【作者】 陈鲲；

【导师】 高孟潭；

【作者基本信息】 中国地震局地球物理研究所 ， 固体地球物理学， 2013， 博士

【摘要】 大地震(M≥7.0)是地震灾害的主要原因,建筑物倒塌是人员伤亡的直接原因。我国大地震频度大、分布广、危害大。我国当前的抗震设防体系在防御大地震,确定大震概率性设计地震动参数方面存在诸多不足。本文探讨了“大地震”与罕遇、极罕遇地震作用的区别与联系,并详细分析了基岩场地上罕遇地震动(超越概率50年2%)、极罕遇地震动(年超越概率1×10-4)峰值加速度(PGA)与基本地震动(超越概率50年10%)比值(分别定义为K2和K1)的统计特征和空间分布规律,探讨了K极值所对应的地震环境,开展了不同地震环境认识引起K2和K1空间不确定性方面的影响研究。在不同形状超越概率曲线的基础上耦合了结构倒塌能力的不确定性,提出了一般建设工程抗倒塌风险的控制方法。针对城市与城市群的抗震设防,本文尝试着考虑场点间地震危险性的空间相关性,以重现期和区域内地震动参数允许被同时超越面积为风险指标,提出了利用蒙特卡罗(随机模拟)模拟区域内二维的地震动场空间分布的区域地震危险性分析方法。最后建议建立健全软、硬结合的大地震综合防御体系才能切实减轻大地震所造成的灾害。本文首先回顾了20世纪前后历史上的大地震对我国造成的巨大灾难。利用我国丰富的历史地震资料分析了我国大地震(M≥7.0)地震的空间分布和频度分析特征；利用我国第五代地震动参数区划图震级上限大于7.0的潜在震源区(以下简称“潜源”)资料,探讨了我国高震级上限潜源的空间分布特点；最后分析了我国高震级上限潜源内城市分布的特征。研究分析表明我国地处地质构造活跃地区,易发生大地震的形势严峻。较多城市位于高震源上限潜源内部,设防大地震的任务紧迫。本文阐明“大地震”与罕遇、极罕遇地震作用的区别与联系,以龙门山地震带中段的北川-映秀潜源为例揭示“大地震作用”与罕遇、极罕遇地震作用的关系。然后利用我国第四、五代地震动参数区划图所确定的六套潜源方案,获得了全国范围内各网格点上K1和K2值,统计不同潜源方案、不同地震区、不同衰减关系分区及不同加速度分区全国范围内K2和K1值的统计特征和频度分布特征。明确了不同潜源方案K2和K1值的面积统计关系、不同级别城市的K2和K1值分布特点,以及探讨极大与极小值的空间分布特征及相应的地震环境,最后揭示了不同潜源方案引起K2和K1值标准差和变异系数的空间分布特征。可以得到如下认识：中国大陆地区K值分布在空间位置分布相当不均匀,这种分布与其相应的地震环境紧密联系。总体上说强震活动区的K2和K1值相对小一点,而中强地震活动区的K2和K1值稍大一点。具有极大与极小K值的场点其地震危险性主要是受单一潜源所控制。潜源方案不确定性导致K2和K1标准差和变异系数的空间分布形态基本上不受超越概率水平的影响,超越概率水平仅仅影响标准差和变异系数的大小,并且标准差和变异系数均随着风险水平的增大而增大。标准差和变异系数较大的地区主要位于我国东部地区,西部则主要沿着大型断裂带分布。对于我国现行的抗震设防体系中大震下的一般结构的变形验算,本文建议使用单一超越概率(50年10%)加速度值所确定的区划图、考虑不确定性的K2值空间分布图及相应的土层放大系数共同确定大震下的抗震设防参数值；强震活动地区,“防大地震”就应该考虑极罕遇地震作用；高震级上限潜源内部的地震动参数设防值应该使用确定性方法和概率性方法的最大值。本文以汶川地震后修改的潜源方案为数据基础,在不同形状的超越概率曲线的基础上耦合了ATC-63所推荐的倒塌能力的不确定性,提出了建筑物抗倒塌风险的控制方法,并获得了全国范围内96189个网格场点上对应于MCE水平PGA的倒塌概率、50年1%倒塌概率所对应的PGA以及50年1%倒塌概率所对应的PGA与MCE水平PGA比值(本文称“风险系数”)。研究分析认为(1)中国大陆地区MCE水平的PGA大致相当于50年1%倒塌率所对应的PGA,中国大陆地区风险系数绝大部分集中在0.8-1.2之间,MCE水平的PGA只需做较小的调整就能达到50年1%的倒塌率的风险水平。(2)虽然中国大陆地区MCE水平的PGA大与50年1%倒塌率所对应的PGA空间分布形态较为相似,为了满足“小震不坏、中震可修、大震不倒”的功能要求,对于一般建筑本文建议利用风险系数图对MCE水平的PGA进行调整,才能在全国范围获得一致的倒塌率。(3)MCE水平PGA对应的倒塌概率50年2-5%的地区,除了人口稀少地区外,其它地区例如台湾西海岸包括台北盆地在内,以及我国东南沿海部分地区都属于人口稠密、经济发达地区,MCE水平下倒塌率明显高达其它地区,应该引起大家重视。本文针对大城市与城市群的防震设防,以中强地震活动的湖南示范区(长株潭城市群)作为研究区域,选取了衡阳核电潜源方案常德7.0级、长沙—益阳6.0级及湘潭—湘乡5.5级潜源及其地震活动性参数,提出了利用蒙特卡罗(随机模拟)模拟区域内二维地震动场空间分布的区域地震危险性分析方法,开展了传统的特定场点的地震危险性分析方法与本文提出的区域地震危险性方法的比较研究。研究表明,(1)传统的特定场点的地震危险性分析方法可能低估区域内罕遇大震的影响；(2)特定场点地震危险性分析方法控制着更加活跃源附近的设计加速度；区域性地震危险性分析方法控制着高震级源附近的设计加速度。(3)建筑物抗震设计的地震荷载应该同时满足特定场点风险和区域性的风险,能一定程度能解决罕遇大地震时控制其破坏的空间范围和破坏程度的问题。(4)考虑场点间地震危险性空间相关性的区域地震危险性分析方法为大城市及城市群的防震设防提供了理论基础。最后建议建立软、硬件防灾相结合,城市规划和防灾规划一致的大地震综合防御体系才能真正为我国未来的防震减灾提供坚实的基础。更多还原

【Abstract】 Great earthquakes (M≥27.0) are the main reason of the earthquake disaster and the collapse of buildings is the direct cause of the casualties. Great earthquakes in China are frequently occurred, widely distributed, great harmful. There are many shortcomings in the current seismic fortification system of China, especially, determination design ground motion parameters for rare ground motion. This article expbres difference and relationship between "great earthquake" and rare ground motion, very ground motion, and detailed analyzed the statistical characteristics and spatial distribution of the ratio between basis ground motion(10%probability of exceedance in50years) and c(2%PE in50years), very ground motion(1×10-4PE in one year) on rocks, and defined as K2and Kl, respectively. Coupling the probability