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基于所建立的反映岩石冲击压缩、拉伸损伤理论模型以及深孔微差爆破数值模拟结果,研究了爆炸载荷作用下岩石损伤演化和破碎规律,分析了岩石的动态力学特性;通过对水平边界条件下爆破破岩物理、力学过程的研究,探讨了深孔微差爆破的作用机制和爆破设计原则。 相似文献
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在传统键基近场动力学模型的基础上,提出可以反映岩石类材料应力-应变变化特点的改进型模型,弥补了传统近场动力学模型在模拟岩石类材料时无法反映岩石内应力随应变先增加再减小最后破坏这一特性的不足。运用改进型模型,对含有单裂纹试件在不同预制裂纹角度及拉伸荷载条件下的裂纹扩展过程进行了数值模拟,分析了开裂角度在不同预制裂纹角度及拉伸荷载条件下的变化。结果表明：预制角度及拉伸荷载对开裂角度都有影响,在试件周围拉荷载接近的情况下会获得较小的开裂角,并且在拉荷载一定的条件下开裂角会有先增加后减少的规律。同时模拟了含裂纹岩石在单轴压缩条件下的裂纹扩展情况,将数值模拟的结果与室内试验的结果对比,验证了所提出新模型的有效性。所提出的新模型可以较好地模拟岩石类材料在拉荷载条件下的力学特性,在岩石数值模拟方面有着较为广泛的应用前景。 相似文献
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岩石损伤过程中的热-流-力耦合模型及其应用初探 总被引：3，自引：0，他引：3
岩石损伤过程热-流-力（THM）耦合问题的研究对于深部采矿等许多工程领域都具有重要的理论意义。以岩石的损伤为主线,在多场耦合分析方程中引入损伤变量,基于质量守恒和能量守恒原理,提出岩体损伤过程中的THM耦合模型。通过把均匀弹性介质THM耦合响应的模拟结果与理论分析结果进行对比,验证了程序及有限元实施的正确性。然后,用该耦合模型进行了不同地应力条件下流固耦合过程的数值模拟,探讨了水压力对于岩石损伤过程的作用机制。数值模拟表明,水压力导致了拉伸损伤范围的扩大和损伤程度的加剧,同时亦对剪切损伤具有抑制作用。 相似文献
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岩石破裂过程的自组织临界特征初探 总被引：5，自引：0，他引：5
自组织临界状态。是广延耗散动力学系统所普遍具有的行为特征。实验表明，岩石破裂过程也具有自组织临界特征。本文运用数学－力学分析和计算机模拟等手段。研究了岩石破裂过程中所现出的累进性破坏及无序向有序演化等特征的内在机理，从而加深了岩石破裂失稳定过程机制的认识。 相似文献
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单轴压缩下绿砂岩长期强度的尺寸效应研究 总被引：1，自引：0，他引：1
岩石的蠕变特性是影响岩体工程稳定性的重要因素,而岩石的长期强度是确定岩体工程长期稳定的一个重要指标。由于岩石材料的非均质性,其长期强度具有明显的尺寸效应。为了研究岩石长期强度的尺寸效应,首先,在幂函数模型基础上,基于损伤力学理论,建立了能够描述岩石蠕变全过程的非线性蠕变损伤模型;然后,把运用该模型计算得到的单轴压缩蠕变数值模拟结果与室内单轴压缩蠕变试验结果进行对比,验证了模型的正确性;最后,采用所提出的模型对7个不同尺寸的岩样进行了单轴压缩蠕变数值模拟,并对岩石长期强度尺寸效应进行了分析。数值模拟结果表明：随着试样尺寸的逐渐增大,岩石长期强度值逐渐减小,当试样尺寸增大到一定程度时,岩石长期强度稳定在一个特定值附近。 相似文献
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为了反映热-力耦合作用下岩石蠕变变形的全过程,依据断裂力学原理提出了岩石裂纹扩展的临界损伤应力和一个新的可描述岩石在稳态蠕变阶段与临界损伤应力相关的非线性黏性分量,在传统西原模型和Burgers模型的基础上,将指数形式的损伤变量、临界损伤应力以及与其有关的非线性黏性分量引入到流变微分方程,通过叠加原理推导了考虑温度效应的单轴和三轴压缩条件下岩石的流变本构关系,建立了岩石的热-力耦合损伤蠕变本构模型。利用不同温度、不同应力条件下花岗岩的三轴蠕变试验曲线和本文蠕变模型的计算曲线进行比较,结果表明本文蠕变模型能够较好地模拟岩石在初始瞬态、稳态和加速蠕变阶段全过程的变形规律,验证了所建模型的有效性和合理性。该模型为分析高温、高应力环境下岩石工程的长期变形和稳定情况提供了理论依据。 相似文献
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考虑体积变化影响的岩石应变软硬化损伤本构模型及参数确定方法 总被引：2，自引：0，他引：2
针对现有岩石损伤模型的局限性与不足,将应力作用下的岩石抽象为空隙、损伤与未损伤材料三部分,以空隙率反映岩石体积或空隙的变化,以损伤变量或损伤因子反映岩石力学性态的改变程度,通过对各部分材料的微观受力及其与宏观应力和应变的关系进行分析,建立了可反映岩石变形过程中体积或空隙变化特性的新型岩石损伤模型;从岩石微元强度合理度量方法研究入手,引进统计损伤理论,建立了可考虑损伤阀值影响的岩石统计损伤演化模型,进而建立了能模拟应变软硬化全过程的岩石统计损伤本构模型,并提出了参数确定方法。该模型不仅能反映岩石应变软硬化特性,而且能反映岩石变形的初期压密和后期扩容的特性。通过实例分析与讨论,表明模型合理与可行。 相似文献
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单轴压缩下岩石蠕变失稳破坏过程数值模拟 总被引：3，自引：0，他引：3
在岩石破裂过程分析（RFPA2D）系统的基础上,考虑岩石损伤过程的时间因素影响,引入岩石细观单元蠕变本构方程,建立了考虑流变效应的岩石破裂过程RFPA2D数值模型。应用该模型模拟了恒定荷载作用下岩石的蠕变破坏过程,得到了岩石蠕变破裂的3个典型阶段：初始蠕变阶段、稳定蠕变阶段和加速蠕变阶段,模拟结果同实验室试验所观察到的现象十分吻合。这表明考虑流变效应的RFPA2D数值模型适用于模拟岩石的蠕变破坏这一复杂的、非线性演化问题。此外,数值模拟还揭示了岩石的宏观蠕变破坏实质上是细观层次上单元损伤累计的结果,这些结论对岩石工程的长期稳定性研究具有重要的理论指导和实践意义。 相似文献
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为研究岩石切削过程中刀具的力学特性以及刀具平均峰值作用力的预测,基于断裂力学和有限元理论建立了岩石切削的数值模型。模拟分析岩石对刀具的反作用过程,得到不同力学特性岩石和刀具作用条件下刀具所受的反作用力,结果表明,冲击速度在一定范围内对刀具平均峰值作用力影响较小;岩石体积呈阶跃性递减,刀具作用力大小与崩落岩石碎片体积变化一致。对模拟、实验以及已有理论计算得到的刀具平均峰值作用力进行线性回归分析,研究结果表明,数值方法计算结果与实验结果、Goktan[1]理论计算结果的线性相关系数分别为0.812、0.930,相关性较好,表明所建数值模型用于模拟岩石切削是正确和可靠的。 相似文献
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基于细观分析的黏土本构模型 总被引：1，自引：0，他引：1
根据黏性土在固结排水条件下的加、卸载变形特征,分析了孔隙水,固体骨架在不同变形阶段的力学响应行为,按照细观力学分析中的自洽方法,建立了在固结排水条件下的黏土损伤本构模型。模型中考虑了孔隙水和固体骨架在加、卸载阶段的不同特性,认为在损伤阶段整体剪切模量的降低是由固体骨架颗粒接触面滑移而引起,与骨架中滑动相的体积百分比和滑动相的剪切模量有关,并给出了求解整体变形模量的解析方法,最后将模型预测与不同初始固结压力,不同应力路径的排水试验结果作了比较,证明该模型是合理的。 相似文献
