tributaries and channels) on July 10th 2013 in the Wenchuan county, and caused 29 casualties and about 633×10^6 USD losses. This work aimed to analyze characteristics, hazards and causes of these events and explore mitigating measures based on field investigation and remote sensing images interpretation. The debris flows contained clay content of 0.1%~3.56%, having densities of 1.72-2.14 t/m^3, velocities of 5.0-m.7 m/s, discharges of 335-2353 m^3/s and sediment yields of 0.10-1.26×10^6 m^3, and also numerously occurred in large watersheds with the area over lo km^2. Large debris flows formed 3 hazard-chains in slopes, gullies, watersheds and rivers, which all evolved in dammed lakes and outburst flood, and 26 dammed lakes and lO newly ones were generated along the rivers of Min and Yuzi. The remarkable spatial difference of loose solid materials accumulation and intense rainfall, with the cumulative of about or more than 150 mm and the hourly of over 16mm, caused debris flows in the sections from Yingxiu to Miansi and Gengda. The damages on buildings, reconstructions, highways,factories and hydro power station originated from the impacting, scouring, burying of debris flows, the submerging of dammed lake and the scouring of outburst flood, and the huge losses came from the ruinous destructions of control engineering works of debris flows as well as the irrational location and low- resistant capabilities of reconstructions. For hazards mitigating of debris flows in long term, the feasible measures for short term, including risk-reassessing of foregone and potential hazard sites, regional alarming system establishing and integrated control in disastrous sites, and middle-long term, including improving reconstruction standard, rationally disposing river channel bed rise and selecting appropriate reconstruction time and plans, were strongly suggested.
文摘Cities ability reducing earthquake disasters is a complex system involving numerous factors, moreover the re-search on evaluating cities ability reducing earthquake disasters relates to multi-subject, such as earthquake sci-ence, social science, economical science and so on. In this paper, firstly, the conception of cities ability reducing earthquake disasters is presented, and the ability could be evaluated with three basic elements the possible seis-mic casualty and economic loss during the future earthquakes that are likely to occur in the city and its surround-ings and time required for recovery after earthquake; based upon these three basic elements, a framework, which consists of six main components, for evaluating citys ability reducing earthquake disasters is proposed; then the statistical relations between the index system and the ratio of seismic casualty, the ratio of economic loss and re-covery time are gained utilizing the cities prediction results of earthquake disasters which were made during the ninth five-year plan; at last, the method defining the comprehensive index of cities ability reducing earthquake disasters is presented. Thus the relatively comprehensive theory frame is set up. The frame can evaluate cities ability reducing earthquake disasters absolutely and quantitatively and consequently instruct the decision-making on reducing cities earthquake disasters loss.
文摘Over the past decade, seismically induced damage to bridges has been widely reported following major earthquakes such as the 1994 Northridge, 1995 Kobe and 1999 Chi-Chi events. Since these earthquakes, restrainers and stoppers have been installed on bridges to prevent unseating and excessive displacements, respectively. Alternatively, column jacketing has also been proven to be effective. However, the enhanced shear strength may result in extra retrofitting works on the footing. For bridges damaged in the Chi-Chi earthquake, investigations revealed that most bridge columns experienced none-to-minor damage in the longitudinal direction. The reason for this unexpected performance was the construction practice of using a rubber bearing, which is an unbolted design that may slide under large lateral forces. In this paper, parametric studies on simply-supported bridges retrofitted by a restrainer or concrete shear key along the longitudinal and transverse axes were carried out. The research focuses on finding suitable combinations of the design force and gap spacing so the restrainer and concrete shear key can be used as an unseating prevention device, with respect to the allowable column damage in terms of displacement ductility under near-fault type earthquakes. A two-lane PCI-girder bridge was selected as the benchmark model. In the longitudinal direction, a total of nine combinations considering yielding strength and gap spacing for the restrainer were analyzed; while parameters for the concrete shear key were divided into three shear force levels and three gap spacings. In the transverse direction, a similar approach was adapted, except smaller gap spacing was used. For each of the above mentioned earthquakes, seven input ground motions were selected and their PGAs were adjusted to 0.36g and 0.45g as the Design earthquake and Maximum Considerable Earthquake, respectively. Based on the results of nonlinear time history analyses, proper parameters to design the restrainers and concrete shear keys are obtained. Responses obtained from numerical simulations under the Chi-Chi earthquake leaded to new implications to design those devices. Restrainer should not exceed its breaking strain and sufficient unseating length will be needed always. Concrete Shear key was determined by considering both displacement demand of the superstructure and displacement ductility of the column at the same time. Further study is needed to provide optimal design parameters for use in performance based bridge design.
基金"973"National Key Basic Research and Development Program(No.2012CB518202)Project of Qinghai Development of Science and Technology(No.2011-N-150)
文摘During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.
文摘In view of disaster-prevention and evacuation functions of urban green spaces, data collection, field investigation and questionnaire survey were integrated to analyze current situation and functions of green spaces in Dujiangyan City. Suggestions for enhancing disaster-prevention and evacuation functions of urban green spaces were proposed on the basis of analyzing and summarizing investigation results.
文摘As an earthquake-prone country, China has made sustained efforts in the study of earthquakes and disaster mitigation during the past several decades, with China Seismological Bureau (CSB) as the backbone of these efforts. Working towards this purpose, a series of key projects were implemented in the “Ninth Five-Year Plan” (1995-2000) to upgrade earthquake monitoring systems and to improve the supporting infrastructure, significant results in earthquake science were achieved. In the new century, we have worked out a blueprint for earthquake preparedness and disaster mitigation in the “Tenth Five-Year Plan”, which emphases 3 systems (i.e. Seismic Monitoring & Prediction, Seismic Hazards Prevention, Emergency Response), and 10 key projects in earthquake science and technology.
基金supported by the School of Political Science and Public Administration of Shandong University(Qingdao,China).
文摘China's earthquake emergency management policies have experienced a total of four types of paradigms:the paradigm focusing on disaster relief from 1949−1966,the paradigm focusing on earthquake prevention from 1966−1989,the paradigm focusing on earthquake mitigation from 1989−2016,and the paradigm integrating disaster prevention,mitigation,and relief from 2016 to present.Path dependence can be found in China’s earthquake emergency management policies,which have accumulated to implement comprehensive disaster mitigation based on a pure focus on disaster relief.In addition,earthquake emergency management policies also have a change logic in which subjects are increasingly diversified,policy tools are continuously developed and influenced by the economic system,and policy paradigm changes are influenced by the international environment,national strategies,and emergencies.In the future,earthquake emergency management policies should start from organizational change,digital change and rule of law construction to promote the modernization of China's earthquake emergency governance system and capacity.
文摘Aim:Based on the experience of the 5.12 Wenchuan Earthquake and the 8.8 Jiuzhaigou Earthquake,the emergency management strategies for nosocomial infections were compared between the two earthquakes.The experience shared in the present study provides a guideline for the emergency medical rescue of future earthquake.Methods:The patients involved in this study were those injured in the earthquake and admitted to the hospital for treatment.As an earthquake relief center,the hospital participated in the emergency rescue work of the two recent major earthquakes in western China.Review analysis was carried out in the hospital's infection control experience adopted in the two major earthquakes.It was emphasized that,targeting the characteristics and difficulties in the prevention and control of nosocomial infection,different innovative infection control emergency strategies were adopted by the frontline disaster relief hospitals,under the special circumstances and medical conditions in an earthquake disaster.Results:According to the different focus of infection control in the two earthquakes,different hospital infection control strategies were adopted,and the incidence of nosocomial infections was effectively controlled.