深部巷道围岩变形破坏机理与稳定性控制原理研究

发布时间：2018-04-16 20:07

本文选题：高应力 + 塑性区　；参考：《湖南科技大学》2017年博士论文

【摘要】：随着浅部煤炭资源的枯竭,资源开采不断向地球深部延伸,千米级深部矿井资源开采越来越多。由于深部矿井围岩典型的“三高”赋存环境与资源开采过程中的采动等因素的影响,导致巷道冒顶事故频发、帮部挤出量大、底鼓问题严重、支护失效较为普遍,巷道围岩变形难以得到有效控制,直接制约了深部煤炭资源的安全高效开采。因此,对深部高应力巷道围岩的控制方法和支护技术研究具有重要的理论工程意义。本研究依托国家自然科学基金重点项目(51434006)和国家自然科学基金面上项目(51374105),采用理论分析、数值模拟、岩体力学试验和现场工程试验等相结合的综合研究方法,系统研究了深部巷道围岩变形破坏力学机理,分析了塑性区时空演化规律与几何分布形态对巷道围岩稳定性的影响,揭示了深部高应力巷道围岩变形破坏难以控制的力学本质,探讨了锚杆(锚索)锚固机理,提出了深部高应力巷道围岩稳定性控制支护原理与方法,取得了如下研究成果:根据深部巷道围岩体峰值强度前后应变硬化与应变软化特性,从能够表征岩体强度特征参数的内摩擦角和内聚力角度出发,引入硬化系数和软化系数概念,采用岩石应力、应变的弹性-塑性硬化-塑性软化-塑性流动四线模型,并基于莫尔-库仑屈服准则与非关联流动法则,建立了深部巷道围岩力学模型,获得了圆形巷道围岩弹性区、塑性硬化区、塑性软化区、塑性流动区应力、位移以及半径的解析表达式。对于巷道围岩塑性硬化区,其径向与切向应力随内摩擦角、内聚力硬化系数的增大而增大,径向与切向应变也随内摩擦角硬化系数的增大而增大;而对于塑性软化区,其径向与切向应力随内摩擦角、内聚力软化系数的增大而减小,径向与切向应变也随内摩擦角软化系数的增大而减小。提高巷道围岩塑性硬化区的内摩擦角、内聚力硬化系数与降低塑性软化区的内摩擦角、内聚力软化系数可提高围岩承载能力。深部巷道的开挖过程就是围岩的卸荷过程,对煤矿开采中常见的白砂岩进行了岩体力学试验。单轴压缩作用下的岩体破坏形态呈现“X”型,三轴压缩和恒轴卸围压作用下的岩体破裂形态呈现沿单斜面剪切破坏;当围压卸荷速率相同时,初始围压越大,岩体变形破坏所需要的时间越长,较高的原岩应力是导致巷道围岩长时间变形而不能收敛的主要原因。岩体的峰值强度与残余强度以及达到峰值强度时的轴向应变、环向应变均随围压的增高而增大,若将支护阻力看作围压,如果能够提供与围岩强度处于同一数量级的支护阻力,增大支护阻力有助于提高巷道围岩的峰值强度、残余强度以及允许变形能力,增强巷道围岩抵抗破坏的能力。深部巷道围岩所处的地质环境非常复杂,其应力状态也是不断变化的,经历了复杂的加卸荷应力路径演化过程。三轴加载-卸围压-单轴压缩与三轴加载-卸轴压-单轴压缩作用下的岩体沿试件轴向出现多个破裂面和相当数量的裂纹,宏观与微观裂纹数量随初始轴压的增大而逐渐增多,单轴抗压强度随初始轴压的增大而逐渐减小。岩体加载历史会对其本身产生一定程度的损伤和一定量的塑性变形,其损伤程度、塑性变形受制于加卸载方式和应力水平的大小。采动对巷道围岩的影响程度是以原岩应力为基础,原岩应力是巷道围岩产生损伤的本真属性,采动是引起围岩损伤的附加属性,原岩应力越大,采动越强烈,围岩内部损伤程度越严重,围岩塑性区范围越大。深部高应力巷道围岩的变形破坏过程实质上是由围岩塑性区的形成与扩展引起的,塑性区的几何分布形态和范围决定了围岩的破坏模式和程度。非等压条件下的深部高应力巷道围岩塑性区时空演化过程相继经历V个阶段:I塑性点阶段、II塑性环阶段、III塑性区均匀扩展阶段、IV塑性区恶性扩展阶段、V塑性区不均匀扩展阶段。采动在原岩应力的基础上,一方面改变巷道围岩主应力的大小,使工作面前方回采巷道围岩垂直方向应力升高,水平方向应力减少,该种情况下的围岩更容易产生蝶形塑性区,且蝶叶发育尺寸和塑性破坏范围很大;另一方面使巷道围岩主应力方向发生改变,蝶形塑性区几何分布形态随之发生旋转,当蝶叶位于巷道顶板正上方时,顶板稳定性最差,变形量最大,此时的顶板存在冒落风险。预应力锚杆对围岩应力场、塑性区影响不明显,对巷道较深部围岩的变形控制作用有限,但对抑制锚固区破裂围岩体之间的离层和滑动,减少张开滑移等非连续性变形作用非常明显。以目前的支护强度对控制巷道围岩变形作用有限,总是存在一定的围岩变形依靠现有支护水平无法控制,将此部分无法控制的围岩变形称之为“给定变形”。深部巷道围岩的这种“给定变形”是由高地应力造成的,“给定变形”量随原岩应力的增加而增大。基于现有支护水平无法实现巷道围岩大变形控制的事实,提出了巷道围岩稳定性控制原理与方法,在为巷道预留适当变形空间的条件下,允许围岩有较大的变形,并采取合理的支护方法降低围岩的非连续性变形,增强巷道围岩的整体性与稳定性,减少巷道维修量,降低支护成本。基于深部高应力巷道围岩稳定性控制原理与关键支护技术,并结合现场工程地质围岩条件,以赵固二矿I盘区胶带运输大巷支护为工程实例,在巷道掘进时预留一定的变形空间以容纳围岩部分“给定变形”,并有针对性的提出以“可接长锚杆+刚性长螺纹钢锚杆+锚网+W钢带+喷射混凝土”为主体,并辅以可接长锚杆强化顶板的综合控制技术支护方案。服务期间的巷道围岩变形满足矿井安全生产需求,未曾翻修,也未发现锚杆杆体破断、锚固失效与围岩冒顶、片帮等情况,降低了巷道维护费用,保障了巷道服务期间的安全使用。
[Abstract]:With the depletion of shallow coal resources, mining resources continue to extend to the deep earth, 1000m deep mine resource exploitation more and more. Because of the influence of deep mine rock typical of the "three high" environment and resources in the process of mining mining and other factors, resulting in frequent tunnel collapse accident, part of large amount of extrusion, the floor heave problem, supporting failure is more common, it is difficult to effectively control the deformation of surrounding rock, directly restricts the deep coal resources safety and high efficiency mining. Therefore, the deep high stress has important significance to control the engineering theory and research method of surrounding rock stress roadway supporting technology. This study is based on the National Natural Science Foundation of China the project (51434006) and the National Natural Science Foundation of China (51374105), by means of theoretical analysis, numerical simulation, rock mechanics test and field engineering test etc. the combination of integrated research methods, system Research on the system of the deep roadway surrounding rock deformation and failure mechanism, analysis of the plastic zone evolution patterns and geometric distribution influence on the stability of surrounding rock, reveals the nature of damage mechanics is difficult to control the deformation of surrounding rock of deep roadways in high stress area, discusses the bolt (cable) anchoring mechanism, put forward the deep and