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We present a micromechanical approach based on zero-thickness interface elements for modelling advanced localization and cracking states of cemented granular materials, such as reservoir sandstones. The proposed methodology is capable of reproducing the complex behaviour of intergranular and intragranular localization, cracking, and fracturing of rock formation that leads to sanding in hydrocarbon production. The model is calibrated at the macroscale, using only a few physical parameters, by reproducing the typical behaviour of compression element tests. The model exhibits clear transition behaviour from brittle dilatant to ductile compactant behaviour with increasing confining stress. The methodology is implemented for sand production prediction analysis based on the simulation of 2D micromechanical models of hollow cylinder cross sections. The obtained results are compared well with published experimental data from hollow cylinder tests characterized by strong scale effect in the range of small perforations. 相似文献
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A theoretical–experimental approach to elastic and strength properties of artificially cemented sand
Evaluating the behavior parameters of soils and soil-binder mixes by means of theoretical models that are supported by laboratory tests still remains a key challenge in foundation design. In this context, the paper investigates some aspects of the mechanical behavior of artificially cemented sands (ACS) by means of experimental characterization and micromechanics-based modeling. Particular emphasis is given to the increase in elastic stiffness and strength brought by cementation. Based on the concept of a fictitious continuum medium and the homogenization theory, the effective elastic properties of ACS are evaluated using the Mori–Tanaka and self-consistent schemes. The elastic micromechanical approach is supported by bender element tests. Finally, the effective strength properties of ACS are assessed by means of micromechanics-based failure criterion formulated within the context of non-associated plasticity. Validation and calibration of the theoretical model are achieved by comparison with data from unconfined compression tests. 相似文献
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This paper is devoted to micromechanical modeling of induced anisotropic damage in brittle geomaterials. The formulation of the model is based on a proper homogenization procedure by taking into account unilateral effects and interactions between microcracks. The homogenization procedure is developed in the framework of Eshelby's inclusion solution and Ponte‐Castaneda and Willis (J. Mech. Phys. Solids 1995; 43 :1919–1951) estimate. The homogenization technique is combined with the thermodynamics framework at microscopic level for the determination of damage evolution law. A rigorous crack opening–closure transition condition is established and an energy‐release‐rate‐based damage criterion is proposed. Computational aspects on the implementation of micromechanical model are also discussed. The proposed model is evaluated by comparing numerical predictions with experimental data for various laboratory tests on concrete. Parametric studies on unilateral effects and influences of microcracks interactions are finally performed and analyzed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Experimental evidence has indicated that the critical state line