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与纯膨润土相比,混合型缓冲回填材料(膨润土与石英砂混合物)能够实现防渗阻隔能力、热传导性能、力学强度和可施工性能的最佳组合。选用高庙子钠基膨润土(GMZ001)为缓冲回填材料的主料,添加不同比例的石英砂,对掺砂比分别为0、10%、20%、30%、40%和50%的膨润土-砂混合物压实试样进行室内试验。结果表明,混合物的液限、塑限随掺砂率的增大而线性降低;膨胀力随时间呈指数增长。初始含水率较大时,最大膨胀力随初始含水率的增大略有降低。掺砂率一定时,最大膨胀力随初始干密度指数增长。提出了有效黏土密度的概念,建立了一定初始含水率条件下,任意掺砂率和初始干密度的高庙子膨润土-砂混合物最大膨胀力归一化模型,为混合型缓冲回填材料膨胀力的预测与控制提供了依据。
Compared with pure bentonite, mixed buffer backfill material (bentonite and quartz sand mixture) can achieve the best combination of impermeability, thermal conductivity, mechanical strength and workability. In this paper, GMZ001 was chosen as the main ingredient of cushioning backfill material, different proportions of quartz sand were added, and the bentonite-limestone mixture with 0, 10, 20, 30, 40 and 50% Sand mixture compacted samples for indoor testing. The results show that the liquid limit and the plastic limit of the mixture decrease linearly with the increase of sand content, and the expansive force increases exponentially with time. When the initial water content is larger, the maximum swelling force decreases slightly with the increase of initial water content. With a certain sand content, the maximum expansion force increases with the initial dry density index. The concept of effective clay density was put forward. The normalized model of maximum swelling force of Gaomiaozi bentonite-sand mixture with arbitrary initial sand content and initial dry density was established under certain initial moisture content. Prediction and control provided the basis.