distribution for the collapse capacity with a corresponding ground motion hazard curve for the location of the structure, we proposed method of controlling collapse risk for general construction projects. We attempted to consider correlation of seismic risk for different sites, and using Monte Carb (stochastic simulation) simulate two-dimensional distribution of ground motion, to proposed aggregate seismic hazard analysis method Finally in order to achieve better urban disaster prevention and mitigation work, we suggested that only integrated defense system of soft and hard Measures for great earthquake should be established and improvedFirstly we reviewed the great earthquake disaster before and after20th century in China, using rich data of historic earthquake in China, analyzed spatial distribution and frequency feature of great earthquakes (M≥7.0); using potential seismic source zone with magnitude greater than7.0in China’s fifth generation ground motion map, analyzed the space distribution characteristics of potential source zone with high magnitude limit, final analyzed the distribution characteristics of urban in potential seismic source zone with high upper limit magnitude. The analysis shows that our country is located in an active tectonically regions, and is prone to occur great earthquakes. More cities located in potential seismic source zone with high upper limit magnitude, and the task of fortification against great earthquakes is urgent.This article stated that difference and relationship between "great earthquake" and rare ground motion, very ground motion, and taking Beichuan-Yingxiu potential seismic source zone in middle of Longmenshan seismic belt as example to reveal relationship between "great earthquake" and rare ground motion, very ground motion. And then using six of potential seismic source zone schemes of the fourth, fifth generations seismic ground motion parameter zonation, the K1and K2values on each grid point in China was obtained and analyzed the statistical characteristics and frequency distribution characteristics of the Kl and K2values in different potential seismic source zone schemes, different seismic zones, different partition of attenuation relationship and different acceleration Zoning. Finally, the space distribution characteristics of maximum and minimum value of K2and Kl values, as well as standard deviation and coefficient of variation for K2and Kl value were made clear. We can get the following understanding:Distribution of K-value was quite unevenly, which was closely linked to its earthquake environment. K2and Kl values in seismic active area were small relatively, but slightly larger overall in Stable area. Seismic hazard of sites with a maximum and minimum value of K is mainly controlled by a single potential seismic source zone. Uncertain of potential seismic source zone does not affect the spatial distribution of standard deviation and coefficient of variation of K2and Kl, only affect its area. And standard deviation and coefficient of variation increases with the level of risk. Areas with larger Standard deviation and coefficient of variation are mainly located in eastern China, mainly distributed along big active fault in western China. We suggested