| The advance prediction of coal mine tunneling working surface is an important work to ensure the safety production of coal mine.Mine direct current method is widely used for strong resistance to electromagnetic interference.Based on the influence of geological anomalies in different locations and roadway,the paper carries out finite element forward numerical simulation on the mine DC detection method.The different geoelectric models under the condition of multi-point source power supply are solved,and have a certain understanding of the electric field distribution of the whole space without roadway electric field;On this basis,the existing model of roadway is established.Different models are established by changing the position of multi-point current source in the roadway,the number of power supply electrodes and the distance between power supply electrodes.The recognition and resolution ability of different field source parameters to abnormal body is analyzed,and the distribution law of electric field of multi-point current source in roadway is summarized.The research has achieved the following results:(1)This paper derived the potential expression of any point source,selecting free tetrahedral mesh for segmentation,carrying out a positive simulation of the three-dimensional spatial distribution based on the finite element method.(2)Through finite element calculus,the potential of different ground electric models under multi-point source power supply is solved.The electric field distribution law is summarized,and the electric field distribution characteristics is analyzed,in the whole space with and without roadway.The arrangement direction of the power supply electrode has been changed,without the roadway,which basically has no impact on the abnormal body response.With the increase of the number of supply electrodes and pole distance the response to the amplitude of abnormal body raised,and the overall trend has not change greatly.(3)By changing the position of multi-point current source in the roadway,the number of power supply electrode and the pole distance,the identification ability of different field source parameters is analyzed and the distribution law of multi-point current source is summarized in the roadway.The arrangement direction of power supply electrode in the roadway affects on the identification of abnormal body.Geologic anomalies are more responsive when the power supply electrode is arranged along the shorter side of the roadway section.Increasing the number of power supply electrodes and the pole distance of the power supply electrode can improve the positioning ability of the anomaly,the amplitude of the apparent resistivity is also enhanced,and the amplitude of the apparent resistivity is positively correlated with the product of the number of power supply electrodes and the pole distance of the power supply electrodes.(4)Affected by the cavity shielding of the tunnel,with the source away from the roadway,the amplitude of the response to the geological anomaly becomes smaller. |
