【作者】 娄培杰；

【导师】 谢文兵；

【作者基本信息】 中国矿业大学 ， 采矿工程， 2014， 博士

【摘要】 淮北矿区芦岭煤矿二水平主要开拓和准备巷道不受采动影响时,巷道维护状况良好,但在受到煤层开采的扰动时,变形强烈,不但巷道受影响的超前距离长,而且影响程度也大,巷道的变形和破坏极为严重,几乎所有底板巷道都要经过多次翻修,造成巷道维护困难,严重影响了矿井的正常生产秩序。本文采用理论分析、实验室试验、数值模拟和工业性试验相结合的综合研究方法,系统分析了动压影响底板巷道围岩大变形力学机理、采场底板应力分布规律及底板破坏深度、动压影响底板巷道围岩变形破坏规律,以及不同支护方式下动压影响底板巷道围岩稳定性时空演化规律。主要研究成果如下：(1)通过引入岩体强度软化模量Q=(σε-σcb)/ε0pb-ε0εp,建立静、动压条件下考虑应变软化条件时圆形巷道围岩弹塑性力学分析模型。然后推导出静、动压条件下的巷道围岩破裂区、塑性区、弹性区三区应力、位移新解。新解算例表明,应变软化模量对围岩“三区”范围影响显著,能够更为客观地反映静、动压条件下巷道围岩强度随应变增加而降低的特性。若岩石力学参数选择合理,则从理论上可以得到更为合理的解析解。通过提高破裂区岩体残余强度,可以有效控制破裂区半径,并可以作为今后动、静压巷道布置、支护设计施工的有效依据。(2)通过岩石力学试验,得到芦岭矿Ⅱ82采区石门砂岩岩块的单轴抗压、抗拉、抗剪强度。通过分析采动岩体的力学特性和运用roclab软件对采动岩体力学参数进行优化。通过X射线衍射实验可知：该巷道围岩所含膨胀性岩石组份极少,基本可以排除物化膨胀型的变型力学机制。通过现场调查可知：该巷道附近没有断层、褶曲等地质构造,岩层结构较好,没有特别软弱的夹层,层理、节理也不发育,基本可以排除结构变形型力学机制。认为该巷道变形仅为单一的应力扩容型变型力学机制,属于IID工程偏应力型软岩；(3)基于圣维南原理,将采场底板支承压力进行线性简化,引入分区函数ζ,求得工作面走向底板支承压力分布不同区域的集度q,并在此基础上求得底板应力分量σx、σy、τxy的积分表达式,并据此分析底板走向支承压力的分布规律；(4)假设采动应力场为弹性薄板中间矩形开孔问题,在基于Westergaad应力函数的采场围岩应力计算模型基础上求解得到采场附近应力场。从传统的采场附近应力场简化公式求得：①平面应力条件下采场边缘主应力值σ1、σ2、σ3边界方程r、采场底板岩体最大破坏深度值h,并根据上述公式求得8#煤开采底板最大破坏深度hm；②平面应变条件下采场边缘主应力值σ1、σ2、σ3’,边界方程r1、采场底板岩体最大破坏深度值h,并根据上述公式求得8#煤开采底板最大破坏深度hm；(5)提出一种“大、小塑性区”条件下留设底板巷道合理位置的计算公式：该公式即考虑采场底板塑性区范围又考虑动压影响底板巷道塑性区半径。据此,求得II82采区石门理论位置为距采场底板38.66m；(6)通过数值模拟分析得到巷道围岩内部大变形活动规律：该类巷道先后受到工作面超前支承压力和工作面后方老顶破断、回转的影响,巷道围岩不同部位、不同深度均产生极不均匀变形,该极不均匀变形极易导致U型棚或一次锚网承载结构结构性失稳,由“弱结构”部位继而引发整体结构性失稳。(7)提出二次锚网索支护中结构补强锚索作用机理为：针对单一锚杆支护承载结构的薄弱位置进行结构补强,可以提高原有支护方式中锚杆组合拱的厚度,改善了围岩的自承载能力,大幅度增强了锚网索支护承载结构的稳定性和承载能力。提出棚索耦合支护中结构补强锚索作用机理为：针对棚式支护被动承载结构的薄弱部位进行结构补强,大幅提高了U型棚帮部结构稳定性和承载能力,既充分利用U型棚的高强护表能力,又充分发挥锚索主动承载性能,大幅度提高了U型棚支护承载结构的稳定性和承载能力。(8)基于以上研究,提出两套巷道支护方案：①棚索耦合+底板锚网索+注浆；②二次锚网索结构补强+底板锚网索+注浆。矿压观测表明：两套方案均能比一次锚网支护更好的控制该类巷道围岩的极不均匀大变形,减小巷道表面位移,降低维护成本,具有较大的推广应用价值。更多还原

【Abstract】 Luling coal mine, huaibei mining area two level of the main development and preparation of roadway is not affected by mining, roadway maintenance in good condition, but by coal bed mining disturbance, deformation, advance roadway affected not only the distance is long, but also big influence degree, deformation and failure of tunnel is very serious, almost all floor roadway after many renovations, cause roadway maintenance difficulties, seriously affected the normal production order of mine.Based on the theoretical analysis, laboratory test, numerical simulation and industrial test the integrated research methods of combining systematic analysis of the dynamic pressure influence mechanism of large deformation mechanics, stope floor of roadway surrounding rock stress distribution and floor damage depth, the dynamic pressure influence floor of roadway surrounding rock deformation and failure regularity, under different supporting method and the dynamic pressure influence the space-time evolution of floor roadway surrounding rock stability.The major achievements of this thesis are given as below:(1)By introducing rock mass strength softening modulus Q=σc-σbc/εpb0-εep0, the elastic-plastic mechanical analysis model of round roadway surrounding rock with consideration of strain softening condition under static pressure and mining pressure was set up. Then, the stress and new displacement explanation of elastic-plastic three area of roadway surrounding rock under static pressure and dynamic pressure were deduced. The new explanation example shows that strain softening modulus has remarkable impact on surrounding rock "three areas" scope, which can objectively reflect the features of roadway surrounding rock strength decrease along with strain increase under static pressure and dynamic pressure. This is the mechanical mechanism of large deformation for this kind of roadway. If reasonable rock physical and mechanics parameters are selected, then more reasonable analytic solutions can be obtained in theory. By improving residual strength status of fracture zone, the fracture zone radius can be effectively controlled. It is the mechanical mechanism of the roadway surrounding rock stability control, which can provide effective gist for the roadway arrangement and supporting design construction under static pressure and dynamic pressure.