煤矿地下水库岩体碎胀特性试验研究

鉴于岩石碎胀特性对于煤矿地下水库储水能力及地表沉陷的重要影响，选取神东矿区某矿22615面为工程背景，利用相似材料模型试验探究采空区垮落岩体应力及碎胀系数分布规律，明确垮落岩体应力-碎胀系数关系，并通过岩石压实试验进行验证，揭示饱水岩石压实特性。研究结果表明：沿采空区走向，边界附近老顶悬臂梁结构限制覆岩下沉，垮落岩体应力最低仅为0.32 MPa，碎胀系数最大达1.48；中间区域老顶结构失稳覆岩完全下沉，垮落岩体应力趋于1.5 MPa，碎胀系数降至1.09。沿采空区垂向，垮落岩体应力随高度负相关改变，而碎胀系数成正相关变化。无论沿采空区走向或垂向，垮落岩体碎胀系数与应力均满足负对数关系。与自然岩石相比，受载饱水岩石碎胀系数减幅更为明显，两者相差8.514%，为煤矿地下水库储水量和地表沉降量预测提供了基础理论依据。

Experiment study on rock bulking of coal mine underground reservoir

Given that rock bulking is of great significance to water storage capacity and ground surface subsidence of coal mine underground reservoir, the 22615 working face in one mine of Shendong coalfield was selected as the engineering background. The stress and the bulking coefficient distribution laws of caving rock in goaf were analyzed by using the similar material model test, and then the stress-bulking coefficient relation of caving rock was established, which was verified by rock compaction experiment. Moreover, the compaction characteristic of saturated rock was revealed. The results show that: along goaf advancing direction, overlying strata subsidence is limited by the structures of cantilever beam near the boundary where the stress of caving rock is relatively low (0.32 MPa), and the corresponded maximum bulking coefficient reaches 1.48. Due to the instability of main roof structure, caving rock is compacted by overlying strata in the middle area, rock stress trends toward 1.5 MPa, while bulking coefficient reduces to 1.09. It is clear that the height exhibits a negative correlation with caving rock stress but a positive correlation with bulking coefficient in goaf vertical direction. There is a negative logarithmic relationship between stress and bulking coefficient of caving rock along either advancing direction or vertical direction. By comparing with natural rock, the bulking coefficient damping of saturated rock shows obviously under loading, which has a difference of 8.514%. This study provides a theoretical basis for water storage capacity and ground surface subsidence predictions of coal mine underground reservoir.