厚煤层综放双巷工作面巷间煤柱尺寸研究

为解决厚煤层综放双巷布置工作面巷间煤柱的留设问题,以某矿四盘区4301工作面运输顺槽与辅助运输顺槽之间的煤柱为工程背景,首先对巷间煤柱进行理论分析:一次采动影响后将巷间煤柱沿倾向划分为采动影响区、相对稳定区和锚杆支护区,应用极限平衡理论分析得出了一次采动影响区的宽度为2.82 m,进而得出巷间煤柱的宽度为7.83 m。其次,应用数值模拟的方法系统地分析了宽度分别为4、6、8、10、12、15、20 m时,在两次采动影响下巷间煤柱的应力演化、破坏、巷道围岩变形规律;一次采动影响后,随着煤柱宽度增大,髙应力由实体煤向煤柱内转移;给出了最大临界尺寸、最小临界尺寸的定义,并指出巷间窄煤柱宽度应小于最大临界尺寸。综合分析数值模拟研究结果,同时结合理论分析结果及煤柱留设原则,最终确定巷间煤柱宽度为8 m。最后,通过现场工程实践验证了所确定的巷间煤柱宽度的合理性。研究结果对类似条件下综放双巷布置工作面巷间煤柱宽度的确定具有参考意义。     

特厚煤层区段防水煤柱稳定性评价及保护技术研究

留设合理宽度的区段煤柱是确保特厚煤层综放工作面顺利接续和安全回采的关键。为确保芦子沟煤矿3107特厚煤层综放工作面仰斜开采过程中,双侧采空煤柱能够稳定承载并有效隔水,分析区段煤柱覆岩结构特征,建立区段煤柱应力计算模型,理论计算了双侧采空煤柱应力,结合数值模拟及理论分析手段对煤柱稳定性进行综合评价。通过实施科学合理的深孔爆破切缝卸压方案,降低了3107工作面采动应力对煤柱的影响,优化了煤柱应力环境,提高了煤柱稳定性,保证了3107工作面的安全回采。研究结果对类似开采条件下的区段煤柱宽度确定及坚硬顶板条件下煤柱卸压具有一定意义。     

超长工作面过大断面空巷三维应力演化及综合治理技术

为解决超长工作面过大断面空巷极易发生片帮和大面积冒顶等难题,以晋城成庄矿某超长工作面为背景,建立大断面空巷的三维模型,将工作面顶板划分为煤柱顶板、空巷顶板和待采区顶板3部分。通过理论分析,推导了煤柱失稳的判据,并利用FLAC3D数值模拟分析了大断面空巷顶板应力演化过程。结果表明:煤柱宽度W≤40 m时,工作面超前支承应力与空巷超前支承应力在煤柱上叠加,煤柱开始发生塑性变形;W≤10 m时,煤柱顶板应力逐渐达到峰值16.6 MPa,煤柱发生破坏并失去承载能力,工作面超前支承应力向待采区转移,空巷顶板应力达到峰值12.7 MPa。根据空巷顶板应力演化规律,确定高水材料充填支柱支护的合理强度及空巷两帮煤壁注浆加固的时机,辅以空巷锚索梁补强,提出了大断面空巷综合治理措施,现场应用效果良好。      

大断面综放沿空巷道煤柱合理宽度与围岩控制

确定合理的区段煤柱宽度及巷道支护型式和参数,对于提高资源回采率和巷道安全性及实现综放开采高产高效意义重大。以王家岭煤矿20103区段运输平巷为工程背景,采用FLAC3D数值分析了不同煤柱宽度下围岩主应力差、变形及破坏演化规律,认为合理煤柱宽度为6～10 m,并结合实际地质和生产条件确定试验巷道煤柱宽度为8 m。采用理论分析和现场钻孔窥视方法综合确定基本顶断裂线位于距采空区约7 m处,认为由于综放沿空巷道围岩性质结构和应力分布沿巷道中心线呈明显非对称性,将引发煤柱侧顶板严重下沉和肩角部位煤岩体错位、嵌入、台阶下沉等非对称破坏特征,靠煤柱侧顶板及肩角部位是巷道变形破坏的关键部位。在此研究基础上,针对性地提出了以高强锚梁网、不对称锚梁、锚索桁架为主体的综合控制技术,详细阐明了具体支护措施的控制机制,并进行现场应用。工程实践表明,8 m煤柱宽度合理,该支护技术能够保证窄煤柱沿空巷道围岩稳定,并已在王家岭煤矿大面积推广应用,对类似工程条件的支护技术具有一定的理论意义和实用价值。     

