酸腐蚀后灰岩动态压缩力学性质的试验研究

发布时间：2018-06-07 06:36

本文选题：灰岩 + 酸腐蚀　；参考：《岩土力学》2017年11期

【摘要】：地下水化学腐蚀在岩石圈中广泛存在,而岩体也常因承受动荷载而变形破坏。为探究酸腐蚀后灰岩的动态力学性质,将试样分别在pH=3的NaCl和KHSO_4混合溶液中浸泡不同时间,通过核磁共振测试获得了部分试样的孔隙率、孔径分布及成像灰度图,并利用分离式Hopkinson压杆开展了5种应变率的单轴冲击试验。结果表明:随腐蚀时间增加,灰岩孔隙率从自然状态下的0.26%剧增到3.20%(腐蚀28 d),微孔隙尺度也同步增大;动态抗压强度大幅劣化(30.3%),并可根据下降速率区分为2个阶段,而其弹性模量和比能量吸收值则随时间呈指数衰减。自然状态和腐蚀后灰岩的应变率响应规律基本一致:随应变率增大,破坏模式由典型的劈裂破坏向拉剪混合、剪切破坏过渡,直至粉末状破坏;抗压强度和弹性模量近似线性增加,但自然状态下二者对应变率的敏感程度较腐蚀后强烈。酸腐蚀对灰岩动态承载能力和抗变形能力具有重要影响,在工程实践中应加以考虑。
[Abstract]:Chemical corrosion of groundwater exists widely in lithosphere, and rock mass is often deformed and destroyed by dynamic load. In order to investigate the dynamic mechanical properties of limestone after acid corrosion, the samples were immersed in the mixed solution of NaCl and KHSO_4 of pH=3 for different time. The porosity, pore size distribution and image grayscale of some samples were obtained by nuclear magnetic resonance (NMR). The uniaxial impact tests of five strain rates were carried out using the split Hopkinson compression bar. The results show that with the increase of corrosion time, the porosity of limestone increases sharply from 0.26% in natural state to 3.20% (28 days after corrosion, the micropore scale also increases, and the dynamic compressive strength deteriorates to 30.3%, and can be divided into two stages according to the decreasing rate. However, the elastic modulus and specific energy absorption value decrease exponentially with time. The natural state is basically consistent with the strain rate response of the corroded limestone: with the increase of the strain rate, the failure mode changes from typical split failure to tensile shear, shear failure transition to powder failure; The compressive strength and elastic modulus increase linearly, but their sensitivity to strain rate in natural state is stronger than that after corrosion. Acid corrosion has an important influence on the dynamic bearing capacity and deformation resistance of limestone, which should be considered in engineering practice.
【作者单位】：中国矿业大学深部岩土力学与地下工程国家重点实验室;中国矿业大学力学与土木工程学院;
【基金】：国家重点基础研究发展计划(973)项目(No.2013CB036003) 国家自然科学基金(No.51579239,No.51374198)~~
【分类号】：TU45

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