基于核磁共振技术的酸性环境下灰岩力学特性劣化试验

发布时间：2018-03-24 17:25

本文选题：酸性环境　切入点：核磁共振　出处：《煤炭学报》2017年07期

【摘要】：为研究灰岩在酸性环境下宏观力学性质的劣化度及细观结构的损伤规律,以重庆某采区的灰岩为研究对象,对经酸性溶液(pH=3,5)和蒸馏水(pH=7)浸泡前后的试件进行核磁共振测量(NMR),并对浸泡后的试件进行三轴压缩试验,分析了灰岩浸泡前后孔隙度及力学参数的劣化规律。试验结果表明:酸性环境作用下,灰岩内部孔隙呈整体变大的趋势,pH=3时次生大孔隙的生成率较高;在pH=3,5,7条件下,试件孔隙度分别增加12.15%,6.67%,3.43%;随pH值的降低,灰岩的延性特征更明显,峰后应力降进一步减小;除弹性模量的劣化度呈二次减小外,其它力学参数(单轴峰值应力、泊松比、内摩擦角、黏聚力)均呈线性减小的规律。此外,酸性环境对灰岩变形参数的影响大于强度参数,而强度参数中,对黏聚力的影响大于内摩擦角。
[Abstract]:In order to study the degradation degree of macroscopic mechanical properties and the damage law of meso-structure of limestone in acidic environment, the limestone of a mining area in Chongqing is taken as the object of study. The specimens before and after soaking in acid solution and distilled water were measured by nuclear magnetic resonance (NMR) and triaxial compression tests were carried out. The degradation law of porosity and mechanical parameters of limestone before and after soaking is analyzed. The experimental results show that under the action of acid environment, the formation rate of secondary macropores is higher at pH = 3, and the formation rate of secondary macropores is higher under the action of acid environment. With the decrease of pH value, the ductility of limestone becomes more obvious, the stress drop after peak decreases further, and the other mechanical parameters (uniaxial peak stress, Poisson's ratio) except the deterioration of elastic modulus are decreased twice. In addition, the influence of acid environment on deformation parameters of limestone is greater than that of strength parameters, and the influence of strength parameters on cohesion is greater than that on internal friction angle.
【作者单位】：重庆大学土木工程学院;重庆大学山地城镇建设与新技术教育部重点实验室;重庆大学煤矿灾害动力学与控制国家重点试验室;
【基金】：重庆市基础与前沿研究计划资助项目(cstc2013jcyj A30005) 国家自然科学基金资助项目(51108485)
【分类号】：TD315

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