地质雷达在隧道掌子面及基底岩溶探测中的应用

Application of Ground Penetrating Radar in Tunnel Heading Face and Karst Detection at the Base

摘要: 隧道施工进入复杂围岩段后，掌子面前方围岩条件和基底稳定性往往变化较快，若判断不及时，容易引发掉块、局部失稳、渗水等问题。地质雷达具有无损、快速、分辨率较高和现场操作灵活等特点，近年来在隧道短距离超前地质预报中应用较多。本文依托天水至陇南铁路的马街隧道3号横洞小里程段，结合现场掌子面超前探测、基底岩溶探测及掌子面地质素描资料，对地质雷达在两个不同应用场景中的使用效果进行了分析。结果表明，地质雷达能够较敏感地反映围岩破碎、节理裂隙发育及局部含水异常等信息，对基底浅部异常区也具有较好的识别能力。工程应用表明，将地质雷达用于掌子面超前预报和基底岩溶排查，能够为施工中的短进尺开挖、初期支护加强和截排水措施调整提供较直接的依据，具有较大的推广应用价值。

Abstract: After tunneling enters a complex surrounding rock section, the geological conditions of the rock mass ahead of the heading face and the stability of the base often change rapidly. If these changes are not promptly identified, issues such as rock falls, local instability, and water seepage may occur. Ground Penetrating Radar (GPR) is characterized by being non-destructive, fast, having high resolution, and offering flexible on-site operation. In recent years, it has been widely applied in short-range advanced geological forecasting in tunneling. This paper, based on the small mileage section of the No. 3 cross tunnel of the Majie Tunnel on the Tianshui-Longnan Railway, analyzes the effectiveness of GPR in two different application scenarios by integrating on-site advanced detection at the heading face, karst detection at the base, and geological mapping data from the face. The results show that GPR can sensitively reflect information on rock mass fragmentation, the development of joints and fissures, and local water content anomalies. It also demonstrates good capability in identifying shallow abnormal zones at the base. Engineering applications indicate that using GPR for advanced forecasting at the heading face and for karst investigation at the base can provide direct evidence for short-step excavation, reinforcement of primary support, and adjustment of interception and drainage measures during construction. This approach holds significant potential for broader application and promotion.