Natural Clogging Design for Tailings Pond Filters

Filters serve as critical facilities for ensuring the seepage stability of earth-rock dams and tailings dams; their failure poses severe threats to dam safety. Traditional filter design criteria are constrained by the diversity of soil types and fail to account for the influence of pore characteristics (e.g., constriction size) on the soil retention and hydraulic conductivity of filters. Design methods recommended in design codes only provide gradation envelope boundaries without specifying exact gradation curves. This paper proposes a filter design approach based on the natural clogging concept. Using Terzaghi’s interlayer coefficient as the initial parameter, this method induces stable clogging layers of base soil within the filter through sediment-laden seepage, adopting the post-clogging gradation as the design gradation. Experimental results demonstrate that: (1) when the initial interlayer coefficient α of the filter is ≤10.4, the base soil retention rate exceeds 97% (soil loss < 3%), surpassing the conservative limit of α < 4 in Terzaghi’s criterion; (2) the final interlayer coefficient α of filters ZS-2 to ZS-5 ranges between 1.15 and 2.48, with ib/if values between 6.26 and 23.68, simultaneously satisfying Terzaghi’s requirements for soil retention and hydraulic conductivity; (3) this method explicitly defines the specific gradation curve of the filter, with the final gradation curve of ZS-5 largely falling within the envelope recommended by design codes. The proposed method integrates Terzaghi’s interlayer coefficient criterion with the influence of pore characteristics on filter performance, offering a new design strategy for tailings dam filters with fine-grained base soils, preliminarily validated under laboratory conditions.