【作者】 杨圣奇；

【导师】 徐卫亚；

【作者基本信息】 河海大学 ， 岩土工程， 2006， 博士

【摘要】 岩石流变力学试验不仅是了解岩石流变力学特性的最重要手段,而且是构建岩石流变本构模型的重要基础。水利水电工程高坝坝基大多建于硬岩岩基上,高坝的建设往往伴随着岩石高陡边坡和大型地下洞室群的岩石工程问题,为了预测岩石工程的长期稳定性,有必要开展硬岩的流变力学特性研究尤其是三轴流变试验研究。岩石流变力学理论作为岩石力学中的前沿课题,近年来,研究工作进展较快,特别是利用实测试验资料反演流变模型参数、进而发展到对未知模型的辨识等。但岩石流变力学理论至今还不很成熟,许多重大岩石工程的建设为岩石流变力学理论研究带来了严峻的挑战,当前岩石流变力学特性和本构模型理论的研究仍是其难点和热点问题。有鉴于此,本文采用试验研究、理论分析和数值模拟相综合的研究方法,基于岩石的三轴流变试验,运用非线性力学与损伤力学理论探讨岩石流变力学特性,主要研究硬岩在不同围压作用下的流变力学特性,建立岩石非线性流变本构模型,并将岩石流变力学特性的研究成果应用到重大水利水电岩石工程实践中。 本文的主要研究工作如下: (1)基于在伺服试验机上得到的不同尺寸岩石单轴压缩瞬时力学特性试验结果,分析了岩石材料力学参数与尺寸之间的关系,采用损伤力学理论,考虑微元体破坏以及弹性模量与尺寸之间的非线性关系,建立了考虑尺寸效应的岩石损伤统计本构模型。采用伺服试验机对岩石进行了三轴压缩试验,从强度、变形以及能量角度,研究了围压对岩石三轴压缩瞬时力学特性的影响规律,分析了岩石三轴压缩瞬时破坏机理。 (2)采用岩石全自动三轴流变伺服仪,对坚硬大理岩与绿片岩进行了三轴流变试验,研究了岩石在不同围压作用下的轴向应变以及侧向应变随时间变化规律,探讨了不同应力水平下的轴向以及侧向流变速率变化趋势,分析了岩石三轴流变过程中的变形特性,讨论了岩石体积流变及流变速率规律,掌握了坚硬大理岩与绿片岩三轴流变特性的基本规律,为流变数值分析时参数的辨识提供了可靠试验依据。为了从机理和本质上对岩石流变力学特性有更清楚地认识,通过对瞬时加载和长期荷载作用下岩石破坏断口进行电镜扫描试验分析,考察岩石细观组构变化对三轴流变力学特性的影响,从岩石微细观角度来解释宏观流变力学特性,明确了复杂应力状态下岩石流变破裂机制。 (3)基于岩石三轴流变试验研究结果,提出了一个新的非线性粘性元件,并更多还原

