地震危险性分析模型对于我国西部地区的适用性探讨

Discussion of applicabilityof seismic risk analysis model for China's western regions

地震危险性分析是地震动估计的一种重要方法,其准确性对抗震设计至关重要,因此,该方法是一项极为重要的实际工程问题.我国东、西部地区大震等震线存在明显的不同,主要表现为:西部大震的最内层等震线为沿断层延伸的条带型区域,东部大震的等震线却完全不同,用椭圆形来描述更为合适.椭圆模型是我国地震危险性分析中应用最广泛的模型.由于东、西部大震等震线的差异,假设龙门山断裂发生一次与汶川地震同等级的地震,分析成都某场地峰值加速度的超越概率.结果表明:椭圆模型对我国西部地区的危险性分析并不完全适用;对于本地区的危险性分析,用断层破裂模型或反映断层破裂长度的椭圆模型更为理想.

Seismic hazard analysis is a main method of ground motion estimation, whose accuracy is essential for seismic design, so it is a important practical problem in engineering. There exist obvious differences of the big earthquake isoseismals between Eastern and Western regions in China, the innermost one of the western earthquake isoseismals is a strip-type region extending along the fault, and the eastern earthquakes are completely different, ellipse described more appropriately. The Ellipse model is a most widely used model of the seismic hazard analysis in China. Due to differences between big earthquake of East and West, we assume one earthquake would occur with equal magnitude of Wenchuan great earthquake in the Longmenshan fault zone, and analyze exceedance probability of PGA for a site in Chengdu. The results show that the ellipse model for risk analysis of China＇s western region is not fully applicable, and fault rupture model or ellipse model which takes into account the length of the fault rupture is more ideal.