瞬态多道瑞利面波实验中的模型尺度影响  

Approach to the model scale influence in the experiments of multi-channel Rayleigh waves

作　　者：韩超[1] 刘争平[1] 熊自英[1] 张慧来[1] 李阳[1] 

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《地球物理学进展》2016年第3期1313-1319,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(41274107)资助

摘　　要：在瞬态多道瑞利面波实验室研究中,通常使用的有限尺度模型与实际半无限空间介质存在很大的差异.本文基于三维有限元数值模拟技术对实验室有限尺度模型中激发的声波波场进行了数值模拟,研究和分析了模型有限尺度的瑞利面波波场特征,以及模型侧边界影响对利用瞬态多道瑞利面波地震记录拾取频散曲线的干扰特征.研究表明,来自平行观测排列两侧边界面的反射面波是拾取速度频散曲线主要的干扰因素,模型的半宽度至少应近于或大于实验激发波场的主波长一个量级条件下（5-10倍）,该反射面波的干扰可以通过常规面波处理流程消除.此外,本文还研究和提出了在不改变模型尺度硬件条件下,应用τ-p变换分离波场方法可有效消除模型尺度影响.本文最后以一模型实验实例,验证了本文提出的问题和解决方案的可行性.In the experiments of multi-channel Rayleigh waves,there is a great size difference between the small-scale model in the laboratory and the semi-infinite space model in field conditions.Based upon the three-dimension numerical modeling by Finite Element Method, this article simulates the acoustic wave field excited in finite size models,and analyzes the characteristics of Rayleigh wave field in the sized models and the effects to picking up the dispersion curve. The researches show that the reflected Rayleigh waves from the both side interfaces of a model along with the observation layout are main interference factors to picking up the dispersion curve,and if the half wideness of the model is close or large over an order of magnitude（ 5 - 10 times） of the main wavelength of Rayleigh wave approximately,the interference could be deleted by the conventional processing method for Rayleigh waves. Moreover,the article also presents a method to reduced the interference based on the wave separation with τ-p translation without the need to enlarge the model size. Finally,an experiment case is given to verify the interference problem and the flexibility of the solution scheme illustrated in the article.

关 键 词：瑞利面波 模型尺度 数值模拟 波场分离 

分 类 号：P631[天文地球—地质矿产勘探]