采场围岩力链演化特征及其关键物理量研究

发布时间：2018-06-15 02:46

本文选题：力链演化 + 采场围岩应力壳　；参考：《中国矿业大学(北京)》2017年博士论文

【摘要】：本文以力链为主线,运用理论分析、数值模拟与实验室实验相结合的综合研究方法,对采场围岩力链分布特征及其关键可测物理量进行了系统深入的研究。开展了采场围岩力链分布特征及其演化规律研究,实现了力链在采场围岩中的可视化;在采场围岩力链分布特征及其演化规律的基础上,基于矩张量理论,建立了声发射数值模拟模型,获得了力链与声发射时-空-强响应规律;采用实验室声发射和数学计算的研究方法,获得了能够表征不同岩石岩性的力链关键可测物理信息;采用数值模拟和实验室实验的综合研究方法,揭示了采场煤岩上覆岩层组合岩体的破断机制及力链关键可测物理量的特征,实现了采场围岩力链关键物理信息的定量描述。论文取得了以下主要研究成果:1.首次采用离散元颗粒物质方法对采场围岩的力链分布特征及其时空演化规律进行了模拟研究,实现了采场围岩力链的可视化基于谢桥煤矿21116工作面工程地质和开采技术条件,运用离散元软件PFC3D全面再现了采场围岩的力链分布特征与演化规律,并揭示了力链的形成机制与宏观应力壳的力学本质。主要结论如下:(1)发现了采场围岩中存在由大量力链组成的力链体系,力链能承受较大的法向外力,法向力越大则力链越稳定,能承受的切向作用力较小,超过其切向载荷极限时力链发生断裂。(2)首次采用离散元颗粒物质方法对采场围岩力链的分布特征及时空演化规律进行了模拟研究,发现随着工作面开挖,工作面周围力链集中程度不同,上下隅角及工作面前后方煤壁内侧处力链明显强于其他位置,采空区内为力链强度降低区。(3)随着工作面的推进,在走向和倾向方向剖面上都形成了强力链束组成的力链拱,在整个采场上覆岩层中形成了类似“椭球体”的由强力链束构成的宏观应力壳,应力壳为上覆岩层的主要承载力系,应力壳内的力链强度大于壳外的力链强度,且应力壳随着工作面的推进而不断演化。应力壳主要力学特征为壳体中的力链强度最大,壳体内外的力链强度相对较低。2.基于矩张量理论,揭示了力链与声发射的时-空-强响应规律基于矩张量理论,采用数值模拟与实验室实验的方法对轴向加载条件下岩石试件的宏观与细观破坏特征、力链演化规律、裂隙演化规律、力链与声发射响应规律等方面进行了研究,揭示了力链与声发射的时-空-强响应规律。主要结论如下:(1)颗粒物质内部形成的强力链呈“树根状”形态分布,在轴向应力作用下,强力链方向受控于应力加载的方向,进一步揭示了强力链的集中为采场围岩中宏观应力壳形成的力学本质。(2)岩石受载过程中内部力链数量与形成力链强度呈负相关,揭示了岩石材料裂隙形成与扩展的根本原因为力链集中造成的断裂与失稳。(3)基于矩张量理论,将岩石试件单轴压缩状态下对应的声发射响应分为微弱阶段、稳定阶段、稳定增强阶段、急剧增强阶段及峰值阶段,展现了各阶段声发射的空间分布形态和强度。(4)力链、裂隙与声发射在时间上呈现同步性,空间上呈现同区域性,强度上呈现一致性。岩石内部裂隙及声发射现象产生的力学本质是外力作用后材料内部力链发生了转移、转化、断裂和重构。在轴向应力加载条件下,力链断裂失稳释放的能量使得力链上的煤岩颗粒发生失稳偏离,致使力链受到破坏,产生损伤形成微裂隙,部分未被吸收的能量释放出来形成声发射现象。3.基于声发射的不同岩性力链关键物理信息获取为了获得能够表征不同岩性的力链关键物理信息,对采场上覆相同岩性、不同岩性岩石进行声发射实验,对比分析了声发射一般特征值和主频特征规律,获得了不同岩性的力链关键可测物理信息。主要结论如下:(1)同一岩性不同岩石试件的声发射幅值和能量等特征值随着应力的加载,呈现了相似的规律,不同岩性的同一声发射特征值随载荷加载过程中的演化规律相似,但特征值大小不同,表明声发射幅值和能量等特征值并不能作为区分上覆岩层不同岩性的信息。(2)采用快速傅里叶变换方法对实验中获得的声发射波形数据进行变换,提取出了不同岩性岩石的主频值。采用归一化方法对主频值进行处理获得了谢桥煤矿各种岩性岩石的主频值分别为:细砂岩300 KHz、粉砂岩95 KHz、中砂岩245KHz、灰岩130 KHz、岩浆岩310 KHz及原煤88 KHz。确定了以声发射主频值作为不同岩性岩石力链特征的关键物理信息。4.揭示了组合岩体剪切条件下力链关键物理信息的特征,实现了力链关键可测物理量的定量描述。采用数值模拟和实验室实验方法对软硬互层组合岩体的剪切破断机制、表面应变场演化及力链失稳致灾等方面的分析,揭示了组合岩层加载过程中的力链机制,定量描述了力链关键可测物理量的特征。主要结论如下:(1)采用数字散斑和数值模拟方法揭示了组合岩体的剪切破断规律。组合岩体剪切加载过程中首先在软岩层发生破坏,其次为较薄硬岩层,最后为硬厚岩层。软岩层的存在一方面缓和了组合岩体破坏造成的冲击性,另一方面也使组合岩层的破断规律更加复杂。(2)组合岩体剪切条件下力链与裂隙的形成与演化呈相互促进效应,组合岩体承受剪切载荷形成内部力链局部集中,导致裂隙的产生,而裂隙的产生引起力链进一步集中,揭示了采场上覆岩层剪切破断失稳的力链机制。(3)组合岩体剪切实验过程中,岩层主频值保持不变,随着应力的增加主频值对应的幅值出现小幅波动,整体保持稳定,但岩层力链断裂失稳时主频值对应的幅值数量级突然增大。揭示了主频值对应幅值的演化规律,确定了主频值对应的幅值为力链关键可测物理量。
[Abstract]:Taking the force chain as the main line, using the theoretical analysis, the combination of numerical simulation and laboratory experiment, this paper makes a systematic and thorough study on the distribution characteristics of the force chain of the surrounding rock of the stope and its key measurable physical quantities. The distribution characteristics of the force chain of the surrounding rock of the stope and its evolution law are carried out, and the force chain in the surrounding rock of the stope is realized. On the basis of the distribution characteristics and evolution law of the force chain of the surrounding rock of the stope, a numerical simulation model of acoustic emission is established based on the moment tensor theory, and the law of the force chain and acoustic emission time and space strong response is obtained, and the key measurable material which can characterize the rock lithology can be obtained by the research method of the acoustic emission and mathematical calculation in the laboratory. By means of the comprehensive research method of numerical simulation and laboratory experiment, the breaking mechanism of combined rock mass in the overlying strata and the key measurable physical quantity of the force chain are revealed, and the quantitative description of the key physical information of the rock force chain of the stope is realized. The main research results are obtained in the paper: 1. for the first time, the discrete element particles are used. The material method has carried on the simulation study on the distribution characteristics of the force chain of the surrounding rock of the stope and its spatio-temporal evolution law. The visualization of the force chain of the surrounding rock of the stope is based on the engineering geology and mining technical conditions of the 21116 