【Abstract】 Rheological mechanical experiment of rock is not only the most important means to know about the rheological mechanical properties of rock, but also an important base to construct the rheological constitutive model of rock. Many high dam bases in hydraulic and hydropower engineering are constructed on the batholiths of hard rock. Moreover the construction of high dam accompanies often with some rock engineering problems of high sleep slope and huge underground caves. Therefore study on the rheological mechanical properties of rock, especially triaxial rheology experiments of rock, must be carried out in order to predict the long-term stability of rock engineering. Construction of rock rheology model is an important part of theoretical research on rock rhelogy. In recently several years, many important developments on rock rheology model have been impressive, especially in conversing rheological parameters according to field experimental data, and then developing the identification for unknown models. However, rheological model theory of rock material has not been very mature up to now. Many great rock engineering are being or will be designed or built in recent decade, which will bring severe challenge for theoretical research on rock rheology model. Research results that can reflect the accelerative rheological model of rock material are not very ideal. Nowadays, study on rheological properties of rock and constitutive model theory is still the difficult and hot problem. Therefore, the comprehensive method of experimental investigation, theoretical analysis and numerical simulation is adopted in this thesis. Based on the triaxial rheological experimental results of rock, rheological mechanical properties of rock are made a detailed discussion by non-linear and damage mechanics theory, which investigates mainly the rheological mechanical properties of hard rock with different confining pressures under saturated state. And then non-linear rheology constitutive model of rock is proposed. In the end, the investigation results on rheological mechanical properties of rock are applied to the practice of great hydropower rock project, which solves the practical problems.In this dissertation, the main investigation work focuses on the following.(1) With the servo-controlled testing machine, uniaxial compressive experiment is performed on the marble specimens with different length-to-diameter ratios. Onbasis of experimental results of marble specimens with different sizes, the relation between mechanical parameters of rock material and size is analyzed. A damage statistical constitutive model with considering size effect of rock, which considers the non-linear relation of unit volume failure or elastic modulus and the size, is established by adopting the damage constitutive theory of continuous medium. Triaxial compressive experiments of rock are carried out on the servo-controlling testing system. The effect law of confining pressure on the transient mechanical properties of rock under triaxial compression is investigated from the strength, deformation and energy view. At the same time, the transient failure mechanism of rock under triaxial compression is made a detailed analysis.(2) In order to know about the rheological properties of rock specimen in Jinping First Stage Hydropower Project, triaxial compression rheological experiments with rock specimens were carried out on the rock servo-controlling RHEOLOGY testing machine. Based on the triaxial rheological experimental results, the variance law of axial and lateral strains of greenschist specimens with the time under different confining pressures is investigated. The variance tendency of axial and lateral rheological rates under different deviatoric stresses is discussed in detail. The deformation property of rock during the course of triaxial rheology is also analyzed. At the same time, volume rheology and rheological rate law is made a discussion. The triaxial rheological law of hard rock specimen is mastered, which brings important reference for the identification of parameters when carrying out the rheological numerical finite element analysis. In order to have a more clear knowledge for the mechanical property of rock rheology from the mechanism and essence, the SEM experiments are carried out for fracture shaping of rock specimens under the action of short-term and long-term loading. Through investigating the effect of microscopic structure variance in rock specimen on triaxial rheological mechanical properties, macroscopic rheological mechanical properties of rock are explained from the microscopic viewpoint, which illustrates the rheological fracture mechanism of rock under complex stress states.(3) Based on the triaxial rheology curves on rock servo-controlling rheology equipment, a new non-linear viscous component is put forward. When non-linear viscous component is parallel connected with the plastic component, a new non-linear visco-plastic body (NVPB) can be gotten, which may reflect the accelerative rheological properties of rock. At the same time, by connecting NVPB model andfive-component visco-elastic model in series, a new seven-component non-linear visco-elasto-plastic rheology model of rock(Hohai Rheology Model) can be proposed, which can describe better the three-stage creep deformation of rock, especially non-linear accelerative creep deformation of rock. Then using complete compressive and shear rheological curve gained on rock servo-controlling RHEOLOGY testing machine, the proposed seven-component non-linear visco- elasto-plastic rheology model of rock (Hohai Rheology model) is carried out the identification successfully. On basis of proposed Hohai Rheology Model, the rheological equations of rock at the constant stress and stress rate, constant strain and strain rate are deduced. The non-linear creep property and relaxation property of rock are carried out the analysis and investigation on the theory. At the same time, three-dimension creep equations of rock are deduced by adopting non-linear visco-elasto-plastic model theory. What’s more, based on the Hohai Rheology Model, a new generalized non-linear visco-elasto-plastic rheology model of rock with considering the stress threshold by introducing a plastic component.(4) Shear rheology experiments were carried out for the shale in Longtan Hydropower Project by using a servo-controlled shear rheology testing machine. The variance law of shear displacement of shale with the time is analyzed. The variance tendency of shear rheological rates under different stress states is discussed. At the same time, the variance of shear strength of rock with the time is made a discussion. When the proposed nonlinear rheological component (NRC model) by the author is parallel connected with Kormanura model, a new nonlinear rheology model can be gained, which can describe the accelerating rheological properties. Using the shear rheological curves of shale, the proposed nonlinear viscoelastoplastic shear rheology model of rock is carried out the identification, which gets the viscoelastoplastic rheological parameters of the shale.(5) The cohesion and internal friction coefficient are important material parameters that decide the strength and deformation property of rock. By taking into account the variance law of cohesion and internal friction coefficient of rock with time, a new non-linear visco-plastic body of rock with considering the cohesion and internal friction coefficient (CF-NVPB model) is put forward. And then by connecting CF-NVPB model and generalized Kelvin visco-elastic model in series, a new non-linear visco-elasto-plastic rheology model of rock with taking into account the cohesion and internal friction coefficient is proposed, which can reflect fully theaccelerative rheological property of rock. Based on proposed non-linear visco-elasto-plastic rheology model of rock with considering cohesion and internal friction coefficient, non-linear creep and relaxation property of rock are made a detailed analysis.(6) Based on the analysis of non-linear rheology damage mechanism, a non-linear creep damage model of rock, which can reflect the accelerative rheological property, is put forward by adopting time damage and energy damage theory. At the same time, proposed creep damage model is carried out to validate fully in accordance with complete experimental curves of rock rheology. On basis of proposed non-linear visco-elasto-plastic rheology model of rock, after damage variable is introduced in the proposed non-linear visco-elasto-plastic rheology model by adopting damage mechanics theory, a non-linear visco-elasto-plastic rheology damage constitutive model is constructed. Moreover, non-linear creep damage and relaxation damage equations of rock are deduced, and non-linear rheology damage properties are analyzed.(7) Experimental and theoretical investigation results on rheological mechanical properties of rock are applied to the engineering practice of rock mass engineering in the high dam base of Jinping First Stage Hydropower Project and high slope rock engineering in the right bank of Goupitan Hydropower Project. The long-term stability of rock engineering under complex stress state is predicted, which brings forward reasonable evaluation and suggestion for long-term stability and safety of rock engineering.更多还原