Identifying drivers of urban landuse changes in the Wenchuan earthquake- affected area by using night-time light data

To learn the process of urban land evolution before and after an earthquake is vital to formulate the urban reconstruction control policies and recovery measures in the earthquake-stricken areas.However,spatiotemporal evolution and its driving factors of urban land in earthquake-prone areas remains limited due to the scarcity of ground observation data.This research,leveraging night-time light remote sensing imagery and land cover data,conducted a comprehensive analysis of the long-term evolution characteristics of urban land in earthquake-prone areas.It introduced methodologies for assessing the socio-economic impact and the primary natural environmental factors driving urban land evolution in these regions.To validate the proposed methods,the 2008 Wenchuan earthquake-affected area in China was selected as a representative study area.The results indicated that the average Digital Number(DN)values in socio-economically impacted areas showed a trend of rising,falling,and then rising again after the earthquake.DN values in three types of damaged areas including Type Ⅱ,Type Ⅲ,and Type Ⅳ exceeded pre-earthquake levels.The analysis of determinative factors influencing urban land evolution revealed that slope and elevation were key elements in controlling urban land expansion before the earthquake,whereas factors such as slope,elevation,lithology,and faults had a stronger influence on urban land expansion after the earthquake.It can be seen that,in view of the differences in the natural conditions of regions for post-disaster reconstruction,the local government need to actively adjust and adapt to urban spatial planning,so as to leverage the scale effect of large-scale inputs of funds,facilities,human resources and other factors after the disaster,thus enhancing resilience and recovery efficiency in response to disaster impacts.

Key technologies of earthquake early warning system for China’s high-speed railway

Purpose–The purpose of this study is to introduce the top-level design ideas and the overall architecture of earthquake early-warning system for high speed railways in China,which is based on P-wave earthquake early-warning and multiple ways of rapid treatment.Design/methodology/approach–The paper describes the key technologies that are involved in the development of the system,such as P-wave identification and earthquake early-warning,multi-source seismic information fusion and earthquake emergency treatment technologies.The paper also presents the test results of the system,which show that it has complete functions and its major performance indicators meet the design requirements.Findings–The study demonstrates that the high speed railways earthquake early-warning system serves as an important technical tool for high speed railways to cope with the threat of earthquake to the operation safety.The key technical indicators of the system have excellent performance:The first report time of the P-wave is less than three seconds.From the first arrival of P-wave to the beginning of train braking,the total delay of onboard emergency treatment is 3.63 seconds under 95%probability.The average total delay for power failures triggered by substations is 3.3 seconds.Originality/value–The paper provides a valuable reference for the research and development of earthquake early-warning system for high speed railways in other countries and regions.It also contributes to the earthquake prevention and disaster reduction efforts.

A new early-warning prediction system for monitoring shear force of fault plane in the active fault

The most common method used to describe earthquake activity is based on the changes in physical parameters of the earth＇s surface such as displacement of active fault and seismic wave.However,such approach is not successful in forecasting the movement behaviors of faults.In the present study,a new mechanical model of fault activity,considering the shear strength on the fault plane and the influence of the resistance force,is established based on the occurrence condition of earthquake.A remote real-time monitoring system is correspondingly developed to obtain the changes in mechanical components within fault.Taking into consideration the local geological conditions and the history of fault activity in Zhangjiakou of China,an active fault exposed in the region of Zhangjiakou is selected to be directly monitored by the real-time monitoring technique.A thorough investigation on local fault structures results in the selection of two suitable sites for monitoring potential active tectonic movements of Zhangjiakou fault.Two monitoring curves of shear strength,recorded during a monitoring period of 6 months,turn out to be steady,which indicates that the potential seismic activities hardly occur in the adjacent region in the near future.This monitoring technique can be used for early-warning prediction of the movement of active fault,and can help to further gain an insight into the interaction between fault activity and relevant mechanisms.

A Preliminary Analysis of the Earthquake Disaster of Buildings during Two Destructive Earthquakes in Xinjiang

This paper introduces the characteristics of earthquake disasters in the 2013 Urumqi MS5. 1 and the 2015 Pishan MS6. 5 earthquakes,which are directly beneath the cities. Based on the discussion on regional tectonic background,site conditions,seismic fortification level of buildings,we preliminarily analyzed the causes of earthquake disaster for buildings caused by the two earthquakes. Finally,we give some advice on earthquake resistance for residential buildings and earthquake damage prevention in Xinjiang.

