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运用实验相似材料模拟、数值分析、理论分析等方法， 对采场支架－围岩关系中的老顶砌体梁结构的“Ｓ－Ｒ”稳定条件， 直接顶岩层的破断角， 直接顶变形破坏特征， 直接顶内的应力场、位移场分布特征， 采场支架工作阻力－围岩下沉量关系等进行了细致深入的研究， 在此基础上建立了采场围岩整体力学模型， 给出支架临界工作阻力的确定方法。论文视直接顶为可变形体， 发现直接顶岩层破断角的大小与直接顶的强度及高度有关， 软弱直接顶的破断角为８３°， 要远远大于坚硬直接顶的破断角（４９°）。直接顶越坚硬， 破断角越小。随直接顶高度的增加， 坚硬直接顶破断角有一极限值。当直接顶高度为６ 倍采高时， 此破断角的极限值为６０°。直接顶顶部破断角的极限位置位于支架尾部垂直正上方， 不可能出现在此位置之后。分析了不同直接顶高度时的变形破坏特征， 得到传统的Ｐ－Δｌ双曲线关系并不适用于直接顶的高度成倍增加以后的情况。由此提出直接顶“临界高度”的概念， 即将老顶的给定变形压力为零时的直接顶的最小高度定义为直接顶的临界高度， 并将直接顶按临界高度分为三类： 零刚度、似零刚度、中间型刚度。应用弹性力学中能量原理分析了非零刚度直接顶的支架工作阻力与顶板下沉量的关系曲线为
The S-R stability conditions, the breaking angle of the direct top rock formation and the direct top deformation failure of the roof-top masonry beam structure in the stope-surrounding rock relationship are simulated by means of experimental similiar materials, numerical analysis and theoretical analysis. Characteristics, direct inland stress field, distribution of displacement field, working resistance of stope support - the relationship between the surrounding rock subsidence and so on. On this basis, the overall mechanics model of surrounding rock is established, Method of determining the critical working resistance of the support. It is found that the breaking angle of the direct roof rock is related to the strength and height of the direct roof. The breaking angle of the weak roof is 83 °, which is much larger than the breaking angle of the hard roof (49 °) . The more direct the more hard, the smaller the breaking angle. With the increase of the direct top height, there is a limit value for the hard direct top break angle. When the direct top height is 6 times mining height, the limit of this breaking angle is 60 °. The ultimate position of the top top breakage angle is located vertically above the tail of the support and may not appear after this position. The characteristics of deformation and failure under different direct top heights are analyzed. The traditional P-Δl hyperbolic relationship is not suitable for the case that the height of the direct top is doubled. Therefore, the concept of direct top “critical height” is proposed. That is to say, the minimum height of the direct top at a given deformation pressure of the old top is defined as the critical height of the direct top and the direct top critical height is divided into three categories: zero Stiffness, like zero stiffness, intermediate stiffness. The application of energy principle in elastic mechanics analyzes the relationship between working resistance and roof subsidence of non-zero stiffness direct top bracket as