【作者】 张鑫；

【导师】 孟祥喜；

【作者基本信息】 山东科技大学 ， 资源与环境（专业学位）， 2025， 硕士

【摘要】 防水煤岩柱是隔离采空区积水的唯一介质与关键屏障,防水煤岩柱一旦发生失稳破坏,采空区中的积水就会涌入采掘作业空间,造成人员伤亡与财产损失。本文聚焦位于采空区中受积水影响的防水煤岩柱,通过室内实验、理论分析、数值模拟等手段,研究采空区积水影响下煤岩体的力学性能弱化规律与响应特征,开展采空区积水影响下的防水煤岩柱稳定性评价。研究结果如下:(1)根据研究区概况及相关背景,对采空区积水影响防水煤岩柱的若干因素展开分析,针对防水煤岩柱在采空区中的浸水时间不同、采空区积水的水位高度不同、采空区积水流速不同以及防水煤岩柱的煤/岩厚度比例不同,设计煤岩试件单侧浸水实验,模拟防水煤岩柱在采空区受积水影响的场景,开展力学性能测试试验、声发射监测、损伤观测试验,研究采空区积水影响下煤岩体的力学性能弱化规律与响应特征。(2)探究了矿井水单侧浸水环境中多种因素影响下煤岩体力学性能、破坏形态以及结构损伤特征。随着试件在矿井水中的浸水时间增加,煤岩的抗压强度降低,而弹性模量和泊松比出现先降后升的趋势;随着浸水高度增加,煤岩抗压强度显著降低,水位超过试件高度的2/5时,抗压强度下降明显,煤岩刚度减小、塑性变形增强;砂岩占比增加可以减缓矿井水对煤岩组合体力学性能的影响,能有效提高煤岩组合体的抗压强度和刚度;随着流速增加,煤体初始刚度降低,弹性模量与峰值应力因结构损伤加剧而递减,破坏模式由脆性向延-脆性转变,残余强度随动水冲刷作用增强而显著下降。随着浸水时间的增加,破坏模式从剪切破坏、共轭剪切破坏转为以拉伸破坏为主的多种破坏形式共存,碎片化、粉化崩解现象增强。随着浸水高度的增加,煤岩试件的破坏形态逐渐从剪切破坏与拉伸破坏共存转为剪切破坏为主最终呈现以拉伸破坏为主,试件结构严重失稳,出现大范围的层理剥离、脱层和粉化崩解。随着砂岩比例的增加,破坏形态由整体的共轭剪切破坏转为仅发生在煤层的拉伸破坏。随着流速增加,从弱面弯曲剪切破坏逐步发展为整体结构的拉伸破坏,层间断裂逐渐发展为斜横问贯穿试件,而浸水侧煤体破坏特征随流速增加呈现较完整→滑移→粉化的递变规律。在矿井水单侧水环境下,煤体浸水表面和破坏断面的结构特征会发生煤体孔隙膨胀、裂纹扩展以及矿物沉积等现象,煤的结构逐渐变得松散,内外部结构发生损伤,破坏后产生的碎片、碎屑的破碎程度越剧烈,表面、断面也越粗糙,煤岩试件表面、断面图像的分形维数相对越大,反映出煤岩体的力学性能下降。(3)研究分析了矿井水单侧浸水环境中多种因素影响下煤岩试件受载发生破坏过程中声发射响应特征。随着浸水时间的延长,煤岩结构逐渐弱化,裂纹扩展加速,振铃计数显著增加,并在破坏临界时出现波动,能量释放在破坏阶段急剧增大;水位越高煤岩开裂扩展越迅速,能量释放剧烈,破坏过程越复杂;煤比例较高的组合体表现出较强的脆性和裂纹扩展,能量释放剧烈,而砂岩比例较高的组合体则展现出更强的抗压能力和较平缓的破坏过程;随着流速增加,裂纹的产生和扩展变得更加频繁和复杂,煤岩的破裂能量越来越集中在破裂的最后阶段,导致振铃计数和能量释放呈现出更大的波动。(4)基于室内试验结果确定了防水煤岩柱稳定性评价指标,采用模糊层次分析法计算得到各指标的权重:煤柱岩性>动水速率>积水水位高度>浸水时间,基于云模型构建了防水煤岩柱稳定性评价模型,确定防水煤岩柱稳定性指标分级标准,计算各指标的云模型数字特征,通过正态云发生器生成的云图直观展示了各指标在不同稳定性等级下的分布特征,反映煤柱在不同条件下的稳定性状态,最后通过根据工程实际对模型的合理性与可靠性进行了验证并提出防治措施。更多还原

