In order to improve the working performance of drum cutter in mining mechanism, the cutting process of drum cutter under different working conditions was numerically simulated by using discrete element method (DEM). The effects of cutting thickness, rotating speed and tractor speed on cutting resistance, productivity and specific energy consumption were investigated by single-factor analysis and orthogonal testing. With cutting resistance and specific energy consumption of the drum cutter as evaluation indexes, the best working parameters of the drum cutter were obtained by matrix analysis. The results show that as cutting thickness increases, both cutting resistance and productivity increase, while specific energy consumption decreases. With rotation speed increases, cutting resistance and productivity decrease, but specific energy consumption increases. And with tractor speed increases, both cutting resistance and productivity increase, while specific energy consumption decreases. It is concluded that the optimum working parameters of drum cutter are as follows: cutting thickness of 50 mm, rotation speed of 100 r/min, and tractor speed of 0.06 m/s.

In order to clarify the influence of geometric parameters of tapered pipeline on particle flow characteristics in pneumatic conveying, numerical simulation was conducted for horizontal pipelines with 5 kinds of taper ratio and taper length by adopting CFD-DEM coupling method. Influence of geometric parameters of taper ratio and taper length on particle velocity, pressure loss and Froude number in tapered pipeline was investigated. The results show that tapered pipe can reduce particle velocity. As taper length and taper ratio increase, particle velocity increases first and then decreases. And the tapered pipe can also reduce pressure drop in pipeline. As taper ratio and taper length increase, pressure loss in pipeline increases. The higher the taper ratio, the smaller the Froude number in tapered pipe is. As taper length increases, the Froude number decreases more slowly.

In order to improve accuracy in selection of blasting parameters for open-pit mines, a mathematical model was established for determining bench blasting parameters in open-pit mines based on production cost of stope, and the blasting parameters were then optimized by using an improved sparrow search algorithm. The results show that the improved sparrow search algorithm can effectively improve the effect of bench blasting in open-pit mine, but also improves the construction efficiency. With Yulong Mining Industry Company in Xizang as an example, the blasting parameters after optimization are as follows: hole spacing of 6.2 m, row spacing of 4.9 m, and unit explosive consumption of 0.32 kg/t. With these blasting parameters, the stope production cost goes down by 7.5% to 11.06 yuan/t, and the bulk rate can be controlled within 10%.

Tailings slurry with different mass concentration and cement to sand ratio was prepared with a certain kind of tailings, which was taken to study for its rheological properties by adopting Brookfield R/S+ rheometer. It is found that at room temperature, the mass concentration of paste slurry has a stronger effect on the rheological properties of paste than the cement to sand ratio of slurry. When the concentration is lower than 64%, the cement to sand ratio has little effect on the rheological properties. As the slurry concentration increases, its yield stress and viscosity present exponential growth, which increase at the fastest rate when the slurry concentration is 68%. As the cement to sand ratio of slurry increases, its yield stress and viscosity increase approximately linearly. The influences of slurry concentration, cement to sand ratio, gradation and temperature on rheological properties of slurry were studied by experiments, and then the rheological parameters were predicted by using XGBoost based on the obtained experimental data. It is shown that the relative errors and variances between the predicted results and the actual values are within a reasonable range, which has proven the accuracy of the prediction model.

In order to study the influences of diameter, length and installation position of tapered pipeline on the ratio of full pipe flow in gravity-fed pipeline transport of backfill slurry, a small-scale loop pipe test was carried out by using independently developed tapered pipeline. The hydraulic slope and ratio of full pipe flow were tested for gravity-fed transport of slurry via tapered pipeline, and Pearson correlation analysis was also conducted to explore the influence of various factors on the ratio of full pipe flow. The results show that the ratio of full pipe flow significantly presents a negative correlation to the diameter of tapered pipeline, which increases exponentially with the reduction in the diameter of tapered pipeline. The ratio of full pipe flow increases sharply for a pipe with diameter less than 50 mm. Furthermore, the ratio of full pipe flow presents a positive correlation to the length of tapered pipeline, which increases linearly with the increased length of tapered pipeline. However, the installation position of tapered pipeline in horizontal section of pipe has little effect on the ratio of full pipe flow, which can be negligible.

A nine-hole cut blasting method was adopted in a test of Tonglushan stope. In combination with on-site actual situation, cutting blasting with medium hole length was studied by using theories of compensated space and fissure zone. The first circle of blasthole layout for cutting blasting was optimized, and four types of models for first circle of blasthole layout were then established by LS-DYNA software. After simulation calculation, the rock blasting effect was simulated by using RHT constitutive model. The results show that the more number of empty blastholes (that is, the larger the compensation space), the better the blasting effect in cutting area. The uniformity of empty blasthole position (that is the uniformity of compensative space) will also influence blasting effect. It is shown that both the section and height of the trench after blasting in the field test meet the design requirement, which proves that the first circle blasthole layout for cutting blasting is reasonable.

In order to improve the construction efficiency in benching excavation for tunnels in water-rich ground, a main tunnel of Xiaomaliu tailings pond was taken as an example in the study. A three-dimensional digital model was constructed according to the actual situation of the project, and the fluid-structure interaction analysis was conducted by simulating benching excavation with three types of bench length. Then, the effect of benching construction with different bench length was analyzed in terms of seepage field, displacement field, stress field and plastic zone distribution of tunnel after construction, and a comprehensive evaluation was presented by using CRITIC algorithm. Results show that excavation with micro bench can bring the best construction effect for the tunnel in water-rich ground, followed by excavation with long bench, and excavation with short bench presents poor effect.

Based on a deep foundation pit project for Pazhou Station of Guangzhou Metro, numerical simulation was conducted with FLAC^3D finite element software for foundation pit excavation. Shear test schemes with different stress paths were prepared based on the stress state of the surrounding soil of the foundation pit, and the influence of different stress path on the mechanical properties of the soil was also studied. The results indicate that stress path can bring significant impact to the stress-strain relationship, pore pressure, and shear strength indicators of the soil. The shear strength of the soil in consideration of the unloading stress path of the foundation pit is lower than the shear strength obtained from conventional tests.

A thick layer of accumulated debris after landslide is distributed on the slope in the middle of site. And the debris will lose stability due to excavation of slope, resulting in an unstable slope. The physical and mechanical parameters of those accumulated debris after landslide were determined by performing indoor tests and inverse analysis. According to the site environmental conditions and the distribution characteristics of rock and soil layers, the overall and local stability and deformation characteristics of slope under different working conditions were analyzed by simulation with software. Also, the stability and development trend of slope in the middle of site were comprehensively evaluated. Based on the stability analysis and evaluation results, a corresponding prevention and control suggestion is put forward.

Aiming at the problem of high fragmentation by blasting in Baiyinnuoer Lead-Zinc Mine, the unit consumption of explosive and delay intervals between rows in a fan-shaped pattern of blastholes with medium depth were analyzed by numerical simulation with ANSYS/LS-DYNA. According to Von Mises yield criterion, the effective stress, peak value of vibration velocity, and rock damage area of the recorded unit were analyzed. The results show that with unit consumption of explosive at 1.16 kg/m³ and delay interval of 100 ms between rows, the effective stress, peak value of vibration velocity and rock damage area of the recorded unit all can meet the design requirements. The optimized parameters of unit consumption of explosive and delay interval were then applied in on-site blasting with blastholes in a staggered array. The muck pile after blasting was analyzed by using Split-Desktop 4.0, and it is found that the rock fragmentation by blasting is 4.34%, indicating that high fragmentation by blasting can be effectively controlled.