Prevention and rescue treatment of roof accidents in stope

Roof accidents refer to accidents such as casualties, equipment damage (buried), production suspension, etc. caused by coal and rock in the mining and roadway during the underground excavation process. According to statistics, the number of casualties caused by roof accidents accounted for more than 33% of the total number of casualties. It can be seen that the prevention of roof accidents, one of the five major natural disasters, is very important.

Roof accidents can be divided into roof accidents in coal mining face, roof accidents in roadway, and roof accidents in tunnels. The roof accidents occurred in different locations have their own characteristics. This paper introduces the prevention and treatment of the roof accidents in conjunction with the actual production.

The roof accidents in the stope are usually divided into large domes and partial roofs according to their size. The local roof accident is the main type of roof accident in the stope, accounting for about 70% of all roof accidents and about 30% of rolling accidents. In recent years, stope support the promotion of metallization, surface collapse accident is greatly reduced, especially crushed type face collapse accident has been reduced to below 10%, but the large roof collapse accident range, serious disasters should still pay close attention.

1. Prevention of large shovel (predator) at the coal mining face.

As far as mines are concerned, the coal mining face has a large shovel (mainly), which basically includes the old roof to crush the roof, the thick layer is difficult to raise the roof and the roof is large, and the large area leaks the roof.

The pressure-type roofing when the old roof is pressed is caused by: 1) The dome of the dome is crushed (reverse) and the roof bracket causes the roof to fall. 2) The impact of the old top rock block in the fallen belt is crushed (reverse). Due to insufficient initial support of the coal mining face support (or unstable support), the direct top and the old top have been separated before the old top rock block has not been obviously moved. When the old top rock block rolls down, the stope bracket must bear the impact load, and the bracket is easily pushed down, which leads to the roof collapse accident. At present, the coal mine generally promotes the steel beam with the single hydraulic prop support, which improves the support. The strength of the protection, the probability and severity of such a roof is greatly reduced. In order to prevent such accidents, the following measures are often adopted: the supporting force of the stopway bracket should balance the weight of the direct roof of the fallen belt and the weight of the old top rock stratum; the supporting force of the stopway bracket should ensure that there is no separation between the direct top and the old top; The shrinkage of the stopway bracket should meet the requirements of sinking the old roof of the fracture zone; when encountering the parallel working face fault, the fault just emerges from the exposed coal wall, it is necessary to strengthen the support in time (preferably with raft); Control the top distance and replace the metal pillar with the wooden support column, and return to the column after the fault enters the goaf.

Large-area leakage dome, which occurs when the roof is partially soft and broken, and the coal mining face supporting system has a partial leakage when the back top is not strict. The broken roof may start from the working surface upwards. Leakage, resulting in instability of the bracket, resulting in a leakage of the working face. This happened at the upper corner of the 4171 working face of Daqing Mine. The treatment measures for such roofing accidents can be summarized as follows: the appropriate pillars are selected so that the working surface support system has sufficient supporting force and shrinkage, and the top plate must be tightly backed; it is strictly prohibited to remove the brackets by means of shooting, moving, etc. to prevent localized parts. Falling top.

It is difficult to take off (fallen) roofs to a large area, when the coal seam roof is an overall hard rock layer, it is often suspended hundreds of square meters or even thousands of square meters. Such a large-area roof falls down in a very short time, not only because of the weight, but also causes severe impact damage, and more seriously, the air in the taken space is instantaneously squeezed out to form a huge storm, and the destructive force is extremely Strong. For the treatment of such roofs, forced topping is used, and high pressure water injection can also be used for the roof. The so-called forced topping is to use the method of blasting to artificially cut the top plate, so that the top plate can fall a certain thickness to form a meteorite cushion. Cutting the top plate can control the falling area of ​​the top plate and weaken the impact force generated when the top plate falls. The formation of the meteorite layer cushion can alleviate the shock wave and storm generated when the top plate falls. Forcing the topping measures, Daqing Mine was used in the G7 and C1 coal seams. Mandatory topping operation method: forced blasting to top the top plate at the position of the returning column to make the top plate fall down in a small range. The method of blasting generally involves drilling a row of holes of 1.5 m or more along the top line according to the hardness of the top plate. The hole spacing is generally 0.5 m, and three coal mine safety rolls are used for cracking and blasting, and the top plate is cut. When there is a false top on the working surface, no matter whether there is any air noise when the top is asked, whether there is delamination between the false top and the direct top, the blasthole of the pseudo-top thickness should be hit from the top line, and the charge can be cut directly to ensure the 垮It is reliable. From the practice of forced artificial roofing in the C1 and C7 coal seams in Daqing, it is difficult to drill the eye. It is difficult to drill with the electric coal drill, and the depth is not up to the requirement. Therefore, the conditions should be created with the wind drill.

2. Prevention of partial smashing of the coal mining face.

The coal mining face is partially smashed, mainly concentrated near the coal wall, near the ends of the stope, near the top line, and near the geological structure failure zone.

The small roof collapse occurred in the geological structure failure zone. The reason is that the geological failure zone and the roof cracks in the vicinity are developed and broken, and the fault layer is filled with powder or mud; the fault planes are relatively smooth, so that the upper and lower plates are Rocks have no cohesive force, especially when the fault plane becomes a water-conducting fissure, it is easier to separate from each other. If the single-pillar working face encounters a fault perpendicular to the working surface or oblique to the working surface, during the movement of the roof, the broken rock mass near the fault may slide down the level to push the bracket to cause the roof to fall. At the same time, the top plate near the geological belt is often broken. If the top of the roof is not real or not timely, it is easy to leak and cause a roof accident. In order to prevent such accidents, rafts should be added on both sides of the fault to support the iron shed or iron column in the direction in which the rock blocks may slide down. At the same time, the top of the geological structure should be strengthened, and the top of the back must be timely and tight.

