瞬态瑞利波法频散曲线的仿真研究

发布时间：2018-01-11 14:40

本文关键词：瞬态瑞利波法频散曲线的仿真研究　出处：《华中科技大学》2013年硕士论文　论文类型：学位论文

【摘要】：瑞利波勘探是近二十年来发展起来的浅层地震勘探新方法。该方法操作简便、成本低，被广泛的应用于工程地质勘察和工程质量无损检测领域。本文利用有限元软件建立不同土层条件下分层土的轴对称模型，并用MATLAB软件进行数据后处理分析，重点研究了地基土中瞬态瑞利波法频散曲线的一些特性，以及影响频散曲线精度的相关因素。首先，讨论了瞬态瑞利波法有限元模型建立的相关条件，确定了模型尺寸、网格大小和边界条件等计算参数，并论证了合适振源函数的选取；提取均匀介质中的频散曲线，通过与理论结果对比，验证了有限元计算的合理性。其次，根据频散曲线提取的计算流程，对影响瞬态瑞利波法频散曲线的相关因素如干扰波、偏移距和道间距等做了一定的研究与分析，给出了提取高精度频散曲线的一些建议。最后，采用有限元方法模拟多层土层介质模型中，得到荷载作用下地层的波动响应，，通过提取并分析相关频散曲线，得到各土层厚度和瑞利波波速，进而与理论值相比较，论证了瞬态瑞利波法频散曲线用于浅层勘探的合理性，同时对复杂地层如软弱夹层中频散曲线的相关特性包括所谓的半波长解释法展开了进一步的研究。
[Abstract]:Rayleigh wave exploration is developed in the recent twenty years of shallow seismic exploration method. The new method has the advantages of simple operation, low cost, is widely used in the detection field of engineering geological exploration and engineering quality nondestructive. Axisymmetric model by using finite element software to establish the layered soil with different soil conditions, and use MATLAB software for data postprocessing analysis focuses on the foundation of transient Rayleigh wave dispersion curves of some characteristics, and related factors influencing the dispersion curve precision.
First of all, discusses the conditions for establishing the finite element model of transient Rayleigh wave method, to determine the model size, mesh size and boundary condition parameters, and demonstrates the proper source function; extraction medium dispersion curve, by comparing with the theoretical results, verify the rationality of the finite element method.
Secondly, according to the calculation process extracted from the dispersion curve, the related factors which affect the Rayleigh wave dispersion curve are studied and analyzed, and some suggestions for extracting the high-accuracy dispersion curve are given.
Finally, using finite element method to simulate the multilayer soil medium model, response formation fluctuation of loads, through the extraction and frequency dispersion curve analysis, the thickness and velocity of Rayleigh wave, and compared with theoretical values demonstrated transient Rayleigh wave dispersion curve for the rationality of shallow exploration, at the same time the characteristics of the complex formation such as weak interlayer dispersion curves including the half wavelength of the so-called interpretation method carried out further research.

【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P631.4;TU19

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