working face of the Shiqiao coal mine. The distribution characteristics and evolution laws of the force chain of the peri rock in the stope are fully reproduced by using the discrete element software PFC3D, and the results are revealed. The main conclusions are as follows: (1) the main conclusions are as follows: (1) it is found that there is a force chain system consisting of a large number of force chains in the surrounding rock of the stope, and the force chain can bear a large external force. The greater the normal force, the more stable the force chain is, the less the tangential force can be borne, and the force chain is broken over its tangential load limit. (2) the discrete element particle material method is used for the first time to simulate the distribution characteristics and spatio-temporal evolution of the wall rock force chain in the stope. It is found that with the excavation of the working face, the concentration of the force chain around the working face is different, the upper and lower corners and the inner force chain of the inner side of the coal wall are obviously stronger than other positions, and the strength chain strength in the goaf is the strength. (3) with the advancement of the working face, the force chain arch formed by the strong chain beam is formed in the direction and direction section. In the overlying strata, the macro stress shell, which is composed of the "ellipsoid", is formed by the strong chain beam. The stress shell is the main bearing capacity of the overlying strata, and the force chain strength in the stress shell is greater than the shell. The strength of the external force chain and the stress shell evolve continuously with the advancing of the working face. The main mechanical characteristics of the stress shell are the force chain strength in the shell and the relative low strength of the force chain inside and outside the shell.2. based on the moment tensor theory, which reveals that the time tensor theory of the force chain and acoustic emission is based on the moment tensor theory, and the numerical simulation and experiment are adopted. The method of laboratory experiments on the macroscopic and mesoscopic failure characteristics of rock specimen under axial loading, the law of force chain evolution, the law of fracture evolution, the law of force chain and acoustic emission response are studied, and the time space and strong response law of the force chain and acoustic emission is revealed. The main conclusions are as follows: (1) the strong chain formed in the interior of the particle material is "tree" Under the action of axial stress, the direction of the strong chain is controlled by the direction of stress loading under the action of axial stress. It further reveals that the concentration of the strong chain is the mechanical nature of the formation of macro stress shell in the surrounding rock of the stope. (2) the number of internal force chains in the process of loading of rock is negatively related to the strength of the formation force chain, revealing the formation and expansion of the rock material fissure. The fundamental reason is the fracture and instability caused by the concentration of force chain. (3) based on the moment tensor theory, the acoustic emission responses of rock specimens under uniaxial compression are divided into weak phase, stable stage, stable enhancement stage, rapid enhancement stage and peak stage, and the spatial distribution and strength of acoustic emission at various stages are displayed. (4) force chain and crack The gap and acoustic emission show synchronism in time, showing the same regionally in space, and the intensity is consistent. The mechanical nature of the rock internal fissure and acoustic emission phenomenon is the transfer, transformation, fracture and reconstruction of the internal force chain of the material after the external force. The coal and rock particles on the force chain are destabilizing and deviating, causing the force chain to be destroyed, resulting in damage and formation of micro cracks, and some unabsorbed energy is released to form acoustic