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基于不同浓度氯盐作用下充填膏体时效性特征研究

Research on the time-dependent stability of filling paste under the action of different concentrations of chloride salts

  • 摘要: 为研究矿井水作用下充填膏体时效性,配制了质量分数为0%、5%、10%、15%氯盐溶液,开展了侵蚀周期为4次、8次、12次、16次的氯盐干湿循环试验,分析了充填膏体宏观和微观特征,基于构建的压实−弹塑性本构模型获得了充填膏体损伤曲线,探讨了氯盐作用下充填膏体应力演化机制。结果表明:充填膏体质量随氯盐侵蚀周期增加呈急剧增长、缓慢增长和缓慢下降趋势,高浓度氯盐溶液会加速充填膏体质量变化;随氯盐侵蚀周期增加,充填膏体依次呈现出高应力−低应变、低应力−高应变和低应力−低应变宏观力学特征;压实度呈先急剧减小后小幅度增降发展动态,塑性因子呈先稳定后急剧增降变化趋势。氯盐会促使充填膏体损伤进程的平稳发展,抑制塑性后期的损伤激增;质量分数为5%和10%氯盐溶液中经历16次干湿循环后的损伤曲线发展曲率相对较小,质量分数为15%氯盐溶液中经历12次干湿循环后的损伤曲线发展曲率相对较小。化学腐蚀是引起充填膏体胶结性能弱化的重要原因,化学腐蚀的盐蚀产物一部分来源于氯盐与未参与水化反应铝酸三钙(C3A)化学结合,另一部分来源于氯盐与水化产物钙矾石(AFt)化学结合。盐蚀产物与内部结构协调变形是造成充填膏体性能异化的关键因素,盐蚀产物充实抵抗内部应力致使压密性能和裂隙扩展能力降低。可为矿井水中充填膏体时效稳定性分析提供理论依据,对维护充填膏体长期稳定具有重要意义。

     

    Abstract: In order to study the time-dependent characteristics of filling paste under the action of mine water, chloride salt solutions with mass fraction of 0%, 5%, 10%, and 15% were prepared, and chloride salt dry wet cycle tests with erosion cycles of 4, 8, 12, and 16 times were carried out. The macroscopic and microscopic characteristics of the filling paste were analyzed, the damage curve of the filling paste was obtained based on the constructed compaction-elastoplastic constitutive model, and the stress evolution mechanism of the filling paste under the action of chloride salt was discussed. The results indicate that the mass of filling paste shows a sharp increase, a slow increase, and a slow decrease trend with the increase of chloride erosion cycles. High-concentration chloride salt solution accelerate the quality change of filling paste. As the cycles of chloride erosion increase, the filling paste exhibits a macro-mechanical characterized by high stress-low strain, low stress-high strain, and low stress-low strain. The compaction degree exhibits a dynamic evolution characterized by an initial sharp decrease followed by a stable variation, the plasticity factor demonstrates a developmental trend of initial stability followed by a sharp change. The chloride salt promotes the stable development of the damage process of filling paste and inhibits the surge of damage in the later stage of plasticity. The development curvature of the damage curve after 16 dry-wet cycles in 5% and 10% chloride salt solution is relatively small, and the development curvature of the damage curve after 12 dry-wet cycles in 15% chloride salt solution is relatively small. Chemical corrosion is a significant factor leading to the deterioration of the binding properties of filling paste. The salt corrosion products from chemical corrosion partly originate from the chemical combination of chloride and unreacted tricalcium aluminate(C3A), and another portion arises from the chemical bonding of chloride with the hydration product ettringite(AFt). The coordination deformation between salt corrosion products and internal structure is a key factor causing the alienation of the bearing performance of filling paste. The crystalline expansion force of salt corrosion products resists internal stresses of filling paste, resulting in a reduction in compaction performance and crack propagation ability. This study can provide a theoretical basis for the analysis of the time-dependent stability of filling paste in mine water, and this study is of great significance for maintaining the long-term stability of filling paste.

     

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