硫酸盐环境中立井井壁混凝土腐蚀劣化特征及机理研究

发布时间：2018-05-28 06:52

本文选题：井壁混凝土 + 硫酸盐腐蚀　；参考：《北京科技大学》2018年博士论文

【摘要】：随着我国地下资源开发的不断深入,立井作为矿山生产的重要通道,其井筒结构在满足安全性设计的同时,耐久性问题日益突出;尤其我国20世纪八九十年代建设现今服役的大量矿井其井壁结构多采用C30～C40混凝土,由于强度等级较低,随服役时间增加耐久性问题更加严峻,甚至出现井筒变形破裂进而威胁矿井安全和正常生产。矿井井壁混凝土所处服役环境复杂,其服役性能和寿命不仅受地压、扰动等地质条件制约,还与地下水、微生物等环境因素的长期作用密不可分。因此井壁混凝土往往面临力学过程和化学过程的双重破坏,导致服役状态和性能出现劣化。地下矿井水中常富含一些可溶性盐,硫酸盐是常见的一种,会使井壁混凝土受到化学侵蚀,地下水位的变化和矿井水的流动又会对混凝土产生干湿交替的加速破坏作用。因此有必要结合矿井服役条件对硫酸盐腐蚀环境中井壁混凝土材料的劣化特征与机理进行研究,将有助于评价井壁结构服役状态和预测其使用寿命,也能为修复和加固提供参考。本文采用普通C30井壁混凝土,基于硫酸盐腐蚀模拟试验,进行了物理力学测试以及微观性能测试,研究了井壁混凝土在初始损伤、三向受力、加卸载扰动和不同阳离子成分等矿井服役条件和硫酸盐腐蚀环境因素作用下物理力学性能劣化特征和机理,并基于硫酸盐腐蚀机理探索减轻井壁混凝土硫酸盐腐蚀劣化的途径,主要研究内容和成果包括:(1)通过井壁混凝土硫酸盐腐蚀的试验研究,分别基于抗压、劈裂抗拉、抗折等强度值及超声波波速建立劣化因子来定量评价井壁混凝土性能变化,并得到劣化因子随腐蚀加剧而变化的函数关系,进一步基于应力应变关系和声发射累积振铃计数建立井壁混凝土腐蚀受荷损伤演化方程,从而通过数学模型将腐蚀损伤和受荷损伤统一起来。(2)通过不同程度初始损伤下井壁混凝土硫酸盐腐蚀的试验研究,从表观、质量、超声波波速、强度、应力-应变关系及声发射特性等方面对比分析了初始损伤下井壁混凝土硫酸盐腐蚀的性能变化,并通过劣化因子对性能变化进行定量评价和预测,基于应力应变关系和声发射特性建立了初始损伤下井壁混凝土的腐蚀受荷损伤模型,进一步研究了硫酸盐腐蚀对含初始损伤井壁混凝土微结构和矿物元素的改造作用及腐蚀产物组分的变化,揭示了初始损伤井壁混凝土的腐蚀劣化机理。(3)通过对受硫酸盐腐蚀的井壁混凝土开展不同围压水平的三轴压缩试验,分析了腐蚀时间和围压条件对井壁混凝土破坏形式、变形和强度的影响,基于弹性模量和粘聚力变化建立劣化因子来定量表征硫酸盐腐蚀引起的井壁混凝土三向受力性能变化,建立了考虑腐蚀效应的井壁混凝土强度破坏准则,并得到了井壁混凝土在硫酸盐腐蚀和围压作用下的腐蚀受荷损伤演化模型和本构关系,为评价三向受力状态井壁混凝土的腐蚀劣化性能提供参考。(4)通过对受硫酸盐腐蚀的井壁混凝土开展三向应力下的循环加卸载试验,研究了应力扰动下混凝土的腐蚀劣化性能,并基于能量耗散的观点采用能量比来定量研究硫酸盐腐蚀环境中井壁混凝土受加卸载扰动作用的劣化特征,为评价扰动因素作用下井壁混凝土的腐蚀劣化性能提供参考。(5)通过试验研究了 Na+、Mg2+、NH4+三种常见阳离子对井壁材料硫酸盐腐蚀劣化的影响,从表观、质量、超声波波速、抗压及抗折强度变化等方面对比分析了硫酸钠、硫酸镁和硫酸铵腐蚀环境中井壁材料的性能变化,并通过劣化因子对性能变化进行定量评价,采用环境扫描电镜、能谱分析及X射线衍射等微观试验手段观测分析硫酸盐腐蚀环境中Na+、Mg2+、NH4+三种常见阳离子对井壁材料微结构和矿物元素及腐蚀产物组成的影响,进一步揭示了以Na+、Mg2+、NH4+三种阳离子为主的硫酸盐腐蚀环境中井壁材料的劣化机理。(6)针对硫酸盐腐蚀环境,通过引入氢氧化钡利用Ba2+能与SO42-结合生成BaSO4进而调控和影响腐蚀反应,从表观、质量、超声波波速、单轴压缩力学特征等方面对比分析了氢氧化钡的掺入对井壁混凝土宏观性能变化的改善,并借助环境扫描电镜、能谱分析、X射线衍射及热重-差热分析等微观试验分析了氢氧化钡对井壁混凝土微观结构和反应产物的影响,进一步揭示了氢氧化钡的作用机理。
[Abstract]:With the development of underground resources in our country, as the important channel of mine production, the shaft structure of the mine can meet the safety design, while the durability problem is becoming more and more prominent, especially in the large number of mine construction in the present service in 80s and 90s twentieth Century, its well wall structure is mostly C30 to C40 concrete, because the strength grade is low. With the increase of service time, the problem of durability is more severe, and even the shaft deformation and rupture will threaten the safety and normal production of the mine. The service environment of the shaft wall concrete is complicated, and its service performance and life are not only restricted by geological conditions, such as ground pressure, disturbance and so on, but also with the long-term effect of environmental factors such as underground water and microorganism. Therefore, the shaft wall concrete often faces double destruction of mechanical process and chemical process, which leads to deterioration of service state and performance. Underground mine water is often rich in soluble salt. Sulphate is a common kind, which will make the wall concrete suffer chemical erosion. The change of groundwater level and the flow of mine water will produce the concrete. Therefore, it is necessary to study the deterioration characteristics and mechanism of the well wall concrete in the sulphate corrosion environment, which will be helpful to evaluate the service state of the wall structure and predict the service life of the well wall, and also provide reference for the repair and consolidation. In this paper, the common C30 well wall coagulation is used in this paper. Soil, based on the simulation test of sulfate corrosion, the physical and mechanical tests and micro performance tests were carried out to study the deterioration characteristics and mechanism of the physical mechanical properties of the well wall concrete under the initial damage, three direction force, loading and unloading disturbance and different cation components, and sulphate corrosion environmental factors, and based on sulphuric acid. The main research contents and achievements of salt corrosion mechanism are as follows: (1) through experimental research on sulfate corrosion of well wall concrete, based on compression, splitting tensile, flexural strength and ultrasonic wave velocity, the deterioration factor is established to evaluate the performance change of the wall concrete, and the results are obtained. The function relation of the deterioration factor with the aggravation of corrosion, further based on the stress-strain