In order to explore the evolution mechanism of water and mud inrush, based on the fluid-solid coupling similarity theory and a large number of matching tests, fault similar materials with mountain sand, gravel, and red clay as raw materials and surrounding similar rock materials with mountain sand, red clay, cement, and water as raw materials are developed. Similar materials’ physical and mechanical properties and hydraulic properties with different ratios are tested and analyzed. The results show that the red clay content influences the mechanical properties of similar materials and their hydraulic properties, and the gravel substrate mainly influences the fault permeability coefficient. Similar material can be adjusted within a certain range of mechanical parameters. The material is simple and suitable for developing similar materials for different low and medium strength rock masses. Finally, a similar material was used in a model test of the tunnel fault fracture zone to reveal the mechanism of water and mud bursts in the tunnel. The study results can be used as a reference for the development of similar materials for tunnel fracture zone surrounding rocks.
In order to analyze the stability of the stope under continuous mining with the room–pillar method for a kind of orebody with a long inclination, but not deep mining, this paper takes the room–pillar method for the continuous mining of a long-inclination orebody in the Mengnuo Lead–Zinc Mine, Yunnan Province as the research background. On the basis of the analysis of the stope mechanical model of a long, inclined, thin orebody with room-and-pillar mining, based on numerical simulation, the nature of the change in stress, displacement and the plasticity zone of the roof and pillar during continuous mining along the inclination are systematically analyzed. The results show that as the mining depth increases, the roof subsidence of the stope in the middle of the current operation increases. With the continuous mining of the lower middle section, the roof displacement of the stope will continue to increase with the subsequent mining of the middle section until the end of all stope operations, and the roof displacement of the stope has an obvious cumulative effect. The stress on the roofs and pillars increases with the gradual downward movement of the mining in each level, and the distribution of the plastic zone also expands. It shows that the stope structural parameters that are set according to shallow mining cannot fully meet the requirements of stability and safety in mining a deeper orebody. Therefore, for the mining of a non-deep orebody with a greater tendency to extend, the structural parameters of a shallow stope should not simply be used in the mining of a deeper orebody, but the pillar size should be appropriately increased or the spacing between the room and pillar should be reduced to ensure the stability and safety of the continuous stope.
In order to study the evolution process, damage characteristics, and occurrence mechanism of water and mud inrush disaster in deep tunnel fault zone with infiltration instability under complex conditions, a set of the three-dimensional physical model test systems of water and mud inrush flow-solid coupling in tunnel fault zones is developed. The system mainly comprises a rigid test frame, ground stress loading system, hydraulic loading system, multiple information monitoring and acquisition system, and mud and water protrusion recovery system. The system’s main features are that it can meet the model’s simulation of the ground stress field, water pressure, and other complex environments subjected to ground stress, and water pressure gradients can be controlled. The system is characterized by high rigidity, high-pressure strength, visualization, good sealing, and expandability. Taking the water fault zone of a well in the Dazhu Mountain Tunnel of the Darui Railway as the research object, the new fault zone and surrounding rock similar materials applicable to the flow-solid coupling model test are designed using the self-developed flow-solid coupling similar materials. The system is used for model tests to reveal the spatial and temporal changes of the surrounding rock stress field and seepage field during the tunnel excavation process. The test results show that the system is stable and reliable, and the research method and results are of guiding significance to the research of the same type of underground engineering.
In order to study the deformation evolution law of fault activation caused by deep mining in Shizishan Copper Mine, China, a monitoring system for fault activation slip is designed and implemented on the basis of the field investigation of footwall fault activation of the main orebody in the mining area. The displacement and stress of the fault are monitored by the multipoint displacement meter, bolt stress meter, and borehole stress meter. According to the measured results, the activation deformation laws of fault F2, fault F3, and fault F4 during deep continuous mining are analyzed in detail. The results show that, when the influence range of underground mining spreads to the fault, the increase in the additional tensile stress on the fault plane will reduce the shear strength of the fault and increase the slip of the fault. When the shear stress exceeds the shear strength of the fault plane, the shear failure of the fault plane occurs, the rock mass on both sides of the fault loses stability, and the fault becomes active; when the orebody in the deep sublevel 14 and sublevel 15 were continuously stoped, the development of the mining influence area to fault F2 leads to fault F2’s activation. When stoping the orebody in sublevel 16, fault F3 also activates. With the continuous downward mining of the deep part, the slip amount increases continuously. The fault activation sequence is from fault F2 to fault F3, and then to fault F4.
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