含水率和干密度对某铀尾砂基质吸力的影响研究

Research on influence of water content and dry density on matric suction of uranium tailings

为探究不同水土特性状态下铀尾砂基质吸力变化规律及特性,采用滤纸法在不同含水率和干密度条件下测定了3种铀尾砂的基质吸力,利用Van Genuchten (VG)模型对其水土特性曲线(SWCC)进行拟合,并构建了吸力应力特性曲线(SSCC)。研究结果表明:在高含水量阶段铀尾砂基质吸力随含水率减小而缓慢增加,当含水量小于临界值时基质吸力急剧增大。尾砂颗粒越均匀,孔隙体积越大,其残余含水率越低;在同等含水率下,随着干密度的增大,铀尾砂基质吸力有所提高,但吸力增量会因含水率增加而逐渐减小。1#和2#尾砂吸力应力随有效饱和度增长呈现出先减小后增大的规律,3#尾砂则呈现出先迅速降低后增大且增幅不断变缓的趋势,表明当1#和2#尾砂作为主要筑坝材料时,基质吸力对铀尾矿坝抗剪强度及安全性系数的影响十分有限。

In order to explore the change laws and characteristics of matric suction for the uranium tailings under different wa- ter and soil characteristic status, the matric suction of three types of uranium railings were measure under different water contents and dry densities by using the method of filter paper. The soil-water characteristic curve （SWCC） was fitted by using the Van Genuchten （VG） model, and the suction-stress characteristic curve （SSCC） was established. The results showed that in the stage of high water content, the matric suction of uranium railings increased slowly with the decrease of water con- tent, and it increased sharply when the water content was less than the critical value. The more uniform the railings particles and the larger the pore volume, the lower the residual water content. Under the same water content, the matric suction of uranium railings increased with the increase of dry density, but the increment of suction would decrease gradually with the increase of water content. The suction stress of 1 # and 2# railings decreased first and then increased with the increase of effective saturation, while that of 3# railings rapidly decreased first and then increased, with a continuously slowing amplification. It showed that when taking 1# and 2# railings as the main materials of dam construction, the influence of matric suction on theshear strength and safety coefficient of uranium tailings dam was extremely limited.