using acceleration values of a single probability of exceedance (50years,10%), the spatial distribution of K2values with uncertain and amplification coefficients of soil jointly determine seismic fortification parameter values of rare ground motion; very rare ground motion should be considered, in order to "anti-great earthquake "; the maximum value of deterministic method and Probability approach should be used to fortify in potential seismic source zone with high upper limit magnitude.Using data of potential seismic source zone modified after the Wenchuan earthquake, and coupling the probability distribution for the collapse capacity recommended by ATC-63with a corresponding ground motion hazard curve for the location of the structure, method of controlling collapse risk for general construction projects was proposed And accessed the probability of the collapse targeted at the MCE level PGA, PGA corresponding to the50-year probability of1%collapse and ratio for PGA of50-year1%collapse probability and PGA of MCE level,(hereinafter referred to as "risk factor") on96,189grid point. Research and analysis shown that (1) PGA of MCE level is roughly equivalent to PGA for50years the rate of1%collapse in China and risk factor in China is most concentrated in the0.8-1.2. PGA of MCE level slightly adjusted to the risk level of the collapse rate of1%in50years.(2) Though spatial distribution PGA of MCE is similar to PGA of the collapse rate of1%in50years, we proposed use of risk factor of this paper to adjust PGA of MCE level,in order to get a consistent collapse rate in China.(3) Collapse rate for PGA of MCE level was significantly higher than other regions, for example, the west coast of Taiwan, including Taipei Basin, and the southeast coast of China, and this should arouse the attention.Using Monte Carb (stochastic simulation) to simulate the two-dimensional distribution field of PGA, aggregate seismic hazard analysis method was proposed for fortification of big cities and urban agglomerations. Selecting potential seismic source zone of Changde7.0, Changsha-yiyang6.0and Xiangtan5.5to carry out seismic risk analysis for specific and aggregate site, and comparison of this two methods was made. Studies have shown that (1) site-specific seismic hazard analysis method may underestimate the impact of great earthquakes rarely occurred in the region;(2) design acceleration near more active source was controlled by site-specific seismic hazard analysis; acceleration near source with high magnitude was controlled by aggregate hazard analyses.(3) Seismic design of buildings should meet site-specific seismic risk and aggregate risk at the same time, which can to some extent control the spatial extent of the destruction and the extent of the damage under great rare earthquake.(4) Aggregate seismic hazard analysis method, which considers spatial correlation of seismic hazard among sites, can provide a theoretical basis of earthquake fortification for the big cities and urban agglomerations.Finally, we suggest that only combination of soft and hardware disaster prevention system, Consistency of urban planning and disaster planning can really provide a solid foundation for earthquake disaster reduction in future.更多还原