emission phenomenon..3. based on the key physical information of different lithologic force chains based on acoustic emission to obtain the key physical information that can characterize different lithology, overlying the stope The acoustic emission experiments with the same lithology and different lithology are carried out. The general characteristic values of acoustic emission and the characteristics of the main frequency are compared and analyzed. The key physical information of the force chain of different lithology is obtained. The main conclusions are as follows: (1) the eigenvalues of acoustic emission amplitude and energy of different rock specimens are similar with the stress loading. The characteristic values of the same acoustic emission of different lithologies are similar to the evolution laws of the load loading process, but the eigenvalues are different, indicating that the eigenvalues of the acoustic emission amplitude and energy can not be used as information to distinguish the different lithology of the overlying strata. (2) the acoustic emission waveform data obtained by the fast Fourier transform method are used to get the acoustic emission waveform data obtained in the experiment. The main frequency values of different lithologic rocks are extracted by line transformation. The main frequency values of various lithologic rocks in Shiqiao coal mine are obtained by the normalization method. The main frequency values of various lithologic rocks in Shiqiao coal mine are: fine sandstone 300 KHz, siltstone 95 KHz, medium sandstone 245KHz, limestone 130 KHz, magmatic rock 310 KHz and raw coal 88 KHz. to determine the main frequency value of acoustic emission as different rock. The key physical information of the characteristics of the sexual rock force chain (.4.) reveals the characteristics of the key physical information of the force chain under the shear condition of the combined rock mass, and realizes the quantitative description of the key measurable physical quantities of the force chain. The shear breaking mechanism of the soft and hard interbedded rock mass, the evolution of the surface strain field and the force chain instability induced by the numerical simulation and the laboratory experiment method are adopted. The force chain mechanism in the loading process of composite rock strata is revealed and the characteristics of the key measurable physical quantities of the force chain are described quantitatively. The main conclusions are as follows: (1) the shear breaking law of the combined rock mass is revealed by digital speckle and numerical simulation. The second is the thinner hard rock stratum, and the last is the hard and thick strata. The existence of the soft rock layer reduces the impact caused by the failure of the combined rock mass on one hand, on the other hand, it also makes the breaking law of the composite rock more complicated. (2) the formation and evolution of the force chain and the fracture are mutually promoting effect under the shear condition of the combined rock mass, and the combined rock mass is subjected to the shear load formation within the rock. The local concentration of the force chain leads to the formation of the crack, and the formation of the crack causes the force chain to be further concentrated, which reveals the force chain mechanism of the shear breaking and the instability of the overlying strata on the stope. (3) during the shear experiment of the combined rock mass, the main frequency values of the rock strata remain unchanged, and the amplitude of the corresponding amplitude of the main frequency increases with the increase of the stress. However, the magnitude of the magnitude of the main frequency value increases suddenly when the fracture of the rock stratum is unstable. The evolution law of the corresponding amplitude of the main frequency is revealed, and the corresponding amplitude of the main frequency value is determined as the key measurable physical quantity of the force chain.
【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD31

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