The longwall may relax some safety problems, but the other safety problems such as hard roof rock, the colliding and friction of the caved rock each other may be induced or intensified .

• 但是也可能诱发一些安全问题,如坚硬顶板对支架的冲击、采空区垮落岩石的撞击与摩擦诱发瓦斯事故等。