【作者】 高红；

【导师】 郑颖人； 冯夏庭；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2007， 博士

【摘要】 岩土材料的屈服和破坏是岩土工程中最基础也是最为重要的问题,前人对此已开展了大量的研究工作并取得了丰富的研究成果,但由于岩土材料力学性质的复杂性,目前仍存在一些问题尚未很好的解决:如何反映岩土材料不同于金属的特殊力学性质,如何建立岩土材料的能量屈服准则,如何描述破坏,仍有待进一步研究。针对上述问题,本文比较了岩土材料与金属的性质差异,认为岩土材料属于多相体的摩擦型材料,基于此建立了岩土材料的三剪能量屈服准则,并从应力、应变、能量角度对材料屈服准则进行了系统的研究;通过分析材料的屈服和破坏,建立了岩土材料延性剪切破坏的应变标准。本文主要研究成果概括如下:(1)在比较岩土类材料与金属的材料特性差异及由此导致的力学性质差异的基础上,认为岩土类材料属于多相体的摩擦型材料,具有内摩擦性质,分析了岩土材料的抗剪强度机理并重点讨论了摩擦强度,基于此给出了不同类型材料弹性应变能的计算公式。(2)从能量角度对岩土材料的屈服进行研究,在分析岩土材料破坏特性的基础上建立了岩土类材料的三剪能量屈服准则及其相应的Drucker-Prager准则,并利用真三轴试验结果进行了验证,结果表明三剪能量准则比Mohr-Coulomb准则误差小,更接近试验结果。最后从应力、应变、能量角度对材料屈服准则进行了系统的研究。(3)基于前面提出的三剪能量屈服准则,建立了岩土材料的理想弹塑性三剪能量本构模型并进行了数值实现,研究了三剪能量本构模型在边坡稳定、洞室开挖、地基承载力等工程中的应用并取得了良好效果,算例分析表明,Mohr-Coulomb模型比三剪能量模型偏于保守。(4)对材料的屈服和破坏进行分析,认为屈服和破坏是两个不同的概念,应力达到极限同时应变也达到极限才是真正的破坏。比较了屈服和破坏应采用的不同描述方式,建立了岩土材料延性剪切破坏的应变标准,并推导了最大主剪应变的计算公式,最后从研究初始屈服—塑性区贯通—破坏过程开始进行了一些初步的探讨。更多还原

【Abstract】 The yield and failure of geomaterials are the most fundamental but most important problems in the geotechnical engineering, then vast research has been carried out and abundant achievements have been acquired. However, because of the complexity of geomaterials’mechanical characteristics, some problems still haven’t been solved now. How to reflect geomaterials’special mechanical characteristics which are different from those of metals? How to establish the energy yield criterion and how to describe failure of geomaterials? In order to solve the problems put forward above, the characteristics, the energy yield criterion and the failure of geomaterials are researched in this paper. The main study works and results are listed as follows:1. After comparing the difference of materials properties and the induced difference of mechanical characteristics between metals and geomaterials, it′s concluded that geomaterials are frictional materials with multiphase and has frictional characteristics. The shear strength mechanism of geomaterials especially the frictional strength is analyzed, and then the calculation methods of elastic strain energy for different types of materials are presented.2. Based on the analysis of geomaterials’failure characteristics, the yield of geomaterials is researched on the energy point of view, then the triple shear energy yield criterion and the corresponding Drucker-Prager criterion are established. The Mohr-Coulomb criterion and the triple shear energy criterion are used to validate the true triaxial test data, and the errors show that the results of the triple shear energy criterion are more close to the test data than those of the Mohr-Coulomb criterion. It’s proved that the energy criterion is correct. At last the materials’yield criteria are systematically researched by the means of stress, strain and energy.3. Based on the triple shear energy yield criterion, the perfect-plastic triple shear energy constitutive model of geomaterials is established and numerically realized. The triple shear energy constitutive model is used in slope stability, cavern excavation, bearing capacity of foundation engineering and so on. The results indicate that the Mohr-Coulomb model is conservative than the energy model.4. Based on the analysis of yield and failure of materials, it’s concluded that the two conceptions are different, and the real failure occurs only when both stress and train reach limit values. The different description methods of yield and failure are compared, and the strain criterion for ductile shear failure based on the largest principal shear strain for geomaterials is established. Some tentatively discussions are carried out by researching the failure process from first yield to the connection of plastic zone and then failure at last.更多还原