| 摘要: |
| 【目的】研究高水压力环境下混凝土内部孔隙结构的变化特征，揭示混凝土经高压水力劈裂损伤的微观机理。【方法】将混凝土试件于105 ℃下恒温持续干燥115.5 h直至试件达到干燥状态，待试件自然冷却后，利用恒定水压加载系统对干燥后的混凝土在不同高孔隙水压力（0，1，2，3 MPa）下进行加载，采用X ray CT扫描仪对试件进行扫描，基于VG Studio MAX 2.2分析平台模拟三维重构后分析其内部孔隙的个数、直径、体积、球度及离散性。【结果】各组试件面层孔隙率的离散性随高孔隙水压力的增加而降低；与高孔隙水压力作用前相比，作用后试件的孔隙率提高，其中1，2，3 MPa水压力下试件的孔隙率较作用前分别增加了2.79%，8.38%，23.46%；高孔隙水压力作用后的孔隙数较作用前均有所增加，但孔隙数随水压力增大呈先升后降的趋势，2 MPa水压力下的孔隙数最多，为69 259个；不同大小的孔隙中以孔径≥0.5～＜1.0 mm孔隙出现比例最大，在0，1，2，3 MPa水压力作用下试件该孔径孔隙数量分别占孔隙总数的52.28%，61.87%，62.03%和59.72%；在不同水压力下，孔隙球度随孔隙直径的增大呈现下降趋势。【结论】高孔隙水压力增大可使混凝土内部孔隙结构发生改变，孔隙总体积随之增大。 |
| 关键词: 混凝土 高孔隙水压力 X ray CT扫描 孔隙结构特征 |
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| 基金项目:国家自然科学基金项目(51969010);国家重点研发计划项目（2017FYC405101）;云南省基础研究计划项目（2019FD-052） |
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| Characteristics of microscopic pores of concrete under |
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ZHANG Guohui,GU Yanshuang,LI Zongli,et al
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| Abstract: |
| 【Objective】The variation characteristics of internal pore structure of concrete under high water pressure were studied and the microscopic mechanism of high pressure hydraulic splitting damage of concrete was revealed.【Method】The concrete specimens were dried continuously at a constant temperature of 105 ℃ for 115.5 h until they reached a dry state.After cooled naturally,the dried specimens were loaded at different high water pressures (0,1,2 and 3 MPa) using a constant water pressure loading system.Then,the specimens were scanned by an X-ray CT scanner and the internal pore distribution characteristics were analyzed after simulating the three-dimensional reconstruction based on the VG Studio MAX 2.2 analysis platform,the number,diameter,volume,sphericity and dispersion of internal pores were analyzed.【Result】 The discreteness of surface porosity of each group decreased with the increase of high pore water pressure.The porosity of specimens was increased by high pore water pressure,in which the porosities under the pressures of 1,2 and 3 MPa were increased by 2.79%,8.38% and 23.46%,respectively.The number of pores was also increased by high pore water pressure,but the number of pores increased first and then decreased with the increase of water pressure.The 2 MPa water pressure had the largest pore number of 69 259.The pore size of ≥0.5-<1.0 mm was the most and the fractions under water pressures of 0,1,2 and 3 MPa were 52.28%,61.87%,62.03% and 59.72%,respectively.Under different water pressures,the sphericity of pores showed a decreasing trend with the increase of pore diameter.【Conclusion】 The increase of high pore water pressure could promote the change of internal pore structure of concrete and increase the total volume of pores. |
| Key words: concrete high pore water pressure X ray CT scan pore structure characteristics |
