There are many geological environmental problems in mines in Shandong Province, the main types of which are geological environmental pollution and geological disasters.

I. Water and soil pollution

(A) Cascade pollution of groundwater

1. Present situation and harm of cross-layer pollution

After long-term exploitation of coal resources in Zibo, especially large-scale exploitation in the 20th century, Zibo coalfield has entered an aging period, and mines all over the country have been closed one after another. At present, 6 mines are closed, with a total of 18 wellhead. According to the designed service life, all coal mines in Zibo will be closed and shut down in the next 5 ~ 10 years. Coal mine pit closure and pit drainage have changed the original state of groundwater system, which has a great impact on groundwater hydrodynamic field and hydrochemical field, resulting in the deterioration of groundwater quality, and adversely affecting the life of local residents and industrial and agricultural production.

Cascade pollution of groundwater in Zibo mining area was formed as early as the early 1990s. According to "Investigation and Prevention Measures of Water Pollution in Zibo Mining Area" submitted by/KLOC-0 in February, 1990, Ordovician limestone water in Longquan 428 well is polluted by groundwater in upper coal measures, and the content of each component has obviously changed compared with Ordovician limestone water in other areas. At the end of 1990s, with the gradual depletion of coal resources, the number of state-owned closed pit mines has also increased, among which Zichuan closed pit mines have the largest number. There are 7 state-owned coal mines in this area, with independent production wells 13. By the end of 1996, 7 wells have been scrapped, and other wells are aging mines, which will be stopped mining and scrapped one after another. At present, the mining scope of the seven independent wellheads that have stopped mining starts from Nie Village in Luocun Town in the north, reaches Shuanggou Line in Shuanggou Town in the south, reaches Wangmushan Fault in the west and reaches 10 coal weathering zone in the east, covering an area of about 57km2. After some mines stopped draining water, the groundwater level rose sharply. For example, when the north inclined shaft of the former Zhaili Coal Mine1996 stopped pumping in early February, the mine water level rose sharply from -24m, and has now risen to about +24m. The mine water level rose sharply, which polluted the Ordovician limestone water under the coal measures strata and the sandstone fissure water in the upper part of the mining area to varying degrees. Among them, the Ordovician limestone water pollution in Hongshan coal mine from large suspension bridge to small suspension bridge is the most serious. The average content of SO2-4 in groundwater is 1265.4mg/L, exceeding the standard by 5.06 times, and the average content of total hardness is 15 17mg/L, exceeding the standard by 3.37 times. Its content is not only much higher than that of Ordovician limestone water in peripheral areas, but also has obvious changes compared with Ordovician limestone water quality when some wells in the mining area are closed. In July, the water quality analysis results of holes 133 and 1993 showed that the so42- content of Ordovician limestone water reached 1320.82mg/L, and the total hardness was1664.0 mg/L. Obviously, mine water (including coal measures)

2. Pollution channels

Mine water pollution karst water belongs to cascade pollution, in which there must be pollution channels. There may be three communication channels between mine water and karst water in Hongshan coal mine area: one is fault structure; The second is tunnel drilling; The third is the water supply well. According to preliminary investigation, although Hongshan mining area is surrounded by fault structures, there are few small-scale faults in the mining area, and some faults fail to communicate their hydraulic relationship. During the mining process, grouting effectively blocked the faults that threatened mining, and no major water inrush accident occurred during the mining process. Hongshan coal mine does have water supply holes for tunnels. However, with the construction of surface water supply boreholes, from 1979 to 1982, the underground boreholes were effectively blocked for five times, reducing the tunnel water inflow17308.8m3/d. Blocking various water-filled sources is a consistent practice in mines, with the purpose of reducing drainage costs and ensuring safe production. Therefore, the main way to communicate mine water and karst water is water supply well. As mentioned above, most of the water supply wells for exploiting karst water in this area have to pass through coal measures, while the water supply wells and some agricultural irrigation wells built in the early stage have no water stop measures at all. Some water supply wells have poor water quality and poor water sealing effect. In addition, due to the stratum deformation in the mined-out area of coal mine, the water-stop sleeves of some water supply wells are corroded by mine water or the water-stop technology fails. All these communicate the hydraulic connection between high-quality karst water and inferior coal mine water.

