卸荷裂隙岩体变分问题及内时理论的研究应用

发布时间：2018-05-01 20:33

本文选题：卸荷理论 + 裂隙岩体　；参考：《南昌大学》2013年博士论文

【摘要】：裂隙岩体是岩体工程最普遍的施工对象之一。由于工程施工的扰动,岩体原有的平衡状态被打破,由此引起岩体内的应力重分布,促使岩体中内在裂纹(裂隙)不断累积和发展,进而产生宏观的时效断裂,导致岩体发生破坏失稳。在实际工程中边坡稳定计算、变形等多数考虑的是加载理论,往往岩体卸荷裂隙是影响边坡岩体稳定性的重要因素。本文首先揭示了裂隙岩体在卸荷状态下裂隙岩体本构关系的各个阶段的力学机理,运用半反推法建立了卸荷岩体分别在小变形和大变形初值问题的以σij、uij或σij、εij为二类变量变分原理。在建立变分原理的基础上以引入拉氏乘子的方法将变分约束条件加入到能量泛函中从而导出广义变分原理,因此分别建立卸荷裂隙岩体在小变形和大变形以σij、εij或σij、εij为变量的广义变分原理能量泛函。根据Vananis提出的内时本构基础理论是依赖于材料的性质和变形历史,是用来描述整个变形和温度的历史功能的历史依赖性的力学响应。裂隙岩体是非线性材料,建立卸荷裂隙岩体在初级阶段的内时本构关系,并将理论值与实验值测得的应力应变进行比较,验证了内时变分理论在卸荷裂隙岩体初级阶段应用的正确性。结合以井冈山某工程为例,该工程在开挖过程中有地裂缝出现,首先对该实际工程中岩体出现的裂缝进行勘察。根据高密度电法原理查明了地裂缝的延伸范围、发育深度及裂面倾斜方向等要素并分析其形成原因,为实际工程提出相关建议和措施。运用分析软件ABAQUS一方面对井冈山某工程开挖后的下部边坡在考虑不同工况(天然状态下、降雨后、地震作用、新建建筑物建成后等)下建立计算模型,输入场地材料参数,进行边坡稳定性计算分析,计算出不同工况下的稳定系数,评价了该场地的稳定性。结合卸荷理论考虑井冈山某工程上部边坡开挖即卸荷过程对下部边坡的影响,选择开挖过程中含地裂缝的稳定性等综合因素较差的边坡作为原型,建立相应的ABAQUS计算模型,模拟开挖过程的卸荷情况,考查分析在开挖过程中地裂缝的应力应变的变化规律及与卸荷裂隙岩体的内时本构理论比较,发现在地裂缝的左右两侧应力应变呈现不同的变化规律,为实际工程提供一定的理论依据,将内时理论的应用进一步扩展。
[Abstract]:Fractured rock mass is one of the most common construction objects in rock mass engineering. Due to the disturbance of engineering construction, the original equilibrium state of rock mass is broken, which leads to stress redistribution in rock mass, which promotes the accumulation and development of internal cracks (cracks) in rock mass, and then produces macroscopic time-dependent fracture. The failure and instability of rock mass occurred. In practical engineering, the loading theory is the most important factor in the calculation of slope stability, such as deformation and so on, and often the unloading fracture of rock mass is an important factor affecting the stability of slope rock mass. In this paper, the mechanics mechanism of the constitutive relation of fractured rock mass at different stages under unloading condition is first revealed. In this paper, the variational principles with 蟽 ijjuij or 蟽 ij, 蔚 ij variables for the initial value problems of unloading rock mass with small deformation and large deformation are established by using the semi-inverse method. On the basis of establishing variational principle, the variational constraint condition is added to energy functional by introducing Lagrangian multiplier to derive generalized variational principle. Therefore, the generalized variational principle energy functional of unloading fractured rock mass with 蟽 ij, 蔚 ij or 蟽 ij, 蔚 ij variables in small deformation and large deformation is established, respectively. According to the internal time constitutive theory proposed by Vananis, it depends on the properties of materials and deformation history, and is a historical dependent mechanical response to describe the historical function of the whole deformation and temperature. Fracture rock mass is a nonlinear material. The internal constitutive relation of unloading fractured rock mass at the primary stage is established, and the stress and strain measured by the theoretical value and the experimental value are compared. The application of the internal time-varying theory in the initial stage of unloading fractured rock mass is verified. Taking a project in Jinggangshan as an example, there are ground fissures in the course of excavation. Firstly, the cracks of rock mass in the actual project are investigated. According to the principle of high density electric method, the extension range, development depth and slanting direction of the ground fracture are found out, and the reasons for its formation are analyzed, and the relevant suggestions and measures are put forward for practical engineering. On the one hand, the analysis software ABAQUS is used to establish a calculation model for the lower slope of a project excavated in Jinggangshan under different working conditions (natural state, rainfall, earthquake action, new building construction, etc.), and input site material parameters. The stability coefficient of the slope under different working conditions is calculated and the stability of the site is evaluated. Combined with unloading theory, considering the influence of excavation and unloading process on the lower slope of a certain project in Jinggangshan, the slope with poor stability of ground fissures during excavation is selected as the prototype, and the corresponding ABAQUS calculation model is established. Simulation of unloading during excavation, analysis of stress and strain variation of ground cracks during excavation and comparison with internal constitutive theory of unloading fissured rock mass, It is found that the stress and strain of the left and right sides of the ground fissure show different changing laws, which provide a certain theoretical basis for the practical engineering, and further expand the application of the internal time theory.
【学位授予单位】：南昌大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

【参考文献】