不同应力路径下粉砂岩力学特性及卸荷本构模型研究

发布时间：2018-02-13 00:30

本文关键词： 应力路径卸围压速率力学特性强度准则卸荷本构模型　出处：《中国矿业大学》2015年硕士论文　论文类型：学位论文

【摘要】：地下工程岩体的开挖从本质上说是一个卸荷的过程,不加区别的把加载岩石力学的相关理论和方法应用于具有明显卸荷特征的开挖工程的设计、施工及稳定性分析中可能会造成较大的偏差。为了深入研究岩体在不同加卸荷应力路径下的变形特征、极限承载能力以及破坏特性,本文通过选取具有典型特征的粉砂岩试件,进行实验室常规三轴压缩试验以及恒轴压卸围压、升轴压卸围压、恒主应力差卸围压、恒轴向位移卸围压四种应力路径下的卸围压试验,模拟开挖卸荷过程中岩体内各种可能的应力调整路径,对比分析岩体在加卸荷条件下变形特征、强度特性及破坏特征等力学特性的差异;研究不同卸荷应力路径下粉砂岩的力学特性。试验过程中通过改变卸围压速率,分别研究不同卸荷应力路径下,卸围压速率对卸荷岩体力学特性的影响。并通过对破坏断面取样后进行显微电镜扫描,分析岩体在不同应力路径和卸围压速率下发生破坏时破裂面的微细观特征。根据试验结果,分析评价几种得到广泛应用的岩石强度准则;基于弹塑性力学,结合Hoek-Blown强度准则和Griffith强度准则,推导符合试验结果的岩体卸荷本构模型。研究的结果具有一定的理论和实践价值。
[Abstract]:The excavation of rock mass in underground engineering is essentially a unloading process. The relevant theories and methods of loading rock mechanics are applied to the design of excavation project with obvious unloading characteristics without distinction. In order to study the deformation characteristics, ultimate bearing capacity and failure characteristics of rock mass under different loading and unloading stress paths, the siltstone specimens with typical characteristics are selected in this paper. The conventional triaxial compression test in laboratory and the four kinds of stress release tests under constant axial pressure unloading confining pressure, lifting axial pressure unloading confining pressure, constant principal stress difference unloading confining pressure and constant axial displacement confining pressure relief are carried out. Various possible stress adjustment paths in rock mass during excavation and unloading are simulated, and the differences of deformation, strength and failure characteristics of rock mass under loading and unloading conditions are compared and analyzed. The mechanical properties of siltstone under different unloading stress paths are studied. The effect of confining pressure relief rate on mechanical properties of unloading rock mass. The microcosmic characteristics of fracture surface of rock mass under different stress paths and confining pressure relief rates are analyzed. Based on the test results, several widely used rock strength criteria are analyzed and evaluated, based on elastic-plastic mechanics, Combined with the Hoek-Blown strength criterion and the Griffith strength criterion, the unloading constitutive model of rock mass is derived, which accords with the experimental results. The results of the study are of certain theoretical and practical value.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD313

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