Research Of Safety Mining Techniques Of Shallow Work Face Under Thick Wind Sands

The number of shallow work faces will be bigger and bigger as national coal miningstrategy moves towards western. Howevef, research for their safe1y mining techniques isfarly limited in domestic and overseas. As far as Shendong is concemed, the miningregions in mines are located in 100m underground mainly. Shallow imbedding, thin solidsocks and loose-and-scattered sands overlie are their twical characters. The ob1iquity ofcoal beds is nearly horizontal. Coal beds are steady. Thickness of gas is low Miningconditions are predominant. That mining pressure is smart and trend of goaf nature fire isobvious are factors that affect the safe productions. Under present conditions, thattechniques and theories of safely mining of shallow coals Which axe good to westerncoalfields are reseaxched and established is of great importance theoretically andpractically to promote their high-efficiency and safely mining productions. TherefOre,this paPer is fOcused on research of two aspects: laws of work-face mining pressure andmovement of overlie rocks, laws of wind movement and prevention and cure of goafnature fire.The basal laws of mining pressure and sinking and destroy of shallow mining-faceand two laneways under thick wind sands are primarily mastered and, such factors asinitial caving steps of immediate roofs, initial caving steps of main roofs, periodiccaving steps of main roofs and incidence of work-face advanced pressure, etc. aregained through systemically testing and academically analyzing the mining pressure of12205 work face in well Huojitu, mine Daliuta. The result of spot measure shows f suchright-selected factors as initial bearing pressure of work-face support, workingresistance and mining rate of hydraulic supports insured that work-face roofS collapsedidn't haPpen during all the mining process and, deferred the sinking of sidesteps. Butthe working resistance of individual suPports is too big because their initial bearingpressure is not even.The dynamic developing process of destroy of mined overlie rocks of l2205 workface has been simulated by a kind of softwaxe--arPA and, its result inosculates resultof spot measure. Distribution laws and their main parameters of movement anddistortion of 12205 work-face surface are gained thIough systemically observing andaccouning the surface movement of 12205 work face.On the base of diagnoses of the nature fire status of 2l208 work face, the criticalconditions of simulating its nature fire are decided by spot measuring its ventilationsystem. Such parameters as distribution law of surface air leak, distribution law of windpressure a1ong the sections of goaf and streamline and speed of air leak and, distributionof p1ane wind pressure and speed fields and compositive flow in goaf and, work-facevariety curve and distribution of air leak are gained thIough simulating air leak flowstatus and plane flow status of goaf "Three straPs" of goaf nature fire are decided and,the factors that affect goaf nature fire, such as work-face mining distances andwind-quantity variety are analyzed and, positions of potential nature fire in goaf areforecasted. The ways of prevention and putting out goaf fire are researched in terms offacts of shallow work faces under thick wind sands in Shendong field. Simulating andanalyzing are carried out combined with ground drilling nitrogen-injection prOject thatis most feasible one presently and, such parameters as positions, drilling intervals and' quantity of nitrogen-injection of ground drilling nitrogen-injection are researched anddecided, then its effect can be simulated.Through research of this paPef, mechanisms and theories and teclmiques ofprevention and cure of shallow roof disaster and goaf nature fire disaster under thickwind sands are primarily established.