弹性波在层状地质结构中的传播特性仿真研究

Simulation Study on Propagation Characteristics of Elastic Waves in Layered Geological Structures

利用弹性波进行地质结构探测是地球物理勘探中最主流的方法之一,其主要利用弹性波在不同地质结构中的传播特性进行探测,由于地层介质按物性具有层状结构,因此研究弹性波在不同构成的层状地下半空间的传播特性是弹性波地质勘探的基础。针对弹性波在层状地质结构中的传播问题,本文首先推导了层状地层结构中的基本波动方程,然后基于有限元仿真软件COMSOL建立几种常见的地层结构模型并进行仿真分析。结果表明,只有两层高速覆盖层地质结构和速度递减型三层地质结构,其中弹性波能量能够传播到最下层,其余类型地质结构,弹性波在分界面会发生反射,弹性波基本都集中在表面层介质。本研究能够用于指导弹性波地质探测工程实践,具备一定的工程参考价值。

Geological structure detection using elastic waves is one of the most mainstream methods in geophysical exploration. It mainly uses the propagation characteristics of elastic waves in different geological structures for detection. Because the formation medium has layered structure according to physical properties, studying the propagation characteristics of elastic wave in different layered underground half space is the basis of elastic wave geological exploration. For the propagation of elastic waves in layered geological structures, this paper firstly deduces the basic wave equation in the layered geological structure, and then establishes several common stratigraphic structure models based on the finite element simulation software COMSOL and conducts simulation analysis. The results show that there are only two-layer high-speed overburden geological structures and velocity-decreasing three-layer geological structures, in which the elastic wave energy can propagate to the lowest layer, and for other types of geological structures, elastic waves will be reflected at the interface, and elastic waves are basically concentrated in surface layer medium. This research can be used to guide the engineering practice of elastic wave geological exploration, and has certain engineering reference value.