三维离散元块体-质点模型及其应用

IMECH-IR > 力学所知识产出(1956-2008)

	三维离散元块体-质点模型及其应用
	饶莹
导师	李世海
	2003
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位类别	硕士
学位专业	工程力学
关键词	三维离散元块体-质点模型单轴抗压试验单轴抗拉试验巴西试验数值模拟
摘要	本文在离散元面-面接触刚性块体模型的基础上，提出三维离散元块体一质点模型，在新的模型中认为岩体是由结构面分割的岩块组成的，岩块内部山质点和连接质点的弹簧构成的。质点弹簧系统构成的岩块间的界面反映了岩体结构面的特性，而弹簧-质点系统可以描述岩块的可变性和可断裂特性。给出了确定岩块内弹簧刚度的基本方法，标定了弹簧刚度。运用三维离散元块体一质点模型，编制了C语言的计算程序实现了以实际存在的结构而划分任意的平行六面体单元的变形计算，能够模拟材料的断裂过程，材料断裂后实现应力重分配，裂缝扩展，直到破坏，对整体刚度矩阵进行了优化存储，提高了计算效率，并初步给出了新模型下的强度准则及弹簧的相对伸长量准则。采用新模型数值模拟了单轴拉、单轴压缩变形试验，得到了与弹性力学相一致的结果，模拟了相同条件下的破坏过程，所得到的图像与试验结果相同。模拟计算采用垂直或平行受力主轴方向的三组正交结构面划分长方体单元，完成了岩石试件应力场、位移场的模拟，经过与解析解和商用有限元计算结果的对比，验证了其正确性和准确性。对含节理条件下的巴西试验进行了模拟，比较了将试件作为弹性体和含节理两种情况下不同破坏机制，指出了巴西试验在含有节理的情况下其破坏是剪切破坏作用的结果。运用该模型编制的程序对反倾边坡卸荷问题进行了模拟，计算所得的地应力场与实验结果相吻合，并分析了坡体参数与卸荷节理之间的关系。对茅坪滑坡实例进行了研究，分析影响坡体稳定性的主要物理参数对坡体稳定性的作用。证明了该边坡在变形阶段即产生了大量裂缝，增加了滑坡不稳定的因素。为研究问题方便，编制了前处理和后处理程序。前处理程序可以将测绘数据转换为计算网格生成所需的数据，能够更好的反映地形对坡体稳定产性的影响，后处理程序输出供绘图软件Origin使用的数据文件，可以绘制出空间任意剖面或结构面上的应力、位移、主应力、最大剪应力图以及滑动和断裂的单元位置图。研究分析表明，将三维离散元块体一质点模型应用于对于岩体宏观力学参数的研究，或是对实际岩体工程的稳定性分析都是可行的，但在岩体破坏参数选择方而有待更深入的研究，其结果也有待于更多工程的验证。
英文摘要	According to surface-to-surface contact model, a new numerical simulations model is built, which could be used to simulate both continuous and discontinuous materials. In this model, the parallelepiped elements have been created by the intersection of three sets of physical joints in rock mass and those parallelepiped elements are dispersed as a spring system composed by 25 particles and the springs connecting the particles. Then by using the variation of the function, the stiffness of the springs could be obtained. Computing codes in C language were programmed according to this new block-particle model. This model could express the deformation and cracking in material. The whole rigidity matrix is optimized, which could improve the calculation efficiency. The rule of spring intensity corresponding the rock mass intensity has been build. Numerical simulations were carried out for uniaxile compress test, pure shear test, cracking test. The rule of the deformation and cracking agree well with theoretical results and test data, It is shown that the new model have the desired accuracy and could also be used to study the failure process of materials. Then the new model is used in numerical simulations of Brazil test, the result of numerical simulation is that the pull stress and the shear stress both induce the cracking. Numerical simulations were carried out for some regular slope subject. The result inosculates the laboratory test. In the simulation of slope at Maoping, conclusion was gained by studying the stabilities of two sets of joints. The effect of some critical parameter to the slope stability is studied. The result presents that the cracking have already formed in the deformation stage, which adding the instability. The post-disposing code provides an interface between the computational data and the plot software-Origin. Graphs of stress fields, displacement fields, main forces, max shear force and the position of elements sliding or cracked can be plotted. It is feasible to use the new model in studying of rock parameters or stabilities of practical projects. Of course, further research is needed in building the cracking rule. The results of this method also require to be verified by more projects.
索取号	30057
语种	中文
文献类型	学位论文
条目标识符	http://dspace.imech.ac.cn/handle/311007/23664
专题	力学所知识产出(1956-2008)
推荐引用方式 GB/T 7714	饶莹. 三维离散元块体-质点模型及其应用[D]. 北京. 中国科学院研究生院,2003.

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