Environmental geological impact assessment and ecological restoration of abandoned mines

3.3 Soil and groundwater pollution risk assessment

At present, soil pollution survey and risk assessment of construction land are mainly used. Due to the lack of relevant laws and regulations on environmental pollution of abandoned mines, there is almost no investigation and risk assessment on environmental pollution of abandoned mines. It is difficult to find the pollution of soil or groundwater in the surrounding farmland by mines, and it can only be found through soil pollution survey or environmental pollution accidents. Therefore, it has become an urgent task to introduce relevant laws, regulations and standards. At present, the pollution status of contaminated farmland or construction land can only be investigated by referring to the evaluation standards related to agricultural land or construction land, but even if the corresponding pollutants are detected, it is difficult to block the pollution source. Because the waste minerals generally have a large area and generally higher terrain, the soil at the foot of the slope is in the upstream of the surface water and groundwater, and it is easy to cause pollutants to migrate to the soil at the foot of the slope along the current, resulting in a large area of soil pollution.

Therefore, the pollution risk assessment of the abandoned mine not only involves the abandoned mine itself, but also includes the surrounding soil and groundwater that it may affect.

4. Restoration measures for abandoned mines

4.1 Control of landslide

In the control of the landslide, we must ensure the stability of the mountain, in order to carry out the control of the landslide, if the stability of the landslide can not be guaranteed; Once a secondary landslide occurs, it will not only affect the treatment process, but also endanger the life and safety of the relevant personnel. In the actual management, we should carefully observe and field survey, and comprehensively consider the surrounding geological conditions, and use the relevant theoretical knowledge of engineering mechanics, mine geological environment, etc., to conduct a comprehensive analysis of relevant data and information; After the discussion, they will work out a new management plan. Finally, the engineering scheme is simulated by using the relevant software to determine the feasibility of the scheme. After the demonstration by experts, the feasibility of the scheme is determined.

4.2 Treatment of abandoned open-pit mines

In the relevant treatment of the abandoned mines, it is difficult to treat the open pit mine. The open-pit mine generally covers a wide area, has a large topographic relief, and has a severe damage to the geological environment, while the natural recovery time is long and the effect is poor. The amount of money needed to repair the huge project is insufficient and the gap is huge. The most economical and effective way to deal with this situation is to fill shallow mines, and then use these shallow soils as farmland and forest land; As for deeper mines, they can be used for aquaculture, but when they are built, protective fences should be built around the mines and warning signs should be set up to avoid accidents.

4.3 Mining area collapse geological control measures

In geological reclamation of landslides, the subsidence of the foundation and the condition of the soil should be fully considered, and the stress analysis should be carried out to avoid sliding and deformation during the filling of slag and pit. Cement mortar is used to fill out the cracking and collapsing position to ensure its bearing capacity and stability and prevent secondary collapse. In filling, appropriate grouting scheme should be adjusted according to the direction and structure of the tunnel, so as to prevent the holes after grouting. Of course, it is the most economical to cover the soil after the natural collapse of the collapse area, but its time span is longer.

4.4 Land reclamation and vegetation reconstruction

Through the rational development of the abandoned mine land, it can be better adapted to the needs of social development, and the local geological environment can be creatively reformed. For example, in low-lying places, the harmful minerals and slag in the mine are removed first, and then the foundation pit is levelled; The bottom of the mine is paved with mud humus suitable for the growth of fish, and it is used as a fish pond for rational use. As for agriculture and forestry, this can be achieved through reasonable sloping land and artificial filling.

In the aspect of vegetation restoration, we should focus on the research from the aspect of breeding. Because the soil of the mine is prone to salinization and lack of nutrient supplement, it is necessary to choose plants that are suitable for arid environment and soil is not fertile. In loose soil areas, by selecting plants with developed roots, the soil can be effectively fixed, which not only increases the survival rate of vegetation but also avoids soil damage. In the desert mining areas in the north, shrubs and other drought-resistant tree species dominate. It is best to test the new varieties that are easy to raise, easy to manage and easy to survive, which can greatly improve the survival rate and recovery efficiency of plants, and greatly reduce the cultivation and cultivation costs of seeds, and achieve better greening effects with the same time and labor costs.