【作者】 马凯；

【导师】 白海波；

【作者基本信息】 中国矿业大学 ， 工程力学， 2018， 硕士

【摘要】 在薄基岩厚松散层地质条件下进行煤层开采时,导水裂隙带容易贯通基岩,波及松散层中的含水层,给矿井安全生产造成巨大威胁,并且会引起上部土层的变形和沉降,造成潜水位下降甚至潜水含水层被疏干,对生态环境造成严重破坏。本论文从松散层土体物理力学性质和薄基岩的变形及破坏角度出发,结合三元煤矿实际地质条件,综合运用室内试验、理论分析、数值模拟等方法对薄基岩厚松散层隔水性能进行研究。主要得出以下研究成果:(1)根据土的物理和力学性质的试验,将三元煤矿松散层土体分成浅部、中部、深部三段,深部粘土为低压缩性饱和粘土,渗透性差,抗破坏的能力好,与基岩形成的稳定结构共同起到阻水作用,可作为良好的顶板隔水层。(2)考虑了采动破碎岩体对上覆岩体的支撑作用,建立四边固支的Winkler地基模型,根据能量法推导了其挠度表达式以及应力表达式,得到了薄基岩挠度与地基系数的关系及临界载荷随工作面推进距离的变化规律。(3)基于普氏地压学说对煤层采动上覆粘土层成拱效应进行分析,得到粘土层破坏成拱的形状受侧压力分布形式及侧压力系数的影响。侧压力的分布及侧压力系数的大小决定了压力拱的形状;随着侧压力系数的增加,拉、压分界点逐渐向外扩展。(4)分析得到三元煤矿薄基岩厚松散层区粘土层不被破坏的极限基岩厚度为38m左右,此厚度对于利用粘土层的隔水性能有参考作用;3301工作面上部松散层水及地表积水受相邻工作面开采的影响较小,不会导致3301工作面上方地表沉陷区积水溃入工作面。更多还原

【Abstract】 When coal seam is mined under the geological conditions of thin bedrock and thick alluvium soil strata,the water-conducting fissure zone result from mining can easily penetrate the thick bedrock,affect aquifer of the strata above,which brings huge threat to mine safety,it also cause the deformation and subsidence of the upper soil layer,resulting in the decrease or even the dewatering of the phreatic water,causing serious damage to the ecological environment.In this thesis,based on the physicomechanical properties of alluvium layer soil,the deformation and failure of thin bedrock,and combined with the geological conditions of Sanyuan coal mine,indoor test,theoretical analysis,and numerical simulations were applied to study the impermeability of thin bedrock thick alluvium strata.The main results are as follows:(1)According to the experiment of physical and mechanical properties of soil,the alluvium strata of Sanyuan mine can divide into three sections: shallow,middle and deep.The soil in deep section is low-compressibility saturated clay,with poor permeability and good resistance to damage,it together with the stable structures formed by bedrock play a role in water-blocking and can be used as good roof aquifuge.(2)Considering the supporting effect of mining broken rock masses on overlying rock masses,a Winkler foundation model with four sides fixed branches was established.The deflection expressions and stress expressions were deduced according to the energy method,The relationship between thin bedrock deflection and the Winkler foundation coefficient,and the variation of the critical load with the advancing distance of the working face are obtained.(3)Based on Protodyakonov’s theory,the arching effect of overlying clay layer in coal seam mining was analyzed,and the influence about arch shape affected by the lateral pressure distribution and lateral pressure coefficient was obtained.The distribution of lateral pressure and the magnitude of the lateral pressure coefficient determine the shape of the pressure arch.With the increase of the lateral pressure coefficient,the boundary points of tension and pressure gradually expand outward.(4)The analysis shows that the ultimate bedrock thickness of the clay layer which is not destroyed in the thick alluviumr of the Sanyuan coal mine is about 38 m.This thickness has a reference effect on the water-blocking property of clay layer.The loose aquifer and the surface water in the upper of the 3301 mining face are less affected by the mining influence of the adjacent mining face.It will not cause water in the surface subsidence area above the 3301 mining face to crash into the working area.更多还原