Stability Analysis of Irregular Coal Pillars in Bilateral Goaf

In order to determine the stability degree of irregular coal pillars in the state of goaf on both sides of working face, the minimum safety size of irregular coal pillars and the stability coefficient of coal pillars are calculated by mathematical model. On this basis, the stress variation law of irregular coal pillars in the state of goaf on both sides is analyzed by means of numerical simulation. The results show that the minimum safe size of coal pillar is 31.2 m, which is larger than the irregular size of coal pillar in the range of 36.5 m in 3303 working face. The stability coefficient of coal pillar is 1.14. According to the criterion of coal pillar stability, the coal pillar is in stable state. The stress of irregular coal pillar increases with the advancing distance of working face, and the maximum stress value is basically consistent with the theoretical minimum value of bearing strength of coal pillar. The irregular coal pillars can keep stable under the condition of bilateral goaf.