地表破裂断层近场速度大脉冲研究

Study on Large Velocity Pulses near Surface Rupture Faults

在分析和研究近场强震记录的基础上,对地面运动速度大脉冲进行了数值模拟。研究结果表明:有速度大脉冲的地面运动主要产生在断层周围,是地震发生时断层两盘突然错动在周围场地产生的特殊运动效应,单耳速度大脉冲常伴随有较大的地面永久位移,双耳或多耳速度脉冲常对应于位移大脉冲及可恢复位移,其产生机理与断层的破裂速度关系不大,与断层两盘的位移量有直接关系。速度大脉冲对近断层的长周期结构作用显著,值得研究。

On the basis of analyzing and studying near-fauh records of strong earthquakes, the large velocity pulses of near-fault ground motions are numerically simulated. The results show that the large velocity pulse is a kind of special ground motion around faults caused by abrupt fault dislocations. The one-ear large velocity pulse is normally accompanied with a permanent ground displacement, whereas the two-ear large velocity pulse always goes with ＇a large displacement pulse with retrievable displacement. The genetic mechanism of velocity pulse has little relation with fault rupture velocity, but has direct relation with fault dislocation. The large velocity pulses have significant influences on long-period structures near faults, and thus are worthy of further studies.