Research On Continuous Flow Method Of Coal Roadway Outburst Risk Prediction

Coal and gad outburst is one of most serious natural disasters that threaten coal mine safe product, while the number of coal and gas outburst in advancing coal way accounts for the top of the total number of coal and gas outburst in coal mines. So research on outburst prediction of advancing coal way makes sense very much.By analyzing common questions of existing outburst predict indicators of advancing coal way, and research status quo in domestic and abroad, the technology of continual flux method to predict outburst in coal way is brought forward in this paper. Dynamic releasing law of methane in borehole, equipment manufacturing for prediction and trial in coal mine are also studied in this paper.This paper summarizes the research actuality of outburst prediction of advancing coal way in domestic and abroad, analyzes shortage of existing predictive technology in China, finds the technical approach to establish predictive indicator of advancing coal way. OnИ.В. Paclv's theory from the former Soviet Union basis, the author established indicator by measuring initial releasing flux in borehole continually, which can reflect the influence of geological stress, methane pressure and coal intensity which can be as a token of coal and gas outburst in front of the advancing workface. The author's academic basis is pressure-release area theory and spherical shell lose stability theory.The author established dynamic model of methane released from borehole wall in the course of drilling in bastard coal and in structure coal that in bastard coal using Flac3d software; derived formula between accumulated methane volume from coal dust and time, based on FICK diffusion law, associated with characteristic of methane release from coal dust; and also derived dynamic law of released methane volume from borehole in the period of drilling with drill length by mathematic superposition method: in the course of drilling, methane volume released from borehole wall increases gradually while the length of borehole extended, methane volume comes to peak at the moment drill length does not extend; under circumstance of falling across structure coal there will be a inflexion, a sudden increase will be present.On fluid mechanics, leakage mechanics and seal doctrine basis, according to analyzing borehole seal mechanism and the demands of predictive equipment and any other factors, author derived formula of leakage volume, and relationship among borehole diameter, clearance between borehole seal equipment and borehole and seal length.Continual flux method coal way outburst predictive equipment ZTL20/1000 is invented. The equipment not only realize real time data selection with borehole length extended but also realize data display, data storage and feedback control.The equipment has been used in XueHu coal mine ,not only validates the dynamic law referred before, but also predicts the distribution of structure coal in front of advancing workface, which provide coal mine for correct advice that whether or not to take action to prevent outburst, which speed up advance efficiency, generate better economic benefit and safety benefit.