Abstract: To investigate the occurrence mechanism of rockburst and outburst accidents induced by returned stress of surrounding rocks, a Stress Returning (SR) concept was proposed on the basis of a case-study within a 25110 working face in a coal mine (locates in Henan Province, China) , where two typical accidents had been occurred before. The process of occurrence, mechanical mechanism, and corresponding prevention countermeasures of the SR phenomenon were thoroughly studied using methods of theoretical analysis, numerical simulations and field measurements, etc. The results indicate that the SR is characterized by hysteresis and an eclipse period and that the excessive pressure relief of deep coal body reduces its load-bearing capacity and the abutment pressure is coerced back to the roadway,which is the main reason for occurrence hysteretic rockburst and outburst. Countermeasures adopted according to the results have been applied in the 25110 working face to guarantee the mining safety.

Key words: surrounding rocks stress, hysteretic rockburst and outburst, stress returning, numerical simulation, microseismic monitoring