强地震动随机合成中震源谱模型的改进

Improvement of source spectrum model for synthesis of strong ground motion

为了消除合成的地震动幅值对子源尺寸的依赖,全面介绍了地震动随机合成中震源谱模型的一个改进,突出凹凸体对高频地震波的控制作用,拐角频率与子源错动量相关,且随着破裂的发展、破裂的子源数目逐渐增加有所降低。同时,提出在震源谱模型中增加标度因子补偿震源谱参数随破裂面扩展变化引起的能量损失的方法,通过算例说明了远场总辐射能随子源尺寸的变化明显减小。

A source spectrum model for stochastic synthesis of strong ground motion is introduced in order to eliminate the dependence of the motion on the size of sub-source.In the model,the domination of asperity on high-frequency motion is emphasized.The corner frequency is related with the slip of sub-source and decreases with the rupturing,i.e.,number of ruptured sun-sources.Furthermore,an approach is presented to add a scaling factor into the source spectrum model to counterbalance the energy loss from the change of source spectrum parameters with the spreading of rupture area.By means of this approach,an obvious decrease of variation of the total radiated energy at far field is demonstrated by a case study.