The disturbance such as deep engineering blasting and excavation is prone to induce rock burst. To study the conditions and characteristics of rock burst induced by cyclic disturbance in deep tunnels under different stress conditions, granite specimens with semi-circular arches penetrating the tunnel were used to conduct true triaxial disturbance rockburst tests. The occurrence conditions, characteristics of rock burst in deep engineering, the evolution process of acoustic emission, and the energy evolution characteristics inside the rock were analyzed. The test results are concluded as follows. Firstly, when the disturbance amplitude exceeds 10 MPa, rock burst will occur in the specimen. For every additional 10 MPa of disturbance amplitude, the time from the start of disturbance loading to the occurrence of rock burst in the specimen is reduced by about 30%. The greater the disturbance amplitude, the more severe the damage to the specimen, and the more shear cracks on the rock surface. Secondly, cyclic disturbance significantly promotes the generation and extension of shear cracks. The disturbance not only increases the number of shear cracks but also accelerates the speed of crack propagation. Thirdly, the accumulated elastic strain energy inside the specimen increases with the increase of disturbance amplitude. When the specimen fails, these accumulated energies are rapidly released, leading to more severe failure of the specimen.

The Shaiqihe Phosphate Mine in Yichang, Hubei has entered deep mining, and rock burst disasters are frequent in the excavation working face. Water injection was used to soften the surrounding rocks in the working face to prevent rock burst, and reasonable water injection parameters affected the prevention and control effectiveness of rock burst. The uniaxial compression tests of phosphorite under different water-containing states were carried out. The relationship between water content and rock burst tendency of phosphorite was analyzed based on the rock strength brittleness coefficient. Numerical simulation was used to explore the distribution characteristics of water content in the surrounding rocks of the working face during water injection, and the optimal water injection parameters for the excavation working face of the Shaiqihe Phosphate Mine were determined. The results show that when the water content of the phosphorite reaches 0.424%, the phosphate rock layer is in a moderate rock burst tendency, and the change in strength brittleness coefficient with water content is no longer significant after water injection. When the water injection time is 1 hour and the drilling depth is 10 meters, the growth rate of effective wetting distance is the highest, and the water injection effect is the best. The research results have certain guiding significance for improving the water injection process parameters of phosphate rock and reducing the risk of phosphate rock burst.

Reasonable nozzle structural parameters are crucial for the desorption performance of walking tracks of deep-sea mining vehicles. Taking the adherent substrate between the walking tracks of the mining vehicles as the research background, numerical simulation of the walking track desorption effect was carried out using Ansys software for the structural parameters and layout design of the nozzles, and the optimal parameters of the nozzles for the desorption of the walking tracks were determined from the calculations and analysis of the velocity of jet impacting on the track teeth and the distribution of the dynamic pressure on the surface of the track plate. The results show that the cavitation effect of the nozzle is very weak when the submerged depth is 5 000 meters, and the design of the nozzle for deep-sea submerged jets may not consider the cavitation effect. Increasing the diameter of the nozzle can significantly increase the length of the core area of the jet. For diameter straight nozzles which are 10 mm, 20 mm and 30 mm, the jet velocity starts to decay rapidly around at 0.09 m, 0.2 m and 0.31 m respectively. The optimal desorption effect of the walking track is achieved when 7 straight nozzles with a diameter of 30 mm and a 90° spray angle are used. Numerical simulation results can provide a strong theoretical basis for the study of the desorption performance of seafloor traveling tracks of deep-sea mining vehicles.