Although the communication between Ordovician aquifer and mine water has a long history, in the normal production process of coal mine, the mine water level drops very low, far lower than the Ordovician karst water level in the same period (the water level difference between them is mostly 40 ~ 50m), and the karst water supplies the mine water, so there is no problem of cascade pollution of karst water by mine water. However, once the coal mine is closed, the discharge of mine water will stop, which will lead to a sharp rise in mine water level. When the water level in the mine is higher than the karst water, cascade pollution first occurs in the communication well, and then the pollution continues to spread, and the pollution scope gradually increases, which directly endangers the life and water supply for industrial and agricultural production (Figure 9-5).

During normal mining in Hongshan Coal Mine of Zibo Coalfield, the mine water level dropped below-24m, while the Ordovician karst water level was 30 ~ 50m. Hongshan Mine/KLOC-0 was scrapped in April, 1994.1July, 1997, the mine water level rose to +45m, and the mine water flowed to the surface along the inclined shaft. At this time, due to over-exploitation, the karst water level dropped to about 5m, and the mine water level was nearly +73m higher than the karst water level, which led to a large number of mine water reverse recharge karst.

3. The causes of cascade pollution

Carboniferous and Permian coal measures strata are generally composed of sandstone, shale, limestone, coal seam and other interlayers, and coal seam is a relative water-resisting layer. Under natural conditions, due to the barrier of coal seam, the hydraulic connection between aquifers in coal measure strata is weak. After coal seam mining, the roof of coal seam (including the main roof) is fractured and dislocated, the horizon is displaced (collapsed), and a large number of cracks appear in the mining influence zone, even making the upper and lower aquifers hydraulically connected with the river water, which destroys the occurrence conditions of groundwater. After the mine drainage stops or the drainage volume decreases, with the continuous rise of groundwater level in the aquifer, on the one hand, the high-quality groundwater in the shallow buried area is filled into the goaf through various water-conducting cracks, which is transformed into pit water to form pollution, or the inferior water in the deep confined aquifer in the mining area is hydraulically connected with the upper aquifer through the goaf, resulting in "cascade" pollution of groundwater (coal-bearing sandstone fissure water); On the other hand, when the water level of inferior ore is higher than the karst water level of the underlying high-quality Ordovician limestone, it will be replenished by leakage and form "cascade" pollution.

Zichuan District, located in the middle and upper reaches of Fu Xiao River Basin, is the main concentrated distribution area of Zibo coalfield. Large-scale pit closure and drainage stop not only have a serious impact on industrial and agricultural production and people's lives in the mining area and downstream, but also cause serious damage to the ecological environment of the basin. Therefore, how to properly handle the contradiction between mine drainage and pollution and effectively curb the pollution of mine water to groundwater environment has become an urgent task at present.

Oil pollution scattered in oil and gas exploration areas

Shandong Province is rich in oil and gas resources, mainly distributed in Dongying City and Binzhou City. Over the years, oil and gas exploration activities have caused different degrees of pollution to the surface water, groundwater and soil environment in this area.

1. Pollution Status of Oil Production in Dongying City

Oil exploitation is the primary pollution industry in Dongying City, and its pollution load accounts for 49.5% of the city's cross-industry pollution load. According to the Geological Environment Monitoring Report of Dongying City (1996 ~ 2000), among the1kloc-0/rivers monitored all the year round in Dongying City, except the Yellow River, the 10 rivers such as Zhinv River, Yanghe River, Hezi River, Xiaoqing River and Guangli River are heavily polluted, among which The detection rate of petroleum in coastal waters is also relatively common, and most of them exceed the standard. For example, the oil in salt culture areas and nature reserves exceeds the standard by more than 2 times.

