(1.Mine Safety Technology Branch，China Coal Research Institute Co.，Ltd.，Beijing ，China；2.National Key Lab of Coal Mining and CleanUtilization，Beijing ，China;3.School of Architectural Engineering,Zhongyuan University of Technology，Zhengzhou ,China)

In order to study the abnormal mining pressure law of the concentrated coal pillars in the underlying working face of the coal seam group, the No.42107 working face of the Bultai coal mine was used to enter the No.2-2 coal seam residual concentrated coal pillar as the engineering research background. By analyzing the law of monitoring data, based on field measurement, similar simulation and theoretical analysis method, the characteristics of strong strata behaviors were summarized , the mechanism of strong strata behaviors was revealed and the calculation formula of the fracture surface of the working face and the support load was deduced, and the accuracy was verified by similar simulation experiments. The results show that during the period when the underlying working face enters the concentrated coal pillar, the boundary of the concentrated coal pillar is affected by the stress concentration. The basic top breaking position is deeper than the width of the coal body, the total breaking step is reduced, and the support load is obviously increased, resulting in abnormal mine pressure on the working surface. Similar simulation results show that when the coal pillar is concentrated, the stress on the underlying working face concentrates, the immediate roof rock block fractures, and the step distance of the slump are reduced. The experimental and theoretical analysis results are basically consistent.

国家重点研发计划资助项目（2017YFC0804202-002）;国家自然科学基金资助项目（51704159）