Theoretical Research On Large-Strain Condolidation With Both Horizontal And Vertical Drainage Of Upstream Tailings Dam

Drainage consolidation issue of the tailings has been a focus for researchers and the large strain consolidation is one of the most important natures for the slurry, leading to geotechnical problems more serious. For this purpose, the research output is also more abundant. However, based on the process for slurry landfill and large strain consolidation theory to promote the application of the dewatering installation is rarely reported.In the flow coordinate system, according to the landfill technology of the slurry and a kind of drainage device, mathematical model and boundary conditions are established and governing equations of large-strain consolidation with both horizontal and vertical drainage is reduced. In this governing equation, excess pore water pressure is one of the control variables. In addition, the governing equation can be degenerated to Barron consolidation formula by conditions simplify. In this paper, finite difference method and chase method were used to solve the governing equation. In order to research the consolidation character of the slurry, the solved equation was used to establish and calculate the two-layer model, which Pingguo aluminum tailings conducted the background to provide computing parameters. The results show that:1) To the established model in this paper, the effective drainage radius is80cm, and with the horizontal drainage distance increase, drainage effect decreasing.2) In the conditions of bottom drainage boundary, the maximum excess pore water pressure appeared in lower middle of soil layer, and with the process of the consolidation, the maximum excess pore water pressure is gradually transferred to the middle position of soil layer.3) Average strain consolidation degree is bigger than the average stress consolidation degree at any time, of which the gap is reducing gradually with time growing.4) When the drainage radius rp=1m and stress consolidation degree reached up to60%, upper layer need19d, bottom layer need16d; while strain consolidation degree reached up to the same degree, upper layer need16d, bottom layer need14d.5) The initial void ratio for calculating, the bigger equal to2.31(e=2.31) and the smaller equal to1.83(e1.83), if the consolidation degree need to achieve the same degree that the former is hysteretic to the latter, the former need more time to achieve it. So, the initial void ratio is important.Based on the large consolidation theory, this paper provided theoretical support to promote the use of drainage consolidation device. Finally, the research findings are summarized and suggestions for further research are put forward.