某面板堆石坝垫层料和过渡料渗透变形及反滤试验研究

某在建面板堆石坝拟将现场开挖获得的砂砾石料筛除300 mm以上粒径组后作为上坝过渡料，筛除100 mm以上粒径组后作为上坝垫层料。此法获得的垫层料小于5 mm颗粒含量低于设计要求，垫层料与过渡料的级配包络线范围较窄且两者相差不大。由此造成垫层料与过渡料渗透性范围交叉覆盖，存在排水不畅，水力过渡不好组合的可能性。针对以上情况，对天然开挖筛分后垫层料掺入5 mm以下粒径组颗粒，以提高上坝垫层料小于5 mm颗粒含量，使其级配满足设计要求并提高其内部稳定性。掺配后的垫层料在反滤料的保护下，可以承受远超过渗流场计算得到的最大比降。本研究成果及现场工程实践表明，对垫层料掺配一定比例的细料，是类似条件工程中改善垫层区与过渡区水力过渡，提高反滤作用效果的有效途径。

Experimental studies on the seepage deformation characteristics and filtering function of the cushion and transition materials for a Concrete Faced Rockfill Dam

The excavated sands and gravels are used for dam filling in a concrete faced dam. The sieved materials with maximum diameter of 300mm are used as transition materials. The materials with max diame-ter of 100mm are used as cushion materials. The fine soil particles content of sieved cushion material is lower than the design requirement. The gradation curves of cushion and transition materials are in a sharp range without obvious difference. So the hydraulic transient of the dam is likely to be bad. To avoid seep-age deformation, the sieved cushion materials are mixed with small granules which are finer than 5mm. The interior structure of the mixed cushion material will be more stable. So it can take on a water pressure which is far exceeding the calculated max value with the filter protection of transition material. The experi-mental study and the worksite practice show that mixing fine granules to the cushion material is an effi-cient way to improve hydraulic transient and filtering protection in similar conditions.