Abstract: In order to improve the precision and accuracy in forecasting the risk level of opening roof only applying single index, affecting factors and mechanism of roof caving in opening area are studied with methods of RFPA numerical simulation and analysis hierarchy process. The mechanism shows that the difference in rock strength and stiffness leads to a dramatic variation in the separation size between roof strata, which has a direct impact on the degree of roof carving. Also, it points out that the anchor bolt (cable) supporting quality and the structure of roof strata are two main factors affecting roof caving in opening area. Taking these two factors as forecast indexes, the danger-area forecast system of opening roof was built up, and forecast of the danger-area is made in opening area of 12018 working face basing on this system. The forecast result illustrates that roof caving danger exists in more than 50% area of the roof in opening area, and the danger-areas distribute in the upper and lower end position and in the central position. According to this forecast result, reinforcing supported the danger-area to ensure the safety and reliability of mining operation, with a separate minor average size of 12 mm and a gradual falling rate of 0.2 mm/d.

Key words: face opening, roof caving mechanism, affecting factors of roof caving, danger-area forecast of roof caving