【作者】 傅晏；

【导师】 刘新荣； 张永兴；

【作者基本信息】 重庆大学 ， 岩土工程， 2010， 博士

【摘要】 水-岩相互作用作为岩土工程相关学科研究的前沿领域,是工程岩土体稳定研究的重要内容,而干湿循环过程是水-岩相互作用的重要组成。干湿循环过程中,岩石改变了水的赋存状态,同时自身也受到水的反复侵蚀。干湿循环作用将造成岩土体岩性劣化,进而影响其强度和变形,并对岩土工程的稳定性和耐久性产生重要影响。论文在前人研究的基础上,从干湿循环作用的劣化过程出发,通过理论分析、室内试验、数值模拟等方法,对岩石在干湿循环作用下的劣化机理进行了较为系统深入的研究。论文的主要研究内容和成果如下:①通过完整砂岩的室内干湿循环试验,揭示了砂岩的干湿循环劣化规律。试验结果表明,循环作用对岩石的影响是渐进性的,表现为初期影响较大,随着作用时间的延长,该劣化效应逐渐减弱。在此基础上,探讨了岩石物理力学参数与干湿循环次数之间的函数关系,进而定义了干湿循环劣化系数,用于表征干湿循环作用对各参数的影响程度。②在试验研究的基础上,运用连续损伤力学和统计理论,导出了干湿循环作用下岩石的统计损伤本构模型。通过砂岩试验结果对该模型进行了验证,分析表明干湿循环作用对砂岩应力应变曲线的影响可分为两部分:通过杨氏模量E的变化影响其中近似线性部分,通过Weibull分布参数m和F0的变化影响其中非线性部分。干湿循环次数的增加将引起分布参数m和F0、临界损伤有效应力σ1c*的降低,并使临界损伤值Dc增加。③通过室内试验和细观颗粒流数值试验,统计了岩石宏细观参数之间的基本关系,分析了宏细观参数的影响效应,得到了宏细观参数关系的定量表达式。在此基础上,建立了基于颗粒流理论的岩石细观参数半定量确定方法,进而对颗粒流计算结果进行了分析,结果表明,峰值应力条件下相同围压下的颗粒接触网络和力链的分布形态均相似,但颗粒粘结的断裂数量随干湿循环次数增加而增大。同时利用颗粒微梁的能量关系,导出了细观强度参数与断裂韧度之间的定量关系,解释了岩石细观强度参数的物理意义。④探讨了干湿循环作用下的砂岩细观参数和细观应变能密度的变化规律,定义了干湿循环细观劣化系数,用于表征干湿循环作用对各细观参数的影响程度。通过对颗粒细观损伤的分析,建立了以细观模量为基础的砂岩细观损伤模型,探讨了砂岩干湿循环作用下的细观损伤效应。⑤在前人研究的基础上,建立了节理岩体完整性系数和体积节理数与GSI评分系统的定量关系,对GSI评分表进行了修正,基于广义Hoek-Brown准则将完整岩石参数推演到岩体参数,并探讨了干湿循环作用对岩体力学参数的影响。从抗剪强度曲线折减的概念出发,改进了基于Hoek-Brown准则的强度折减法,并运用FLAC^2D的FISH语言进行了相应程序化研究,对岸坡在干湿循环作用下的正常和极限状态进行了计算分析,探讨了干湿循环作用下岩体劣化效应对库岸边坡稳定性的影响。更多还原

【Abstract】 As the advancing edge of geotechnical engineering and its related science studies, water-rock interaction is a crucial content of the study of the stability of engineering rock-mass and soil. And in the procedure of cyclic drying-wetting, which is one of water-rock interaction’s important compositions, rock-mass altered the current state of water, while suffering repeated erosion itself, which would result in the deterioration of rock and soil, influence its the strength and deformation parameters, and leave significant effect on the stability and durability of geotechnical engineering. Based on previous studies and from the prospect of deterioration procedure of effect of cyclic drying-wetting, this thesis is about to proceed a systematic and deep study on the deterioration mechanism of rock-mass under cyclic drying-wetting effect with research methods like theoretical analysis, laboratory test, and numerical simulation. Major contents and results are as the following:①Rules caused by effect of cyclic drying-wetting are discovered with the laboratory test of cyclic drying-wetting effect on integrated sandstone. It is a gradual process as suggested in the experiment results, in whose primary stage the influence is the greatest, and deterioration effect fades as time passes by. Therefore, the function relationship between the rock mechanics parameters and cycles of drying and wetting are discussed, and degradation coefficient of cyclic drying-wetting is furthermore defined to signify the degree of influence of cyclic drying-wetting effect on each parameter.②On the basis of experimental study, continuum damage mechanics and statistical theory are applied in the introduction of the statistical damage constitutive model of rock-mass under the effect of cyclic drying-wetting. The model is testified with the sandstone experiment results, and the analysis indicates that the effect of cyclic drying-wetting on the sandstone’s stress-strain curves can be categorized into two sorts: the approximate linear part is influenced by the variation of young’s modulus E, while the nonlinear part the Weibull distribution parameters m and F0. The increase in number of drying-wetting cycles would decrease the distribution parameters m and F0 and critical-damage effective stressσ1c*, and increase critical damage value Dc.③With the laboratory test and microscopic particle flow numerical experiments, the basic relationship between the rock’s macroscopic and microscopic parameters is concluded, and the influence effect of macroscopic and microscopic parameters is analyzed, hence the quantitative expressions of the relation between macroscopic and microscopic parameters. Then, half-quantitative confirming method of rock’s macroscopic and microscopic parameters is established based on particle flow theory. The analysis of the particle flow calculation results show that contact network of the grains under the same confining pressure under peak stress own the similar distribution form. The number of cracks under peak stress is increased with cycles of drying and wetting. The energy of equivalent micro-beam is used to educe the quantitative relation between micro-strength parameters and fracture toughness, which explains the physical significance of the micro-strength parameters of rock.④Rules of density of strain energy and micro-strength parameters of the sandstones are discussed and micro-degradation coefficient of cyclic drying-wetting is defined to signify the degree of influence of cyclic drying-wetting effect on each micro-parameters. Micro-damage constitutive model of sandstone is established with the analysis of contact normal and shear modulus, and micro-damage effect of cyclic drying-wetting is probed into.⑤Quantitative relation between integrity coefficient of jointed rock mass and GSI system is established on basis of previous study, and so is volumetric joint count. Then, GSI classification is amended. Parameters of rock mass are deduced based on generalized Hoek-Brown criterion. And the effect of cyclic drying-wetting on rock mass is discussed. The concept of shear strength reduction is applied to deduce the improvement of strength reduction method based on Hoek-Brown criterion, and it is programmed with FISH language. Numerical simulation of both the normal and limit conditions of reservoir bank mode4l via FLAC2D is proceeded, and the stability of reservoir bank caused by degradation of rock mass with the effect of cyclic drying-wetting is discussed.更多还原