关键词: 地震危险性, 不确定性, 概率法, 场地影响, 地震场地相关反应谱

Abstract: In the first part of the paper, the status and tendency of development of the methodology of seismic hazard assessment are reviewed with reference to recent documents such as Standard Specification ASCE 4-86 and IAEA 1991 Safety Guide, and in the remaining sections three main problems, i.e. the consideration of uncertainties, site effect and earthquake and site-dependent spectrum, are discussed. Under the topic of uncertainty, it is pointed out that the still popular deterministic method considers the uncertainty by empirical and subjuctive judgement, while the probabilistic method considers its explicity in terms of exceedance probability of occurrance of a given ground motion. There are two types of deterministic methods for seismic hazard assessment: one gives the most probable or average estimate and anothor the most conservative estimate, both being subjective. In China, many people believe that the later deterministic method gives always a safe estimate than the former with annual exceedance probability of 10-4. The paper explains that it may not be so because the deterministic method currently used in China did not consider the uncertainties and the subjective choices were not always safe enough. The probabilistic approach is recommanded. Under the topic of site effect analysis, the paper discusses firstly the importance of site effect analysis for nuclear facilities, especially those on soft sites, then the selection of input boundary and the uncertainties involved, and also the importance of considering earthquake-dependent and site-dependant design spectra, especially of those facilities on soft sites.

Key words: Seismic risk, Uncertainty, Probabilistic method, Site effect, Eeathquake dependent and site-dependent spectra