【摘要】 通过相似模拟实验和理论分析,研究了综放条件下上位直接顶"散体拱"结构的形成机理和移动演化过程.认为在综放条件下,以散体状态出现的直接顶岩块在渐进流动过程中的某一时刻,由流动孔口周边作用的垂直剪切力与上方垮落岩体重力之间形成的应力平衡是上位直接顶"散体拱"结构形成的力学条件;工作面的不断推进及"散体拱"结构的不对称性而导致的承载能力不均,造成后拱脚和前拱脚先后失稳是"散体拱"结构不断失稳、重组和前移的原因.更多还原

【Abstract】 Simulation testing and theoretical analysis were made to study generating mechanics and moving evolutionary process of "granular arch" structure of upper immediate roof in top coal caving.The studies show that as caving rocks of immediate roof in granular state in top coal caving move progressively,vertical shear will be produced at any time from the periphery of flowing porthole.And the stress balance between the vertical shear and gravity force of caving rock mass from above is mechanical condition to form "granular arch" structure of upper immediate roof.As working face advances progressively,the non-symmetry of "granular arch" structure results in the unbalance of its bearing capability.And this unbalance makes its rear spring unstable first and then its front spring unstable,which is the reason for the restructuring,the continuous destabilization and the progressive advancing of "granular arch" structure.更多还原