relationship and the sound emission cumulative ringing count to establish the damage evolution equation of the shaft wall concrete corrosion, and then unite the corrosion damage and the load damage through the mathematical model. (2) through the different degree initial damage of the shaft wall concrete sulphate The performance changes of sulfate corrosion in well wall concrete under initial damage are compared and analyzed from the aspects of apparent, mass, ultrasonic wave velocity, strength, stress strain relationship and acoustic emission characteristics, and the quantitative evaluation and prediction of the performance changes are carried out by the deterioration factor, based on the stress-strain relationship and acoustic emission characteristics. The corrosion damage model of the shaft wall concrete under initial damage is used to further study the modification of the sulfate corrosion to the initial damage wall concrete microstructures and mineral elements and the changes in the components of the corrosion products. The corrosion deterioration mechanism of the initial damaged well wall concrete is revealed. (3) the well wall coagulation of the well wall concrete is coagulated by the sulfate corrosion. Three axial compression tests with different confining pressure are carried out in the soil. The influence of corrosion time and confining pressure on the damage form, deformation and strength of the wall concrete is analyzed. Based on the modulus of elasticity and cohesion, the deterioration factor is established to quantify the three direction behavior changes of the shaft wall concrete caused by sulfate corrosion, and the corrosion effect is considered. In order to evaluate the corrosion deterioration performance of well wall concrete in three direction in stress state, the damage evolution model and constitutive relation of the shaft wall concrete under the action of sulfate corrosion and confining pressure are obtained. (4) under the three direction stress of the well wall concrete subjected to sulphate corrosion, the corrosion deterioration performance of the well wall concrete is provided. The corrosion deterioration performance of concrete under stress disturbance is studied by cyclic loading and unloading test. Based on the energy dissipation, the energy ratio is used to quantitatively study the deterioration characteristics of the loading and unloading disturbance of the well wall concrete in the sulfate corrosion environment, which can be used as a reference for evaluating the corrosion deterioration performance of the wall concrete under the effect of disturbance. 5) the effects of three kinds of Na+, Mg2+ and NH4+ cations on Sulphate corrosion deterioration of well wall materials were studied through experiments. The performance changes of the well wall materials in the corrosive environment of sodium sulfate, Magnesium Sulfate and ammonium sulfate were compared and analyzed in terms of apparent, mass, ultrasonic wave velocity, compression and flexural strength, and the performance changes were changed by the deterioration factor. The effects of three kinds of common cations, Na+, Mg2+, NH4+, on the microstructure of well wall materials and the composition of mineral elements and corrosion products were observed and analyzed by the environmental scanning electron microscopy, energy spectrum analysis and X ray diffraction, and the three cations based on Na+, Mg2+ and NH4+ were further revealed. The deterioration mechanism of well wall materials in the environment of salt corrosion. (6) according to the sulfate corrosion environment, Ba2+ can be combined with SO42- to generate BaSO4 by introducing barium hydroxide and then regulate and influence the corrosion reaction. From the aspects of apparent, mass, ultrasonic wave velocity, and uniaxial compression mechanical characteristics, the mixing of barium hydroxide to the macro wall concrete macroscopically is analyzed. By means of environmental scanning electron microscopy, energy spectrum analysis, X ray diffraction and thermogravimetric differential thermal analysis, the effects of barium hydroxide on the microstructure and reaction products of the well wall concrete were analyzed by environmental scanning electron microscopy, and the mechanism of barium hydroxide was further revealed.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2018
【分类号】：TU528;TD262

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