【作者】 李培；

【导师】 熊章强；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2011， 硕士

【摘要】 瑞雷面波勘探法是一种新型的工程地球物理勘探方法。该方法具有检测速度快、检测设备简单、分辨率高、对环境无破坏等优点,因此在实际生产和科研中得到广泛应用。瑞雷面波频散曲线的反演解释是瑞雷面波勘探技术最重要的一个环节。由于瑞雷面波传播速度与岩土力学性质密切相关,通过反演瑞雷面波频散曲线可以直接进行地质分层并且可以获取重要的岩土力学参数——横波速度,进而求取更多的地质参数,进行合理的地质解释。目前用于瑞雷面波频散曲线反演的方法很多,线性反演方法以其简单、快速的优点得到广泛应用。本文采用加权阻尼最小二乘法反演瑞雷面波频散曲线。但是在求解瑞雷面波反演方程的时候,经常会遇到系数矩阵“病态”的情况,这是由地球物理问题的特殊性所导致的,奇异值分解技术的运用可以有效地改善方程的病态程度,避免系数矩阵奇异。权重矩阵和阻尼因子的运用有效地改善了系数矩阵的条件数。本文设计了两种最常见的模型,即层速度递增介质模型和层状含软弱夹层介质模型,采用快速矢量传递矩阵算法进行正演模拟,并利用改进之后的阻尼最小二乘法对所提取出来的频散曲线进行反演,验证该算法的反演效果。反演的结果表明,该算法具有反演速度快、精度高、稳定等优点。最后通过实测频散曲线进行反演,也取了比较好的效果,验证了该算法的实用性。更多还原

【Abstract】 Rayleigh wave prospecting is a new method of engineering geophysical exploration. It has been used widely in production and scientific research, since it has many advantages such as fast detection speed, simple testing equipment, high resolution, no damage to the environment and so on. In recent years, more and more researchers have been devoted to exploiting and utilizing Rayleigh wave. It will become one of the most powerful approaches in shallow geophysical survey and engineering quality inspection.Inversion of Rayleigh wave dispersion curves is the most important aspect in Rayleigh wave exploration technique because the shear-wave velocity can be obtained, which is an important geotechnical parameters, and the stratum can be divided. So we can know more geotechnical parameters so as to solve the geological problems. Currently many approaches can be used to invert the Rayleigh wave dispersion curve, but the linear inversion method can be used widely since it is simple and fast. In this paper, the weighted damped least square is used for the inversion of Rayleigh wave dispersion curve. However, the coefficient matrix will always be the "sick" situation when we solve the equation of Rayleigh wave inversion. It is due to the special nature of geophysical problems. The use of singular value decomposition technique can effectively improve the equation pathological level to avoid the coefficient matrix is singular. The condition number of coefficient matrix can be effectively improved by weight matrix and the damping factor. This paper designs two of the most common model which are the model of increasing velocity and the model of layered media with weak interlayer, using the fast vector-transfer algorithm for forwarding the model and using the improved damping least square method for the inversion of the two models to verify the effect of inversion. The results show that this algorithm is fast, high accuracy and stability. Finally, using this algorithm to inverse the measured dispersion curve, we can obtain correct results. It verifies that the algorithm is practical.更多还原