Experimental study on the sedimentary structure of tailings storage facilities.

Purpose: The non-uniform sedimentary structure of tailings storage facilities (TSFs) has significant adverse effects on dam seepage and stability. However, the spatial distribution of tailings is disordered and the resulting sedimentary structures of TSFs have not been thoroughly understood. The objective is to investigate the complex sedimentary structures of tailings under different discharge conditions. Methods: A flume with a length of 20 m and a width of 2 m was built, and a series of flume tests with different discharge parameters were conducted. The depositional characteristics and formation mechanism were statistically investigated in terms of particle size distribution in the horizontal and vertical directions, the micro fabric of sediment, and the interlayer structure. Results: The hydraulic sorting is obvious. In the transitional region between the channel zone and laminar flow zone, d₅₀ and d₁₀ both undergo a sudden decrease. Vertically, the mean particle size of sediment is linearly related to the depth of each profile. The fabric pattern of sedimentary particle orientation changes from a spindle shape to a circular shape with increasing slurry concentration or decreasing discharge flow rate, indicating that particle deposition is clearly anisotropic and directional. Three new types of interlayers were observed: silt or clay interlayers in sand layers, sandy lenticles interbedded in muddy sediment and bedding structure interlayers. Conclusions: This study represents the first effort to analyse the micro fabric characteristics of tailings sediment and the formation mechanism of interlayer structure. This quantitative study provides useful information for the modelling and safety evaluation of TSFs. [ABSTRACT FROM AUTHOR]