榆神府矿区开发过程形成了大范围的房柱式采空区，产生了大面积悬顶区域。悬顶区域煤柱经过长时间的自然风化、蠕变等作用，支撑强度弱化，存在失稳破坏的危险，甚至引发矿震灾害。本文以河西联办煤矿5^-2煤层房柱式采空区悬顶区域治理为背景，通过理论分析、物理实验和数值计算等方法，分析了房柱式煤柱稳定性，确定了充填方案，进行了房柱式采空区充填模拟，揭示了矸石似膏体充填料浆在复杂采空区中的流动沉降规律。研究得出：

（1）通过理论分析初步判断河西联办煤矿房柱式采空区煤柱处于基本稳定状态，鉴于不能排除以往开采过程悬顶区域存在采掘不规范等情况，对悬顶区域进行充填处理是防止大面积顶板来压灾害的主动性控灾措施，进一步确定了充填体单轴抗压强度至少为3.43MPa。通过方案对比确定了管输注浆充填宽块段方案。

（2）通过分析不同固体质量分数矸石似膏体充填材料的力学性能、流动性能及流变特性发现，随固体质量分数的增加，矸石似膏体充填材料的单轴抗压强度、屈服应力、表观粘度及触变性增强，其泌水率、沉降率、坍落度及扩展度降低。矸石似膏体充填料浆流变特性服从屈服胀塑性体流变规律，符合Herschel-Bulkley粘度模型。综合对比确定了矸石似膏体充填料浆固体质量分数为74%。

（3）通过相似模拟得出了矸石似膏体充填料浆在复杂采空区中的沉降规律，料浆中部和下部超声波波速随时间变化呈上升趋势，上部则先减小后缓慢上升；料浆整体具有较优的静态抗离析性能；沿流动方向粗（细）颗粒质量分数逐渐降低（增加），相邻煤柱之间靠近排气孔侧的质量分数略高；下部粗（细）颗粒质量分数相对较大（小），上部粗（细）颗粒质量分数相对较小（大）；充填试样强度沿流动方向表现出波浪型变化规律，在靠近排气孔侧的强度较高，充填试样强度随深度增加呈上升趋势。研究亦表明充填试样表面产生宏观缺陷与料浆内部产生的气泡无法顺利排出有关。

（4）基于CFD方法揭示了矸石似膏体充填料浆在复杂采空区中的流速分布和流线分布规律，靠近进料口侧料浆的流速较高，流动过程中流速不断降低。根据充填料浆在复杂采空区中的流动情况可分为壁面低速流、核心流和支流。充填料浆在复杂采空区流动过程中会产生大小不一的涡量，这也是造成充填体分布不匀和内部缺陷的原因之一。

研究结果可为悬顶区域充填工程实践提供借鉴，对煤矿绿色开采与耕地保护协同发展具有重要意义。

The development process of the Yushenfu mining area has formed an extensive range of room and pillar goaf, resulting in a large area of suspended roof area. After a long period of natural weathering and creep, the support strength of the coal pillar in the hanging roof area is weakened, and there is a risk of instability and failure and even a mine earthquake disaster. In this paper, the stability of room-and-pillar coal pillars is analyzed using theoretical analysis, physical experiment and numerical calculation based on the treatment of hanging roof area in room-and-pillar goaf of 5^-2 coal seam in Hexi Lianban Coal Mine. The filling scheme is determined, the filling simulation of room-and-pillar goaf is carried out, and the flow and settlement law of gangue paste-like filling slurry in complex goaf is revealed. The study concluded that :

(1) Through theoretical analysis, it is preliminarily judged that the coal pillar in the room-and-pillar goaf of Hexi Lianban Coal Mine is basically stable. Because it can not be excluded that there was non-standard mining in the suspended roof area in the past mining process, the filling treatment of the suspended roof area is an active disaster control measure to prevent large-area roof weighting disasters, and it is further determined that the uniaxial compressive strength of the filling body is at least 3.43 MPa. The scheme of filling a wide block with tube infusion slurry was determined by scheme comparison.

(2) By analyzing the mechanical properties, flow properties and rheological properties of gangue paste-like filling materials with different solid mass fractions, it is found that with the increase of solid mass fraction, the uniaxial compressive strength, yield stress, apparent viscosity and thixotropy of gangue paste-like filling materials increase, and their bleeding rate, sedimentation rate, slump and expansion decrease. The rheological properties of gangue paste-like filling slurry obey the rheological law of yield expansion plastic body and conform to the Herschel-Bulkley viscosity model. The solid mass fraction of gangue paste-like filling slurry was determined to be 74 % by comprehensive comparison.

(3) The settlement law of gangue paste-like filling slurry in complex goaf is obtained through a similar simulation. The ultrasonic wave velocity in the middle and lower parts of the slurry increases with time, while the upper part decreases first and then increases slowly. The slurry has better static anti-segregation performance as a whole; the mass fraction of coarse ( fine ) particles gradually decreases ( increases ) along the flow direction, and the mass fraction near the vent side between adjacent coal pillars is slightly higher. The mass fraction of coarse ( fine ) particles in the lower part is relatively large ( small ), and the mass fraction of coarse ( fine ) particles in the upper part is relatively small ( large ). The strength of the filling sample shows a wave-like variation along the flow direction. The strength near the vent side is higher, and the strength of the filling sample increases with depth. The study also shows that the macroscopic defects on the surface of the filling sample are related to the fact that the bubbles generated inside the slurry cannot be discharged smoothly.

(4) The flow velocity distribution and streamline distribution of gangue paste-like filling slurry in complex goaf are revealed based on the CFD method. The flow velocity of the slurry near the inlet side is higher, and the flow velocity decreases continuously during the flow process. The flow of filling slurry in complex goaf can be divided into wall low-velocity flow, core flow and branch flow. Filling slurry will produce a vorticity of different sizes in the flow process of complex goaf, which is also one of the reasons for uneven distribution and internal defects of the filling body.

The research results can provide a reference for filling engineering in the suspended roof area, which is significant to the coordinated development of green mining and cultivated land protection in coal mines.