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Purpose:Taking the tailings discharged from a tin ore beneficiation plant in Yunnan as the object, this study analyzes the influencing factors of tailings slurry pipeline transportation mode and sand transportation efficiency through experimental research and numerical simulation. Method: The distribution pattern of tailings gradation was measured through water screen test, and the rheological characteristics of slurry were measured through slurry rheological test. Combined with ANSYS-FLUENT, the slurry pipeline transportation model was simulated and calculated. Conclusion: By comparing and analyzing the shortcomings criteria of Wasp et al.,a new criterion for pipeline transportation mode based on particle size distribution was proposed. The sand transportation efficiency was calculated by combining the distribution model and rheological parameters. The absolute error between the results and the measured values was within 5%,indicating that the new criterion is reasonable. At the same time, a new model for calculating sand transportation efficiency was constructed. Significance: The research provides a new criterion for the pipeline transportation mode of tailings slurry, which can provide a certain reference value for the application of similar situations in mine tailings slurry pipeline transportation. [ABSTRACT FROM AUTHOR]

The roof of a large-span broken rock mass is supported by prestressed anchorage, which can maintain the stability of the roadway roof to the greatest extent. Therefore, it is of great significance to study the supporting mechanism and supporting effect of prestressed anchorage on the roof of large-span broken rock mass for ensuring the long-term stability of large-span underground engineering and open-pit large-section tunnel engineering under broken rock mass. The strength change of anchorage body after anchorage is analyzed and the pre-stressed anchorage support mechanism of the roof of large-span broken rock mass is analyzed. Taking the support problem of large-span roadway in grade IV broken rock mass of Jinchanghe Polymetallic Mine as the engineering background, a numerical model is established for its support mode. The layout of structural unit Cable in FLAC3D software, the key part of numerical model establishment's analyzed. A new three-stage layout method is designed. The bolt and anchor cable are divided into pre-tightening section, free section, and anchorage section at FLAC3D software level, and their specified parameters are given for numerical calculation. Three groups of numerical simulation schemes with different support methods are established to prove the effect of prestressed anchorage support. The results show that the tensile stress of the roof in the support area is less than the tensile strength of the broken rock mass roof. Compared with the ordinary non-prestressed support design scheme, the plastic zone volume decreases by 61. 95%, and the vertical settlement of the roof in the Z direction decreases by 83. 90 %. The surrounding rock in the prestressed anchorage range is effectively controlled, and the safety of the stope roof is guaranteed. [ABSTRACT FROM AUTHOR]

In this paper,the stability of the roof-cutting strip-shaped mine column at the top of the Stage open-stope backfilling method of the Jinchanghe ZnV3 orebody is taken as the research object. By analyzing the distribution law of the stress state of the stope at different stages, combined with the current situation of the anchoring support of the broken surrounding rock of the roof, in order to improve the stability of the strip-shaped mine column, the method of combining theoretical analysis and numerical simulation is used for research and analysis. The research results show that the optimization scheme of alternately arranging 4 m wide drilling chamber and 3 m wide strip-shaped mine column on both sides of the roof-cutting contact channel can effectively share the influence of stress concentration on the strip-shaped mine column and greatly improve the stability of the strip-shaped mine column. The optimization scheme changes the roof support area and further improves the stability of the roof after the goaf. According to the research results, industrial experiments were carried out to verify the feasibility of the optimization scheme, which is of great significance to safety production and can be applied in mines. The optimization of the roof cutting project further improves the stability of the roof under the condition of improving the stability of the strip-shaped mine column, which can provide a reference for similar mines. [ABSTRACT FROM AUTHOR]

The deterioration of cable joints will lead to the increase of heat loss,and then lead to the rise of surface temperature of the joints.At the same time,the surface temperature is affected by many factors such as operating load,environmental temperature.In general,the relationship between deterioration degree and temperature data shows a non-linear distribution.For this reason,a prediction method based on improved sparrow search algorithm(ISSA) optimization for kernel extreme learning machine(KELM) is proposed to predict the insulation deterioration degree of cable joints.Firstly,based on the experimental validation of the multi-physical coupling model of cable joints,the surface temperature distribution data of cable joints at different deterioration levels,loads and ambient temperatures are obtained for building the training set,validation set and test set.Secondly,the sparrow search algorithm is optimized based on the idea of flight behavior in the bird swarm algorithm(BSA),which ensures global convergence without losing population diversity and effectively jumps out of local optimum.Then,ISSA algorithm is used to optimize the penalty coefficient C and the kernel function σ of KELM and the prediction model of insulation deterioration state is obtained.Research results show that the predictive effect of ISSA-KELM is much better than that of other models.