跨孔地震CT技术在地铁工程施工溶洞探测 方面的应用

本文介绍了在南京地铁4号线某区间应用跨孔地震CT技术进行现场数据采集的方法，并运用Matlab语言编制程序，通过最小二乘法对大型线性稀疏矩阵方程进行求解，由生成的三维网格数据绘制波速等值线图，从而实现了孔间介质波速层析成像的功能。根据成像图中低速带范围及波形分析确定了溶洞位置和充填情况，经checkerboard测试，并与钻探资料和地质雷达影像对比分析，结果表明跨孔地震CT技术用于地下岩溶探测时可靠性高，能够实现对孔间岩溶发育状况的超前预报。

Theapplication of Cross hole Seismic CT Method in the Karst Cave Exploration of Metro Engineering Construction

A survey method of the cross hole seismic CT technology was introduced to karst exploration in a section of metro line 4,Nanjing City. A Matlab program was compiled to realize the function of velocity tomography between two boreholes through solving the least squares solution of the linear sparse matrix equation, generating 3D grid and wave velocity contour map. The position and size of karst caves along with whether or not filled were determined according to the range of low velocity zone and seismic waveform characteristics. The result of checkerboard resolution test directly shows that the major characteristics of CT image are reliable. Through interpreted results were consistent with the drilling data and ground penetrating radar (GPR) image. Thus, this geophysical method had a high reliability on detecting karst caves. And advance forecast on karst developing status could be finally achieved.