Application of surface-to-roadway TEMs for detecting deep aquifers in coal fields: An example from North China

Transient electromagnetic methods (TEMs) are effective tools for hydrogeological investigations of coal mines. However, traditional ground-based and underground-based TEMs typically fail to detect deeply buried waterbearing bodies in the majority of coal mines in northern China, where the Quaternary overburden is generally thick and many aquifers exist. In the present study, a surface-to-roadway TEM configuration was proposed that utilized grounded-wire sources to transmit signals with large moments on the surface and required receivers that had the ability to record signals with high resolution in underground mining roadways. First, the proposed device was introduced. Subsequently, a synthetic model was established based on the existing information of the Zhuxianzhuang coal field in Anhui Province, China, along with the analysis of forward and inversion results. Finally, the acquisition and processing of field data were conducted. Both the synthetic modeling and field results demonstrated the feasibility and superiority of the proposed method. The deeply buried aquifers were better characterized by the surface-to-roadway configuration than by ground-based surveys.