Damage Investigation of the Hutubi Ms6.2 Earthquake on December 8,2016

The Hutubi M_S6.2 earthquake occurred on December 8, 2016, in Hutubi County,Xinjiang Uygur Autonomous Region, causing three people injured. The earthquake effected areas mainly included 25 townships and towns,plus Hutubi County and Manas County in Changji,Hutubi and Manas. The total effected area is 12,450 km^2. In this paper,we summarize the seismo-tectonic background and geomorphic features of the earthquake zone. Under the guidance of the standard "The Earthquake Site Works-Parts4: Assessment of Direct Loss",the damage to buildings and lifeline systems with various structural types are introduced,and we ultimately estimate the direct economic losses to mud-wood houses and the destruction of brick-wood houses. Our results indicate that"The Urban and Rural Seismic Safe Housing Project"played a key role in reducing this earthquake disaster.

The Reconstruction Strategies of Vrisa, Greece after the 2017 Earthquake

This paper focuses on a small Greek village named Vrisa and a specific condition of Lesbos as the arrival island for hundreds of thousands of refugees, aiming to reconsider places in state of emergency and think of flexible future reconstruction strategies which are able to adapt to the new unpredictable conditions of post-disaster. After the 2017 earthquake, the buildings in Vrisa were marked with red, yellow and green which shows different levels of damage. Also, there are some regulations to restrict the fa?ade, square meter, decoration and funding of rebuilding. By analyzing the characteristics of Vrisa village before earthquake and situation after earthquake, we came up with three reconstruction strategies from different aspects to find solutions. Meanwhile, this paper hopes to provide a reference and suggestions for similar cases of post-earthquake reconstruction.

Damage Analysis of the Great East Japan Earthquake

This paper tries to comprehensively summarize the reasons of damages at the Great East Japan Earthquake on March 11, 2011 and what are the lessons in terms of earthquake and tsunami safety of building and cities. The paper examines the damage of tsunami affected areas and analyses the damage to extract lessons in order to safely reconstruct the affected areas from the view point of building regulations such as ＂Disaster Risk Area＂ provided by the Article 39 of the Building Standard Law and the Urbanization Control Area and UPA （Urbanization Promotion Area） provided by the Article 8 of the Ordinance of the City Planning Law of Japan.

泸定6.8级地震城镇居住建筑典型震害及启示

为分析泸定68级地震中城镇居住建筑的破坏情况,对位于震中磨西镇及周边城镇居住建筑的典型震害进行调查,总结了城镇居住建筑中框架结构及砌体结构的震害特征,详细介绍了一栋采用框架结构的高层住宅及一栋采用砌体结构的多层员工宿舍的破坏情况,并分析破坏原因。调查与分析结果表明:本次地震中,框架结构和砌体结构破坏普遍在底层更严重;框架结构震害总体较轻,未合理设计的楼梯及填充墙依然是框架结构中震害集中区;砌体结构墙体出现常见的各种斜向裂缝;除设计因素外,造成少量砌体结构倒塌可能原因是传统砌体结构抵抗竖向地震作用能力不足以及特殊场地地震放大效应。根据两种结构类型的建筑震害特征,对灾区重建及既有房屋改造提出了重点加强老旧建筑合规性排查、合理计算不利地段建筑的地震作用、适当引入合适的减隔震装置等针对性的设计建议,以提高城镇居住建筑的抗震能力,同时体现韧性城镇的设计理念。

泸县6.0级地震城市建筑群震害模拟与震害机理分析

结合建筑群震害调查与精细化数值仿真等手段,对城市建筑群的震害机理进行研究。首先,建立了泸县6.0级地震中泸县县城的建筑群震害仿真模型,并采用现场震害调查数据,从典型小区、城市整体两个层面,对模型的有效性进行验证。基于震害仿真模型,选取4条具有不同持时和频谱特性的地震动,比较不同地震动对泸县建筑群的破坏力特征,研究不同地震动破坏力随时间和峰值加速度(PGA)的演化特征。研究结果表明:地震动的频谱特性对不同层数、不同类型建筑具有选择性破坏作用,进而影响城市建筑群损伤程度与分布;不同地震动在不同时刻破坏力差异很大,进而导致建筑群损伤发展速度差异明显,前期破坏力较低的地震动仍可能对在后期对建筑群产生严重破坏;对地震动的PGA进行归一化,当PGA较小时,不同地震动造成的建筑群损伤程度接近,随着PGA的放大,不同地震动作用下建筑群损伤差异不断增大,其损伤指数差异可达数倍。

