湖南中强地震活动地区Ⅱ类场地放大效应研究

Study on Amplification Effect of Type Ⅱ Sites in Moderate Earthquake Area of Hunan

利用工程场地地震安全性评价工作中大量实际钻孔和土工实验资料,建立了实际工程场地模型,在50年超越概率为63%、10%、2%共3种地震动输入下,采用SHAKE91和ELSSRA两种等效线性化方法,研究了湖南省Ⅱ类场地土层的放大效应。计算结果表明:湖南省50年超越概率10%的场地效应放大因子为1.30,若使用《中国地震动参数区划图(GB18306-2001)》认定的1.25系数,将低估湖南中强地震活动地区的场地放大效应。湖南省50年超越概率63%、10%、2%这3个设定水准的场地效应放大因子满足1.10∶1.00∶0.95的关系。这些结果有益于为湖南省提供更为合理的抗震设防标准。

Real models of engineering site are constructed on the basis of the quantitative data of real boreholes and soil tests in Safety Assessment Work. Under 63.2%, 10% and 2% exceedance probability in 50 years, amplification effects of Type II sites in Hunan Province are studied in detail by 2 equivalent linear seismic response methods, SHAKE91 and ELSSRA respectively. The results indicate that the amplification effect of Type II sites in Hunan Province on condition of 10% exceedance probability in 50 years is 1.30 against the previous coefficient 1.25 in National Standard ＂The Zonation Map of Earthquake Ground Motion Parameters in China （GB18306-2001）＂, which will underestimate site effects in moderate earthquake areas such as Hunan. 63.2%, 10% and 2% exceedance probability in 50 years in terms of amplification effects of Type II sites in Hunan accord with the relations at the levels of 1.10：1.00：0.95. All these results are helpful for more reasonable standards of engineering aseismic design in Hunan Province.