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超声波模型实验能够模拟含高速薄层组模型的特殊震相。本文把含高速双夹层的二维模型作为高速薄层组模型的一个实验例子来加以研究,并结合爆破地震记录的分析,获得赝首波传播的基本特性。沉积层的折射勘探和地壳深部测深可利用赝首波信息反演浅部或深部的薄层构造,本文为解释实际资料中的赝首波震相提供了实验依据,并就其传播机制提出了我们的看法。本文指出,赝首波可由两类性质不同的波叠加形成:1.在通过高速薄层(组)时作波型转换的透射行波(也称被屏蔽波);2.由上覆高速薄层产生的下行首波。在特定条件下,如上覆高速薄层(组)的层厚度远小于首波波长值以及赝首波形成层在层厚和介质弹性等方面占有优势,赝首波可以在振幅上大于超前的波。赝首波的透射能力和波型转换次数受震源的强度、震源在非近场下的波谱特性、介质的吸收特性、转换薄层的层数、各界面的速度反差,以及赝首波形成层的厚度、弹性和连续性等诸多因素的制约。
The ultrasonic model experiment can simulate the special phase of the phase with the high-speed thin-layer model. In this paper, a two-dimensional model with high-speed double-layered sandwich is studied as an experimental example of the high-speed thin-layer model. Combined with the analysis of blasting seismic records, the basic characteristics of pseudoplastic primary wave propagation are obtained. The refraction of sedimentary layer and deep crustal depth can be obtained by using pseudo-prion wave information to retrieve shallow or deep thin-layer structure. This paper provides experimental evidence for explaining the pseudoecho-first seismic facies in real data and proposes its propagation mechanism Our opinion This paper points out that the pseudoschemic wave can be formed by two types of superposition of different types of waves: 1. Transmitted traveling waves (also known as shielded waves) that are mode-converted when passing through a high-speed sheet (group) Layer generated the first wave of the downlink. Under certain conditions, the layer thickness of the overlying high-speed thin layers (groups) is much smaller than the first-wavelength value and the pseudoplastic first-layer forming layer has advantages in terms of layer thickness and dielectric elasticity. The pseudo-first wave can be larger in amplitude than the advanced wave . The transmissivity and the number of mode transitions of the pseudo-first wave are affected by the source intensity, the spectral characteristics of the source in non-near-field, the absorption properties of the medium, the number of layers converted, the velocity contrast at each interface, The thickness, flexibility and continuity and many other factors.