竖向地震引起的城市高架桥的车‒桥耦合作用

建立了典型城市高架桥的车‒桥耦合作用简化模型,利用非线性接触单元模拟桥面和车辆之间的耦合,并选取不同频谱特性的竖向地震动作为激励,研究汽车质量、频率、地震动频谱特性和峰值加速度等多个参数对车‒桥耦合系统动力响应的影响。结果表明,车辆质量和车辆振动频率以及地震动频谱特性均对车桥耦合系统有较大的影响,在共计1866个工况中有221个工况出现了车桥分离的现象;车桥分离对桥梁竖向位移响应多表现为不利,同时还大幅增加了车辆对桥面的碰撞力;在统计意义上,车桥分离的峰值加速度的平均值随着汽车质量的增加而增加,随着汽车频率的增加而减小,随着地震动平均周期的增大而减小。

隋唐·安得广厦千万间--漫步地震五千年(9)

隋唐时期的史载地震主要在关中地区,显现了秦岭南侧存在一条北西向的石泉—房县活动断裂带。地震活动和房屋抗震一直是社会关注的大事,以蓟县独乐寺为典型代表,重点介绍了唐代木结构建筑的抗震技术:地基坚固和均匀、木结构的隔震机制、筒体结构的强抗震性能、斗拱构件的阻尼系统,都对后世的技术发展产生了深刻影响。在现代建筑方面,介绍了地震区划的基本原则,分析了农村藏式民居的弱点和改进措施,讨论了城市建筑的3种抗震结构及今后的发展方向。

Study on Functions and Countermeasures of Disaster Prevention and Reduction of Urban Green Land

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.

区域性地震安全性评价成果应用研究——以雄安新区为例

为总结区域性地震安全性评价成果应用,以雄安新区为例,着重介绍规划建设区区域性地震安全性评价工作。雄安新区在完成活动断层探察、地震动参数区域划分、地震地质灾害风险评估的基础上,建设了区评成果管理应用系统,取得的成果应用于服务新区规划建设、工程抗震设防、地震地质灾害防治等方面。本研究对区评成果服务于城市规划、工程建设、防震减灾能力提升具有一定的促进作用。

基于等效场景的供水管网抗震可靠性评估

供水管网抗震可靠性是满足用户在可能地震作用下用水需求的能力。目前,多数供水管网抗震可靠性评估采用蒙特卡洛模拟产生大量的震损样本进行评估。然而,此方法在评估大型、复杂管网时,将带来极大的工作量和超高的时间成本。为了克服这些问题,提出等效场景方法以提高计算效率。首先,利用震损场景生成后验概率;然后,利用后验概率生成等效场景;最后,通过等效场景确定节点可靠性指数和系统可靠性指数。将文中所提算法与传统蒙特卡洛方法的模拟结果进行对比。研究结果表明:基于后验概率生成等效场景方法是可行的;地震烈度8度时采用100个等效场景评估其可靠性,存在少数评估误差超过10%的节点,其余小地震烈度评估误差均小于5%。将100个等效场景提高至250个,可将评估误差控制在5%以内。因此,该文提出的算法可以在保证结果准确的同时提高计算效率。

地震荷载作用下大跨城市地下综合管廊抗震性能分析

文中利用有限元软件建立地震荷载作用下综合管廊抗震分析数值模型,分析舱室数量、土体性质、覆土厚度等对大跨城市地下综合管廊抗震力学响应的影响。结果表明,覆土厚度从3、5 mm增至7 mm,顶板峰值应力降幅分别为9.5%、12.7%,底板峰值应力降幅分别为5.4%、10.7%,左侧墙峰值应力降幅分别为25%、31.2%,右侧墙峰值应力降幅分别为9.1%、18.2%。土体从粉土到粉质黏土再到沙土,顶板峰值应力增幅分别为44.2%、90.7%,底板峰值应力增幅分别为51.4%、131.4%,左侧墙峰值应力增幅分别为14.3%、185.7%,右侧墙峰值应力增幅分别为100%、340%。

Seismic vulnerability assessment of urban buildings and traffic networks using fuzzy ordered weighted average

Urban buildings and urban traffic network are considered as the vital arteries of cities which have particular effects especially after the crisis in the search and rescue operations. The aim of this study is to determine the vulnerability of urban areas especially, buildings and traffic networks using multicriteria geographic information systems and decisionmaking methods. As there are many effective criteria on the seismic vulnerability that they have uncertain and vague properties, the method of this paper is applying fuzzy ordered weighted average(OWA) to model the seismic vulnerability of urban buildings and traffic networks in the most optimistic and pessimistic states. The study area is district 6 of Tehran that is affected by the four major faults, and thus will be threatened by the earthquakes. The achieved results illustrated the vulnerability with different degrees of risk levels including very high, high, medium, low and very low. The results show that in the most optimistic case 14% and in the pessimistic case 1% of buildings tolerate in very low vulnerability. The vulnerability of urban street network also indicates that in the optimistic case 12% and in the pessimistic case at most 9% of the area are in appropriate condition and the North and NorthEast of the study area are more vulnerable than South of it.

