广州市区浅层横波速度六分量地震探测试验

Six-component Seismic Detection Test of Shallow Shear Wave Velocity Structure in Guangzhou City

理论上,通过平移与旋转运动联合观测的六分量地震记录,在单物理点上即可实现浅层横波速度结构的反演。本文主要目的为结合正演模拟设计六分量面波数据处理的流程,并将此单物理点方法应用至广州市区所采集的数据当中。本次研究在正演模拟的阶段中,通过时频域滤波方法实现了基阶面波数据的提纯,设计了使用单物理点的六分量数据实现浅层横波速度结构反演的流程;在实际应用阶段,通过数据的波形和偏振分析,介绍了甲烷气爆震源激发下的六分量波场特征,并分析出基阶面波所在的时频区域,结合时频域滤波、基阶面波相速度反演得到了试验区的横波速度结构。其结果与区域地质调查结果有较好的对应性,说明此六分量地震观测方法在工程地震领域的应用是可行的。

Theoretically,the inversion of shallow transverse wave velocity structure can be achieved at a single physical point from a six-component seismic record observed by the joint translational and rotational motion.Therefore,this paper aims to establish a process for processing six-component surface wave data in conjunction with forward simulation,and apply this single-physical-point method to data processing acquired in Guangzhou urban area.In the forward simulation stage,the fundamental surface wave data is purified by time-frequency domain filtering,and the process of inversion of the shallow transverse velocity structure using single physical point sextant data is established.In the practical application stage,the waveform and polarisation analysis of the data introduces the characteristics of the sextant wavefield under the excitation of the methane gas explosion source,and analyses the time-frequency region where the fundamental surface wave is located.The cross-wave velocity structure of the test area is obtained by combining the time-frequency domain filtering and the phase velocity inversion of the fundamental surface waves.The results correspond well with the results of the regional geological survey,indicating that this seismic observation method can be applied in the field of engineering seismic study.