【作者】 初影；

【导师】 王来贵；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2009， 硕士

【摘要】 岩石具有抗拉不抗压的力学特性,由于这一特点引发的工程灾害数不胜数。地裂缝灾害是岩石工程导致的地面变形灾害之一。采煤沉陷区往往存在大量地裂缝,使环境恶化、严重危害人们的生活和财产安全。研究煤层开采过程中地表受拉破坏的过程和规律,在工程实践中具有重要意义。文章研究采煤沉陷区地裂缝演化过程,探讨采煤诱发地裂缝分布规律。主要介绍岩层移动破坏规律规律、岩石变性破坏的力学分析以及采煤诱发沉陷地裂缝的力学分析等相关理论,以岩石受拉破坏的理论为基础,给出了岩石拉张破裂的四个判据,建立有限元模型,计算得出数值模拟结果,分析模拟采煤诱发地裂缝的演化过程和地表破裂的结果。有限元方法是目前应用最为广泛的研究工具,但是传统的有限元方法,是建立在连续性假设基础上的,不能模拟岩石拉张破裂后形成的不连续结构,不能直接处理岩石拉破坏现象问题。利用可描述拉张破裂的有限元方法,对不同抗拉强度、不同工作面推进长度、不同开采深度和不同煤层倾角下,沉陷区地裂缝演化过程进行数值模拟。模拟结果表明:煤层开采后,采空区破坏到一定程度后,沉陷区外边缘地表形成地裂缝并向深处扩展。抗拉强度越小,工作面推进的长度越大,开采深度越小,地表形成的裂缝增多。覆岩抗拉强度越小,工作面推进长度越大,煤层埋深越浅,地表越容易形成沉陷地裂缝,甚至形成地面塌陷。地裂缝上宽下窄,扩展方向大致与工作面推进方向相垂直。地裂缝的发生、发展过程是力学作用过程在岩层中的表现,拉张破裂形成不连续面后,裂缝周围应力状态发生改变,开裂点处应力被释放,应力重新分布,导致岩石裂纹进一步扩展形成二次破裂,这个过程不断反复。沉陷地裂缝形成的过程就是形成新结构的过程,相应导致应力状态不断的调整和改变。拉张破裂有限元程序可为研究采煤诱发地裂缝机理和裂纹的扩展规律提供新的方法。更多还原

【Abstract】 The rock has the low tensile strength mechanics characteristic, this characteristic initiation’s project disaster is innumerable.The ground fissure in one of the ground distorts disaster which caused by rock projects.The mining coal depressed area often has massively the ground fissure, causes the environmental deterioration, the severely impair people’s life and the property security. In the research coal mining causes the ground fissure process and the rule, has the important meaning in the project practice.Research the evolution process of ground fissure in mining subsidence area and the distribution law of ground fissure induced by mining. The main introduction rock layer migration destruction rule, the rock denaturation destroys mechanics analysis as well as the mining coal suggestion settlement crack’s mechanics analysis and so on correlation theories, is pulled take the rock the destruction the theory as a foundation, gave the rock to pull the tension fracture four criteria, established the finite element model, the computation obtains the numerical simulation result, the result which the analysis simulation mining coal suggestion crack’s evolutionary process and the surface burst.The finite element method is the present application most extensive research tool, but the traditional finite element method is established in the continuous supposition foundation, which cannot simulate the rock formation the uncontinuous structureto after tension fracture, cannot the direct processing rock tension destruction phenomenon question. Do the numerical simulation of the evolution process of ground fissure with different tensile strength, working surface advancement length, mining depth and inclination angle in mining subsidence area by using the finite element method describing tensile failure.The analogue result indicated: At the outer edge of subsidence area surface the ground fissures are formed and extended to depths after the goaf is damaged to certain degree with the propulsion of the working face.The tensile strength is smaller, the working surface advancement’s length is bigger, the mining depth is smaller, the surface forms the crack increases. The cap rock tensile strength is smaller, the working surface advancement length is bigger, the coal bed burying depth is shallower, the surface is easier to form the settlement crack, even forms the fall of ground. The cracks in the earth sew on widely under narrow, the expansion direction is vertical approximately with the working surface advancement direction. Tocrack the occurrence and development process is the role of process in rock mechanics in the performance of tensile rupture of the formation of discontinuities, the cracks around the stress state changed, the cracking point the stress was released, the stress redistribution, resulting in the further expansion of the formation of the rock cracks secondary rupture, this process constantly repeated. Subsidence in the process of crack formation is the process of the formation of the new structure, the corresponding stress state leading to constant adjustment and change. The tension fracture finite element procedure to be possible provides the new method for the research mining coal suggestion crack mechanism and the crack expansion rule.更多还原