基于模拟的岩石类材料在动载作用下的裂缝扩展研究

发布时间：2019-02-18 21:39

【摘要】：随着高层建筑和地下工程的发展,岩石类材料的动力特性在理论和工程中越来越受到重视。岩石作为一种非均匀性显著的准脆性材料,在动态荷载达到强度极限时,能量的瞬间释放会引发应力的重分布,诱使局部力学性质迅速劣化,引发裂缝高速扩展,并以弯曲和分叉为基本表现形式。因此,研究岩石类材料在动荷载作用下的裂缝扩展,直是研究者关注的重要问题。本文基于统计分布和损伤力学的RFPA(Realistic Failure Process Analysis)方法,从细观力学角度对岩石类材料的裂缝动态扩展问题展开详细研究,具体研究可以分为以下几个方面： 1.基于Weibull随机分布函数可以描述岩石类材料的细观非均匀性的普遍规律,在考虑细观单元非均匀性的基础上,建立了岩石在动力作用下的弹脆性损伤演化本构模型。通过引入粘弹性边界方法,研究了非均匀无限域的波动问题。 2.基于动接触二步法和细观线性行为可以反映宏观非线性行为的原理,详细研究了非均匀材料的碰撞问题。由于考虑了撞块和被撞击物的相互作用,可以通过接触方法反映因材料损伤引起的加载变化,模型与实际更贴近。通过选取有代表性的三个侧向撞击模型,并与试验现象进行了验证对比,验证了该方法可行性的同时,更系统分析了不同程度的非均匀性对裂缝扩展的影响,丰富和扩展了前人的研究成果。 3.分析了冲击作用下不同均质度的岩石以及砂砾岩的响应规律。结果表明：应力波传播过程中产生的拉应力是裂缝萌生和扩展的关键。与静态岩石破碎过程相比,冲击作用下岩石的应力改变具有时间效应,应力波传播过程中表现出压、拉变化。 4.利用数值模拟方法,从细观力学角度揭示宏观裂缝扩展的非对称性和非连续性的形成机理。数值模拟结果较好的再现了试验现象和规律,说明考虑细观上的非均匀性可以实现宏观破坏过程中的非线性,细观上的简单本构关系可以模拟复杂的宏观破裂现象。
[Abstract]:With the development of high-rise buildings and underground engineering, the dynamic characteristics of rock materials are paid more and more attention in theory and engineering. Rock, as a kind of quasi-brittle material with remarkable inhomogeneity, when the dynamic load reaches the strength limit, the instantaneous release of energy will lead to the redistribution of the stress, induce the local mechanical properties to deteriorate rapidly, and cause the crack to spread at high speed. And bending and bifurcation as the basic form of expression. Therefore, the research on crack propagation of rock materials under dynamic load is an important issue that researchers pay attention to. Based on the RFPA (Realistic Failure Process Analysis) method of statistical distribution and damage mechanics, the dynamic crack propagation of rock materials is studied in detail from the point of view of meso-mechanics. The specific research can be divided into the following aspects: 1. Based on the Weibull random distribution function which can describe the general law of meso-heterogeneity of rock-like materials, a constitutive model of elastic-brittle damage evolution of rock under dynamic action is established on the basis of considering the nonuniformity of meso-element. In this paper, the viscoelastic boundary method is introduced to study the wave problem in the inhomogeneous infinite domain. 2. Based on the principle that the dynamic contact two-step method and the mesoscopic linear behavior can reflect the macroscopic nonlinear behavior, the collision problem of inhomogeneous materials is studied in detail. Because the interaction between the impingement and the impinged object is considered, the loading change caused by material damage can be reflected by contact method, and the model is closer to reality. By selecting three representative lateral impact models and comparing with the experimental results, the feasibility of the method is verified, and the influence of different degrees of nonuniformity on crack propagation is analyzed systematically. Enrich and expand the previous research results. 3. The response law of rocks with different homogeneity and sandy gravel under impact action is analyzed. The results show that the tensile stress generated during the propagation of stress wave is the key to crack initiation and propagation. Compared with the static rock fracture process, the stress change of rock under impact has a time effect, and the pressure and tension changes occur during the stress wave propagation. 4. The mechanism of asymmetry and discontinuity of macroscopic crack propagation is revealed from the point of view of mesomechanics by numerical simulation method. The numerical simulation results reproduce the experimental phenomena and laws well. It shows that considering the nonuniformity in meso scale can realize the nonlinearity in the process of macroscopic failure, and the simple constitutive relation in meso can simulate the complex macroscopic fracture phenomenon.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45;TU521

【参考文献】