Groundwater pollution, especially oil pollution, is very common in Dongying city. Because of the wide distribution of undrinkable salt water, the harm is not prominent, but it is more obvious in areas with shallow fresh water distribution. 1999 the investigation of groundwater pollution along the coast of He Zi shows that the shallow and deep groundwater along the coast of He Zi are polluted to varying degrees, and the pollution factors are mainly petroleum, followed by CODCr and minerals. The polluted area of shallow groundwater is 45.8 ~ 52.5km2, and the maximum value of petroleum in deep groundwater is1.32mg/L. ..

Figure 9-5 Schematic Diagram of Interlayer Pollution in Closed Pit Mine

2. Pollution status of oil production in Binzhou City

According to the Geological Environment Monitoring Report of Binzhou City (1996 ~ 2000), the water quality monitoring of Xiaoqing River, Zhulong River, Fuxiao River, Zhimagou River, Dehui New River, etc. 10 shows that the detection rate and over-standard rate of petroleum in river water (according to the groundwater III standard) are as high as10. The groundwater in Xiahe, Dansi, Dudian, Xiaoying and Chunhua centralized oil production areas has been polluted by oil.

Second, mine geological disasters

At present, coal, iron, gold, building materials, gypsum, talc and other minerals are the most prominent geological disasters in Shandong mining areas. The main disasters are goaf collapse, karst collapse and mine water inrush.

(A) the goaf collapse

Goaf collapse is the most important geological disaster in Shandong mining area, involving coal mines, gold mines, iron mines, gypsum, talc and other minerals, among which the harm caused by goaf collapse in coal mines is the most prominent. Ground cracks and mountain cracks are often accompanied by goaf collapse. The goaf collapse is mainly distributed in coal mine goaf, followed by gold, iron ore, gypsum, talc and other goaf, but in terms of suddenness and safety of people's lives and property, gold, iron, gypsum and talc are more serious. There are 17 cities in the province, and there are 10 mined-out collapses of different scales. The areas with large subsidence are Tai 'an (mainly distributed in Xintai, Ningyang and Feicheng, which are rich in coal resources), Jining (mainly distributed in Yanzhou and Jining coalfields), Zaozhuang (mainly distributed in Tengzhou, Taozao coalfields, Yicheng and Dige gypsum mining areas), Laiwu (four state-owned coal mining areas, Zhangjiawa, xiaoguanzhuang iron mine area and Mazhuang mining area of Laiwu iron mine area) and Yantai (mainly distributed in Tengzhou, Taozao coalfields).

The collapse of goaf is caused by the bending and delamination of the strata above goaf under the action of gravity after coal seam (body) mining. According to the degree of rock failure, the surface of goaf can be divided into three different deformation influence zones, namely caving zone, fracture extension zone and bending deformation zone. Relevant data show that the influence height of caving zone and fracture zone is ten times or even dozens of times of coal seam mining thickness. When the mined-out area caving zone affects the surface, the surface appears collapse pit; If only the fracture zone develops to the surface, the surface is dominated by ground fissures; When all three zones are developed, the surface above the bending deformation zone often forms a subsidence basin, with the largest subsidence depth in the center and the smallest edge. Due to the large angle between the cross section around the subsidence body and the horizontal plane, the area of subsidence basin is generally slightly larger than that of goaf.

The influencing factors of goaf collapse are complex, and its occurrence and development process and surface morphological characteristics mainly depend on coal seam conditions, roof lithology characteristics, geological structure, mining height and mining conditions.

Goaf collapse is one of the most harmful geological disasters in mining area, which destroys the surface vegetation, soil and stratum structure, seriously deteriorates the natural ecological environment, causes huge economic losses, directly affects people's living and production environment, seriously threatens people's life and property safety, and restricts the sustained and healthy development of the national economy. It has a great influence on people's production and life. Most of the coal resources in Shandong Province are concentrated in the piedmont plain and mountain plain. These areas are fertile and flat, and there are often concentrated villages and towns and densely populated areas. Therefore, the ground collapse caused by mining not only forces a large number of villages to move and buildings to be damaged in the affected area, but also makes a large area of fertile land abandoned or stopped production due to the influence of factors such as excessive terrain fluctuation, groundwater accumulation and ground fissures, which wastes huge manpower, material resources and financial resources and even causes fatal accidents. Excluding the cost of moving residential areas by coal mining, the annual income per mu is 2,000 yuan, and the new subsidence area is about 20km2 every year, with an annual loss of 60 million yuan. Five years of negligence will cause a loss of 300 million yuan. According to experience, if the average input per mu is more than 1 10,000 yuan, then the economic loss caused by ground subsidence caused by coal mining is still more than 1 100 million yuan every year, which is a very considerable figure, excluding the cost of road maintenance and building demolition. The collapse of goaf also seriously damages public facilities and road traffic, poses a threat to deep mining and destroys surface water and groundwater resources.

