电磁波CT揭露重大工程岩溶发育特征--以某地铁岩溶勘察为例

灰岩地区岩溶发育程度严重影响重大工程建设，以钻探为主的城市岩溶勘察，很难充分查明地下岩溶发育特征及规模，而高密度电法、浅层地震反射等其余地球物理方法因场地条件限制和干扰因素较多，在城市岩溶探测中很难实施。鉴于此，本文采用井间电磁波CT层析技术对某地铁进行岩溶探测，应用联合迭代重建技术（simultaneous iterative reconstruction technique 简称SIRT）进行反演，获取电磁波CT吸收系数等值线图，并通过吸收系数判断岩溶发育状态。研究结果表明：电磁波CT层析技术可较好揭露地下岩溶发育规模和特征，探测结果与钻孔资料揭露岩溶信息高度吻合。该方法的成功引入为重大工程岩溶探测提供了新思路，其探测成果结合钻孔信息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。

The characteristics of karst development in major projects are revealed by electromagnetic wave computed tomography :A Case for karst investigation of a Metro

The degree of karst development in limestone area seriously affects the construction of major projects. It is difficult to fully identify the characteristics and scale of underground karst development in urban karst exploration based on drilling, while other geophysical methods, such as high-density electrical method and shallow seismic reflection, are difficult to implement in urban karst exploration due to site conditions and many interference factors. In view of this, this paper uses the cross well electromagnetic wave computed tomography technology to detect the karst of a subway, uses simultaneous iterative reconstruction technique to carry out inversion, obtains the electromagnetic wave computed tomography absorption coefficient contour map, and then judges the karst development state through the absorption coefficient. The results show that the electromagnetic wave computed tomography technique can better reveal the scale and characteristics of underground karst development, and the detection results are highly consistent with the karst information revealed by borehole data. The successful introduction of this method provides a new idea for major engineering karst exploration. The exploration results combined with borehole information can be used as a reliable geological reference for major engineering construction, with good scientific significance and popularization value.