一种用于波速测试的正演和反演算法

A Forward and Inversion Algorithm for Wave Velocity Test

波速测试的正演和反演算法是通过地表或井间观测到的地震波走时,推算地下或井间的介质速度结构和地震波的传播路径。其步骤如下:(1)数据采集。(2)将地下介质离散成一定大小的网格并初始化慢度(速度的倒数)场,采用射线追踪技术推导各网格节点的射线路径和最小旅行时。(3)建立线性方程组。(4)反演求解线性方程组,并修正初始慢度模型。(5)重复(2)-(4)步骤,不断修正慢度场,直到满足精度要求为止。本文采用最短路径射线追踪正演算法和同时迭代重建(SIRT)反演算法在二维平面上进行求解计算,并且把得到的结果与传统单孔法比较,从而了解本文所采用的波速测试方法的可靠性、实用性及其精度情况。

Forward and inversion algorithm of wave velocity test to calculate the underground or medium of cross-hole velocity structure and seismic wave propagation path through traveling time of the earth＇s surface or cross-hole seismic earthquake wave.The steps are as follows：（1）Data collection.（2）The underground medium must be divided into the same size of the grid and initializes the slowness （the reciprocal of speed）,Ray tracing technology is used to derive the ray path and minimum travel time of the grid nodes.（3）Establishing linear equations（4） solving linear equations by using inversion techniques, then correcting the initial model of the slowness.（5）Repeating steps （2） to （4）,Continuously revising slowness, until meet the precision requirement.This paper uses the shortest path ray tracing algorithm and the improved simultaneous iterative reconstruction techniques（SIRT） to ifnd the result in 2 d plane ,and compares the results to- that got with the traditional single hole method so as to understand the reliability,practicality and accuracy of wave velocity test method in this article.