复杂介质的折射波射线追踪

本文由二维层状介质模型出发论述了折射波逐段迭代射线追踪的原理，由于连接炮点和接收点之间的初始射线路径满足费马原理，因此其上任意连续三点之间的射线路径也满足费马原理。据此即可分别推导出透射中间点和折射点的一阶修正公式，进行折射线逐段迭代计算求出整条射线路径。将此原理推广到二维块状介质模型，用于解决复杂介质中的折射波射线追踪，推导出任意界面上折射点的一阶显式增量修正公式。避免了高次多元方程的求解，具有计算速度快，能够适用任意界面的特点。文中还指出了在块状介质模型中用逐段迭代法进行射线追踪较在层状介质中难度大的原因在于射线路径点的增、删。实例试算表明。文中所述方法是一种有效的折射波射线追踪方法。

Refraction ray-tracing in complex medium.

Starting from 2-D layered medium model,the paper described the theory of iterative refraction ray-tracing segment by segment: as the primary ray-paths connecting shot-points and receiver points met Fermat's principle,the ray-paths connecting three arbitrary points also met the Fermat's principle.Accordingly,the first-order modified formula for transmitted intermediate points and refracted points is derived and whole ray-path can be computed for refracted ray iteratively segment by segment.The first-order explicit modified increment formula at refracted points of arbitrary interface is derived and the principle is popularized to the 2-D blocky medium model,which is used to solve refraction ray-tracing in complex medium that avoids solve the high-order,multivariate equations and is characteristic of fast computational speed and suitable for arbitrary interface.The paper also pointed out that the reasons having bigger difficulties in blocky medium than in layered medium when using iterative ray-tracing segment by segment are in increasing and deleting the ray-path points.The real case showed that the method in the paper is an effective refraction ray-tracing method.