high stability rock roadway control principle and method, has achieved the following results: according to before and after the peak strength of deep roadway surrounding rock body strain hardening and strain softening characteristics, starting from the perspective of cohesion to characterize the strength of rock mass parameters and the angle of internal friction, is introduced into the hardening coefficient and softening coefficient, the rock stress, strain the elastic - plastic hardening plastic softening and plastic flow of four line model, and based on the Mohr Coulomb yield criterion and non associated flow rule, established a mechanical model for deep roadway, The circular tunnel in elastic zone, plastic zone, plastic softening zone, the stress displacement and plastic flow area, the radius of the analytical expressions for the plastic hardening zone of roadway surrounding rock, the radial and tangential stress increases with the increase of internal friction angle, cohesion hardening coefficient increases with increasing diameter, to the tangential strain with the internal friction angle of the hardening coefficient increases; and the plastic softening zone, the radial and tangential stress increases with the increase of internal friction angle, cohesion softening coefficient decreases with increase of radial and tangential strain with internal friction angle decreases. The softening coefficient of high plastic tunnel the hardening zone of surrounding rock of the internal friction angle, cohesion hardening coefficient and reduce the plastic softening zone of the internal friction angle, cohesion softening coefficient can improve the bearing capacity of surrounding rock of deep roadway. The excavation is the surrounding rock unloading process of common coal mining in the white sandstone of rock strength Experimental study on uniaxial compression of rock. The failure pattern of the present "X" type, three axial compression and constant axial unloading confining pressure rock rupture form shear failure along single inclined plane; when the unloading confining pressure at the same rate, the initial increase of confining pressure, the deformation and failure of rock mass need more time the higher, the original rock stress is the result of long time and deformation of the surrounding rock convergence cannot be the main reason. The peak strength and residual strength of the rock mass and peak strength when the axial strain increases, ring strain increases with the increase of confining pressure, the support resistance as the confining pressure, if we can provide with the strength of surrounding rock at the same level of support resistance, increasing support resistance is helpful to improve the peak strength of surrounding rock, residual strength and allowable deformation ability, enhance the ability to resist destruction of surrounding rock of deep roadway. The geological environment is very The complex stress state is also changing, has undergone a complex loading and unloading stress path. The evolution process of three axis loading and unloading confining pressure - uniaxial compression and three axial loading and axial unloading and uniaxial compression of rock specimens along the axial multiple fracture surface and a considerable number of crack, increase in the number of macro and micro crack with the initial axial pressure and increase gradually increased, the uniaxial compressive strength with the initial axial pressure decreases gradually. The rock loading history of plastic deformation will produce a certain degree of injury and a certain amount of itself, and the degree of injury, the plastic deformation subjected to loading and unloading method and the stress level of the size of the mining influence degree of the surrounding rock is based on the