地震CT在岩溶精细探测中的应用与探讨——以深圳地铁14号线为例

因场地条件限制和干扰因素较多,地震反射、电法等地球物理探测手段在城市岩溶探测中很难实施。利用地震波CT(computerized tomography)层析成像技术对深圳地铁14号线进行岩溶精细探测,将获取的井间地震波初至走时进行反演,并对数据处理与分析进行研究,最终获取地下介质内部波速结构,并以此判断岩溶发育状态。实验结果表明:地震CT层析成像技术能较好查明基岩面起伏形态,并能以小于1 m的分辨率精细探测地下岩溶发育规模,其探测结果与钻孔资料高度吻合。该方法的成功引入为城市轨道交通岩溶探测提供了可行性方案,其探测成果可作为重大工程建设可靠的地质参考依据,具有较好的科学意义和推广价值。

Application and Discussion of Seismic CT in Detailed Karst Detection:A Case of Shenzhen Metro Line 14

Because of the limitation of site conditions and many interference factors, it is difficult to implement seismic reflection, electrical method and other geophysical detection methods in urban karst exploration. In this paper, seismic CT tomography technology is used to detect karst in Shenzhen Metro Line 14. The first arrival travel time of cross-well seismic wave is inverted, and data processing and analysis are studied. Finally, the velocity structure of underground media is obtained, and the development state of karst is judged.The experimental results show that the seismic CT tomography technology can better identify the fluctuation shape of bedrock surface, and can fine detect the scale of underground karst development with resolution less than 1 m. The detection results are highly consistent with the borehole data.The successful introduction of this method provides a feasible scheme for Karst Detection of urban rail transit. The results of this method can be used as a reliable geological reference for major engineering construction, and have good scientific significance and popularization value.