酸雨环境下砂岩腐蚀过程及物理力学特性研究

发布时间：2018-01-16 00:09

本文关键词：酸雨环境下砂岩腐蚀过程及物理力学特性研究　出处：《西安建筑科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：近些年来,随着国民经济建设的快速发展,人类生产生活对环境造成了严重的损害,环境污染是目前环境岩土工程学科面临需要重点研究的课题。大气中酸性气体急剧增加,从而导致酸雨产生,酸性环境会严重影响岩石的物理力学性质。为此,本文采用PH=2、PH=3.5及PH=5的HCl溶液模拟室内加速腐蚀试验,用定义的物理量及超声波检测技术获得的物理力学参数,定量分析岩样腐蚀过程中物理化学性质的变化规律,通过CT图像及CT数分析物理力学参数变化对岩样化学损伤的影响,得到如下研究成果:1.在不同浓度HCl溶液的腐蚀过程中,岩样的质量变化、溶蚀速率和孔隙率变化表现出明显的阶段性。0~30及70~90天随着质量损失率的增加孔隙率迅速增加,30~60天质量损失率减小,孔隙率增加缓慢,每个阶段的溶蚀速率呈现先增后减的趋势。2.运用超声波检测技术对浸泡在不同浓度HCl溶液的岩样进行进行测试,发现不同腐蚀阶段湿岩样的纵波波速和振幅变化较为明显,其变化规律为:0~30天,波速变化率较大,之后波速增加缓慢,70~90天波速趋于稳定。3.对不同浓度HCl溶液中H+、Na+、Ca2+、K+、Mg2+等阳离子的跟踪观测表明,初始浓度不同的HCl溶液中PH值随腐蚀时间的增加而增加,阳离子溶解速率随HCl溶液浓度变化呈现阶段性特征。第一阶段PH=2的HCl溶液中Na+溶解速率在初期最大为264.78 mol/d,PH=3.5及PH=5的HCl溶液中Na+溶解速率在中期达到最大值;PH=2的HCl溶液中Ca2+溶解速率最大为489.50 mol/d,分别是PH=3.5及PH=5的HCl溶液中Ca2+溶解速率的5倍和4倍。4.单轴压缩试验发现,腐蚀后的岩样的应力-应变曲线上非线性段增加,岩样发生整体破坏的时间延长,且化学腐蚀使岩样抗压强度、弹性模量减小,力学性能劣化。CT扫描结果发现,溶液的腐蚀作用使岩样发生化学损伤,不同扫描层面和测量区域内的损伤变量呈现区域性特征,中间扫描层损伤变量最小。
[Abstract]:In recent years, with the rapid development of national economic construction, human production and life have caused serious damage to the environment. Environmental pollution is a subject that needs to be studied in the field of environmental geotechnical engineering at present. The acid gas in the atmosphere increases rapidly, which leads to acid rain, and acid environment will seriously affect the physical and mechanical properties of rock. In this paper, the indoor accelerated corrosion test was simulated by HCl solution of PH2 + PH3. 5 and PH=5, and the physical and mechanical parameters obtained by using the defined physical quantity and ultrasonic testing technique were used to simulate the indoor accelerated corrosion test. The changes of physical and chemical properties of rock samples during corrosion are quantitatively analyzed. The effects of the changes of physical and mechanical parameters on the chemical damage of rock samples are analyzed by CT images and CT numbers. The following results are obtained: 1. The quality of rock samples changes during the corrosion process of HCl solution with different concentrations. The change of dissolution rate and porosity showed that the mass loss rate decreased rapidly with the increase of mass loss rate at 30 ~ 30 and 70 ~ 90 days, and the mass loss rate decreased at 30 ~ 60 days with the increase of mass loss rate. The porosity increased slowly and the dissolution rate of each stage increased first and then decreased. 2. Ultrasonic testing technique was used to test rock samples immersed in different concentrations of HCl solution. It is found that the variation of longitudinal wave velocity and amplitude of wet rock samples in different corrosion stages is obvious, and the variation rule is: 0 ~ 0 ~ 30 days, the rate of change of wave velocity is large, and then the wave velocity increases slowly. The wave velocities of 70 ~ 90 days tend to be stable .3.The trace observation of H ~ (2 +) Na ~ (2 +) Ca ~ (2 +) Ca ~ (2 +) K ~ (2 +) mg _ (2) ions in different concentrations of HCl. The PH value of HCl solution with different initial concentration increases with the increase of corrosion time. The dissolution rate of cationic ions varies with the concentration of HCl solution. In the first stage, the dissolution rate of Na in HCl solution of PH=2 is 264.78 mol/d. The dissolution rate of Na in HCl solution of PH=3.5 and PH=5 reached the maximum in the middle phase. The maximum dissolution rate of Ca2 in HCl solution of PH=2 is 489.50 mol/d. The dissolution rate of Ca2 in HCl solution of PH=3.5 and PH=5 is 5 times and 4 times of that in HCl solution, respectively. Uniaxial compression test shows that the nonlinear section of stress-strain curve of corroded rock samples increases. The whole damage time of rock sample is prolonged, and chemical corrosion reduces the compressive strength and elastic modulus of rock sample, and the mechanical property deterioration. Ct scan results show that the chemical damage of rock sample is caused by solution corrosion. The damage variables in different scan planes and measured areas showed regional characteristics, while the middle scan layers showed the smallest damage variables.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45;X141

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