【摘要】 在复杂地表区采用传统的射线追踪算法得到的近地表速度结构与微测井测量结果偏差较大,造成这种情况的主要原因是求取射线路径的精度较低。采用常规的基于旅行时平方的非线性插值法虽然提高了射线路径和旅行时间的计算精度,但是不适用于速度变化剧烈地区。本文在分析此类非线性插值法误差来源的基础上对该方法进行改进,在充分考虑各种可能射线路径的基础上,采用非线性旅行时插值方法计算地震初至波的射线路径和旅行时。数值计算结果表明:本方法在保证地震波旅行时计算精度的前提下,可以采用较粗的计算网格提高射线追踪的效率,并能够适应各种复杂的速度结构。更多还原

【Abstract】 There is large difference in near-surface velocity structure between the results of uphole survey and traditional ray-tracing algorithm in complex surface area, the main reason of which is lower precision of computed ray path. The traditional non-linear interpolation based on travel-time square although improved the computational precision of ray path and travel time, the algorithm is not suitable for the area the velocity violently changed. Based on analyzing the error source of this kind of non-linear interpolation, the paper improved the algorithm, using non-linear travel-time interpolation to compute ray path and travel time of seismic first breaks on the basis of fully considering various possible ray paths. The numeric computational results showed that the approach can use sparse computational grid in a precondition of guaranteeing computational precision of seismic travel times, improving efficiency of ray tracing and can suitable for various complex velocity structures.更多还原