According to the survey data in recent years, the mined-out subsidence area of various mines in Shandong Province is 403.0 1km2, of which coal mine is the largest, accounting for 97% of the mined-out subsidence area. The status quo of goaf collapse of main minerals is described as follows:

1. Coal mining subsidence

Shandong province has a long history of coal mining, and the mining mode has changed from small-scale mining to large-scale mechanized deep mining. With the continuous expansion of mined-out area and mined-out area, a series of mined-out collapses with different scales and shapes have occurred in various coal mining areas. According to incomplete statistics, there are more than 800 mined-out collapses caused by coal mining in Shandong Province, with a cumulative collapse area of 392.625km2, of which the unproductive area of crops is more than 50km2, and the average ground collapse rate of 10,000 tons of coal is 0.0037km2 See Table 9-3 for the situation of mined-out collapses in coal mining areas in Shandong Province.

Table 9-3 Statistics of Goaf Collapse in Coal Mining Areas of Shandong Province

The plane shape of the subsidence is mostly round and oval, and the subsidence depth in the center of the basin varies from place to place, with the maximum subsidence depth of 12.5m (Wangguadian, Feicheng) and the minimum subsidence depth of 0. 1m (Huang Zhuang Coal Mine, Zaozhuang). Among them, the maximum subsidence depth in the subsidence area is less than 1.5m, and the total subsidence area with relatively slight changes in surface morphology is 124.6km2, accounting for 3 1.74% of the total subsidence area in the province. The subsidence depth in the subsidence area is greater than 1.5m, and the subsidence area with relatively large changes in surface morphology is 268.03km2, accounting for 68.26% of the total subsidence area in the province. In the latter type of subsidence distribution area, the surface topography fluctuates greatly, and in areas with large Quaternary sedimentary thickness or shallow groundwater level, seasonal or even perennial waterlogged depressions often form, which makes land reclamation difficult or impossible. According to incomplete statistics, at present, the perennial water accumulation area in some old subsidence areas in the province has reached more than 48.2km2, resulting in a large area of arable land being out of production.

Due to the difference of coal-forming conditions (thickness, buried depth, roof and floor lithology, etc.). ) In different areas, different mining areas have different mining methods, and the development scale of goaf collapse in different mining areas is quite different. Among the seven coal mining areas in Jining, Zaozhuang, Tai 'an, Longkou, Linyi, Zibo and Fangzi, the development scale of goaf collapse in Zibo coal mining area is small, and the goaf collapse in other areas is serious. In particular, the coalfields under the jurisdiction of Jining, Zaozhuang and Tai 'an have the most serious goaf collapse, with a cumulative collapse area of 3 12.8 1 km2, accounting for 79.67% of the total goaf collapse area in the province. Not only the subsidence area is large and the subsidence depth is deep, but also the accumulated water area is wide, causing huge losses and social impact.

(1) Jining coal mining area

It mainly includes Yanzhou Coalfield and Jining Coalfield, with 2 ~ 3 layers of minable coal seams, coal seam dip angle of 8 ~ 12, thickness of 8 ~ 12m, maximum 18.77m, and coal seam buried depth of 200 ~ 1000m. There are 40 coal mining enterprises. Since 1968, all kinds of mines have been built and put into operation one after another, with an annual production capacity of 48.38 million t and a mining depth of100 ~ 600 m. In recent years, due to long-term large-scale mining of underground coal seams, ground collapse of mined-out areas has occurred one after another. According to incomplete statistics, the goaf subsidence area in this area has reached 127.96km2, accounting for 9.9 1% of the total mining area, of which the reclamation area is 36km2. The subsidence depth is generally 2.5~7.5m, and the maximum is 9.2m Because the subsidence depth is generally deep, the terrain fluctuates greatly, and the Quaternary deposition thickness in the subsidence area is large, the subsidence area is mostly perennial or seasonal stagnant water basins. According to incomplete statistics, the accumulated water area in the subsidence area is 20km2 and the average water depth is 4m.