Aiming at the problems of difficult mining, low mechanization and limited resource utilization of gently inclined thin ore body in a fluorite mine in Guizhou, combined with the occurrence characteristics and mining technical conditions of the ore body, it was recommended to adopt mechanized upward horizontal layered filling mining method. According to the structural parameters of the stope and the extraction technology, the stability of the stope was analyzed using Mathews stability graph method and numerical simulation software. The results show that the stope span, the exposed area of the hanging wall and the roof are less than the theoretical limit. The roof settlement of stope is between 0.96 − 4.32 mm. The maximum floor heave value of the bottom is 3.5 mm. The maximum compressive stress of the mining room is 9.8 MPa. The tensile stress value is far less than the tensile strength of the filling body 0.44 MPa. The plastic zone does not form penetration and the stope is always stable. After field application, the production capacity of the ore block is 150 t/d, the mining-cut ratio is 12.96 m/kt, the loss rate is 10%, and the dilution rate is 8%, which has achieved good economic benefits.

Aiming at the problems of low production capacity, many mining and cutting projects, high cost, poor working environment, many hidden dangers and high risks in the 2 230 m and 2 170 m middle stopes of Pakrut Gold Mine, based on the rock physical and mechanical properties tests and RMR (rock mass geomechanics classification index), the reasonable stope size was obtained by using Mathews stability diagram method. The stope was changed from the original four 12 m low segments to two 21 m high segments. Taking the mining width as the variable, the stability of the stope under the condition of mining one block separated by three blocks was simulated by FLAC3D, and the optimal stope width was determined to be 11−12 m. The industrial test indicated that after optimizing the structural parameters of stope, the stope production capacity was increased by 20%, the loss rate was reduced by 4.67 percentage points, the dilution rate was reduced by 3.25 percentage points, and the kiloton mining ratio was reduced by 36%, and the stope did not collapse, the desired results had be reached. The research shows that based on the rock physical and mechanical properties tests and RMR rock classification, the method of optimizing stope structure parameters by Mathews stability diagram method and FLAC3D numerical simulation and then verifying the parameters by industrial test has a high application value.

In order to improve the utilization rate of point pillar resources in Xianglushan tungsten mine and control the impact of point pillar mining of shallow buried depth, analysis was conducted on the technical conditions for mining the underground residual pillars. Combined with the current common point pillar mining schemes and selection principles to determine two filling and mining schemes suitable for point pillar in Xianglushan tungsten mine of shallow buried depth. Furthermore, numerical simulations were conducted to calculate and analyze the displacement and plastic failure of each scheme at burial depths of 50 m, 100 m, 150 m, and 200 m. At the same time, to reduce the impact of underground blasting vibration on ancient buildings, the relationship between the maximum allowable single section dosage and the distance for underground blasting was calculated. Finally, industrial tests were conducted in the 610 mining area of Xianglushan Tungsten Mine to verify the mining scheme. The research results show that during the implementation of the mining scheme, there is no significant change in ground pressure and displacement monitoring data, and the stability of the goaf is good. The total amount of extracted ore is about 21 000 t, and the residual ore recovery rate within the height of the goaf in the mining area reaches about 38.33%, achieving good economic benefits.

The stope structure parameters of the mine are important factors to ensuring safe and efficient mining. With the background of the No. I ore body of a copper mine in Yunnan Province, four different point pillar sizes were proposed by engineering analogy method. And the displacement and stress of the stope under different point pillar sizes were analyzed by FLAC3D numerical simulation software. The results show that when the excavation is to the fourth layer, the 4 m×6 m and 5 m×5 m point pillar size schemes can withstand the maximum tensile stress beyond the mining site, and the two schemes can be excluded. The tensile stress of mining sites with 5 m×6 m and 6 m×6 m point pillar size schemes has not reached the limit state, but the optimization effect of rectangular point pillar is obviously better than that of square point pillar. Finally, the reasonable size of point pillar has been determined to be 5 m×6 m, which can provide a reference for mine stope test.

