| ABSTRACT:Because of the brief method, intuitive results, and the high precision and good resolution of geological radar on geological structure and abnormity underground, it is more applied on ground recently. But when used in the mine, because of the special explotion-proof environment and finite space, it is more difficult for spreading application in mine. So under the sponsor of project of the state basic research development program of china (973program)"rule of response of physical parameters for evolutionary process of dynamic disaster of coal and rock"(2005CB221505), the project of state key program of national natural science of china "the detection thory and method of coal and gas outburst danger zone"(50534080), the major project of "ten-five" national key technologies R&D peogram of china "the research of electromagnetical detection and equipment (2004BA803B0101)", this paper start new work on research of new shock pulse explosion-proof geological radar method and equipment which fit for the mine environment of our country.At first, accoding to introduction, absorption and innovation, we developed KJH-D impulse-type explosion-proof mine geological radar, which is the first new mine geological radar in our country. This not only obtaines "MA", but also fill the gap in this area of our country.The second, with the further research of radar thory, we build models of radar wave propagation, forward modeling the general geological anomaly in mine, intake and has a general knowledge of the rules of propagation of radar wave.The last, for the special circumstances in mine of our country, we research on the working method and data peocessing of new radar, developed a whole detection technology in mine. Taking a lots of detection experiments in the typical major gas enrichment zone, abtain the radar chromatographs of fractures, collapse columns and other geological anomalies. The experiments achive better geological effect. It indicates that the new radar detection nethod and equipment have a good solution of close range high resolution detection difficults in mine, enrich the means of mine geological prospecting, improve the geological prospecting level, and has benefit to guarantee safe production of mine.The research of this paper bears major fruits as follow:(1) It begain research of circuit board improvement of radar equipment. Design the explosion-proof power source and circuit board of geological radar, developed100MHz shield antenna. Developed KJH-D impulse-type explosion-proof mine geological radar which fit for mine at first time. And it is also the first impulse-type explosion-proof mine geological radar which abtain the MA, fill the gap in this area of our country. The technology level has been identified as advanced world standard by the experts from secretary for planning, science and technology of state administration of work safety, abtain title of ChongQing major new product and second prize of china coal industrial science and technology awards.(2) We analysis the propagation characteristic of radar wave in the media underground, derive the computing formula of reflection coefficients of radar wave. The reflection coefficients r is determined by relative dielectric constant of media of both sides of the interface, the absolute value is less than1. When the reflection coefficients|r|>0.1, it is better fit for detecting and distinguish target by geological radar.(3) Because the circumstance and condition of mine is further more complex than free space ground, after analysis of and research on the characteristic of electrical of general medium in coal series stratum, we find that the propagation velocity of electromagnetic wave in mine is faster than in rock. Since the absolute value of reflection coefficient of interface is greater than0.1, so it is very good reflection interface for radar wave, and is benefit to radar detection. Fractures, collapse columns, aquifer, hollow and other geological anomalies in geology all have good reflection interface for radar. So the geological radar can have a better work for detecting and distinguish of them.(4) Building sigle medium wave field models of fix point source, modeling the propogation of radar wave in the three representative medium models:free space, limestone, and coal seam. On the basis of that, we build radar wave medium wave field models in mine, build three typical wave field models in mine:coal bearing layer medium, coal seam medium which contain abondoned drill pipe, coal (rock) fracture medium model.Show results of wave field modling, achive a good modeling effect. The results indicate that the radar wave has obvious reflection on interface of anomaly, and this certify the efficiency of radar detection in mine.(5) We use matlab numerical recipes software to program the two dimension finite-difference time-domain forward modeling program, which introduce second order Mur absorbing boundary conditions and GPML absorbing boundary conditions. Base on this program we forward modeling the most typically geological model which appears most frequently in actual detection-fructure model. In addition we forwading model some kinds of typical geoelectric models for mine geological radar detection such as collapse columns, karst cave, coal seam medium which contain abondoned drill pipe and so on, and obtain the simulation image of radar echo.Prove the feasibility of geological radar detection for mine geological anomaly in terms of geophysical forward calculation.(6) We take further study of radar signal processing technology and method based on Matlab computing method. Take emphasis research on preparatory work before datas process, traditional processing method, KL transformation method, wavelet transform processing method.etc. Program corresponding process program, refine the radar signal processing technology and method.(7) Starting the research of radar detectionmethod and technology in mine, put forward "one two three" principle for detection work in mine-one principle, two modes, three directions. One principle means survey line must be perpendicular to target as far as possible; Two modes mean two ways of geological detections:fixed translation mode and common-mid point mode; Three directions mean three detection directions in mine:driving head detection, side detection,top and bottom detection.Detailed analysis the purpose, significance, working method and expected results of three direction detections.(8) We carry out lots of various and broad detecting experiments at typical underground tunnel in gas enrichment area of our country by the new KJH-D impulse-type explosion-proof mine geological radar. These contain not only advanced detection on driving head in tunnel, but also side detection, top and bottom detection. The targets contain fault structures, collapse columns, washout zone in coal seam, interface of coal and rock, near coal seam, drilling pipe, etc. And we also obtain the typical radar image of general geological anomaly. In ChengZhuang coal mine, the actual velocity of in-situ collected radar wave in3rd coal seam is0.152m/ns. According this, we conclude that the relative permittivity of3rd coal seam is3.9.(9) A one-year continuous application experiments in underground tunnel at HuaiNan mine, a total of52times geologic radar detection, forecasting distance of2390meters.it indicates the shock pulse explosion-proof geological radar can define the geological anomaly in front of head effectively. According the experiments results, we find out that it can distinguish the fracture which’s gap greater than2/3coal thickness; For the fracture which’s gap lessr than2/3coal thickness, the success ratio also achive87.5%. The achievement identificated by office of science and technology in AnHui province, has achived advanced world standard.In future detecting work, it needs to summarize the relation of the radar echo and every anomaly in coal seam unceasingly, campare the results with geological materials from borehole at same time, analyze the problem, learn the rules, Enable the technique and equipment of mine explosion-proof geological radar become mature continuously. |
PDF Full Text Request