original rock stress as the foundation, the original rock stress of roadway surrounding rock is produced essential attribute of mining damage, is caused by additional properties of rock damage, the original rock stress, surrounding rock mining more intense, internal The more serious the damage, the plastic zone of the surrounding rock. The deep soft rock under high stress deformation and failure process is essentially formed by the plastic zone of the surrounding rock and the expansion caused by the plastic zone distribution and geometric range determines the extent and pattern of failure of the surrounding rock. The plastic zone of surrounding rock of roadway space force have experience of V evolution stages of deep non isobaric conditions should be high: I plastic stage, II plastic ring, III plastic zone uniform expansion stage, IV plastic zone malignant expansion phase, V plastic zone uneven expansion stage. Based on the mining of rock stress. On the one hand, the change of surrounding rock stress, the vertical direction of working face surrounding rock roadway side stress increased, horizontal stress is reduced, the surrounding rock conditions are more prone to butterfly plastic zone, and the butterfly leaf size and plastic damage range is large; on the other hand the lane The surrounding rocks along the direction of the principal stress change, butterfly plastic zone geometry distribution occurs when rotating, butterfly leaves located just above the roof, the roof stability is the worst, the maximum deformation, the roof caving risk. Existing prestressed bolt on the surrounding rock stress field, effects of plastic deformation zone is not obvious. The control effect on roadway deep surrounding rock is limited, but the inhibition between the anchorage zone of the surrounding rock rupture separation and sliding, reduce open slip discontinuous deformation effect is very obvious. The supporting strength to control the deformation of surrounding rock deformation effect, there are always rely on the existing support level to control the surrounding rock this part, will be unable to control the surrounding rock deformation is called "given deformation of deep tunnel". This "given deformation is caused by high stress," given deformation "with Yuan Yan stress. With the increasing support level can not be achieved. The large deformation of surrounding rock control based on the facts, put forward the principle and method of surrounding rock stability control in roadway reserved deformation space under the condition of large deformation of surrounding rock is allowed, and adopt reasonable support method to reduce non continuous deformation of surrounding rock, enhance the integrity and stability of surrounding rock roadway, reducing the amount of maintenance, reduce the cost of support. The surrounding rock stress roadway stability control principle and key supporting technique of deep high stress based on the engineering geological conditions of surrounding rock and the field, to Zhao Gu two mine I mining area belt transport roadway as an example, the deformation space the reserved in the tunnel to accommodate the surrounding part of "given deformation", and put forward a long rigid long thread steel bolt + anchor + +W steel shotcrete "main body" acceptability, and auxiliary The lengthened bolt reinforcement of roof control technology supporting scheme. The deformation to meet the mine safety requirements, no revision of roadway surrounding rock during the service, also found no anchor rod breaking, anchorage failure and rock roof spalling, etc., to reduce the cost of roadway maintenance, guarantee the safe use of roadway service period.

【学位授予单位】：湖南科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD322;TD353

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