In order to explore the optimization of the mining effect of the gently inclined medium-thick orebody and the migration law of ore and waste rock, the gently inclined medium-thick orebody in the middle section of－400 m to－360 m in Caogou Mine was taken as the research background. Physical tests of three different mining sequences were designed to study the influence of mining sequence on the mining effect of orebody. The discrete element software PFC2D was used to study the migration law of ore and waste rock. The results are concluded as follows. Firstly, the ore recovery rate of the mining sequence III is 45.56%, the ore dilution rate is 19.29%, and the difference of recovery and dilution is 26.27%. Compared with the difference of recovery and dilution of the mining sequence I and the mining sequence II, the difference of recovery and dilution of stoping sequence III increased by 1.95 percentage points and 4.01 percentage points respectively. Therefore, the mining sequence III is the optimal mining scheme, that is, the upper caving orebodies of the No.3 and No.2 outlets being alternately mined for three cycles, then the upper caving orebody of the No.1 outlet will be continuously mined; and after the No.1 outlet being mined, the upper caving orebody of the No.2 and No.3 outlets will be alternately mined. Secondly, in the early stage of ore drawing, the displacement vector of ore and waste rock particles above and around the ore drawing port tends to the center of the ore drawing port axis. In the later stage of ore drawing, the displacement vector of ore and waste rock particles above the ore drawing port gradually tilts to the left. Thirdly, before the start of ore drawing and after the end of ore drawing, the contact force chain of ore and waste rock particles is in equilibrium. In the process of ore drawing, the contact force chain of ore and waste rock particles is in an unbalanced state.

The shape of the ore draw-out body is the basis for determining the stope structural parameters of the non-pillar sublevel caving method, and the ore moisture content and the fine particle content are the two important factors affecting the shape of the ore drawing body. Taking the ore under the overlying rock of an iron ore caving stope as the research object, the similar physical experiment and numerical simulation of ore drawing were carried out under the conditions of ore moisture content of 0−8% and fine particle content of 5%−25%. The values of λ₁and λ₂ of the vertical and horizontal axis ratios were used as indicators to evaluate the shape of the ore drawing body, and the shape characteristics of the ore drawing body under the synergistic effect of moisture content and fine particle content were explored. The results show that the values of λ₁ and λ₂ of drawing body of physical ore drawing test are consistent with those of the numerical simulation. With the decrease of moisture content or fine particle content, the values of λ₁ and λ₂ of the drawing body decrease, and the shape of the drawing body is closer to the shape of pour water drop. On the contrary, the closer the shape of the drawing body is to the ellipsoid shape. When the moisture content of the ore is 0 and the fine particle content is 5%, the shape of the drawing body is the best, and the ore drawing effect is the best. When the moisture content of the ore is 8% and the fine particle content is 15%−25%, the ore drawing is blocked and the ore drawing effect is the worst. When the moisture content is 2% and the fine particle content changes in the range of 5%−25%, or the fine particle content is 10% and the moisture content changes in the range of 0−8%, the change of the values of λ₁ and λ₂ of the drawing body is the smallest, and the shape of the drawing body is the least affected by the synergistic effect of moisture content and fine particles. The research results provide a reference for the optimization of stope structure parameters of the non-pillar sublevel caving method.

A lead-zinc mine adopts the sublevel rock-cutting stage room method to mine a sharply inclined medium-thickness ore body. On the basis of ensuring the stope stability, in order to further improve the benefits of mining, the Mathews stability diagram method was used to analyze the stope stability of the No.I ore body of the mine as the research object. By calculating the stability coefficient and hydraulic radius, the limit span of roof surrounding rock and side wall surrounding rock is 55.79 m and 44 m respectively, which shows that the current span of the mine of 50 m is reasonable. Combined with the calculation results, 9 schemes with different stage heights and roof thicknesses were formulated, and the numerical simulation studies on the stope stability under 9 schemes were carried out using FLAC3D to compare and analyze the maximum principal stresses, the minimum principal stresses, roof displacements, and plastic zone maps of the different schemes. Through the analysis of the simulation results, it is found that the optimization of the roof thickness from 8 m to 7 m and the stage height of 40 m are reasonable parameter combination, which can not only ensure the stope stability, but also improve the profitability of mining.