The traditional stress arch hypothesis during longwall mining fails to elucidate the formation mechanism of stress arch, and the morphological characteristics and evolution of stress arch are indefinite. To solve these problems, a mechanical model was established for elucidating the formation mechanism of stress arch in overlaying strata. The influencing of key strata on the morphological characteristics of the stress arch was studied. Finally, the evolution of the stress arch during longwall mining was studied through numerical simulation. The results show that the bearing structure of the overlying strata served as the key strata, and the stress arch was formed when the key strata were subjected to deflection after playing a bearing structure role. This was the result of coordination and redistribution of major principal stress in the key strata. The morphological characteristics of the stress arch changed accordingly with the change in key strata. When the thickness of key strata and the distance between key strata and coal seam were gradually increased, the height and width of the stress arch increased accordingly; however, its height was always terminated at the top interface of key strata. At this time, the peak value of the abutment pressure of the working face gradually decreased while the influencing range gradually increased. During longwall mining, the stress arch developed upward by leaps and bounds with the bearing and fracture of key strata. When the overlying key strata were completely fractured, the stress arch disappeared. The results were verified using the field measurement data on the abutment pressure of the Y485 longwall face in Tangshan Mine.

传统的长壁开采应力拱假说未能阐明应力拱的形成机制，应力拱的形态特征和演化过程不明确。针对这些问题，建立了力学模型，阐明了上覆地层应力拱的形成机制。研究了关键地层对应力拱形貌特征的影响。最后，通过数值模拟研究了长壁开采过程中应力拱的演变。结果表明，上覆地层的承载结构作为关键地层，关键地层在发挥承载结构作用后发生挠曲时形成应力拱。这是关键地层主要主应力协调重新分布的结果。应力拱的形态特征随着关键地层的变化而发生相应的变化。当关键地层的厚度和关键地层与煤层的距离逐渐增加时，应力拱的高度和宽度也相应增加；然而，它的高度总是终止于关键地层的顶部界面。此时工作面的工作面压力峰值逐渐减小，而影响范围逐渐增大。长壁开采过程中，随着关键地层的承载和破裂，应力拱突飞猛进地向上发展。当上覆关键地层完全破裂时，应力拱消失。利用唐山矿Y485长壁工作面台肩压力的现场测量数据对结果进行了验证。