Research on the application of direct current resistivity method in coal seam floor water inrush monitoring

The current researches on the application of direct current resistivity method in coal seam floor water inrush monitoring mainly focus on the resistivity response characteristics of the deformation and damage of the floor, and there are few researches on the resistivity change law of the dynamic development process of water channels. In order to solve the problem of floor water inrush in the North China coalfield, the direct current resistivity method is used to monitor the abnormal structure of floor water-bearing and water-conducting under the influence of mining. Firstly, the paper introduces the working principle of direct current resistivity monitoring system at coal working face and the automatic processing and interpretation method of monitoring data based on three-dimensional inversion of resistivity. Secondly, the paper constructs a geological model for monitoring the process of floor water inrush and carries out the numerical simulation study of the development process of floor water-bearing and water-conducting structures. Finally, the floor direct current resistivity monitoring test is carried out in the coal mine. The numerical simulation results show that the distribution range of abnormal structures of water bearing and water conducting along the survey line can be identified based on the resistivity three-dimensional inversion results. The development of abnormal structures can be inferred from the changing trend of resistivity over time. The low-resistance anomaly response gradually increases as the abnormal water bearing and water conducting structures developing upward, and the low-resistance anomaly increases gradually in the vertical direction. The results of the coal test show that the direct current resistivity monitoring successfully captures the process of water inrush from the floor of coal working face, and the time of abnormal changes in resistivity is earlier than the actual water inrush time of the working face. The low resistance response gradually increases before the increase of water inrush from the working face, which is basically consistent with the numerical simulation results. After the water inrush from the working face, the low resistance abnormality gradually weakens. The results show that the direct current resistivity method can be used for early warning of water inrush from the working face. However, determining the development height of the abnormal structure accurately requires a comprehensive interpretation combined with other monitoring methods.