A 3D Simplified Model Vacuum Preloaded Drainage Board And Its Application In Fine-grained Tailings Ponds Engineering

With the development of mineral processing technology,fine-grained tailings storage has gradually become the future development trend of tailings accumulation,and its safety management problem is more severe compared to conventional tailings storage.The vacuum preloading drainage plate reinforcement technology is an effective measure for weak foundation reinforcement engineering.A few units have applied this technology to fine-grained tailings pond engineering,which has been used for hazard removal reinforcement and wet stacking to change the dry stacking form and achieved good results.However,there is a lack of engineering theoretical guidance.The 3D finite element analysis of vacuum preloading can best reflect engineering practice,but the existing 3D models have problems such as cumbersome model establishment,difficulty in the unit division,and low computational efficiency.Improving the above issues is of great significance for promoting the application of three-dimensional models of vacuum-preloaded drainage boards in foundation reinforcement engineering and fine tailings pond reinforcement engineering.This article adopts numerical simulation,theoretical analysis,and engineering verification methods to research the simplification of the three-dimensional model of vacuum preloaded drainage board and its application in fine-grained tailings pond engineering.The main contents include:improving the unit size scheme of the traditional three-dimensional model of drainage board;Explored the influence of the equivalent form of drainage board and coating area cross-section on the calculation accuracy of the square single well 3D model;Improving the cross-sectional equivalent form of traditional single well 3D models and propose a square equivalent model;Combined with the advantages of drainage Substructure method,the simplified 3D model of drainage board with surface and line instead of the board is proposed.The above research results were applied to the three-dimensional numerical calculation of the drainage board reinforcement of the fine-grained tailings pond project,and the influence of different factors on the reinforcement effect of the fine-grained tailings pond was analyzed.The main research work and achievements of this article are as follows:(1)Analyzed the sensitivity of traditional single well 3D model unit size.The results show that the error of the square single well 3D model increases with the increase in unit size,and there is a maximum value for both horizontal and vertical unit sizes.After exceeding this value,the calculation accuracy cannot meet the engineering needs.Therefore,an optimal size scheme was proposed,with a vertical unit size of 1m,an undisturbed area unit size of 125mm,and a coating area unit size of 50mm,guiding the unit division of traditional 3D models for drainage boards.(2)Explored the influence of the cross-sectional forms of the influence zone,coating zone,and drainage plate on the calculation accuracy of the single well 3D model,and found that the drainage plate,coating zone,and influence zone are equivalent to circular or rectangular sections are constructed simultaneously,with the highest calculation accuracy;Improved the equivalent form of traditional single well three-dimensional drainage plates and proposed a square equivalent model;Combining the advantages of the Substructure method,the drainage board is simplified,and the 3D models of single well with a line instead of board and surface instead of the board are proposed.(3)We have innovated the modeling method for complex group well 3D models of drainage boards,using linear elastic and elastic-plastic constitutive models for engineering case modeling verification.The results show that the array single well method and GUI interactive software parameter modeling method can effectively improve the modeling efficiency of complex group well 3D models;The accuracy and reliability of the proposed group well 3D model have been verified.The square equivalent model has high computational accuracy but low computational efficiency,and is suitable for the group well 3D model with fewer drainage plates;The calculation cost of using surface instead of a plate and using line instead of plate models is low and the calculation accuracy is high,making them suitable for group well 3D models with a large number of drainage plates.(4)A three-dimensional numerical model of a drainage board reinforcement project for fine-grained tailings is established to explore the effects of the depth,spacing,and vacuum load of the drainage board layout on the reinforcement effect of fine-grained tailings reservoirs.The results show that under the action of drainage plates combined with vacuum loads,the consolidation time of fine-grained tailings sand is extremely short,and there is no time effect of vacuum preloading drainage plates on strengthening soft clay;As the depth of drainage board placement and vacuum load increase,the reinforcement effect of fine-grained tailings storage dam increases proportionally;The influence of layout spacing on the reinforcement effect of the tailings dam is very small.The suggestions for strengthening the fine-grained tailings pond project with vacuum preloading drainage boards are as follows:the layout depth is selected as 15m-20m,and the layout spacing is selected as 1.5m-2m to achieve a maximum vacuum pumping rate of 80kPa.