(2) Zaozhuang coal mining area

The goaf collapse in Zaozhuang mining area is mainly distributed in the piedmont plain in the northwest, middle and southeast of the area. Coalfield in this area includes Taozao Coalfield, Guanqiao Coalfield, Tengzhou Coalfield and Hantai Coalfield, and the mining area is 1546km2. There are 6 minable coal seams in total, of whichNo. 14 coal seam of Carboniferous Taiyuan Formation (coal seam thickness is about 1.4m) and No.3 coal seam of Permian Shanxi Formation (coal seam thickness is 3 ~ 8m) are the main mining coal seams, and the buried depth of coal seams is between 20 ~ 500m. There are 8 coal mining enterprises/kloc-0 in the mining area. Since 1965, mined-out collapses have occurred one after another, with a cumulative collapse area of 79.0 1km2, accounting for 5. 1% of the total mining area. At present, the mined-out subsidence is mainly concentrated in Taozao coalfield, with the subsidence area of 45km2, followed by Tengzhou coalfield and Guanqiao coalfield, with the subsidence areas of 27.5 1km2 and 6.5km2 respectively. The subsidence depth in the subsidence area is generally 1 ~ 2.3m, with the deepest of 9m (Chaili Coal Mine).

(3) Taian coal mining area

Taian City is an important coal production base in Shandong Province. Coal mines are mainly distributed in Feicheng, Xintai and Ningyang, with a coal-bearing area of 840km2, accounting for 10.8% of the city's total area and a exploitable area of 240km2. There are 5 ~ 8 layers of minable coal seam, and the average total thickness of coal seam is 2.5 ~ 8m. There are 8 1 coal mining enterprises in the city. The mined-out subsidence is mainly distributed in the coal mining areas of Feicheng, xintai city and Ningyang counties, in which Feicheng coalfield has the largest subsidence area and the most serious damage to geological environment, industrial and agricultural production and urban and rural construction. At present, the accumulated subsidence area of the whole city has reached105.84km2..

2. The mined-out collapse in the iron mine area

The goaf collapse of iron ore in the province is relatively light. Although the mining in Jinan, Laiwu, Zibo and other major iron ore producing areas has reached a large scale, most of the mined-out areas have been filled with tailings after ore mining, and the occurrence of iron ore goaf collapse has been effectively controlled. According to the survey, by the end of 2002, there were only three goaf collapses in the whole province, including Laiwu twice and Zibo 1, with a cumulative collapse area of 2.673km2.

Zibo Heiwang Iron Mine Zhu Ya mining area Miao Zi area (1) goaf collapse.

It happened on June 7th, 1987+ 10, and the collapse was sudden. The plane form of collapse is a strip with a length of 3 10m, a width of 8 ~ 12m and a depth of 6 ~ 8m. Eight families were trapped in the pit, killing or injuring 12 people, and 100 houses were damaged to varying degrees.

(2) The mined-out area of xiaoguanzhuang Iron Mine in Zhangjiawa, Laiwu collapsed.

The goaf collapse of xiaoguanzhuang Iron Mine occurred in the east and west mining areas of Xiaoguanzhuang, with a cumulative collapse area of 2.3km2. The plane shape of the collapse is a circular basin, and its formation process has the characteristics of gradual change. In the early stage of subsidence basin formation, a small area of surface subsidence occurred above the goaf, and then the surface deformation range and settlement increased year by year from the edge to the center, with an annual subsidence rate of 0.69m (western mining area), and a barrel-shaped subsidence pit appeared in the settlement center. Collapse pit diameter 10~30m ~ 30m, depth 20m. After the collapse, there is water in the pit, and the ground collapse continues to develop.

