地面地震CT在浅层勘探中的应用

在地表面沿研究区域的四周布置激发点和检波器 ,进行人工地震观测记录。地震能量由激发点到达接收点 ,利用直达波、反射波和折射波等多震相 ,进行 CT反演 ,得到波速地震 CT图像。该图像给出浅层波速横向分布 ,反映了覆盖层分区及基底岩性特点与构造分布。该方法应用于某工程场地的浅层勘探中 ,所得波速 CT图像与地质露头及开挖相吻合。该方法将地震 CT技术从钻孔和巷道中解放出来。

APPLICATION OF SURFACE SEISMIC TOMOGRAPHY TO SHALLOW GEOLOGICAL SURVEY

Shots and receivers are placed on the ground surface around the studied area ; the observation is performed by using conventional seismic method. The energy exited from sources arrives at receivers. The signals recorded are processed by tomographic inversion and a P-wawe velocity image is produced. The image shows velocity distributions in shallow layers and weathering deposits, as well as geological structure of bedrock. This technique was used in an engineering-geological survey. The velocity CT image obtained is coincident with geologic outcrops and excavation result.