为研究不同含水率时尾矿砂的基质吸力变化规律,在尾矿砂颗粒级配测试的基础上,根据接触式滤纸法,对某尾矿砂吸湿和脱湿2个阶段分别进行了试验,得到了尾矿砂含水率在9%~40%内的12组基质吸力,建立了尾矿砂吸湿和脱湿过程的土-水特征曲线,并分析了其变化特征。试验结果表明:所测尾矿砂试样属于尾粉质黏土类;采用滤纸法可以获得较大吸力范围内的尾矿砂土-水特征曲线,该曲线近似呈倒“S”形;尾矿砂土-水特征曲线可以分为4个阶段,随含水率的增大,基质吸力阶段性减小;滤纸法测得的尾矿坝基质吸力变化范围较大,吸湿过程中为2 711.095~22.459 kPa,脱湿过程中为28.205~3 607.825 kPa。基质吸力在吸湿和脱湿过程中的变化规律基本一致,但变化路径不同,存在明显的“滞回现象”,脱湿过程中的基质吸力高于吸湿过程。

The purpose of this study is to obtain the rule of tailings sand's matric suction varying with different water content. On the basis of particle gradation test of tailings sand, the matric suction in moisture absorption stage and dehumidification stage of tailings sand were tested respectively using contact filter paper method. Twelve groups of matric suction with a water content ranging from 9% to 40% were acquired. The soil-water characteristic curve (SWCC) of tailings sand in moisture absorption and dehumidification stages is established, and the variation characteristic of SWCC is analyzed. Results indicate that the tailings sand belongs to silty clay. The SWCC of tailings sand in a large suction range obtained by filter paper method approximates an inverted “S” shape. The SWCC of tailings sand can be divided into four stages. With the increase of water content, matric suction decreases in stages. The matric suction of tailings dam measured by filter paper method varies in a large range from 2 711.095 kPa to 22.459 kPa in the process of moisture absorption and from 28.205 kPa to 3 607.825 kPa in the process of dehumidification. The variation law of matric suction in the process of moisture absorption and dehumidification is basically the same. However, the change paths are different and obviously hysteretic. The matric suction in dehumidification process is higher than that in moisture absorption process.