(3) The goaf of Mazhuang Iron Mine collapsed.

The collapse of the mined-out area in Mazhuang Iron Mine occurred in Mazhuang Iron Mine, with a cumulative collapse area of 0.37km2. The subsidence area is distributed in a strip shape along the mined-out area, extending 1000m, and the maximum collapse pit depth is10 mm. At present, the collapse has been in a stable state. At present, the new tailings filling technology has been adopted in Mazhuang goaf, and the goaf collapse has been effectively controlled, and generally no goaf collapse will occur in the future.

3. The mined-out area of gold mine collapses

The goaf collapse of gold mines in Jiaodong gold mining area is mainly distributed in Zhaoyuan, Laizhou, Mu Ping, Weihai and other places. According to incomplete statistics, up to now, there are more than 60 mined-out collapses in gold mining areas1km2, and the accumulated collapse area is about 0.85 1km2. The collapse forms are mostly strip collapse pits, and the strike is consistent with the vein strike. The slopes on both sides of the collapse pit are steep, and tensile cracks develop on the surface rock along the vein, and the width of the cracks can reach 20cm. Controlled by the geological characteristics of the vein and the mining scale, the development scale (length, width and depth) of the subsidence pit varies greatly. The length of the collapse pit generally ranges from ten meters to tens of meters, and the longest is 800 meters.

4. The mined-out areas such as gypsum and talc collapse.

Shandong Province is rich in gypsum reserves, the gypsum output is increasing year by year, and the output exceeds the demand, so the problem of goaf collapse in mining areas is becoming increasingly prominent. At present, the mined-out area collapses are mainly distributed in Pingyi County, Cangshan County and Zaozhuang Dige Gypsum Mining Area in Linyi City, with the cumulative collapse area of 1.774km2 and 200 1. By 2002, the Land and Resources Bureau of Linyi City and Zaozhuang City successfully predicted two gypsum mine collapses, avoiding heavy casualties and property losses.

Collapse of goaf in Pingyi gypsum mining area (1)

An area of 0.038km2, 200 1 year. On August 26th, the ground collapsed in the goaf of gypsum mine in Bianqiao Town, Pingyi County, with an area of 1 10,000 square meters. The pit in the central area was more than 5m deep, and the collapsed area was facing more than 30 villagers' houses in Zhuang Xiaodong. Due to the success of the forecast, casualties and property losses of villagers in Zhuang Xiaodong 1 16 were avoided.

(2) Zaozhuang Dige Gypsum Mining Area

Gypsum mine 2 1 block, most of which have a mining history of nearly 20 years, and the mining scale has basically stabilized. The collapse of mined-out area begins at 1990, and there are 6 collapse pits 16, which are mostly east-west, with an area of1.72km2. The subsidence depth of the subsidence area is generally 0.5~2.5m, and the deepest point is 7m. On May 20, 2002, at 2 1 hour, a large area of ground subsidence occurred in the gypsum mining area of Dige Town, Yicheng District, with a contiguous area of 2 14 mu, and then it continued to collapse for more than 40 mu. Due to accurate monitoring and successful prediction, more than 400 miners' casualties in six mines in operation were avoided, and economic losses of more than 4.6 million yuan were avoided.

(3) The goaf of talc mine collapses.

Mainly distributed in Qixia, Laizhou and other places, there have been three goaf collapses. The largest one occurred in the mined-out area of talc mine in Laizhou City, which was an oval basin with an area of about 0.45km2 and a subsidence depth of about 3m. The occurrence of this collapse poses a great threat to the talc mine in Laizhou city in the west. At present, there are many inclined cracks in the fence of the mine yard, and the widest crack of the wall can reach 10cm.

(4) The mined-out area of barite mine collapses.

