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便于不同观测系统的统一,本文定义了广义炮检距概念,给出了空间平界面广义炮检距不同阶地震菲涅耳带表达式。基于波动理论,推导出了广义炮检距地震菲涅耳带横向叠加波场公式。以不同阶几何菲涅耳带形状为参考,分为零炮检距和非零炮检距情况,进行了相似菲涅耳带不同绕射面元大小的横向叠加振幅分析。结果表明:①绕射面元对观测点的波场贡献与炮检距、地表起伏程度、界面倾斜程度、激发点到界面深度、观测方式和干涉叠加区大小等因素有关;②第一菲涅耳带是主要绕射波干涉叠加区,并且该区域对观测点的半振幅贡献约小于所有阶菲涅耳带的振幅贡献;③当绕射面元小于第一菲涅耳带时,即使采用非自激自收观测方式,仍有绕射面元越大观测点振幅越大的结论。
Which is convenient for the unification of different observation systems. In this paper, the concept of generalized offset detection is defined, and the expressions of Fresnel bands of different-order earthquakes with generalized offset detection of space-flat interface are given. Based on the wave theory, the formula of transverse superposition wave field of the Fresnel zone of generalized offset seismometer is deduced. Taking the geometry of different order geometrical Fresnel zones as a reference, the zero-offset and non-zero offset conditions are divided into two parts. The results show that: (1) the contribution of diffracted wave to the observation point is related to the offset, the degree of surface undulation, the extent of the interface tilt, the depth from the excitation point to the interface, the observation method and the size of the interference superposition zone; The earband is the main diffraction interference superposition area, and the contribution of the region to the half amplitude of the observation point is less than the amplitude contribution of all the Fresnel bands. When the diffraction surface element is smaller than the first Fresnel zone, Non-self-excitation self-monitoring methods, there is still the diffraction element larger observation point greater amplitude conclusion.