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周墨臻, 张丙印, 钱晓翔, 孙逊. 堆石料流变应变的硬化特性试验研究[J]. 岩土工程学报, 2020, 42(4): 688-695. DOI: 10.11779/CJGE202004011
引用本文: 周墨臻, 张丙印, 钱晓翔, 孙逊. 堆石料流变应变的硬化特性试验研究[J]. 岩土工程学报, 2020, 42(4): 688-695. DOI: 10.11779/CJGE202004011
ZHOU Mo-zhen, ZHANG Bing-yin, QIAN Xiao-xiang, SUN Xun. Experimental study on hardening effect of creep in rockfill material[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(4): 688-695. DOI: 10.11779/CJGE202004011
Citation: ZHOU Mo-zhen, ZHANG Bing-yin, QIAN Xiao-xiang, SUN Xun. Experimental study on hardening effect of creep in rockfill material[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(4): 688-695. DOI: 10.11779/CJGE202004011

堆石料流变应变的硬化特性试验研究

Experimental study on hardening effect of creep in rockfill material

  • 摘要: 堆石料流变变形是高土石坝工程长期变形的重要来源之一,过大的长期变形可导致发生坝体裂缝和面板挤压破损等问题。目前常用的流变模型主要是根据单级加载流变试验成果建立的,未考虑多级加载情况下堆石料加载变形和流变变形之间的相互影响。研制了三轴仪油压伺服轴向应力稳压器,实现了应变控制进行应力加载和应力控制进行稳压流变的联合控制模式,据此提出了一种进行多级应力加载和流变的三轴试验方法,可有效避免流变的起算时间问题。采用糯扎渡弱风化花岗岩堆石料,进行了系列的多级加载三轴流变试验。根据试验结果,探讨了多级加载条件下堆石料应力应变曲线的分段特性,发现堆石料流变变形会引起堆石料的塑性硬化,可使得堆石料在后续应力加载的一定范围内处于弹性再加载状态。基于弹塑性理论,探讨了堆石料流变硬化特性的作用机理,表明堆石料流变的硬化特性具有普遍性,是流变的一项固有属性。

     

    Abstract: The excessive long-term deformation may lead to crack and damage problems in high earth-rockfill dams. The creep effect of rockfill is crucial for the long-term deformation of rockfill dams. The generally applied creep models are mainly based on the single-stage creep tests, without taking account of the coupling effect of creep and loading during multistage processes. This study improves the triaxial apparatus by developing a stress controller to maintain stable axial stress for long durations. The improved apparatus achieves the switch between strain-controlled mode for loading and stress-controlled mode for creep. Then, a multistage loading-creep coupled test method is proposed, providing a clear determination of the creep starting point. A series of multistage loading-creep coupled tests are specially designed and conducted for rockfill materials which are crushed weakly-weathered granite from the Nuozhadu Rockfill Dam. The test results indicate that the multistage loading-creep processes show apparent cyclic and piecewise characteristics. The creep strain is found to have a hardening effect similar to the loading-induced plastic strain, making the post creep loading behave as a reloading elastic process first and then an elastoplastic process. It is further shown that the hardening effect is an inherent property of creep of the rockfill and can be interpreted by the classical elastoplastic theory.

     

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