综放沿空巷道底板受力变形分析及底鼓力学原理

在分析了综放沿空巷道底板力学环境的基础上，建立了底板力学模型，计算了巷道，窄煤桩，高支承压力区底板岩层的相对位移，提出综放沿空巷道底鼓成因主要有以下3个方面：一是巷道底板一定深度的岩层在等效载荷的作用下产生拉应变而破坏；二是由于巷道底板岩层的破坏降低了高支承压力区底板岩体围压，导致这部分岩体在基形变热能释放过程中破坏而产生的巷道内的塑性流动三是实煤体帮的下沉，并简要分析了煤柱宽度对底鼓的影响。     

复用回采巷道护巷煤柱合理宽度研究

为解决高瓦斯工作面双U型巷道布置中煤柱损失大、相邻工作面复用回采巷道维护困难的难题,综合采用理论分析、数值计算和现场试验的方法,研究得到煤柱宽度对相邻两工作面之间煤柱内复用巷道围岩应力分布和变形特征的影响规律：随着巷道一侧煤柱宽度的增加,巷道围岩垂直应力峰值向一侧移动,并逐渐远离巷道;当巷道一侧煤柱较小时,巷道以窄煤柱帮变形和顶板下沉为主,随着煤柱宽度增加,底鼓增大并成为巷道主要变形。以煤柱内应力峰值比值为指标,分析煤柱宽度与巷道稳定性的关系,并将不同宽度煤柱进行了稳定性分区。研究成果成功应用于工程实践,为类似条件下巷道布置提供依据。     

松软煤层综放面顶底板采动应力分布规律研究

以某矿综放采场为背景,通过现场实测、相似材料模拟等手段,研究了松软煤层综放开采中液压支架受力状态、两巷单体支柱受力特征和顶底板的采动应力分布规律,结果表明液压支架在工作面不同位置受力状态不同,处于中部位置的支架受力最大,同一支架前立柱受力大于后立柱;风巷围岩应力大于机巷围岩应力,两巷的超前采动应力峰值位置在工作面前3～11m;顶板岩层同一层位中采动应力分布随工作面的距离不同而不同;不同层位应力分布也不同,离煤层越近的岩层中应力集中系数越大;底板岩层在工作面前方6m左右处应力达到最大,在工作面处应力为零。该研究结果有效地指导了该矿井同一煤层综放面巷道布置、两巷支护及工作面顶板管理。     

深井孤岛工作面巷道围岩采动应力分区演化特征

针对深井孤岛工作面煤巷大变形问题,采用现场实测手段研究了回采过程中巷道和采空区应力动态演化规律以及巷道围岩变形破坏演化特征。研究结果表明：深井孤岛工作面巷道围岩应力演化与变形破坏具有显著的阶段性特征,工作面前方大于250 m范围,巷道围岩未受采动影响,围岩应力变化较小且变形主要集中在底板与煤柱肩窝;工作面前方100～250 m支护结构受力增大,巷道浅部围岩破碎,顶底板移近及煤柱内挤变形突出,巷道出现明显的非对称变形破坏;工作面前方100 m为强烈采动影响阶段,尤其是在工作面前方20～22 m围岩垂直应力与空间主应力变化比较剧烈,顶底板移近与两帮内挤变形更加突出,巷道围岩表现出明显的大变形破坏特征。根据采空区应力分区特征分析了顶板覆岩结构的动态演化过程。结合应力与变形破坏演化特征,提出了巷道支护对策,以期为深井巷道围岩控制提供一定指导。     

