Influence Factors Analysis of Residual Pillar in Goaf and Its Evaluation Methods

In order to evaluate the stability of a large number of coal pillars in goaf more objectively and comprehensively, influence factors of the stability of coal pillar was divided into internal and external factors. The paper propose a comprehensive evaluation method of the combination of qualitative evaluation and quantitative evaluation; qualitative evaluation is based on external factors, quantitative evaluation is based on internal factors. The example analysis shows that the comprehensive evaluation method is more accurate, objective and reliable, which overcomes the limitation of the single evaluation method, and enriches the theory of coal pillar stability evaluation.