During barite mining in Linyi, Weifang and other places, large-scale goaf collapses occurred one after another, causing serious casualties. 198 1 year1October, the barite mining area 500m south of Dashao Village, Caozhuang Town, Linshu County, Linyi City collapsed, causing 6 casualties of underground mining workers; During the period from 1982 to 1986, the barite mining area near Xihua Village, southeast of Wuwang Township, gaomi city, Weifang also suffered two goaf collapses. The plane shape of the collapse is strip-shaped. The maximum collapse depth in the center of the collapse is 5m, and the cumulative collapse area is 4.5km2, in which 1982 ground collapsed, killing 4 people and causing direct economic losses of more than 200,000 yuan. At 1986, another collapse pit with a width of 5m, a length of 50 ~ 60m and a depth of 4 ~ 5m was formed. After the collapse, some areas were backfilled, so far, no ground collapse occurred in the mining area.

(2) Karst ground collapse

Karst ground collapse is a sudden geological disaster that occurs in hidden carbonate areas. The area of karst collapse caused by solid mineral exploitation in the whole province is about 30.6544hm2. Compared with the collapse of mined-out areas, the area of karst collapse is smaller, which is limited to Laiwu iron mine area, Mengyin Honggou coal mine area and Yinan gold mine area.

1. Laiwu iron ore district

There are more than ten hydrothermal metasomatic iron ores with different scales in the mining area, which have been built and mined one after another since the late 1950s. The collapse first occurred in Gujiatai mining area, which was heavily pumped in 1973. When the water level drops by 22.4m, the water inflow is 2 1385m3/d, and there is a "skylight" in Zhaozhuang and its vicinity, the ground collapses suddenly along the east side of Zhang Gongqing fault, and 12 collapses obviously. At present, the ground subsidence in the mining area has developed to 1 17, and the accumulated subsidence area is 6320m2. The collapse forms are mostly axial or altar-shaped, with a diameter of 0.4~35m and a visible depth of 0.4 ~ 13m. Collapse led to the destruction of some farmland and the cracking of houses, which posed a great threat to people's lives and property. According to the survey, due to the influence of karst collapse, up to now, 328 households in 10 natural villages in the mining area have been forced to move, and 996 dangerous houses need to be repaired but have not been moved.

2. Mengyin Honggou Coal Mine Area

On May 28th, 199 1, a water inrush accident occurred in the underground roadway of Honggou Coal Mine 150m. The underground water level of the roadway rose at a speed of 2.4m/h, and all the mines were flooded the next morning. At the same time, there are 69 collapse pits in the southwest of Honggou Village and the east bank of Honggou River, which are 0.4km away from the water inrush point, forming a collapse peak. Then from May 30th to June 3rd, ground subsidence occurred one after another, making the mining area collapse to 78, and the last time 1 occurred in March 1992. Collapse pits are distributed along the east side of Honggou ancient riverbed, and there are 148 collapse pits in the range of 2000m long and 400m wide. Most of them are round shafts with a diameter of 2 ~ 10m, a visible depth of 3 ~ 5m, the deepest 15m and the shallowest 0.5m, and the cumulative subsidence area is about 0.3km2.

3. Yinan Gold Mining Area

On the night of March 2 1, 1992, water inrush occurred in Yinan gold mine, and then the ground collapsed above the water inrush point. The collapse is distributed in the Tongjing river bed in the southeast of Tongjing town1000 m. There are 0/3 sinkholes/kloc-0, the diameter is 1.5 ~ 7m, the visible depth is 4 ~ 10m, and the accumulated subsidence area is about 224m2. The subsidence pit in the subsidence area has been filled up.

(3) Gravitational geological disasters such as collapse, landslide and flow.

Gravitational geological disasters caused by mining, such as rock fracture, collapse and landslide, are mainly distributed in the middle and low mountain gold mine development zone in the northwest of Jiaodong. After the gold vein is mined along the mountain, the overlying rock may crack and collapse if it is not backfilled in time. At present, such gravity geological disasters are very common in Zhaoyuan, Longkou, Laizhou and Muping gold mining areas in Yantai City, and slag flow caused by unreasonable stacking of gold rubble and tailings often occurs in this area. In addition, the development of stones is easy to cause slope instability, resulting in collapse, landslide and so on. This kind of geological disasters are mainly distributed in the stone development zone in central and southern Shandong and eastern Shandong.

