Control technology of surrounding rock stability based on compensation theory in gob-side entry retaining with composite hard roof

The 110- mining method, a rising and revolutionary non- pillar longwall mining method, can obviously expand coal extraction ratio and minimize roadway incidents. However, in case of composite hard roof, problems such as difficulty in commanding the entry steadiness and insufficient fragmentation and bulking of the goaf gangue are prevalent. In this study, a 110- mining method for roadway surrounding rock stability control technology based on a compensation mechanism was proposed. First, the composite hard roof cutting short cantilever beam (SCB) model was built and the compensation mechanism including stress and space dual compensation was studied. Subsequently, the controllable elements influencing the roadway steadiness were confirmed to consequently put forward a control technology based on stress compensation for entry support and space compensation for the fragmentation and bulking of goaf gangue. The control technology was finally verified through onsite engineering experiments in terms of composite hard roof. The adoption of the 110-mining method with compensation control technology indicated good support effect on the roadway. The initial and residual expansion coefficients of the goaf gangue increased by 0.6 and 0.6, respectively, and the maximum and average working resistances of the working face support decreased by 10.9% and 13.8%, respectively. Consequently, the deformations of reserved entry decreased, and entry steadiness was enhanced. The presented technique and effects got probably have practical values for non-pillar mining functions in comparable field.