Mining subsidence causes more environmental damage than earthquakes



Mining subsidence causes a series of disastrous consequences, such as flat water, crop yield, road cracks, house collapse, etc., which is not only an important reason for the reduction of cultivated land, but also one of the bottlenecks restricting mine production. As far as environmental damage is concerned, the total loss of mine subsidence in China is greater than that of earthquake every year, which must be paid great attention to. It is necessary to vigorously carry out land reclamation, protect the ecological environment, and resolutely put an end to the vicious circle of first development and then management, so as to maintain the sustainable development of mining areas.

Generally speaking, the damage to environment caused by mining subsidence in China is more serious than that caused by earthquake

The rich land and beautiful homes that farmers depend on in mining areas (especially in coal mining areas) in China are often destroyed suddenly or gradually because of large surface collapse caused by large-scale underground mining. Since underground mining activities cannot be detected on the surface, the damage is often hidden and mysterious. For example, arable land has been reduced for unknown reasons; The water channel failed intermittently; An unexplained crack in a house; The well inexplicably dried up; Flat land irreversibly flooded and so on.

Do not think that these damage is only caused by the earthquake, but due to excessive underground mining caused by geological disasters. It is hard to believe that underground mining a few hundred meters deep can be so destructive to the surface, but this is the fact that many mines exist. With reference to the great flood in the summer of 1995 in southern Liaoning Province, a town in the affected area of a coal mining subsidence became a major disaster area because of the surface subsidence, people will realize the harm of mining subsidence more deeply.

The damage to the ecological environment may be slight or there may be damage, but it can be restored in a short time through normal farming and repair. For example, in the disaster areas of Xiuyan, Liaoning Province and Zhangjiakou, Hebei Province, almost no trace of the earthquake can be seen one or two years after the earthquake. The mine subsidence area is different, decades have passed, still can see the shadow of the subsidence. Mining collapse causes many disastrous consequences, such as the destruction of cultivated land, orchards, forests, grasslands, surface water and groundwater, resulting in land wastage, desertification, salinization, and serious deterioration of mine ecological environment. Therefore, in terms of destroying the ecological environment of mining areas, the overall loss of mining geological subsidence disaster every year is no less than an earthquake or flood.

There are tens of thousands of mining enterprises in China, with a total annual mining volume of more than 2 billion tons. Among all kinds of minerals, coal accounts for the largest proportion of production. In all kinds of mines, underground mining is the most important way. According to the survey, the land collapse caused by underground mining per 10,000 tons of raw coal is between O.5-8 mu, with an average of 2-3 mu. According to the calculation of China's raw coal production, the land collapse caused by coal mining industry alone is up to 400,000 mu every year. According to incomplete statistics, the ground collapse area caused by the mining industry in China has reached 5 million to 6 million mu, of which 1.3 million mu of arable land, which is tantamount to worse for our country, which is already very scarce land resources.

The mining industry is also strong in the east and weak in the west, corresponding to the long-term existence of China's economic development. The eastern region is precisely densely covered with towns, villages and densely populated, so the disastrous consequences caused by ground collapse are more prominent. This economic pattern also determines that the eastern region is the worst disaster area for mine subsidence. Taking coal mining as an example, there are thousands of unified coal mines and local coal mines in China, accounting for about 70% in the eastern and central regions, and many towns in the eastern region have gradually developed based on coal mining industry, such as Jixi and Hegang. These towns have problems with mine subsidence. Huaibei mining area in central China, from the year of production to 2000, the total amount of farmland destroyed reached more than 100,000 mu, of which 38% of the perennial water. Due to historical reasons, many mining areas lack unified planning for above-ground cities, buildings and underground mining activities. Cities often develop freely around mines, and the surface of new and old mining areas continues to sink, resulting in continuous and serious damage to buildings and pipelines in above-ground towns. Many cities in the worst-hit areas have been relocated and re-invested in construction. Especially at present, China's coal mines adopt a technology called "fully mechanized caving and caving of top coal at one time full height", the thickness of the first mining is as high as 10-20 meters, the surface subsidence depth is also as high as 80%-90% of the mining thickness, and the land and buildings located in the subsidence area are all damaged, and the loss is more serious.

