Yield stress characterization and numerical simulation of paste backfill based on cylindrical slump tests

Abstract

To address the limitations of rheometer-based yield stress measurements, including procedural complexity, high cost, and limited engineering applicability, as well as the low predictive accuracy of traditional conical slump models due to discrepancies between idealized assumptions and actual slump behavior, this study integrates slump tests, vane rheometry, stereo vision reconstruction, and CFD methods to develop a cylindrical slump numerical model based on the Herschel–Bulkley framework, and establishes a dimensionless relationship between slump and yield stress. The results show that the post-slump geometry of cemented paste backfill is closer to a cylinder, with reconstruction deviations controlled within ±2 mm, an average deviation of 0.775 mm, and a top diameter deviation rate of only 1.13%. The proposed model achieves a MAPE of 1.45% in the low range, reduced by 2.74% and 1.56% compared with existing models; when the dimensionless yield stress range is extended to 0–0.3, the MAPE is 1.35%, representing a further reduction of 0.69%, indicating higher accuracy in the low yield stress region and stable applicability over a wider range. Gray relational analysis further reveals that the influence on slump decreases in the order of density, consistency, yield stress, and flow index, with correlation degrees of 0.818, 0.774, 0.640, and 0.559, respectively. These results demonstrate that the proposed slump model can more reliably characterize the slump behavior and yield-stress evolution of paste backfill, thereby providing a theoretical basis for flowability evaluation and preliminary pumpability assessment.