Discussion on environmental geological problems caused by open pit mining and prevention measures

Over the past ten years, with the rapid development of the national economy, the development and utilization of mineral resources is also rapid development, mining everywhere, large and small mines mushroomed out. At the same time, large-scale mining activities have caused a lot of environmental geological problems. Mine resources are minerals with practical value gradually formed through the action of geological mineralization, showing some solid, liquid or gaseous storage in the crust of a useful resource. Slowly with the continuous progress and development of human society, the demand for mineral resources is gradually increasing, which leads to the development of mineral resources is also increasing, but because of the properties of mineral resources themselves belong to non-renewable resources. Therefore, unreasonable development will cause serious damage to the natural environment, on the other hand, it will also limit the speed of local social and economic development. Therefore, the environmental rectification of the mine address is imminent, not only to change the concept from the ideology, but also to carry out effective measures in combination with the actual management.

1 Environmental geological problems caused by mining

Environmental geology: The discipline that studies the interaction and influence of human technical and economic activities and geological environment. It is the discipline that takes geological environment as the research object (the influence of human activities on geology and environment, such as geological disasters and environmental pollution). The environmental geological problems caused by mining mainly include: (1) destruction of geomorphic landscape and reduction of cultivated land area. Due to open pit mining, excavation and waste slag, waste rock and tailings stacking, a lot of surface vegetation is destroyed and a lot of farmland is occupied. According to statistics, the country has occupied 586×104hm2 of land and destroyed 132.3×104hm2 of vegetation. (2) Waste rock and tailings accumulation causes environmental pollution. Dust and debris flow are easy to form in mine dump and tailings reservoir, causing environmental pollution. (3) Slope collapse and landslide in open pit mining. The mine is not mined according to the design, the slope is too steep and prone to slope collapse and landslide, resulting in casualties and equipment damage. (4) Underground mining causes ground collapse. The damage severity of slow type geological hazards such as ground collapse and ground fracture is lower than that of sliding flow hazards. The main hazards are the destruction of cultivated land and the destruction of surface buildings. It leads to the distortion of railway tracks, the sinking of highways, and endangers the safety of mining facilities and human settlements. In the plain and low-lying areas, it is easy to cause large areas of surface water and farmland flooding. Or the water seepage along the fissure of the depression led to mine flooding and other accidents. Ground cracks usually do not directly cause casualties. It mainly causes cracks in surface buildings and land cracks. Reduce the value of land use. Ground collapse and ground cracks are easy to induce mountain cracking in mountainous and hilly areas, forming disaster chains such as collapse and landslide. In arid areas, ground collapse and ground cracks lead to surface water infiltration, which reduces or even stops flow, and the groundwater level drops or the well spring dries up. Lead to the death of surface vegetation, causing or intensifying land desertification. Make the already fragile ecological geological environment worse. (5) Mining causes the groundwater level to drop and the water source to dry up. Mining activities disrupt the groundwater balance, and mining drainage forms hydraulic funnels, resulting in regional groundwater levels falling and water sources drying up. (6) Geothermal energy. With the increase of mining depth, the geothermal hazard is increasing. Many mines in China have a mining depth of less than 800m, because of the high sulfur content of mines, mining depth and large, the ground temperature is very high. Mine geothermal disaster leads to bad working environment of miners, which seriously affects the normal production of related mines. Ground temperature gradient: the value of the rise of rock and soil temperature for every 100m drop. Ground temperature rate: For every 1℃ increase, the vertical depth needs to be increased. Geothermal gradient = 1/ Geothermal rate Geothermal gradient is (3℃~5℃) /100m. The "Safety Regulations for Metal and non-metal mines" stipulates that the temperature of the excavation site shall not exceed 28 ° C, otherwise, cooling or other protective measures shall be taken. (7) Earthquake induced by mining. The vibration caused by the change of underground stress caused by mining leads to the fracture of rock mass, which has the same characteristics as earthquake. ① Tectonic mine earthquake: the earthquake induced by the stress imbalance caused by mining; (2) Collapse mine earthquake: the vibration caused by the collapse of goaf or roof; ③ Rock burst mine earthquake: high stress caused by shock pressure caused by vibration.