(2)By conducting the tests of indoor rock physical and mechanical properties, the uniaxial compressive, tensile and shearing strengths of sand rock mass at Ⅱ82mining area crosscut in Luling Coalmine were obtained. The shearing strength curve of sand rock was gained by matching. By analyzing the mechanical properties of mined rock mass and optimizing the mechanical parameters of mined rock mass with roclab software, the reliable mechanical parameters of rock mass was offered for the further numerical modeling establishment. Based on the analysis of rock constituents experiment, it can be concluded that the swelling rock constituents are precious few contained in roadway surrounding rock. This is merely single stress dilatation deformation mechanical mechanism rather than materialization dilatation deformation mechanical mechanism. Thus, it belongs to deviatoric stress soft rock of ⅡD project.(3)On the basis of saint venant principle, linear simplification of stope floor abutment pressure was made. Partitioning function ξ was introduced to calculate the intensities of floor abutment pressure distributions at different zones in working face direction. Based on the above, the integral representations of floor stress componentsσx, σy and τxy were computed. Then, the distribution law of abutment pressure in floor direction was analyzed.(4)Provided that mining stress field involves rectangle trepanning in the middle of elastic sheet, stress field nearby stope can be computed based on stope surrounding rock stress calculation model of Westergaad stress function. By simplified formula from stress field nearby traditional stope, it can be obtained:①under plane stress, principal stress value on the edge of stopeσ1,σ2and σ3, boundary equation r as well as maximal destruction depth value of stope floor rock mass h. According to the above equations, the maximal destruction depth value of mining floor in8#Coal hm=22.03m was obtained.②under plane strain, principal stress value on the edge of stopeσ1, σ2and σ3, boundary equation r’as well as maximal destruction depth value of stope floor rock mass h. According to the above equations, the maximal destruction depth value of mining floor in8#Coal hm=20.83m was obtained.(5)The computational formula of floor destruction depth under the condition of "big and small plastic zone" was proposed where both plastic zone radius of dynamic pressure influenced floor roadway and plastic zone range of stope floor were considered. The theoretical burial depth of1182mining area crosscuts had the distance of38.66m from stope floor, which was in line with field reality.(6)By adopting strain softening model in discrete element software UDEC, the mechanical model of stope and dynamic pressure influenced floor roadway was made, distribution features of stope floor abutment pressure were analyzed and following variation laws were acquired. The first is the variation law of floor fracture zone distribution along with working face advancing distance L. The second is that of floor fracture development along with working face advancing distance L. Through comprehensive comparison of influence laws of dynamic pressure on floor roadway surrounding rock equivalent stress, displacement, destruction line and fracture