再生顶板煤自燃是矿井火灾常见类型之一,其顶板裂隙漏风是导致遗留煤炭氧化自燃的关 键原因。 现阶段,对于再生顶板的支护方式仅从“强帮固顶”的角度出发,针对裂隙漏风的控制研 究尚不完善,尤其缺乏在应力集中导致漏风裂隙演化扩展方面的研究。 基于此,针对山东鹿洼煤矿 2304 工作面回风巷再生顶板,以弹性力学理论、临界破坏准则及广义胡克定律为基础,分别推导了 各种措施下的应力集中系数与再生顶板围岩特性参数的关系,并利用再生顶板现场情况结合压溃 实验与分形维数,阐明了各种措施下的再生顶板应力集中控制情况与裂隙演化规律研究。 结果表 明:岩石弹性模量对再生顶板的应力集中影响最为显著,且根据现场工况计算得出,使用锚杆支护 时,最大应力集中系数为 2.341,水泥浆胶结支护时,最大应力集中系数为 1.563,纳米浆泡材料胶结 支护时,最大应力集中系数为 1.393;此外,利用压溃实验发现水泥材料胶结体的裂隙主要从中心向 四周扩散,其横向纵向的裂隙数量均会持续增加,并逐渐贯通,而纳米浆泡材料仅会在原有裂隙基 础上继续演化发育,当单轴压力超过 8 MPa 后,纳米浆泡材料胶结体的裂隙基本不再发育;分形维 数计算结果表明,当压力小于 5 MPa 时,纳米浆泡材料的多孔结构会使分形维数大于水泥材料胶 结体;当压力大于 5 MPa 时,尤其是超过抗压强度后,纳米浆泡材料胶结体的分形维数小于水泥浆 胶结体,故裂隙扩展演化速率更加缓慢,有利于阻止再生顶板的裂隙漏风。

Spontaneous combustion of regenerated roof coal is one of the common types of mine fire,and the air leakage in the regenerated roof cracks is the key cause of oxidation and spontaneous combustion of coal left. At the present stage,the support mode of the regenerated roof is only from the angle of “strong wall support,maintain stable roof”, and the research on the control of air leakage in the regenerated roof cracks is not sufficient,especially the research on the evolution and expansion of air leakage cracks caused by stress concentration. In view of the return airway regenerated roof at No. 2304 working face in the Luwa coal mine of Shangdong Prouince,according to the theory of elas- tic mechanics,the critical failure criterion and the basis of the generalized Hooke’s law,the relationship between stress concentration factors and the regenerated roof characteristic parameters of surrounding rock under the vari- ous measures is deduced respectively. Based on actual situation and the regenerated roof crushing experiments with fractal dimension,the stress concentration control and the crack evolution of regenerated roof under various measures are expounded. Results show that the effect of elastic modulus on the rock stress concentration of regenerated roof is most significant. According to the calculated working conditions on site,using bolt support,the maximum stress con- centration factor is 2.341,using slurry cementing support,the maximum stress concentration factor is 1.563,and using nano-slurry bubble material cementation support,the maximum stress concentration coefficient is 1.393. In addi- tion,in the crushing test,it is found that the cracks mainly propagate from the center of cement material cementation body in all directions,the horizontal and longitudinal fractures will continue to increase,and gradually be connected. For the material of nano-slurry bubble,on the basis of original cracks,the crack evolution continues to be developed, when the stress exceeds 8 MPa,the cracks in nano-slurry bubble material cementation body will be no longer devel- oped. Fractal dimension calculation results show that when the stress is less than 5 MPa,the porous structure of nano- slurry bubble material can make the fractal dimension significantly more than that of the cement material cementation body. When the strees is greater than 5 MPa, especially when it exceeds the compressive strength, the fractal dimension of nano-slurry bubble material cementation body will be significantly less than that of the slurry cementing body,so the evolution of crack extension and evolution rate is slower,which is beneficial to prevent air leakage in the cracks of regenerated roof.