Seismic vulnerability assessment of urban buildings using the rough set theory and weighted linear combination

Seismic vulnerability assessment of urban buildings is among the most crucial procedures to post-disaster response and recovery of infrastructure systems.The present study proceeds to estimate the seismic vulnerability of urban buildings and proposes a new framework training on the two objectives.First,a comprehensive interpretation of the effective parameters of this phenomenon including physical and human factors is done.Second,the Rough Set theory is used to reduce the integration uncertainties,as there are numerous quantitative and qualitative data.Both objectives were conducted on seven distinct earthquake scenarios with different intensities based on distance from the fault line and the epicenter.The proposed method was implemented by measuring seismic vulnerability for the seven specified seismic scenarios.The final results indicated that among the entire studied buildings,71.5%were highly vulnerable as concerning the highest earthquake scenario(intensity=7 MM and acceleration calculated based on the epicenter),while in the lowest earthquake scenario(intensity=5 MM),the percentage of vulnerable buildings decreased to approximately 57%.Also,the findings proved that the distance from the fault line rather than the earthquake center(epicenter)has a significant effect on the seismic vulnerability of urban buildings.The model was evaluated by comparing the results with the weighted linear combination(WLC)method.The accuracy of the proposed model was substantiated according to evaluation reports.Vulnerability assessment based on the distance from the epicenter and its comparison with the distance from the fault shows significant reliable results.

A Preliminary Study on a Seismotectonic Model for the Active Faults in the Xining Urban Area

On the basis of the Xining active urban fault survey, we studied the relationship between the active urban fault and fold deformation. The result of this research shows that the Huangshuihe fault and the NW-striking fault on the northern bank of the Huangshulbe River are tensional faults on top of an anticline, the Nanchuanhe fault is a transverse tear fault resulting from differential folding on two sides of the fault, the east bank of the Beichuanhe River fault is a compressional fault developed on the core or climb of a syncline. By balance profile analysis of fold deformation and inversion of gravity anomaly data, we obtained the depth of the detachment plane and established the seismotectonic model of the ）fining urban area. Based on the seismotectonic model, we analyzed the earthquake potential of the active urban fault.

Option of Fiscal and Financial Polices Based on Monitoring Boom of Urban Employment

With downward pressure of economy facing, monitoring boom index of employment continue to decline. This paper will research on how to cope with urban employment problem using fiscal and financial polices,through building system of boom of urban employment, and identifying risk signal of Chinese urban employment.

中国特色韧性城市的经验探索与未来趋势——从唐山地震到汶川地震

城市作为人类生产生活的主要聚集区域,始终面临着地震、暴雨、台风等各类自然灾害的威胁,以系统的观点加强城市防灾减灾的研究,是土木工程学科所面临的重要课题。韧性城市作为近年来城市防灾减灾领域的新概念,是指城市面临各种自然灾害和人为冲击时,作为一个有机体能够保障居民基本生活的需求并迅速恢复其功能。该文以中国城市防灾减灾史中的2次标志性事件(唐山地震和汶川地震)为依据,通过对系列灾害调查报告的深入分析,以韧性城市的全新视角,详细梳理了2次灾害中城市破坏和恢复的全过程,进行了如下工作:1)从系统的层次重新定义了城市,界定韧性城市的基本概念和量化方式、基本维度和基本特征;2)明确城市灾后恢复的基本过程和功能恢复曲线;3)揭示城市灾后空间分布的异化现象与内在机理;4)讨论了城市生命线工程灾后恢复的基本过程和相互耦合现象;5)进一步明确未曾得到重视的特殊基础设施系统。该文不仅以事实为依据,系统总结了唐山地震和汶川地震中我国在城市防灾减灾领域的经验探索和巨大成就,同时亦可为未来建设有中国特色的韧性城市研究体系和实践体系,提供了有效借鉴。