development, the internal activity law of dynamic pressure influenced floor roadway surrounding rock was given. In summary, this kind of roadway is influenced by lead abutment pressure of working face floor as well as upper roof fracture and revolving in the back of working face. There is uneven deformation for roadway surrounding rock from different parts at different depths, which can easily cause structural instability of support or abutment structure. Furthermore,"weak structure" part then triggers overall structural instability and global deformation.(7)The distribution law of surrounding rock equivalent stress, displacement and plastic zone is in organic connection with that of anchor rod axial force and failure zone wholly. By analyzing mechanical state of mining rock mass, supporting efficiency under different supporting ways was explained. In the same way, supporting efficiency under different supporting ways can be used to analyze mechanical state of mining rock mass. The supporting abutment behaviors of floor roadway at different parts involved transfer in different mining stages in working face. However, the stress was increased and supporting abutment property was improved as a whole. The action mechanism of structural reinforcement anchor rope means: structural reinforcement was made aiming at the weak location of single anchor rod supporting abutment structure to increase the thickness of anchor rod compound arch from original supporting way, enhance self-abutment capacity of surrounding rockand substantially reinforce the abutment capacity and structural stability of anchor netsupporting abutment structure. The action mechanism of structural reinforcementanchor rope on U-steel frame supporting roadway means: structural reinforcementwas made aiming at the weak location of shack supporting passive abutment structureto sharply improve the abutment capacity and structural stability of U-steel framesupport sides. In this way, highly intensive surface-protected capacity of U-steelframe support was fully used and active abutment property of anchor rope was fullydisplayed so to sharply improve the abutment capacity and structural stability ofU-steel frame supporting abutment structure. Suppose that there is the same stress fordynamic pressure influenced floor roadway, the supporting effect of shack-ropecoupling supporting is better than twice supporting of high-strength anchor-net-rope.Thus, beneficial reference can be provided for choosing reasonable supporting waysunder the same condition.(8)On the basis of detailed investigation into Ⅱ82mining area crosscuts geology,mining conditions and reasons of roadway surrounding rock failure, two sets oftesting programs of roadway stability controlling technology were proposed incombination with theoretical analysis and numerical simulation:①S cheme of high-strength stability supporting at U-steel frame②S cheme of high-strength stability supporting at anchor net supporting sectionThe long-term mine pressure observation station was arranged for the testroadway to observe surface displacement. The monitoring results suggest that: underthe conditions of the similar geology, mining conditions, construction techniques andforces, the support effect of shack-rope coupling plus floor grouting is bettercompared with twice structural reinforcement of anchor-net-rope plus floor grouting,which can control the extremely uneven deformation of dynamic pressure influencedroadway surrounding rock to larger extent and reduce roadway surface displacementquantity by a large margin. In addition, the service length of developing systemroadway can be prolonged with bigger promotional value.更多还原