公路下伏采空区瑞雷波传播数值模拟

发布时间：2018-01-19 13:37

本文关键词： 公路下伏采空区瑞雷面波有限差分波场数值模拟绕射波　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国交通事业迅猛发展,路网密度越来越大,在采空区上方修建公路已经不可避免,然而下伏采空区对地表公路是一个巨大的潜在威胁。瑞雷面波勘探法凭其抗干扰能力强、浅层分辨率高、衰减小、快捷轻便等优点,在采空区探测中得到了广泛应用。为更清楚地了解瑞雷面波在地下采空区中的传播规律,提高实测数据的解释精度,并为采集图谱的反演解译提供理论基础,本文基于交错网格有限差分法建立了多种地下介质模型,分析了不同类型的采空区对瑞雷面波传播信号的影响。主要研究结论如下:(1)推导了弹性波动有限差分方程,在此基础上运用C++语言编写了相应的瑞雷面波波场正演数值模拟程序。建立了均匀半空间、两层半空间、三层半空间介质模型,模拟了瑞雷面波在这三种介质中的传播过程,模拟结果表明:瑞雷面波在均匀介质中无频散现象,在层状介质中具有频散现象,这与瑞雷面波的基本传播理论一致。(2)建立了均匀半空间含采空区介质模型,模拟了瑞雷面波在这种介质中的传播过程,模拟结果表明:当地震波传播至采空区边界时,会产生绕射波,因此,在实际工程探测中,可根据地震记录图像是否存在绕射波来预估地下岩层中采空区的存在。(3)建立了层状半空间含不同尺寸、埋深、充填物采空区的介质模型,分别模拟了瑞雷面波在其中的传播过程,模拟结果表明:各个模型中采空区的出现均导致地震记录发生显著变化,即在采空区所在位置处产生绕射波;采空区尺寸越大,单炮记录中绕射波越多;采空区埋深越大,单炮记录中的绕射波产生的时间越晚,且绕射波能量越弱;当采空区为充气、充水或充填碎石时,单炮记录几乎没有差别。(4)对比河南省S323线改建工程下伏采空区探测所得地震记录与对应的数值模拟单炮记录,结果基本一致,说明该数值模拟方法是可行的、有效的,从而可以为瑞雷面波在探测公路下伏采空区中的应用提供一定的理论指导和技术支持。
[Abstract]:With the rapid development of transportation in China, the density of road network is increasing, and it is inevitable to build a highway above the goaf. However, the underground goaf is a huge potential threat to the surface highway. Rayleigh surface wave exploration method has the advantages of strong anti-jamming ability, high shallow resolution, small attenuation, quick and light, and so on. It has been widely used in goaf detection, which provides a theoretical basis for understanding the propagation law of Rayleigh surface wave in underground goaf, improving the interpretation accuracy of measured data, and providing a theoretical basis for inversion interpretation of collection map. In this paper, a variety of underground media models are established based on staggered grid finite difference method. The influence of different goaf on Rayleigh wave propagation signal is analyzed. The main conclusions are as follows: 1) the finite difference equation of elastic wave is derived. On this basis, the corresponding numerical simulation program of Rayleigh surface wave field is compiled with C language, and the homogeneous half-space, two-layer half-space and three-layer half-space medium model are established. The propagation process of Rayleigh wave in these three media is simulated. The simulation results show that the Rayleigh wave has no dispersion phenomenon in homogeneous medium and frequency dispersion phenomenon in layered medium. In accordance with the basic propagation theory of Rayleigh wave, a homogeneous half-space medium model with goaf is established, and the propagation process of Rayleigh wave in this medium is simulated. The simulation results show that when the seismic wave propagates to the goaf boundary, it will produce diffraction wave, therefore, in the actual engineering detection. According to whether there is diffraction wave in seismic record image to estimate the existence of goaf in underground rock strata, a medium model of the goaf with different sizes, buried depth and filling material in layered half-space can be established. The propagation process of Rayleigh wave is simulated respectively. The simulation results show that the occurrence of goaf in each model results in significant changes in seismic records, that is, diffraction waves are produced at the location of goaf. The larger the size of the goaf, the more diffraction waves in the single shot record. The deeper the goaf is, the later the diffraction wave in the single shot record is produced and the weaker the energy of the diffraction wave is. When the goaf is inflated, filled with water or filled with gravel. There is almost no difference between the single gun record and the corresponding numerical simulation single gun record. The results are basically consistent with the seismic records obtained from the underground goaf exploration under the reconstruction project of S323 line in Henan Province. It is shown that the numerical simulation method is feasible and effective, which can provide some theoretical guidance and technical support for the application of Rayleigh surface wave in detecting goaf under highway.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U412.2

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