回采巷道片帮机制及控制技术研究

根据大采高工作面回采巷道帮部围岩的特点,采用断裂损伤理论、弹塑性理论建立了巷帮围岩层裂板结构力学模型,分析了霍州煤电辛置煤矿回采巷道帮部围岩失稳机制,并将注浆锚索支护方式首次应用于巷道帮部围岩的片帮治理。研究表明：回采巷道帮部围岩内部存在大量的裂纹,在高应力的作用下裂纹扩展发育,巷帮围岩演化为层裂板结构,当作用在巷帮围岩上的多重支承压力大于最小临界失稳载荷时即发生片帮;随煤岩体弹性模量、层裂板厚度的增大,层裂板发生失稳时破坏范围扩大;采用注浆锚索支护巷帮时浆液能够填满巷帮围岩深部裂隙,使巷帮围岩成为一个整体,提高了巷帮围岩支护结构的承载能力,控制了巷帮围岩片帮的发生。     

特厚煤层大采高综放工作面煤壁片帮机制分析

针对特厚煤层大采高工作面,将超前支承压力作用的煤体分为破裂区、塑性区和弹性区。考虑支架护帮阻力等因素,建立了支承压力作用的煤体变形破坏及煤壁片帮分析力学模型。通过摩尔-库仑准则和非关联弹塑性分析,推导出了煤壁水平位移量及破裂区和塑性区半径解析表达式,分析了影响煤壁片帮的主要因素。理论结果与现场实测结果误差仅为15.6%,验证了模型的正确性。研究表明,随支承压力集中系数的增大、机采高度的增加以及支架护帮阻力的减小,煤壁水平位移量明显增大,煤壁片帮程度严重。工程实践表明,提高支架工作阻力,减缓煤壁处压力,控制合理采高以及增大支架护帮阻力,可有效缓解大采高综放工作面煤壁片帮程度。     

Research on reasonable coal pillar width of roadway driven along goaf in deep mine

Driving roadway along a goaf is commonly adopted for mining face of thick seam in a deep mine. Determining a reasonable width of coal pillar is a key scientific problem for driving roadway along a goaf in a deep mine. The paper took a roadway driven along a goaf at Zhaolou coal mine which is a typical kilometer-deep mine in China as engineering background. Field monitoring, model test, and numerical experiment are conducted. Stress and displacement evolution mechanism are analyzed with different pillar widths. The test results show that with the increase of coal pillar width, the peak stress value at the coal pillar working slope and integrated coal beside the roadway increases firstly and then tends to be stable, its position is transferred to the side of the roadway, and the deformation of coal pillar decreases gradually during roadway excavation. The coal pillar deformation and roadway vertical displacement increased as the coal pillar width increases under high abutment pressure. In order to reduce the waste of non-renewable resources and meet the requirements of bearing capacity and stability of coal pillars, a method is proposed for setting a reasonable width of coal pillars and the specific width of coal pillars is designed and applied in engineering practices based on the above research. All the tests are significant in the study of driving roadway along a goaf in a deep mine.     

泾河下综放开采隔离煤柱对覆岩破坏控制作用的物理模拟

根据地质资料,分析了下沟煤矿泾河下特厚煤层大面积综放开采的地质特点,为实现水体下安全回采,确定了在各工作面间留设一定宽度隔离煤柱的开采方案。通过相似材料模拟试验,分析了改本区地质条件下各综放工作面间留设一定宽度隔离煤柱对覆岩破坏的影响。研究证实,隔离煤柱对覆岩破坏起到有效的控制作用。根据试验得出的单工作面最大裂采比,通过最小防水安全煤岩柱垂高的计算,认为地质条件满足泾河下安全回采的要求。且研究成果成功指导了5个工作面安全回采,可为该区及类似条件其他矿井的开采提供参考     

细长窄煤柱破坏机理的数值分析

对特厚煤层条件下采用螺旋钻机开采细长窄煤柱的破坏过程进行了数值模拟。模拟结果再现了开采过程中煤柱破坏发生、发展直至塑性区贯通破坏的全过程,并从应力场演化分析了煤柱破坏过程的应力分布特征及破坏机理。     

Research and application of roadway backfill coal mining technology in western coal mining area

