坚硬顶板强制放顶断裂力学模型研究

为了保证坚硬顶板工作面的安全高效生产，根据坚硬顶板初采期间的岩层结构特点，基于断裂力学理论，建立了中部拉槽强制放顶断裂力学模型，推导了基本顶初次破断距的表达式，分析了岩层断裂韧度、裂缝长度等参数对初次破断距的影响规律。研究结果表明:基本顶的初次破断距随断裂韧度的增大而增加，随裂缝长度和基本顶上覆荷载的增大而减小；在基本顶断裂韧度或上覆荷载一定的条件下，人工裂缝长度比达到0.6以后，基本顶初次破断距保持不变。研究结果可为类似工程的设计和施工提供依据。 

Study on the fracture mechanics model of forced caving of hard roof

For the safe and efficient production of hard roof working face, according to the characteristics of strata during the initial mining of hard roof, based on the theory of fracture mechanics, the mechanics model of forced roof caving of middle kerve was established. The expression of the initial weighting distance of the main roof was deduced and the influence law of rock fracture toughness and crack length on the initial weighting distance was also analyzed. The results show that the initial weighting distance of the main roof increases with the increase of the fracture toughness, decreases with the increase of the crack length and the main roof overburden. Under definite conditions of fracture toughness or the overburden load of the main roof, the initial weighting distance of the main roof remains unchanged when the artificial fracture length ratio reaches 0.6. The research results can provide the basis for the design and construction of similar projects.