岩质边坡宏细观力学特性及开挖稳定性分析与控制研究

发布时间：2018-04-19 19:26

本文选题：边坡稳定性 + 宏细观特性　；参考：《北京科技大学》2018年博士论文

【摘要】：随着露天矿山开采深度的增加,边坡加高加陡,开挖扰动引起工程岩体强度不断劣化,应力环境更加复杂。深入研究岩质边坡的力学特性及开挖稳定性,具有重要的科学及工程意义。本文依托国家科学自然基金重点项目“深凹露天矿高陡边坡稳定性研究(51034001)”,针对水厂铁矿露天境界外扩工程,以北采场II区岩质高陡边坡为研究对象,从连续-非连续、宏观-细观的角度,分析边坡岩体的宏细观力学特征和开挖扰动条件下的边坡稳定性,主要结论和成果如下:(1)调研现场地质概况,掌握工程地质特征,开展现场地应力测量、室内岩石力学试验、结构面统计调查,获取了地应力场分布特征、岩体物理力学参数及节理裂隙的空间分布规律。(2)基于颗粒流理论,探讨PFC中细观参数与岩石宏观力学特性之间的响应规律,通过单因素分析、正交试验极差分析,获得了宏细观参数之间的关系,及各细观参数的影响度排序;利用Matlab神经网络,构建了从宏观力学参数到细观参数的预测模型,提出细观参数的标定方法,并以混合花岗岩为研究对象,标定了平直节理接触模型的细观参数;研究颗粒流模型中颗粒尺寸对岩石宏观力学特性的影响,得到了内尺度比的取值范围,为颗粒半径的选取提供依据。(3)开展混合花岗岩的室内单、三轴加载试验、围压卸载试验,从应力-应变角度分析岩石破坏的宏观特征:基于PFC数值试验平台,进行了不同围压下的加、卸载数值试验,从能量演化、微裂纹扩展及破坏模式角度分析试件破坏时的细观特征,由此分析对比加、卸载条件下宏、细观力学特性的差异;以微裂纹数目为细观损伤变量,得到细观损伤变量与宏观变形模量和泊松比变化的关系式,在此基础上建立屈服阶段的本构方程。(4)基于边坡开挖过程中应力分布的变化情况,揭示了在开挖扰动影响下工程岩体参数劣化的力学机制,指出其在工程稳定性分析中的意义与价值:通过试验分析不同围压卸载条件下变形模量的变化规律,得到工程岩体劣化系数A与水平应力降低比例的定量关系式,二次开发FLAC3D内置应变软化模型,构建工程岩体开挖扰动劣化模型,并用于水厂边坡开挖过程的稳定性分析:依据开挖扰动对岩体质量的影响,修正RMR评价方法,建立边坡岩体模糊综合评判模型,采用Visual C#语言,开发了基于Windows平台的边坡岩体质量智能评价系统。(5)基于等效岩体技术,结合现场结构面的调查结果,在PFC中实现了节理岩体的表征,并确定了本文工况条件下表征单元体的尺寸,结合Hoek-Brown准则计算的岩体力学参数,对节理岩体的细观参数进行修正;建立水厂铁矿边坡模型,通过模拟开挖,探究边坡滑坡失稳的细观演化过程,基于张拉-剪切复合破坏准则,利用颗粒流细观强度折减法对边坡的稳定性进行分析:提出了水厂边坡稳定性控制的动态反馈体系,分析不同开挖顺序下边坡岩体的力学响应特征,结合现场和数值分析结果,提出灾害防治建议。
[Abstract]:With the increase of mining depth in the open pit, the slope is high and steep. The excavation disturbance causes the strength of the rock mass to be deteriorated and the stress environment is more complex. It is of important scientific and engineering significance to study the mechanical properties of the rock slope and the stability of the excavation. Study on the stability of steep slope (51034001) ", in view of the external expansion project of the open-pit boundary of the water plant, the high and steep slope of the II area in the North stope is studied. The macro meso mechanical characteristics of the rock slope and the stability of the slope under the condition of excavation are analyzed from the point of view of continuous discontinuity and macro meso. The main conclusions and results are as follows: (1) investigation and research The field geological survey, the engineering geological characteristics, the in-situ stress measurement, the laboratory rock mechanics test and the statistical investigation of the structure surface have been obtained. The distribution characteristics of the ground stress field, the physical and mechanical parameters of the rock mass and the spatial distribution of the joint fissure are obtained. (2) based on the theory of particle flow, the meso parameters in PFC and the macroscopic mechanical properties of rock are discussed. According to the response law, the relationship between macro and mesoscopic parameters is obtained through single factor analysis and orthogonal test extreme analysis, and the influence degree of various mesoscopic parameters is ordered. The prediction model of the macroscopic parameters to the fine parameters is constructed by using the Matlab neural network, and the calibration method of the mesoscopic parameters is put forward, and the mixed granite is the research object and the standard is used. The influence of particle size on the macroscopic mechanical properties of rock in the particle flow model is studied. The range of the internal scale ratio is obtained, which provides the basis for the selection of the particle radius. (3) the indoor single, three axis loading tests, confining pressure unloading tests, and the analysis of rock from the stress strain angle of the mixed granite are carried out. The macroscopic characteristics of rock failure: Based on the PFC numerical test platform, the numerical tests of loading and unloading under different confining pressure were carried out. The microscopic characteristics of the specimen were analyzed from the energy evolution, the micro crack expansion and the failure mode angle, and the difference between the macro and the meso mechanical properties under the loading and unloading conditions was analyzed and compared. The number of micro cracks was the meso damage change. On the basis of the variation of stress distribution in the process of slope excavation, the mechanical mechanism of the deterioration of the parameters of the engineering rock mass under the influence of excavation disturbance is revealed, and it is pointed out that it is in the stability analysis of engineering. (4) based on the variation of stress distribution in the process of slope excavation Significance and value: through the test and analysis of the variation of the deformation modulus under different confining pressure, the quantitative relation between the degradation coefficient A of the engineering rock mass and the reduction of the horizontal stress is obtained. The two development of FLAC3D built-in strain softening model is developed, and the disturbance deterioration model of the engineering rock mass excavation is constructed, and the stability of the slope excavation process in the water plant is used. Analysis: according to the influence of the excavation disturbance on the mass of rock mass, the RMR evaluation method is corrected, the fuzzy comprehensive evaluation model of slope rock mass is established, and the Visual C# language is used to develop the intelligent evaluation system of rock mass quality based on the Windows platform. (5) based on the equivalent rock mass technology and the investigation results of the site structure surface, the joint rock is realized in PFC. The size of the body is determined under the condition of the working condition, and the parameters of rock mass mechanics calculated by the Hoek-Brown criterion are used to modify the mesoscopic parameters of the jointed rock mass. The slope model of the water mill iron mine is set up to explore the meso evolution process of the slope instability by simulating the excavation, and based on the tensile shear composite failure criterion, The stability of slope is analyzed by the method of granular flow meso strength reduction. The dynamic feedback system of slope stability control is put forward, the mechanical response characteristics of rock mass under different excavation sequence are analyzed, and the disaster prevention and control suggestions are put forward in combination with the results of field and numerical analysis.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2018
【分类号】：TD854.6

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