周期性饱水砂泥岩混合料的劣化机理及其演化过程

The mixture of sandstone and mudstone particles, if it is filled in the zone of variable water level during the construction works along reservoir bank or other waterfront projects, will go through the effect of periodic saturation due to the change of the reservoir water level. The periodic saturation may deteriorate the mixture. While the deterioration is large enough, the structure or building along the bank may deform, crack and even fail. Hence, it has become a critical issue that how to use scientifically and reasonably the sandstone-mudstone particle mixture in the hydrographic works as a filling material. In this study, the strength and deformation characteristics of the mixture after periodic saturation will be ascertained using experimental studies. Some advanced instruments will be used in the experimental studies. They include at least the triaxial test equipment, compression test system, and lateral pressure coefficient test system. The three instruments, which can simulate the course of saturation and dry cycle, are developed by the investigators of the present study. The deterioration mechanism of the sandstone-mudstone particle mixture induced by the periodic saturation effect will be revealed on the base of analyzing on the difference in degradation between sandstone and mudstone particles. At the theoretical level, some degradation indexes may be suggested to reflect the characteristics of degradation. The evolutionary process of the deterioration induced by the periodic saturation will firstly be revealed by analyzing the change of the degradation indexes.Then, according to the evolutionary process of the degradation, and the calculating method on the degradation indexes, a mathematical model of degradation will be established or suggested. The mathemetical model can describe the deterioration property of the sandstone-mudstone particle mixture induced by the periodic saturation. It can be certained that the studing conclusion from this study is beneficial to solve the problem how to use the sandstone-mudstone particle mixture in hydrographic construction as a filling material. The researching works in the present study does therefore have important theoretical significance and construction value.

在库岸等涉水工程建设中，当砂泥岩混合料被填筑于库水位变幅区域时，必然因为库水位变化经受周期性饱水作用。周期性饱水作用将劣化砂泥岩混合料，严重时可能导致沿岸结构物发生变形、开裂甚至失稳。如何在涉水工程中科学合理地利用砂泥岩混合料，已成为亟待解决的关键科学问题。项目利用自行研制的土体饱水-疏干循环三轴压缩试验系统、压缩试验系统和静止侧压力系数测试系统等先进仪器开展试验研究，查明周期性饱水砂泥岩混合料的强度及变形特性。在机理层面上，从砂岩颗粒和泥岩颗粒的差异劣化角度入手，揭示周期性饱水砂泥岩混合料的劣化机理。在理论层面上，用劣化评价指标反映劣化特征，先基于劣化评价指标的演变规律，揭示周期性饱水砂泥岩混合料的劣化演化过程；再基于劣化演化过程，确定周期性饱水劣化指标的计算方法，建立能够描述周期性饱水砂泥岩混合料劣化的数学模型。项目成果有益于解决砂泥岩混合料在涉水工程中的利用问题，具有重大的理论意义。

在库岸等涉水工程建设中，当砂泥岩混合料被填筑于库水位变幅区域时，必然因为库水位变化经受周期性饱水作用。周期性饱水作用将劣化砂泥岩混合料，严重时可能导致沿岸结构物发生变形、开裂甚至失稳。鉴于此，开展周期性饱水砂泥岩混合料的劣化机理及其演化过程研究具有重要的理论意义和工程价值。本项目利用自行研制的土体饱水-疏干循环三轴压缩试验系统、单向压缩试验系统和静止侧压力系数测试系统等开展研究，取得的创新成果如下：.（1）查明了周期性饱水砂泥岩混合料的强度、变形特性及其影响因素。通过周期性饱水压缩试验、K0试验、直剪试验和三轴试验等，获得了周期性饱水砂泥岩混合料的强度、变形及K0系数等特性，分析了周期性饱水条件和砂泥岩混合料试样条件等对周期性饱水砂泥岩混合料强度、变形特性的影响规律。.（2）从颗粒劣化的角度揭示了周期性饱水砂泥岩混合料的劣化机理。通过分析泥岩颗粒和砂岩颗粒在物理、力学和水理等性质方面的差异，得出在周期性饱水作用下，泥岩颗粒的劣化先于砂岩颗粒，泥岩颗粒的劣化程度也大于砂岩颗粒，泥岩颗粒和砂岩颗粒的劣化过程存在明显的差异性，导致不同泥岩颗粒含量的砂泥岩混合料在相同周期性饱水条件下的劣化程度、劣化过程也存在差异。.（3）揭示了周期性饱水砂泥岩混合料的劣化演化过程。周期性饱水对砂泥岩混合料的劣化程度随饱水周期数、饱水历时的增加呈非线性增加变化。提出了周期性饱水劣化的定量评价指标，分析了劣化评价指标随饱水周期数、饱水历时的变化特征，获得了劣化评价指标的演变规律，揭示了周期性饱水砂泥岩混合料的劣化演化过程。.（4）建立了描述周期性饱水砂泥岩混合料劣化演化过程的数学模型。提出了劣化评价指标的计算方法，分析了劣化评价指标随周期性饱水次数、饱水历时增加的变化规律，建立了描述周期性饱水砂泥岩混合料劣化演化过程的非线性微元强度统计损伤模型、应变软化统计损伤模型和劣化变形弹塑性模型。