某水电站大坝裂缝化灌混凝土芯样抗剪试验研究

混凝土拱坝、重力坝等的大体积混凝土在浇筑过程中产生的温度裂缝可能会成为大坝的安全隐患,尤其会降低大坝混凝土的抗拉、抗剪力学性能,影响大坝的长期稳定性和降低大坝的寿命。某水电站在大体积混凝土浇筑过程中,部分坝段受温度影响,形成一些贯通裂缝。采用该水电站大坝坝体的裂缝灌浆材料,在室内进行了无缝本体混凝土芯样抗剪试验、带缝(劈裂造缝)坝体混凝土立方体试件及混凝土芯样模拟化灌后的抗剪试验、化学灌浆后裂缝完整粘结的坝体混凝土芯样抗剪试验,并对试验结果进行了比较和分析。结果表明:该工程坝体裂缝经化灌处理后,其抗剪特性参数f'可以达到本体混凝土的83%;c'可以达到本体混凝土的68%;室内模拟灌浆的效果更好,f'可以达到本体混凝土水平,c'可以达到85%以上。化学灌浆是处理大坝裂缝,提高混凝土抗剪强度和抗渗性能的一个有效措施,研究结果可以为化灌后混凝土的力学参数合理取值提供参考。

Shear Tests on the Concrete Core Samples for the Chemical Grouting of Dam Cracks of a Hydropower Project

Temperature crack in the pouring process of mass concrete of concrete arch dam and gravity dam could be a hidden troubles that affects the safety of the dam, especially reduces the tensile strength and shear mechanical properties of concrete dam, and also affects the long?term stability and the service life of the dam. During the pou?ring of mass concrete of a hydropower station, part of the dam was affected by temperature and cracks penetrated through. By using the crack grouting material for the hydropower station dam, we carried out indoor tests and com?pared the test results. The indoor tests include:shear test on the original concrete core sample with no crack from the dam, shear test on cube concrete samples with cracks ( made by splitting) and concrete core samples after sim?ulation chemical grouting, and shear test on concrete core samples with cracks fully bonded after grouting. Results show that after chemical grouting treatment on the cracks, the shear parameter f ′ reaches the 83% of the original concrete, and c′s the 68%of the original concrete. The result of indoor chemical grouting simulation is better, with f′equaling the level of original concrete, and c′reaching above 85% of the original concrete. Chemical grouting is an effective measure to treat dam cracks and improve the shear strength and the impermeability of concrete. The re?search results provide reference for reasonable values of mechanical parameters of concrete after chemical grouting.