At present, the filling mining method is widely used. To study strength evolution laws of cemented tailings backfill (CTB) under different curing ages, in the experiment, mine tailings were used as aggregates, ordinary Portland cement (PC32.5) was used as cementing materials, and different additives (lime and fly ash) were added to make filling samples with the solids mass concentration at 74% and the cement-sand ratios 1:4, 1:6 and 1:8. Based on the nuclear magnetic resonance (NMR) technology, the porosity test of filling samples with curing ages of 3 d, 7 d and 28 d was carried out, and the uniaxial compressive strength test was carried out on the servo universal material testing machine. The relationship between the uniaxial compressive strength and porosity of backfills and the curing age in the three groups was studied, and change laws of the porosity variation and strength growth rate of backfills were analyzed. Based on the variation in porosity, the strength evolution model of the CTB under different curing ages was established, and the model was fitted and verified with test data. Results show that the uniaxial compressive strength, porosity, porosity variation, and strength growth rate of the three groups of backfills gradually increase with the increase of the curing age, the porosity of backfill basically increases with the decrease of the cement–sand ratio, and the porosity of backfill decreases with the increase of the curing age. Porosity variations and relative strength values of the three groups of backfills under different cement-sand ratios obey an exponential function, and the two have a good correlation, indicating that the established filling strength evolution model can well reflect strength evolution laws of the CTB with the change of curing age.

中文翻译：

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从孔隙度角度研究水泥尾矿回填强度演化特征

目前，充填开采法被广泛使用。为了研究水泥尾矿回填物（CTB）在不同固化年龄下的强度演化规律，在实验中以矿山尾矿为骨料，以普通硅酸盐水泥（PC32.5）为胶结材料，并添加了不同的添加剂（石灰和粉煤灰）。添加）制成固体质量浓度为74％的水泥砂比为1：4、1：6和1：8的填充样品。基于核磁共振技术，对3d，7d和28d固化年龄的填充样品进行了孔隙率测试，并在伺服通用材料试验机上进行了单轴抗压强度测试。研究了三组回填材料的单轴抗压强度和孔隙率与固化时间的关系，分析了回填土孔隙率变化和强度增长率的变化规律。根据孔隙率的变化，建立了不同固化年龄下CTB的强度演化模型，并对该模型进行了拟合和测试数据验证。结果表明，三组回填土的单轴抗压强度，孔隙率，孔隙率变化和强度增长率随着固化年龄的增加而逐渐增加，回填土的孔隙率基本上随水泥砂比的降低而增加，回填的孔隙率随固化时间的增加而降低。三组回填在不同水泥砂比下的孔隙度变化和相对强度值服从指数函数，二者具有良好的相关性，