路基下伏地质缺陷弹性波数值模拟

针对我国西部黄土地区特殊的地形地貌、近地表条件和地下浅层目标体，开展了路基下伏地质缺陷地震探测技术的应用研究。为检验不同地震方法的探测能力，设计了一个综合地质地球物理模型，包含凹陷、断层、地裂缝、地下低速体、软弱夹层及滑坡等典型地质缺陷，利用有限差分波场模拟，计算出多分量反射地震记录和面波地震记录，分别进行了反射波成像和高阶面波反演横波速度成像。数值模拟结果表明，反射波成像和高阶面波反演横波速度成像技术对真实模型中的凹陷、断层、浅层低速体、软弱夹层及滑坡等主要地质缺陷均能清晰成像，验证了地震方法探测路基下伏地质缺陷的可行性。数值计算结果表明，不同的地球物理探测方法对地质缺陷的探测效果和适用范围不同。

Numerical Modeling of Elastic Waves for Geological Defects Under Roadbed

Aiming at the special landform, near surface conditions and subsurface objects in loess districts of western China, the authors studied detecting applications of the seismic techniques. To examine the efficiency of different seismic methods, a comprehensive geological model was designed. This model included some typical defects such as sag, fault, ground fissure, hidden low velocity body, weak intercalated layer and landslide. Multi-component seismic reflections and surface wave records were numerically computed with the finite difference method. Reflection imaging and high order surface wave imaging were acquired respectively. The results of numerical modeling proved that all the typical defects models such as sag, fault, ground fissure, hidden low velocity body, weak intercalated layer and landslide were imaged clearly. The numerical modeling results indicated the feasibility of shallow geological defects detection under roadbed by seismic methods.