PSHA区划图检验方法的研究

It is untrustworthy to adopt an untested seismic zoning map as the basis of seismic fortification, even national standard, and it turns into a hot point in PSHA study. To work out a procedure to test PSHA hazard map, as a preliminary study, the project intends to analyze deeply the compiling approaches of the two seismic zoning maps of china issued in 1990 and 2001 respectively, to take the data of destructive earthquakes actually occurred afterwards as the test criterion, by means of expanding spatial range to compensate the lack of data in time domain. The main tasks are to develop a theoretical basis of the test, set forth and demonstrate that hazard map is a long term forecasting of spatial distribution of seismic hazard in the given time period; to build and complete the information system of seismic hazard map and isoseismals; to count the distribution range of each actually happened Intensity after the map issued greater than the corresponding Intensity on the map, and the total areas with various positive Intensity differences, the corresponding ratios; to build preliminarily a seismic fortification information system for engineering structures, and data base of vulnerability matrices, loss rates and casualty rate in every damage grades for various engineering structures in different regions; to calculate the potential damage, loss and casualty during the actually occurred earthquakes after the map issued from the engineering structures designed and constructed according to the Intensities on the map, and to compare with the corresponding data from the post-earthquake survey; to test and evaluate the functions and benefits of the two PSHA maps of China by a criterion with dual indices of marginal cost and casualty.

未经客观检验的地震区划图作为抗震设防的依据，甚至是国家标准，是不可靠的，是国际上目前有争议的热点。为研究提出一套检验PSHA区划图的方法，作为前期研究，拟深入分析中国1990和2001两张区划图的编制方法，通过空间域的扩大弥补时间域数据的不足，以实际发生的破坏性地震为检验的客观标准。主要研究检验的理论基础，阐述、论证区划图是对给定时段危险性空间分布的预测；建立完善地震区划图和地震等震线信息系统；统计区划图颁布后实际发生的烈度超过区划图规定的相应设防烈度的分布范围，不同正烈度差的总面积及比例；初步建立工程结构抗震设防信息系统、各地各类工程结构的易损性矩阵、各种破坏等级相应的损失率、伤亡率数据库；计算各地按两张区划图设防，在随后发生的地震中可能遭受的破坏、损失、伤亡，与实际地震调查的数据对比；采用边际成本与人员伤亡双指标准则，检验、评价我国PSHA区划图发挥的作用、产生的效益。

本项目研究了检验概率地震区划图（PSHA）的必要性和检验的原则，提出以区划图颁布实施后发生的破坏性地震为客观的检验标准，创新发展了检验PSHA区划图的两条技术路线。技术路线1统计实际地震造成的烈度超过区划图相应值的面积总和的占比。以我国1990版和2001版区划图为例，路线1的检验结果显示，截止到2015年两张区划图上的设防烈度被超过的面积总和分别占大陆地区总面积的2.9%和1.8%，相当于50年中有5.6%和6.1%的超越，均低于编图中设定的超越概率10%。技术路线2评估按区划图设防建造房屋在实际地震中减轻经济损失和人员伤亡的效益。以四川省最普遍的砖混和钢混结构房屋为例，与不设防相比，按1990版区划图设防建造的房屋在汶川地震中经济损失减少723亿元，体现经济效益621亿元，死亡减少10285人、重伤减少40716人。对1990 和2001版区划图效益评估的初步结果表明，全国总的减灾效益明显，共减少经济损失491亿元，减少死亡117971人、重伤443701人。进一步对全国各地设防烈度全面提高、降低一度的检验结果说明，我国目前编制区划图采用的抗震设防风险水平大体上是合适的。