determined from undrained compression tests is not identical to that determined from undrained extension tests. The purpose of this paper is to investigate a modelling method that accounts for the non‐uniqueness of critical state lines in the compression and the extension testing conditions. Conventional elastic–plastic cap models can predict only a unique critical state line for the compression and the extension tests. A new micromechanical stress–strain model is developed considering explicitly the location of critical state line. The model is then used to simulate undrained triaxial compression and extension tests performed on isotropically consolidated samples with different over‐consolidated ratios. The predictions are compared with experimental results as well as that predicted by models with kinematic hardening of yield surface. All simulations demonstrate that the proposed micromechanical approach is capable of modelling the undrained compression and the undrained extension tests. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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A self‐consistent approach for micro–macro modeling of elastic–plastic deformation in polycrystalline geomaterials 
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下载免费PDF全文 This paper is devoted to multi‐scale modeling of elastic–plastic deformation of a class of geomaterials with a polycrystalline microstructure. We have extended and improved the simplified polycrystalline model presented in [Zeng T. et al., 2014. Mech. Mater. 69 (1):132–145]. A rigorous and fully consistent self‐consistent (SC) scheme is proposed to describe the interaction among plastic mineral grains. We have also deeply discussed the numerical issues related to the numerical implementation of the proposed micromechanical model. The efficiency of the proposed model and the related numerical procedure is evaluated in several representative cases. We have compared the numerical results respectively obtained from the fully SC model and two simplified ones. It is found that the SC model produces a softer stress–strain response than that of the simplified models. The comparisons between the estimation of overall behavior of a granite in different loading conditions and experimental data are also conducted. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Rock fracture under upper crustal conditions is driven not only by applied stresses, but also by time-dependent, chemically activated subcritical cracking processes. These subcritical processes are of great importance for the understanding of the mechanical behaviour of rocks over geological timescales. A macroscopic manifestation of time-dependency in the brittle field is the observation that rocks can deform and fail at constant applied stresses, a phenomenon known as brittle creep. Here, we review the available experimental evidence for brittle creep in crustal rocks, and the various models developed to explain the observations. Laboratory experiments have shown that brittle creep occurs in all major rock types, and that creep strain rates are extremely sensitive to the environmental conditions: differential stress, confining pressure, temperature and pore fluid composition. Even small changes in any of these parameters produce order of magnitude changes in creep strain rates (and times-to-failure). Three main classes of brittle creep model have been proposed to explain these observations: