Underground pipelines are the lifelines of a modern city. Precise positioning of underground pipelines is crucial to avoid pipeline damage during successive construction above it. However, the detection of deep-buried pipelines in soft clayey deposits remains problematic. Herein, a new surface-to-borehole electromagnetic induction method is proposed by combining the traditional ground electromagnetic induction method with the magnetic gradient response in the borehole. First, a measuring method based on the magnetic flux response to the applied magnetic source in the borehole was established. Second, theoretical analysis was devised to calculate the burial depth and horizontal position of the pipeline using the measured data. By analyzing the magnetic flux response characteristics at different depths, a relationship between the maximum point of magnetic flux response and the spatial location of the target pipeline is proposed. Finally, an in situ test is performed to verify the effectiveness of the proposed method.

地下管道是现代城市的生命线。地下管道的精确定位对于避免在其上方后续施工过程中损坏管道至关重要。然而，软粘土沉积物中深埋管道的检测仍然存在问题。本文将传统的地面电磁感应方法与钻孔中的磁梯度响应相结合，提出了一种新的地对钻孔电磁感应方法。首先，建立了一种基于对钻孔中施加的磁源的磁通量响应的测量方法。其次，设计了理论分析，利用实测数据计算管道的埋深和水平位置。通过分析不同深度处的磁通量响应特性，提出了磁通量响应最大点与目标管道空间位置之间的关系。最后进行了现场测试，验证了所提方法的有效性。