【作者】 罗敏；

【导师】 黄真萍；

【作者基本信息】 福州大学 ， 岩土工程， 2006， 硕士

【摘要】 传统的表面法波动勘测采集到的时域记录通常都是多波耦合、叠加在一起的,大大降低了地震记录的信噪比。虽然人们已经研制出很多压制干扰波的方法, 但这些方法各有其局限性,不能较好地适用于实际工程。因此采用适当的数学手段对记录进行处理,去掉有效波以外的干扰波,提高地震记录的信嗓比是表面法波动勘测必须要解决的课题。本文所讨论的“τ-p变换在表面法波动勘测中的研究与应用”就是针对以上问题和现象,旨在提出一种既能有效地进行滤波,又便于计算机编程的地震波数字处理方法。τ-p变换中的,一般称为水平波慢度即速度的倒数,Τ是指截距期间。在X-了域中混杂的直达波、反射波、折射波和面波在τ-p 域内却能清楚地分离开来,利用这个特性在τ-p域内通过窗口圈定和能量增减就可以分离各种波,从而达到提取有效波,压制干扰波的目的。本文从表面法波动勘测和τ-p变换的原理出发,推导出将二维地震记录变换至τ-p域的公式,并实现这种变换的计算机数值计算.针对各种地震波在τ-p域内的运动特征,通过理论模型试验,探讨了τ-p域内各种地震波分离、提取的方法。同时在Τ—P变换过程中会产生大量的假频和端点效应,严重影响了该变换的质量, 但这却是倾斜叠加所不可避免的缺陷,针对这些缺陷论文详细地探讨了用恒速介质反假频时窗、加以叠加、曲线速度滤波、相似函数法、滤波法和直接切除法厂制假频和端点效应,分析发现单独使用每一种方法其压制假频和端点效应的效果并不理想,但是结合起来,使用可以达到比较完美的效果。论文把上述研究内容应用到实际的工程中,并把通过Τ—P变换处理后的地震资料与传统方法处理的结果相比较,发现经Τ—P变换处理后的有效波更为突出,充分说明了τ-p变换方法的实用价值和无限的工程前景。. 本文的主要创新点:在瞬态瑞雷面波资料处理过程中入τ-p正、反变换, 提高了面波基波的提取效果; 综合使用多种压制假频和端点效应的方法,提高了地震资料的信噪比。更多还原

【Abstract】 The time domain records acquired by traditional surface exploration method always contain several mixed waves, and it sharply reduces the signal-to-noise of seismic records. Though many methods have been already developed to suppress the interference wave, but all these methods have their own limitations, and consequently can’t apply to the engineering project. So it is imperative to choose the appropriate mathematic method to process records, remove the effective wave outside of the interference wave and raise the signal-to-noise of seismic records. ’The study and application of x-p transformation in surface exploration’ discussed in this dissertation is based on the above mentioned problem, in order to raise a new method not only able to filter, but also readily applicable to program. The ’p’ in x-p transformation means the horizontal wave slowness, and the ’x’ means the intercept time. The direct wave, refraction wave, refracted wave and surface wave mixed in time domain can be separated distinctly in x-p domain. By utilizing of this characteristic of x-p transformation separate each kind of waves can be separated, the effective wave can be picked up, and the interference wave can be suppressed by windows selecting and energy changing in x-p domain. Based on the surface exploration and the principle of x-p transformation, this dissertation proposes the formula which can transform two domain seismic records into x-p domain, and also completes the computer numerical calculating. According to the movement characteristic of each wave and the theoretic model, the dissertation also presents the way to separate and extract each wave. Simultaneity, there will be produced abundances of alias and leverage point effects during the x-p transformation, which badly influences the quality of x-p transformation, but this can’t avoid because of slant stack. The dissertation introduces the De-alias windows, weighting slant, hyperbola velocity filtering, similar function, filtering and direct eliminating. By using the introduced method separately, the results are not satisfied. However the excellent results can be obtained by the combination of them. In the end, the T-p transformation is verified in engineering project. By the comparative analysis of the seismic data via x-p transformation and the ones without it, it is obviously that the effective wave is much clearly by the x-p transformation. The x-p transformation is really valuable and useful, and will have a prospering future. The innovative points include of this dissertation is introducing the x-p transformation into transient Rayleigh wave method to improve the extracting effect of fundamental surface wave; utilizing several methods to suppress alias and leverage point effects to raise the signal-to-noise.更多还原