关键词: 三软厚煤层, 大跨距开切眼, 联合支护, 围岩稳定性

Abstract: In soft thick coal seams with soft roof and floor strata, rock masses surrounding the large span open-off cut experiences drastic failure degree. Supporting difficulties in such roadways is greatly improved. In order to realize surrounding rock control with such bad conditions, failure characteristics and corresponding supporting method have been researched in this study by using theoretical analysis and field measurements. Due to soft layers inserted in the roof strata, rock strength is seriously deteriorated and thus, failure degree and region of the roof strata is enlarged. At the same time, top coal is thick and soft, leading to frequent roof fall in the open-cut. Based on the failure characteristics, a combined supporting technique is proposed. Active and passive strengthening mechanisms involved in the technique are explained. With the proposed method, load-bearing capacity of both support structure and surrounding rock are efficiently utilized. After that, supporting parameters for the large span open cut are further put forward. Then, the supporting effectiveness is in situ investigated. The results show that roof subsidence is controlled and supporting load provided by cables increases to a large value quickly. The surrounding rock stability of large span open-cut is promised.