Study on necessity to apply the plugging in mining of gob-side entry retaining

It is popular to apply the plugging technology in mining of gob-side entry retaining.It can improve the recovery rate and reduce the tunnel heading amount.At the same time,it can also aggravate the air leakage of goaf.In order to explain the dangerous of air leakages and the necessary of plugging,the finite element method is applied to compute the distributions of seepage velocity field and oxygen concentration in this paper.The "three zones" distribution of spontaneous combustion is respectively divided by using the superposition of the fields of seepage velocity and oxygen concentration.And the effect of coal oxidization and gas emission were considered in mathematical model.The computed results show that the maximum width is 196m,the average width is 110m of spontaneous combustion zone before plugging,the values respectively turn to 70m and 63m after plugging.Therefore,the existence of leakages have great effect no the "three zones" distribution of spontaneous combustion,and it is very unfavorable to mine fire control.It is so necessary to apply the plugging measures in mining of gob-side entry retaining.