开采扰动及腐蚀环境中富水充填材料劣化机理及其控制

Rich-water packing material is drawing much attention due to its high water-solid ratio, good fluidity and low cost. Meanwhile its promotion and application is affected by its bad performance because of too high water-solid ratio.Due to a large number of ettringite crystals and the combined water in hard, in the stope filling environment, the effect of mining and the the corroding effect of complex mine water can change the equilibrium condition of cemented filling body, leading to the decomposition of crystal structure of rich water material harden body and the instability or disruption of major structure of the cemented filling body. To discuss how to improve the stability of rich-water packing material, this project will analyze the deformation characters, water migration and the relationship of macro mechanics of hardening crystal in the process of creep and raise the ultimate water-solid ratio which can keep the packing body in the stable creep stage and the condition of its long-term stability, by studying the croop property of rich-water packing material in different stress conditions and the evolution characters of microstructure for the corresponding state. Through studying variation law with time of the performance of rich water material hardening body with different water-solid ratios under the complex environment of mine water, this project will discuss the influence of harmful ion concentration and water-solid ratio on evolvement rule of the microstructure of rich water hardening body and show the damage and failure mechanism. By analyzing the damage and failure mechanism of the rich-water packing material hardening crystals in the typical mine environment, this project will look for the technical approach of controlling its damage and failure.

富水类充填材料因其水固比高，流动性好，成本低而备受关注。同时，也由于其水固比过高而导致其充填体性能差而影响推广和应用。由于其硬化体内部存在大量钙矾石晶体和非结合水，在采场中受到开采扰动以及复杂矿井水的腐蚀作用，会使胶结充填体的平衡条件发生改变，导致富水材料硬化体结构的分解、充填体主体结构的破坏或失稳。为探讨如何提高富水充填材料的稳定性，本项目将通过研究不同应力条件下不同水固比时富水充填材料的蠕变性能及微细观结构演化特征，分析充填体在蠕变过程中硬化结晶体的形变特征、水分迁移及其与宏观力学性能的关系，提出充填体保持在稳定蠕变阶段的极限水固比以及保障充填体长期稳定的条件。通过在复杂的矿井水环境下，研究不同水固比的富水材料硬化体性能随时间的变化规律，探讨有害离子浓度、水固比对富水材料硬化体微观结构演变规律的影响，揭示其损伤、失效机理。通过分析典型矿井环境中的劣化、损伤机理，寻求控制失稳的技术途径。

采空区充填开采是矿山绿色开采技术的重要组成部分，具有节能减排、安全环保等优点，已在金属矿山及有“三下”压煤的煤矿开采造成的地下采空区中得到了广泛的应用。由于地下矿井水环境十分复杂，充填体因此处在含有大量腐蚀性介质的环境中，在富水充填材料水化硬化过程中会受到有害离子的影响，导致其稳定性和耐久性降低，硬化结晶体发生分解，最终造成胶结充填体的主体结构发生破坏或失稳。需要对腐蚀环境中富水充填材料的劣化机理进行研究。. 由于富水充填材料硬化体内部存在大量钙矾石晶体和非结合水，受到荷载作用后，会使充填体的平衡条件发生改变，导致充填硬化体的失稳和破坏。本课题将通过研究不同应力条件下不同水固比富水充填材料的蠕变性能及蠕变前后微观结构变化特征，分析充填体在蠕变过程中硬化结晶体的形变特征、水分迁移及其与宏观力学性能的关系，提出充填体保持在稳定蠕变阶段的临界水固比以及保障充填体长期稳定的条件。同时，从非结合水角度揭示其失稳劣化机理。. 本课题制备了满足快硬速凝要求的富水充填材料，并在此基础上对材料基本组分进行优化改进，研制出新型富水充填材料。通过宏观性能检测以及SEM、XRD、红外光谱等微观试验手段，对腐蚀环境中富水充填材料的劣化机理进行分析。通过单轴压缩、蠕变等试验，研究其力学性能与失稳破坏特征。通过XRD、SEM、DTA-TG和非结合水含量测试等微观试验，揭示其失稳劣化机理。. 主要结论有：材料在盐酸溶液中生成Friedel’s盐，主要受到硬化体溶解腐蚀；硫酸溶液中主要受到硬化体溶解腐蚀和二水石膏引起的膨胀腐蚀；氯盐溶液中生成Friedel’s盐，其中氯化钠溶液中出现氯化钠结晶，氯化镁溶液中生成石膏；碳酸钠溶液中生成碳硫硅钙石；对比原富水充填材料，新型材料抵抗侵蚀性溶液腐蚀的能力得到了很大提高。建立了富水充填材料的蠕变损伤模型与本构方程；阐明了富水充填材料蠕变损伤及破坏细观机制；提出富水充填材料改性技术方案，并获得优良性能；提出富水充填材料的水固比适用范围。