【Abstract】 The waterproof coal rock pillar is the sole medium and key barrier to isolate the accumulated water in the goaf.Once the waterproof coal rock pillar becomes unstable and damaged,the accumulated water in the goaf will flood into the mining and excavation operation space,causing casualties and property losses.This thesis focuses on the waterproof coal rock columns affected by water accumulation in the goaf.Through indoor experiments,theoretical analysis,numerical simulation and other means,it studies the weakening law and response characteristics of the mechanical properties of coal and rock mass under the influence of water accumulation in the goaf,and conducts the stability evaluation of the waterproof coal rock columns under the influence of water accumulation in the goaf.The research results are as follows:(1)Based on the overview of the study area and the relevant background,several factors influencing the waterlogging in the goaf on the waterproof coal rock column were analyzed.Aiming at the different immersion times of the waterproof coal rock column in the goaf,the different water level heights of the waterlogging in the goaf,the different flow rates of the waterlogging in the goaf,and the different coal/rock thickness ratios of the waterproof coal rock column,a unilateral immersion experiment of the coal rock specimen was designed.Simulate the scenario where waterproof coal rock columns are affected by water accumulation in the goaf,carry out mechanical property test experiments,acoustic emission monitoring,and damage observation experiments,and study the weakening law and response characteristics of the mechanical properties of coal and rock masses under the influence of water accumulation in the goaf.(2)The mechanical properties,failure modes and structural damage characteristics of coal and rock masses under the influence of multiple factors in the unilateral immersion environment of mine water were explored.With the increase of the immersion time of the specimens in mine water,the compressive strength of coal and rock decreases,while the elastic modulus and Poisson’s ratio show a trend of first decreasing and then increasing.With the increase of the immersion height,the compressive strength of coal and rock decreases significantly.When the water level exceeds 2/5 of the specimen height,the compressive strength decreases significantly,the stiffness of coal and rock decreases,and the plastic deformation increases.The increase in the proportion of sandstone can mitigate the influence of mine water on the mechanical properties of coal-rock complexes and effectively enhance the compressive strength and stiffness of coal-rock complexes.With the increase of flow velocity,the initial stiffness of the coal body decreases.The elastic modulus and peak stress decrease due to the intensification of structural damage.The failure mode changes from brittleness to ductile-brittleness.The residual strength decreases significantly with the enhancement of the scouring effect of dynamic water.With the increase of immersion time,the failure mode changes from shear failure and conjugate shear failure to the coexistence of multiple failure forms mainly tensile failure,and the phenomena of fragmentation and powdering disintegration are enhanced.With the increase of the immersion height,the failure mode of coal-rock specimens gradually changes from the coexistence of shear failure and tensile failure to being dominated by shear failure,and eventually to being dominated by tensile failure.The structure of the specimens is severely unstable,and large-scale layering delamination,delamination and pulverization disintegration occur.With the increase of the proportion of sandstone,the failure mode changes from the overall conjugated shear failure to the tensile failure that only occurs in the coal seam.With the increase of flow velocity,the bending shear failure on the weak surface gradually develops into the tensile failure of the overall structure.The interlayer fracture gradually develops into the oblique transverse penetration of the specimen.The failure characteristics of the coal body on the water-immersed side show a changing law of relatively complete→slip→pulverization with the increase of flow velocity.In the single-sided water environment of mine water,the structural characteristics of the water-immersed surface and the damaged section of the coal body will undergo phenomena such as pore expansion of the coal body,crack propagation,and mineral deposition.The structure of the coal gradually becomes loose,and the internal and external structures are damaged.The more intense the fragmentation degree of the fragments and debris produced after the damage,the rougher the surface and section will be.The larger the fractal dimension of the surface and cross-sectional images of coal and rock specimens is relatively,the more it reflects the decline in the mechanical properties of coal and rock masses.(3)The acoustic emission response characteristics of coal and rock specimens during the failure process under the influence of multiple factors in the single-sided immersion environment of mine water were studied and analyzed.With the extension of the immersion time,the structure of coal and rock gradually weakens,the crack propagation accelerates,the ringing count increases significantly,and fluctuations occur at the critical point of failure.The energy release increases sharply in the failure stage.The higher the water level is,the more rapidly the cracking and expansion of coal and rock will be,the more intense the energy release will be,and the more complex the failure process will be.The composites with a higher proportion of coal exhibit stronger brittleness and crack propagation,and have intense energy release,while the composites with a higher proportion of sandstone show stronger compressive resistance and a more gentle failure process.With the increase of flow velocity,the generation and propagation of cracks become more frequent and complex.The fracture energy of coal and rock is increasingly concentrated in the final stage of fracture,resulting in greater fluctuations in the ringing count and energy release.(4)Based on the results of indoor tests,the stability evaluation indicators of water-resistant coal rock columns were determined,and the weights of each indicator were calculated using the fuzzy analytic hierarchy process:The lithology of the coal pillar>the dynamic water rate>the height of the accumulated water level>the immersion time.Based on the cloud model,the stability evaluation model of the waterproof coal pillar was constructed,the classification standard of the stability index of the waterproof coal pillar was determined,the digital characteristics of each index in the cloud model were calculated,and the distribution characteristics of each index under different stability grades were visually displayed through the cloud map generated by the normal cloud generator.It reflects the stability state of the coal pillar under different conditions.Finally,the rationality and reliability of the model were verified based on the actual engineering situation,and prevention and control measures were proposed.更多还原