Experimental Study On Disaster Water In Floor Of Coal Working Face By The Frequency Domain Electrical Method

With the increasing depth of coal seam exploitation in China,the problem of water damage in the coal mining face is becoming more and more serious.Strengthening the exploration of water damage in the working face is urgently needed.Therefore,it is of great practical significance to further study on the frequency-domain electric field detection method of coal-mining face.Based on the existing research,the paper studies the frequency-domain electrical detection technology of coal-mining face.Among them:(1)By summarizing and analyzing the conventional detection methods,the well-conducting spherical model instead of the water-bearing body of the coal mining face under the full space condition,and the formula of frequency-domain electric field response is derived.Through the calculation and comparison of different model parameters,the analysis shows that the frequency-domain electric field method has good sensitivity to the resistivity,size and spatial position of the model,and points out the complexity of the electric field perspective curve.(2)In order to further improve the test efficiency,perspective distance and signal acquisition accuracy of the frequency-domain electrical method,on the basis of analyzing the traditional electrical equipment,through the expansion of the number of transmitting and receiving channels,and the optimization of the transmitting frequency,and the improvement of the sensitivity of the instrument,and expansion of the receiving voltage range and widening of the dynamic range of the voltage,etc.The YBT-32 mine parallel electric fluoroscopy system are developed.By testing and analyzing the experimental data of two groups of different electromagnetic interference environments,it is determined that the effective observation distance of the system can reach 420 m in an ideal environment,while in a relatively complex mine environment,the system can generally observe 312 m,which reflects YBT-32's large penetration distance characteristics.Through the optimization of the field data acquisition and arrangement,the number of data test points is enhanced and the electric field coverage is increased.In order to further perfect the imaging accuracy of the method,the minimum constructed conjugate gradient inversion algorithm is introduced.The theoretical verification results show that the algorithm has the characteristics of fast convergence and small iteration error in the process of solving large equations,which improves the accuracy of tomography.(3)So as to verify the effectiveness and reliability of the improved system,two sets of physical models experiments with different degrees of complexity were designed.The results show that the frequency domain electrical method can be used to effectively and accurately detect the electrical anomaly of the working face floor and the location of the anomalous body space.The field detection experiment further indicates the accuracy of the method for detecting the water disaster in the working face floor,and can provide powerful guidance for the prevention and control of coal-mining water disaster,which is worthy of popularization and application.Figure[38] Table[5] Reference[78]...