1. Gravitational geological disasters caused by waste hills

The natural angle of repose of gangue hill is 38 ~ 40. Under the action of artificial excavation, rainfall and other external forces, it is easy to lose stability and cause gravity disasters, such as mudslides and collapses. Since the 1980s, there have been more than 20 serious gravity disasters 10 in the waste dump in the whole province, resulting in more than 20 deaths and many injuries. 1994, a dump in the north coal well of Zaozhuang Coal Mine, Shandong Province, collapsed, causing 17 deaths and 7 injuries. In 2002, a spontaneous combustion gangue hill with a height of more than 50 meters collapsed in Jiangzhuang Coal Mine, Zaozhuang City. The main reason is that the mine owner operated the gangue hill without any protective measures, and the lower part of the mountain was excavated vertically, and the upper part slipped due to vibration, resulting in a serious accident in which one car was buried and burned, 1 person was burned, and four people were severely burned. At present, many mines in our province have gravity geological disasters in gangue hills. For example, there are hidden dangers of collapse in seven waste hills of Zibo Mining Group. The collapse of gangue hill in xia zhuang Mine has endangered the safety of nearby residents, which should attract the attention of relevant departments.

2. Gravity geological disasters caused by tailings dam

Disasters caused by the instability of tailings dams occur from time to time in mines in the whole province, mainly in Jiaodong gold mining area. There are two forms of tailings stability hazards:

1) Conventional treatment of water and soil erosion caused by wind;

2) Gravity stability problems such as tailings flow and tailings dam.

Among them, the latter is more harmful. 1In August, 1997, the cover plate of the drainage chute of the tailing pond of Linglong Concentrator in Zhaoyuan Gold Mine was broken and damaged, and the tailings were carried down by mountain torrents, which washed away 10 mu of orchard and 25 mu of farmland in Taishang Village and silted up a small reservoir, making 17 villagers homeless. During the period of 1989, a large amount of water gushed from Taikeng roadway in Jiuqu Jiangjia mining area of Zhaoyuan Gold Mine, which washed away the tailings dam in Jiangjia village and caused mudslides, resulting in direct economic losses of more than 500,000 yuan. Another tailings dam in Jiuqu Jiangjia Village suffered a landslide accident in flood season due to poor design and construction quality, which caused great economic losses. There are dozens of tailings ponds on both sides of Luoshan River in Linglong Town. Every year, a large amount of tailings sand is deposited on the border riverbed in flood season, which requires a lot of manpower and material resources for dredging, which has a great impact on the local economic development.

Third, the destruction of resources

(a) the exploitation of mining occupies and destroys land resources

At present, the total mining area of mining enterprises in the province is about 8049.76km2, accounting for 5. 1% of the total land area in the province. The type of land occupied and destroyed by mine development and construction is mainly cultivated land. The main ways of occupying and destroying land in mine development are open-pit mining yard, solid waste yard, tailings pond and ground subsidence area. Shandong province has a high land utilization rate. In 2007, the province's cultivated land area was 7.07 million hm2, and the per capita cultivated land was 1.066 mu, which was lower than the national average. In recent years, the cultivated land area has been decreasing year by year, from 1990 to 1030 13000 mu to 94.8 million mu in 2007.

(B) the destruction of the landscape

In recent years, with the rapid development of engineering construction in Shandong Province (the largest cement production province in China and the largest highway mileage province), the demand for various building materials such as cement, sand and gravel has increased greatly, especially the number of building materials mines has increased rapidly, covering a wide range of areas, affecting almost all parts of urban and rural areas. The ecological environment problems caused by its development are very prominent, and the restoration of mine ecological environment is very difficult. Long-term open-pit quarrying, sand mining, soil borrowing and engineering construction have left or are forming many quarrying (sand and soil) pits, excavation faces, rolling stone belts and many waste rock (soil) piles, which have seriously damaged the geological and geomorphological morphology, destroyed the original beautiful and natural geological and geomorphological landscape and deteriorated the natural ecological environment.