1. School of Civil Engineering,Chongqing University,Chongqing　 400045,China; 2. Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education, Chongqing University, Chongqing 　 400045, China; 3. State Key Laboratory of Coal Mine Disaster Dynamics and Controls, Chongqing University,Chongqing　 400044,China

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。

In order to discuss the deterioration degree of macroscopic mechanic properties and damage rule of micro structure of limestone under the condition of acidic environment,the limestone of a mine roadway in Chongqing was se-lected for study. The limestone specimens were immersed in solutions of pH = 3,5,7 at the same time and then meas-ured by NMR system to obtain the change rule of porosity. Compared with the dried limestone,the deterioration rule of mechanical properties of pre-immersion specimens were obtained from conventional triaxial experiments. The results of NMR measurements show that the porosity of limestone have a tendency to become larger in acid environment with the high formation rate of secondary macroporosity in pH = 3. Compared with the initial state,the porosity of specimens in-creases 12. 15% ,6. 67% ,3. 43% respectively in pH = 3,5,7. The results of mechanical test shows that the ductility of limestone is more obvious under the acidic conditions and a smaller stress drop after peak is observed with the increase of pH value. Except elastic modulus exhibits a secondary decrease,mechanical parameters (uniaxial peak stress,Poisson’s ratio,internal friction angle,cohesion) exhibits a linear decrease basically with the decrease of the pH value. In addition,the effect on deformation parameters is greater than the strength parameters of limestone with the deterioration of porosity under the acidic environment. And the influence degree of cohesive is greater than internal friction angle.

重庆市基础与前沿研究计划资助项目(cstc2013jcyjA30005)；国家自然科学基金资助项目(51108485)；

Zhong Zuliang, Luo Weikun,Liu Xinrong,et al. Experimental study on mechanical properties deterioration of limestone in acid environ-ment based on nuclear magnetic resonance[ J]. Journal of China Coal Society,2017,42 (7):1740 - 1747.