Research Of The Key Techniques Of Electricity Prospecting For The Excavated Areas In Honghui Coal Mine No.3

The 8^th panel of Honghui Coal Mine No.3 is the main coal-producing area of the mine and the economic vitals of the staff. But mining out of order by small coal kilns in the past years results in large numbers of excavated areas and countless of "water bags" and " fire pits". Especially the water bags have brought great trouble to the process of excavating and mining of the panel, and made the Mine have to stop producing occasionally, which not only influenced the producing order of the panel, but also are great dangers of production. All these make the staff of the Mine live in hard life. Therefore, it is very urgent to prospect the excavated areas and "water bags" in the panel.The author took part in the electricity prospecting for the excavated areas in the panel by Synthesis Prospecting Team of Gansu Coal Geology Bureau. On the basis of collecting and studying the development and achievements of electricity prospecting, the author took part in the collocation of survey net, prospecting, collection of data, theoretical study, interpretation and validation of the achievements, paying the main attention to some key techniques in electricity prospecting for the excavated areas.With the development of geophysical Prospecting techniques, electricity prospecting has been an effective method to detect excavated areas. In the electricity prospecting for the excavated areas in the 8th panel of Honghui Coal Mine No. 3, 25m×60m survey net was collocated and direct current four pole symmetry method was used. Excavated areas show high resistance, and the excavated areas filled with water show hypo-high resistance. The ρ_s curves are divided into two types: HA and HKH。 HA is the typical curve of not excavated areas, whereas HKH is the typical curve of excavated areas. The section of ρ_s can amply reflect the changes of electricity character of strata along the direction of survey line, therefore it is the main basis for ascertaining the location of excavated areas in section. Isoline map of ρ_s represent the boundary and shape, so the location of excavated areas in plan can be ascertained according to isoline map of ρ_s. the depth of excavated areas can be ascertained with the reflectance coefficient method or using the automatic calculating program of the depth in direct current electrical prospecting developed by China Mining University. When excavated areas are filled by water the electricity character show hypo-high resistance, which is the main basis for estimating thewater-filling state of excavated areas.The studied area is divided into three subareas through this electricity prospecting work. The subarea I is excavated area, the subarea II is not excavated area, and the subarea III is abnormity area of high resistance. The information from investigate of small coal kilns, drills and detecting tunnels validate that the fact is consilient with the conclusion from electricity prospecting about the ranges of excavated area and not excavated area as well as the water-filling state in excavated area.Although the method with direct current electricity prospecting for the excavated areas is of availability, author consider that the high dense electricity prospecting method should be used in aftertime in order to overcome the limitation such as indetermination of explanation, the disturbance of electricity character by over high resistance layer.