【作者】 刘金辉；

【导师】 张恩强；

【作者基本信息】 西安科技大学 ， 采矿工程， 2011， 硕士

【摘要】 采场覆岩具有显著的梁的结构特征,研究岩梁及组合结构的受力变形、破坏规律是采场覆岩结构研究的基础。本文采用相似材料模拟实验和理论分析方法对单层及双层岩梁在自重作用下的破断规律及岩梁间的力学作用关系进行了研究,主要内容包括:构建岩梁相似材料模拟实验系统;选择合适的相似模拟材料并确定材料配比;进行试样的物理力学参数测定;对单层岩梁试件进行实验;对不同组合情况的双层岩梁组合结构进行实验并对实验结果进行理论分析;对实验模型进行数值模拟。单层岩梁实验结果与材料力学公式计算结果吻合度较高,表明所选相似材料制作的岩梁试件符合材料力学中梁的要求,可用材料力学分析方法进行分析。双层岩梁组合结构实验及其理论分析结果表明,双层梁的组合结构因组合方式不同而不同:上硬下软无粘结的情况下,层间无力的作用,各层独自运动,垮距同单层岩梁垮距一致;上硬下软弱粘结的情况下,在一定跨距内,交界面处的剪应力小于抗剪强度,双层岩梁按组合梁形式整体运动,超过该跨距后,交界面处的剪应力大于抗剪强度,组合梁遭到破坏,离层逐步发展,各层独自运动直至垮落,各层垮距同单层岩梁垮距基本一致;上硬下软强粘结的情况下,双层岩梁按组合梁结构运动直至垮落,垮距由各层试件力学性质决定。上软下硬的情况下,上部岩梁给下部岩梁加载,但载荷并不是其全部重量,而只是其中一部分,载荷大小取决于上、下岩梁的厚度、容重及弹性模量。对于上述情况均给出了表征岩梁间力学作用的计算式。利用FLAC^3D数值模拟软件对单层及不同组合情下的双层岩梁随跨距增大过程中变形、破坏规律及岩层间的力学作用关系进行了模拟,数值模拟结果同相似材料模拟实验结果以及理论计算结果基本一致。更多还原

【Abstract】 A significant beam structure exists in the stope overlying stratified rock. So the analysis of stresses and deformation failure of the beam and composite structure is the foundation of research of overlying strata’s structure.By similar materials simulation experiment and theoretical analysis, rock beam’s breaking rule under deadweight and the mechanical interaction between rock beams in different combination conditions were studied. The main contents are listed below. Constructed the system of rock beam similar material simulation experiment. Selected the appropriate materials and determined the ratio of the experimental. Measured the physical and mechanical parameters of the specimen. Conducted breaking experiments of single rock beam with different materials and analyze the experimental results by theory. Conducted breaking experiments of double-layer rock beams in different combination conditions and analyzed the experimental results by theory. Conducted numerical simulation about rock beams’breaking experiments.The results got from single rock beams’breaking experiment agreed with the theoretical results, indicated that rock specimens made from selected material lined with the requirements of Mechanics of Materials, analyze the experiment results of selected material by theory of mechanics of materials was suitable.Through double-layer rock beams’breaking experiment and theoretical analysis, such conclusions were got as below. The interlaminar shear strength determine the composite structure’s formation. In the combination of top-hard-bottom-soft with no cementation between two layers, there is no mechanical interaction between rock beams, the two layers move respectively and have the same broken span as single beam. In the combination of top-hard-bottom-soft with weak cementation between two layers, shear stress at the interface is less than the interlaminar shear strength within a certain span, the two layers combined to a composite structure and move together, surpass the span, shear stress at the interface become greater than the interlaminar shear strength, the composite structure is broken, the two layers separate from each other and move respectively until broken and have the same broken span as single beam. In the combination of top-hard-bottom-soft with strong cementation between two layers, the two layers combined to a composite structure and move together till broken, the broken span is affected by mechanical properties of specimens. In the combination of top-soft-bottom-hard, the top layer load to the bottom, but the load is a part not all of the deadweight of the top layer, it is determined by thickness, density and elastic modulus of the two layers. Mechanical formulas are concluded for each condition to introduce mechanics interaction between rock beams.By FLAC^3D numerical simulation software, deformation and failure law of single rock beam and the mechanics relationship between rock beams were simulated, numerical simulation results of rock specimen breaking experiment are the same as similar material simulation results.更多还原