In order to reduce the adverse effect of the blasting vibration velocity to residents in the urban subway blasting excavation construction, and made it meet the requirements of design, based on the stress concentration effect of empty hole, carried out the research of middle empty hole in parallel hole cut blasting. Adopted the technology of middle empty hole in parallel hole cut blasting, by measuring the blasting vibration velocity, the utilization rate of borehole, the half eye tracking rate, and so on, the results showed that the blasting vibration velocity of cut blasting was 0.69cm/s, the blasting vibration of expansion slot blasting was 1.27cm/s, the borehole utilization was 90%, and the half eye tracking rate of periphery holes was 90%. The test results showed that this technology could effectively reduce the blasting vibration under the residential areas in blasting excavation, the effective experiences could be used in the similar projects.
The vertical earth pressure on the top of ditch-buried culverts was analyzed theoretically under the condition of trapezoidal ditch and square culverts. A calculation model to evaluate the earth pressure on the top of the culverts based on Duncan earth model was established. The study results show that the height of plane of equal settlement decreases and turns to a constant gradually as the depth of soil overlying culverts increases. The primary influencing factors of earth pressure are the ditch width and the ratio of height to width of the culverts and the foundation. Each of them can make the coefficient of earth pressure increase or decrease more than 30%. When the width of the culverts become wider, ditch buried culverts turn to projecting buried culverts gradually, and the uniform calculation theory of earth pressure on the top of ditch-buried culverts and positive buried culverts is formed.
This study analyzes the ability of coal mine underground reservoirs to protect groundwater resources. As the demand for coal mining continues to increase, the potential impact on groundwater resources around mines has become a growing problem. Underground water reservoirs, also known as coal mine underground reservoirs, have been constructed as a solution to protect water wastage in mining operations. However, there is a lack of awareness related to the ability of underground water reservoirs in mines to protect groundwater resources. In this study, we used FLAC3D software to analyze the formation process, water storage volume, and central storage location of the underground water reservoir in Zhangshuanglou Coal Mine. The results show that the damaged volume is 3.39 × 106 m3, and the groundwater resources that can be protected by coal mine underground reservoirs in the study area amount to 1.98 × 105 m3. We found that the storage capacity of underground reservoirs is more significantly affected by the extent of mining, which can be expressed as y = 49,056.44 + 255.75x + 1.46x2 (R2 = 0.995) (x ≠ 0). Additionally, the water storage location obtained through simulation can provide a reference for the construction of underground reservoir regulation and water storage projects. The results of the water quality analysis indicate that the concentrations of SO42− decreased by 42% with the closure of the mining area, and the pH also gradually converged to neutral. This highlights the significant role of underground water reservoirs in coal mines in promoting green production and protecting water resources and the environment.
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