The consequences of mining subsidence damage are similar to earthquake, but its occurrence and development process is slow, and the damage degree is gradually developed from slight to severe. Compared with underground mining, there is a time lag process, that is, the underground goaf is often formed weeks, months or even years before the subsidence develops to the surface, and the scope of surface damage is many times larger than the scope of underground goaf. For example, in some mines, the diameter of the drop funnel is 1 km, and the hydrogeological situation has been damaged in an area of 7,500 hectares, which indicates that the surface far from the mine is also affected. Thus, the strange phenomena described at the beginning of this section are not easily detected in time at first, and once detected, the damage is irreversible, especially the damage to the environment cannot be overestimated. The damage does not become apparent even after production has ended. A large number of shocking facts are enough to explain the harm of mine subsidence disasters, but so far, has not caused enough attention to the relevant departments. The state invests a lot of manpower, material and financial resources in the research of earthquake, flood and fire every year, but the investment in the research of mine subsidence disaster is very little, which can not be said to be a misunderstanding.

Mining subsidence damage will continue to occur in our country

During the Ninth Five-Year Plan period, we conducted a field survey on the subsidence damage of large-scale coal mines in Northeast China and eastern Inner Mongolia, and found that all coal mines had the problem of damaging the environment due to mining, and it was very serious.

The Huotai mine and the Longfeng mine in Fushun Mining area mine coal under the urban area, affecting buildings within 160 square kilometers of the surface, and losing 7,200 mu of farmland due to subsidence. In March of this year, hundreds of houses in the Xinqiu mining area of Fuxin city sank and damaged, leading to a collective petition by residents. The subsidence of Hunchun mining area in Jilin Province even affected the opening to the outside world.

According to incomplete statistics, the 12 mining administrations in Northeast China mined 134 million tons of coal and destroyed 22,400 mu of land, an average of 1.7 mu of land per 10,000 tons. These mining authorities in the farmland under the coal reserves of 1.344 billion tons, will also destroy 228,500 mu of land, the situation is extremely serious.

It is necessary to strengthen the study of mining subsidence

It is decided by our energy policy to strengthen the research of mining subsidence science. Theoretically, the reduction and prevention of mine subsidence disasters should be carried out from both the root and the symptom. The most fundamental way is to change our energy structure, like Japan and some developed countries, to oil as the main energy, but this is not in line with our national conditions. It is estimated that in the 21st century, China's energy structure is still dominated by coal (accounting for 50%-60% of primary energy). Coal mine production is the most important factor that causes mine subsidence disaster. Therefore, on the one hand, measures should be taken to avoid or reduce subsidence disasters as much as possible (such as strip mining, filling mining, underground gasification, etc.); On the other hand, for the land that has been damaged and the land that will inevitably be destroyed in the future coal mine production, land reclamation or land restoration measures need to be taken. The purpose of reclamation is to restore the land destroyed by human activities such as mining to the desired state according to local conditions. In terms of land reclamation, many mine and mining residents in our country have created some feasible methods. But these methods must be adapted to local conditions, can not blindly imitate.

According to preliminary statistics, the reclamation area of mine land in China only accounts for 1% of the destroyed area. On the one hand, people do not know enough about the harm and severity of environmental damage in relatively remote mining areas. On the other hand, some enterprises and farmers lack the awareness of land protection and reclamation knowledge, and are unwilling to deal with or do not know how to deal with the destroyed land. There is a long way to restore the ecology in mining area, so it is urgent to research a land reclamation mode which accords with our country's conditions. Mining enterprises should be fully aware of their own responsibility in land and environmental protection, and take the initiative to reduce the extent of mining subsidence damage. It is necessary to raise the awareness of land danger and protection of the whole nation, and jointly pay attention to this easily forgotten corner - mining area.