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With the increasing depth and intensity of coal mining, there is an increasing risk to the working face due to high static load and periodic breakage of the roof. The relation between the support and the surrounding rock under static–dynamic coupling loading disturbance is an important factor affecting the stability of the working face. In this stu...
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This paper studies how the activity of hydraulic excavators found in the Rosia quarry of Jiu affects the environment. For this study we chose the Caterpillar 323D L and 323 D LN hydraulic excavators. The study took place over a period of 30 days. These days we have collected data on the noise level and the level of PM 10 particles in the quarry. Ca...
Citations
... The water content can greatly influence the energy dissipation mechanisms and crushing characteristics of rock, which has a significant impact on the safe construction of underground engineering. In addition, the rock mass is often subjected to dynamic load disturbance in underground engineering construction [1][2][3][4]. Therefore, water content and dynamic load disturbance serve a critical role in the way rock fragmentation characteristics and energy dissipation mechanism [5][6][7][8]. ...
In the process of underground engineering construction, rock mass often faces the dual influence of dynamic load disturbance and groundwater, it is therefore essential to investigate the mechanical response of the rock mass under the coupling effect of dynamic load disturbance and water content. In this paper, dynamic load impact tests were carried out on sandstone with bullet velocities of 5 m/s, 10 m/s, and 15 m/s and water content of 0, 0.3, 0.6, and 0.9, and the mechanical behavior and mechanism response of water content to sandstone were investigated. The research findings indicate that this study has made significant contributions in quantifying the along grain and trans-grain fractures of microcracks. It has explored the influence of water content and dynamic loading on the strength mechanism of sandstone. It was discovered that the dynamic loading and water content significantly affect the ratio of along grain and trans-grain fractures, thereby influencing the dynamic behavior of sandstone. The findings suggest a negative association between rock strength and water content and that its peak strength rises as the bullet velocity rises. The fracture characteristics of rock are influenced by water content and bullet velocity. The sample’s fracture degree increases with an increase in water content, its particle size distribution map is evident, and there is a positive relation between bullet velocity and fractal dimension. The energy conversion mechanism of the rock is influenced by the water content, as the bullet velocity increases, the absorbed energy density of the rock becomes higher. Furthermore, the correlation between the absorbed energy intensity and density and its fractal dimension is quantified. It is found that energy density and strength are positively correlated. The greater the fractal dimension, the higher the energy density absorbed.
... Currently, research on the coal wall stability control is focused on macroscopic aspects: (1) the controlling action of great mining height supports on coal wall stability and the effect of coal wall stability on the stability of the end face roof and supports [20][21][22][23][24][25][26]; ...
Coal wall rib-spalling is regarded as a key technical problem influencing safe and efficient mining of fully mechanized working face with great mining height (FGH) while the coal wall stability is influenced by the strength of the coal body, of which the internal joint fissures have a crucial impact on the strength of the coal body. This research attempted to explore how the coal wall stability of FGH is influenced by the occurrence of joint fissures. This paper uses physical and numerical simulations to systematically analyze the instability characteristics and displacement law of FGH. Research results show that the form and scope of the instability of coal wall rib-spalling depend on the state of the coal seam joint fissures development area, and the development state of coal seam joint fissures is related to the combination of the coal seam joints; under the condition of hard coal, the coal wall stability is better at the inclination angle of 90°, and less stable at 45° and 135°; under the condition of medium-hard coal and joint surface inclination angle of 45° and 135°, the smaller the spacing of joint surface, the larger the area of the working face rib-spalling, and the less stable the coal wall.