phenomenological, statistical, and micromechanical. Statistical and micromechanical models explain qualitatively how the increasing influence of microcrack interactions and/or the increasing accumulated damage produces the observed evolution of macroscopic deformation during brittle creep. However, no current model can predict quantitatively all of the observed features of brittle creep. Experimental data are limited by the timescale over which experiments are realistically feasible. Clearly, an extension of the range of available laboratory data to lower strain rates, and the development of new modelling approaches are needed to further improve our current understanding of time-dependent brittle deformation in rocks. 相似文献
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A new model for describing induced anisotropic damage in brittle rocks is proposed. Although phenomenological, the model is based on physical grounds of micromechanical analysis. Induced damage is represented by a second rank tensor, which is related to the density and orientation of microcracks. Damage evolution is related to the propagation condition of microcracks. The onset of microcrack coalescence leading to softening behaviour is also considered. The effective elastic compliance of the damaged material is obtained from a specific form of Gibbs potential. Irreversible damage‐related strains due to residual opening of microcracks after unloading are also captured. All the model's parameters could be determined from conventional triaxial compression tests. The proposed model is applied to a typical brittle rock. Comparison between test data and numerical simulations shows an overall good agreement. The proposed model is able to describe the main features related to induced microcracks in brittle geomaterials. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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A new data‐mining approach is presented for modelling of the stress–strain and volume change behaviour of unsaturated soils considering temperature effects. The proposed approach is based on the evolutionary polynomial regression (EPR), which unlike some other data‐mining techniques, generates a transparent and structured representation of the behaviour of systems directly from raw experimental (or field) data. The proposed methodology can operate on large quantities of data in order to capture nonlinear and complex relationships between contributing variables. The developed models allow the user to gain a clear insight into the behaviour of the system. Unsaturated triaxial test data from the literature were used for development and verification of EPR models. The developed models were also used (in a coupled manner) to produce the entire stress path of triaxial tests. Comparison of the EPR model predictions with the experimental data revealed the robustness and capability of the proposed methodology in capturing and reproducing the constitutive thermomechanical behaviour of unsaturated soils. More importantly, the capability of the developed models in accurately generalizing the predictions to unseen data cases was illustrated. The results of a sensitivity analysis showed that the models developed from data are able to capture and represent the physical aspects of the unsaturated soil behaviour accurately. The merits and advantages of the proposed methodology are also discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献