为了研究土石混填料在循环荷载作用下的轴向累积应变特性,以土石混填料为研究对象,开展了室内大型动三轴试验,研究了不同动应力幅值和围压对土石混填料轴向累积应变的影响及动孔隙水压力的变化规律,并对轴向累积应变预测模型进行了分析。试验结果表明:土石混填料的轴向累积应变可根据安定性理论划分为塑性安定、塑性蠕变、增量破坏3种类型,且动应力幅值σd越大,试样的轴向累积应变就越大,围压σ3越大,试样的轴向累积应变就越小。动孔隙水压力曲线与对应动应力幅值的轴向累积应变曲线是同一发展类型。针对土石混填料蠕变型轴向累积应变的发展特点,提出了修正后的改进模型,并验证了模型的可行性,该模型能很好地适用于拟合“塑性蠕变型”应变曲线。
Abstract
To investigate the cumulative deformation characteristics of soil-rock mixed fill under cyclic loading, a comprehensive large dynamic triaxial test was conducted. The objective was to determine the influence of different dynamic stress amplitudes and confining pressures on the axial cumulative strain of the fill, as well as the variation of dynamic pore water pressure. Additionally, a cumulative strain prediction model was analyzed. The test results revealed that the axial cumulative strain of the soil-rock fill can be categorized into three types: plastic stability, plastic creep, and incremental damage, according to stability theory. The specimen’s axial cumulative strain increased with larger dynamic stress amplitudes, but decreased with greater confining pressures. The dynamic pore water pressure curve and the corresponding axial accumulated strain curve displayed the same developmental characteristics. In consideration of the development characteristics of creep-type cumulative strain in soil-rock mixed fill, a modified and improved model was proposed. The feasibility of the model was verified, and it can be effectively applied to strain curves exhibiting plastic creep behavior.
关键词
土石混填料 /
大型动三轴试验 /
轴向累积应变 /
动应力幅值 /
动孔隙水压力 /
改进模型
Key words
soil-rock mixed fill /
large dynamic triaxial test /
axial cumulative strain /
dynamic stress amplitude /
dynamic pore water pressure /
improved model
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基金
国家自然科学基金项目(51978237);河北省自然科学基金项目(E2018412002);河北省高等学校科研重点项目(ZD2021068);河北省大学生科技创新能力培育专项
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