In China’s western coal mining area, the traditional room mining technology is facing coal pillar instability, mine earthquake, large-area roof subsidence in the goaf, surface subsidence, water and soil loss, vegetation deterioration, and other environmental problems. To solve the aforementioned problems and to improve coal recovery, the roadway backfill coal mining (RBCM) method was proposed as a solution and its technical principle and key equipment were presented in this paper. In addition, the microstructure and mechanical behavior (strain-stress relation in confined compressive test) of aeolian sand and loess backfill materials were studied for a rational backfill design for underground mines. Further, coal pillar stress, plastic zone change, and surface deformation of the RBCM schemes were studied using the FLAC^3D numerical simulation software, and a reasonable mining scheme of “mining 7 m and leaving 3 m” was determined. The engineering application in Changxing Coal Mine shows that the RBCM method with loess and aeolian sand as backfill materials allows a stable recovery of coal pillars with a recovery ratio of more than 70 %. The maximum accumulated surface subsidence and the maximum horizontal deformation were measured to be 15 mm and 0.8 mm/m respectively, indicating that the targeted backfilling effect can help protect the environment and also control surface subsidence.     

A study of surface subsidence and coal pillar safety for strip mining in a deep mine

Some villages and bridges are located on the ground surface of the working district no. 7 in the Wanglou Coal Mine. If longwall mining is adopted, the maximum deformation of the ground surface will exceed the safety value. Strip mining is employed for the working district no. 7 which is widely used to reduce surface subsidence and the consequent damage of buildings on the ground surface. To ensure the safety of coal pillars and improve the recovery coefficient, theoretical analysis and numerical simulation (FLAC 3D) were adopted to determine the coal pillar and mining widths and to discuss the coal pillar stress distribution and surface subsidence for different mining scenarios. The results revealed that the width of coal pillars should be larger than 162 m, and the optimized mining width varies from 150 to 260 m. As the coal seam is exploited, vertical stress is mainly applied on the coal pillar, inducing stress changes on its ribs. The coefficient of mining-induced stress varies from 2.02 to 2.62 for different mining scenarios. The maximum surface subsidence and horizontal movement increase as the mining width increases. However, when the mining width increases to a certain value, increasing the pillar width cannot significantly decrease the maximum subsidence. To ensure the surface subsidence less than 500 mm, the mining width should not be larger than 200 m. Considering the recovery coefficient and safety of the coal pillar, a pillar width of 165 m is suggested.     

开滦赵各庄矿2137（西下）工作面防水煤柱留设研究

开滦赵各庄矿2137西下工作面为大埋深、急倾斜、特厚煤层开采区。为预防顶板老窑突水灾害,合理留设防水煤柱,采用了FLAC3D模拟方法分析连续介质大变形条件下围岩体积应变分带特征,并与工作面实际情况相结合,确定了该矿冒落带、裂隙带最大高度,合理解释了切眼处采空区上方煤层超高抽冒现象。通过计算决定该矿留设防水煤柱60m,该结果比规程少留煤柱15.75m。经两年的生产实践,证明防水煤柱留设安全可靠。     

Borehole stress monitoring analysis on advanced abutment pressure induced by Longwall Mining

The paper presented the research on the dynamic advanced abutment stress induced by longwall mining with borehole stress meters on mining side coal mass. Twenty vibrating wire borehole stress meters were installed into the extracting coal mass wall of a first mining roadway of 910 m depth in Zhuji Coal Mine, China, and were used to monitor dynamic changes in vertical and horizontal stresses. Three months of continuous monitoring and further analysis showed that the impacting distance of advanced abutment stress induced by mining in the strike of the working face along its central axis was the farthest, greater than 250 m (the face length is 220 m); it gradually decreased in the radial direction of the face from its central axis outward; the pressure peak was located within 24 m in the front of the mining coal wall; non-synchronous caving of the layered mudstone roof at the stope occurred. Comparison between vertical and horizontal stress increments indicated that the horizontal stress was much smaller than the vertical stress in the coal mass of mining side, while the latter’s magnitude determined the drastic degree of mine pressure manifestation. The study has been applied to determine the advanced support length of the working face and further provide a reliable basis to forecast such dynamic disasters as rock burst, coal and gas outburst, etc., as well as to design the asymmetric supports on both sides of a gateway.