基于应变软化模型的岩体裂隙压缩扩展数值模拟研究

发布时间：2018-03-05 22:22

本文选题：岩体裂隙　切入点：FLAC3D　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：岩体裂隙的萌生与扩展机理及岩体的破坏过程研究一直为相关领域众多专家学者所重视。众所周知,许多岩体工程的失稳破坏都与其内部裂隙扩展贯通有着一定的关系。岩体是一种具有不连续性和非均匀性特性的复杂材料,岩体裂隙扩展理论也不够完善,并且在利用真实岩体制作的试件进行裂隙扩展试验时,受观测手段的限制,从而很难观测到岩体内部裂隙扩展过程,导致难以准确地获得裂隙扩展的规律,但数值试验却可以做到这一点,因而可以借助数值模拟对岩体裂隙扩展问题进行研究并获取裂隙扩展规律。目前,虽然已有不少学者们采用有限差分软件FLAC3D对岩体中的裂隙扩展的过程进行了模拟研究,且其所采用的本构模型以摩尔库伦模型为主,但从其模拟结果可以发现裂隙前端区域显现出大片塑性区,却难以模拟出新生裂纹的线条状扩展状态和贯通过程。因此,有必要选择更为适合的本构模型对裂隙扩展情况进行分析研究。本文主要研究内容如下:(1)系统介绍了岩体中裂隙分类情况和断裂力学中关于裂隙扩展的基本理论。(2)详细阐述了裂隙岩体单轴压缩试验条件下的应力应变曲线变化,并以FLAC3D软件为例,先简单介绍了软件中的应变软化基本理论,而后对分别基于FLAC3D的本构模型中摩尔库伦模型和应变软化模型下不同倾角裂隙岩体单轴压缩试验进行模拟,并且对比分析其数值模拟的结果,阐明了本文采用应变软化模型相比于经典摩尔库伦模型更为适合对裂隙扩展情况进行模拟研究。(3)基于FLAC3D中应变软化模型,对在压缩条件下裂隙岩体的裂隙扩展情况进行了模拟研究,通过以裂隙长度、倾角、间距、错距、条数和围压为技术指标,重点探究了其不同取值对裂隙扩展情况和岩体峰值强度的影响规律。并且采用文献中已有的相关实验结果对上述模型的适用性进行了对比分析。
[Abstract]:The mechanism of crack initiation and propagation and the study of rock mass failure process have been paid much attention by many experts and scholars in related fields. The instability and failure of many rock mass engineering are related to its internal crack propagation. Rock mass is a kind of complex material with discontinuity and inhomogeneity, and the theory of rock mass fracture expansion is not perfect. And when using the specimen made of real rock mass to carry out crack expansion test, it is limited by observation means, so it is very difficult to observe the process of crack propagation in rock mass, and it is difficult to obtain the law of crack expansion accurately. But the numerical test can do this, so the crack propagation problem of rock mass can be studied by numerical simulation and the law of crack propagation can be obtained. Although many scholars have used the finite difference software FLAC3D to simulate the process of crack propagation in rock mass, and the constitutive model used is mainly the Moore Coulomb model. However, from the simulation results, it can be found that a large plastic zone appears in the front part of the crack, but it is difficult to simulate the linear propagation state and the transfixion process of the new crack. It is necessary to select a more suitable constitutive model to analyze and study the fracture propagation. The main contents of this paper are as follows: 1) the classification of fractures in rock mass and the basic theory of fracture propagation in fracture mechanics are introduced systematically. The variation of stress-strain curve of fractured rock mass under uniaxial compression test is described in detail. Taking FLAC3D software as an example, the basic theory of strain softening in the software is introduced briefly, and then the uniaxial compression tests of fractured rock mass with different inclination angles are simulated in the constitutive model based on FLAC3D, which is based on the Moore Coulomb model and the strain softening model, respectively. By comparing and analyzing the results of the numerical simulation, it is shown that the strain softening model is more suitable for simulating fracture propagation than the classical Moore Coulomb model. (3) based on the strain softening model in FLAC3D, the strain softening model is used in this paper. The crack propagation of fractured rock mass under compression condition is simulated. The crack length, inclination angle, spacing, offset, number of bars and confining pressure are taken as technical indexes. The effects of different values on crack propagation and peak strength of rock mass are discussed in detail, and the applicability of the above model is compared and analyzed by using the relevant experimental results available in the literature.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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