【作者】 房敬年；

【导师】 周辉；

【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， 2009， 硕士

【摘要】 盐腔溶腔过程中的围岩稳定性问题是在岩盐中实施能源储存的首要问题,而制约溶腔过程中盐腔围岩稳定性的岩盐性质主要包括:岩盐的力学性质、渗透性质、溶解特性及上述性质之间的相互影响作用。前人围绕这一问题开展了大量富有成效的研究工作,但仍存在着许多尚待解决的问题需要进一步地深入研究。岩盐的变形破坏行为与一般的岩石有明显的不同,损伤和塑性机制并存且相互耦合是其基本特点,这种耦合性质对于储库的稳定性至关重要。然而,目前关于这种耦合作用的研究尚不充分,缺乏能够合理描述这种耦合特征的力学模型。在应力作用下,岩盐的溶蚀特性会发生显著的变化,而目前的研究主要是针对无应力作用下岩盐溶蚀特性的研究,以及对单轴压缩应力状态下岩盐溶蚀特性的初步研究,并不能反映复杂应力状态下岩盐变形破坏对其溶蚀特性的影响作用。针对上述问题,本文通过大量的岩盐单轴和三轴压缩试验以及细观力学试验结果分析,对岩盐的弹塑性损伤耦合机制进行了研究,建立了岩盐的弹塑性损伤耦合模型;通过有/无应力作用下岩盐的溶蚀特性试验研究,分析了应力作用下岩盐溶蚀作用改变的机理,建立了考虑弹塑性损伤耦合特性的岩盐溶蚀模型,得到了如下结论:1、通过岩盐单轴和三轴压缩试验以及细观力学试验,对岩盐的典型力学特征进行了分析,发现在岩盐的变形破坏过程中,以裂纹扩展为主要特征的损伤机制和以裂纹错动为主要特征的塑性机制是相互耦合的;通过试验现象对弹塑性损伤耦合作用下的岩盐破坏机理进行了分析,提出了一种能够描述岩盐特性的弹塑性损伤耦合模型,并通过数值模拟与试验结果的对比,验证了该模型的合理性和正确性。2、通过对岩盐溶蚀机理的分析,以及无应力作用下的岩盐溶蚀特性的试验研究,获得了岩盐溶蚀质量与溶液浓度和溶解时间的定量关系;在此基础上,建立了无应力作用下的岩盐溶蚀模型,并依据无应力作用下的岩盐溶蚀特性试验结果,获得了岩盐的扩散系数。3、通过大量应力作用下的岩盐溶蚀特性试验,发现有/无应力作用下的岩盐溶蚀特性存在差异,即应力对岩盐溶蚀特性产生影响;得到了岩盐溶蚀质量与围压、塑性体积应变、溶解时间之间的定量关系,并从宏观上揭示了应力作用下的岩盐溶蚀机理,发现应力作用下岩盐溶蚀速率的变化主要受岩盐表面裂纹的发展演化所控制,因此可以通过研究裂纹的发育和扩展程度来分析应力作用下岩盐溶蚀特性的变化。4、在以上分析的此基础上,结合无应力作用下岩盐溶蚀模型以及等效扩散系数的概念,建立了考虑弹塑性损伤耦合特性的岩盐溶蚀模型。利用编制的计算程序对等效扩散系数进行了计算和分析,得到了等效扩散系数D^*与扩散系数D的比值D^*/D与围压σ₃、塑性体积应变ε_v^p、溶解时间t之间的表达式。更多还原

【Abstract】 The stability of the wall rock, depositing energy sources in the rock salt, is the principle problem during the construction of salt cavern. The main factors affecting the stability of the wall rock are: the mechanical property, permeability and dissolving property of rock salt . The factors mentioned above always couple with each other. Former researchers have done much work on the problem, but many aspects are still unsolved. The deformation and failure character of rock salt is very different from other rocks. The basic feature of rock salt is the coupled phenomenon of damage with plastic mechanism and the feature is very important when analyzing the stability of salt cavern. However, the present research on the coupled phenomenon is not sufficient and a mechanical model is needed to describe the phenomenon. As for the dissolving property of rock salt, from the result of experiments, we can see that the character changes under different stress conditions. The former work is done mainly under the condition without stress or uniaxial compression stress, but those conditions are quite different from the actual situation, which can’t reflect the effct of deformation and failure for the dissolving property of rock salt under complex stress state. Aiming at above problems, based on a lot of conventional uniaxial and triaxial compression testes and meso-mechanical experiments of rock salt, the coupled elasto-plasto-damage mechanism is studied and a coupled elasto-plasto-damage is established. The dissolving property of rock salt under different stress conditions is studied through the comparison of the result of dissolving experiments with stress and without stress. The mechanism of the effect of stress on the dissolving is analyzed. Together with the coupled mechanical model, a dissolving model of rock salt is established.The main conclusions of this thesis are:1: The mechanical property of rock salt is analyzed based on the conventional triaxial compression testes and meso-mechanical experiments. We find that the elastic-plastic is coupling with damage. Through the phenomenon in the experiments and by taking the coupled character of elastic-plastic and damage into consideration, the failure mechanism of rock salt is studied and an elastic-plastic-damage coupled mechanical model is proposed to capture the deformation of rock salt. The model is verified by comparing the simulating result with the experiment result.2: Based on the analysis on dissolving mechanism of rock salt without stress, a quantitative relation of the dissolving quality with the solution concentration and dissolving time is proposed. Then, a dissolving model of rock salt without stress is established and the diffusion coefficient is calculated by using the dissolving experiment result under the condition without stress.3: Through many dissolving experiments under different stress conditions, we find that the dissolving character of rock salt is influenced by stress.The relation of dissolving quality with confining stress, plastic volume strain and dissolving time is put forwarded. The dissolving character under different stress conditions is studied and found that the dissolving rate is related to the cracks on the surface caused by stress. Then, by study the initiation and propagation of cracks, we can get the dissolving rate under different stress.4: Based on the dissolving model which takes no account of the influence of stress and combined with the elastic-plastic-damage coupled mechanical model, a modified dissolving model is proposed by using the equivalent diffusive coefficient. A program is used to calculate the equivalent diffusive coefficient D^*, and the relation of D^* /D with confining stressσ₃, plastic volume strainε_v^p and dissolving time t isproposed, where D is the actual diffusive coefficient.更多还原