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The study of the rheological characteristics of cement paste backfill(CPB) is of great significance for the rational arrangement of filling pipelines and efficient filling operations in mines. Purpose: The purpose of this study is to combine the complex and multifactorial paste rheological parameter measurement tests with advanced machine learning regression prediction models to achieve accurate predictions of paste rheological parameters. Method:The research method involves using 128 sets of paste rheological characteristic test data under different material mix conditions as the model dataset. The Extreme Gradient Boosting Regression Tree(XGBoost) model was selected,and Bayesian Optimization(BO)was used for hyperparameter tuning to establish a multi-objective parameter regression prediction model. Result; The results show that the BO-XGBoost model, optimized by the Bayesian algorithm, significantly improves performance compared to the XGBoost model, with the coefficient of determination R2 increasing by 6 %. The relative error between the actual and predicted values of the BO-XGBoost model is maintained at the 0. 02 level in the yield stress dataset and at the 0. 1 level in the viscosity dataset. Conclusion: The study concludes that the BO-XGBoost model can efficiently and accurately predict the rheological parameters of paste, using an innovative multi-objective regression model, providing a reference for the design of mine filling operations with practical engineering application significance. [ABSTRACT FROM AUTHOR]

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 view of the poor stability of roadway surrounding rock after deep mining in Datun Tin Mine, in order to ensure safe and efficient mining, in this paper, the effects of stope buried depth, hexagonal room span-height ratio and lateral pressure coefficient on surrounding rock stability are analyzed by numerical simulation. The research shows that; 1)Each influencing factor has effect on the displacement and stress of the surrounding rock, and there is a significant interaction between the influencing factors; 2)The influence of buried depth and lateral pressure coefficient on the displacement of surrounding rock is more significant than that of span-height raio. 3) When the width of hexagonal room is greater than the height, the stress of two sides increases linearly, and the influence of span-depth raio on surrounding rock stress Is greater than the buried depth and lateral pressure coefficient. Accordingly, when the depth of the stope and the lateral pressure coeficient are determined, changing the size of the hexagonal chamber can improve the stability of the surrounding rock. The research resutts have certain reference value for mining design. [ABSTRACT FROM AUTHOR]

In order to analyze the rheological properties and viscosity effects of gobi sand-rod-mill tailings filling slurry, the optimal pipeline transport parameters were obtained. Particle size grading analysis was carried out for gobi sand and rod-mill tailings with different particle sizes in the Jinchuan mining area, and the optimal mixing ratio of gobi sand and rod-mill tailings was determined by an experimental method. A high concentration of slurry was prepared for gobi sand and rod-mill tailings with different particle sizes. Rheological parameters were obtained by rheological experiments, and the influence of the response surface method on the rheological characteristics of slurry was analyzed. The results show that the gobi sand-rod-mill tailings filling slurry meets the industrial requirements of the filling slurry, and the rheological model of the slurry conforms to the Herschel-Bulkey model. Mass concentration, cement content, and ratio all significantly influence slurry viscosity, and the influence of mass concentration is the most significant. Based on multivariate analysis, a nonlinear model of viscosity was established with high accuracy, and the correlation coefficient reached 0. 967. Combined with the backfill strength experiment results, the optimal filling slurry concentration was determined to be 82% - 83%, which provided theoretical support for the follow-up pipeline design of filling slurry. [ABSTRACT FROM AUTHOR]

To study the problem of artesian transportation of long distance paste filling pipeline in ultra deep well, according to the actual filling pipeline in a mine in Yunnan Province, a three dimensional numerical model was established by gambit, and the numerical simulation was carried out by ANSYS FLUENT software. Taking horizontal pipeline and elbow as examples, the relationships between the change rule of pipeline pressure and velocity and the loss of pipeline resistance under different proportion, concentration and flow rate were studied. Through the pressure monitoring system of the underground industrial ring network, the monitoring value of the actual underground pipeline pressure in the mine was statistically analyzed. The results of the actual underground monitoring were close to the three dimensional numerical simulation results by using ANSYS FLUENT software, which shows that it is feasible to simulate the long distance paste filling pipeline transportation in the ultra deep well by using ANSYS FLUENT software, and the research results can provide technical support for paste filling pipeline transportation to realize the ultra deep well, long distance and large fold line for the mine. [ABSTRACT FROM AUTHOR]