The reason for the local roofing near the top line is that the force on the top line is uneven. When the worker pulls back the “eaten” column, the column often falls down when the column falls down. If the column is too late to return to the column, it will be too late. When you return to a safe place, you may be shackled and cause a roof accident. When there is a large free rock block formed by cutting, cracking, bedding, etc. in the top plate, the free rock mass will rotate after returning to the column, which may push down the stop support and cause roof collapse. According to statistics, as far as mines are concerned, such accidents have the highest frequency and should be highly valued. The preventive measures for such accidents are mainly to strengthen the geological and observation work, record the location of large rock blocks, determine the special support methods and the steps and routes of the returning columns; strengthen the support with wooden rafts in the area of ​​large rock blocks; When the length of the surface advancing direction exceeds the topping step, the topping distance is extended within the range of the large rock block; the metal bracket is replaced by the wooden bracket (or the raft) (the column is not removed when the column is returned); When the mining area is outside the top, use the winch to return to the column.

The local roofing caused by the coal wall is mainly caused by the staggered fissures in the direct roof of the coal seam. These staggered fissures are easy to divide the direct roof into free rock masses, which are prone to fall off. After coal mining or blasting coal mining If the support is not timely, such free rock blocks may suddenly fall off and cause local topping. The main manifestation is as follows: the direct top is cut by dense cracks, and the free rock mass is formed. The top of the back is not timely or not strict and the roof is topped. The mining height is too large, and the working surface is covered during the pressure period, which expands the roof without support. Measures to prevent such accidents: use brackets that can support the suspended roof in time and use them correctly; when blasting, the blasthole arrangement and charge should be reasonable, try to avoid collapse of the bracket; try to use the main joint direction of the working face and coal seam Vertical or skewed to avoid coal seams. Once the coal seam is supported, it should be supported by the coal seam to prevent the roof from falling.

The local roof at both ends of the stope faces the working surface of the single pillar. The two ends of the stope include the vicinity of the nose of the machine at both ends of the working face (the lower machine socket on the machine working face) and the roadway connected to the working face. At the lower and lower ends of the working surface, the exposed space is large, the supporting pressure is concentrated, and the roadway is advanced in advance, causing deformation and damage around the roadway. It is often necessary to carry out the displacement work of the tail of the nose, and when the old pillar is removed to support the new pillar, the broken roof may further loosen and fall. Roof management at both ends of the stop has become an important task for many production surfaces. Due to the large amount of roof or roof sinking, it is very difficult for the end support and transfer. In order to prevent the occurrence of leakage at both ends of the stope, four-to-one beam, three-column steel beam lifting shed support (ie four pairs of human beam support) has been promoted, and each pair of sheds has a random head and tail moving forward or on the machine. Double-wedge hinged beam support is used at the tail of the nose. At the junction of the working face roadway, it is advisable to use a pair of lifting sheds to move forward and support the shed beam of the original roadway. Double-row advanced support shall be applied within 10m of the advanced working face, and the double-row advanced support shall be provided within 10m ahead; the first 10m to 20m roadway support shall be added with a single center column to prevent roofing.

3. Rescue and treatment methods for roof accidents

After the roof accident occurs, it is first necessary to understand the location, scope, and situation of the injured person, and then act in the rescue of the victims as the first priority (the original principle of the rescue accident). At the same time, it is necessary to know whether there is fresh air in the accident site, whether it is threatened by toxic or harmful gases, and whether the channel is unblocked, so as to take corresponding safety guarantee measures before the rescue. If the dome is large, the exact location of the victims is difficult to determine. You can contact the victims by calling, knocking, etc. (to determine the location of the victims), and then rescue; if the victims are suffocated, toxic and harmful gases, they should be based on On-site conditions provide a variety of ways to supply the wind, water and food to the victims to extend the waiting time, then clean up the collapse and timely rescue.

Generally speaking, for the coal mining face of the regular mine, due to the promotion and application of metal bracket support and (mandatory) full negative pressure supply air in recent years, the small stern can still maintain a considerable amount of air in the stope, and generally can maintain the roof. The air supply requirements of the people in distress (of course, there may be gas concentration in the high-excavation mine due to the top of the working face, the reduction of the ventilation section and the decrease of the air volume, special air supply measures should be taken). Therefore, the main work of the roof accident It is to clean up the collapsed coal rock and save people in time.

Precautions for rescue roof accidents: 1) After the accident, if it can be contacted with the person in distress (call) or contacted at the accident site, it should be calmed down and controlled by means of meteorite padding and material support if possible. The space in the location of the site to prevent serious accidents and to be rescued; 2) personnel responsible for rescue accidents should first control the roof according to the location of the accident, and then clean the passage to the accident site to save people; 3) in the formal coal mining face, from top to bottom In the two directions of exit, roadway cleaning and rescue work are carried out at the same time; 4) When clearing the passage, objective conditions should be used as much as possible, such as clearing the passage along the coal gang, so that the support function of the coal gang can be utilized and the rescue channel can be improved. Cleaning speed; 5) use the equipment of the stope (such as the slippery) as much as possible (such as the original support) and improve the speed of saving people if there is no damage to the person in distress; 6) after the rescued person is rescued, it should be damaged according to the coal mine First aid method first aid; then promptly sent to the hospital for emergency treatment. It should be noted that no matter what the accident, the purpose of the rescue is to first save people in the case of ensuring safety, and then take appropriate measures to clean up the equipment and resume production after the personnel are rescued. After the rescue of the distressed personnel, there are a variety of methods for handling the roof, which can be selected as appropriate, and will not be described here.

Case: A 1610 longwall (residual) working face of a mine was attacked by the “8•7” in 1997. The working face has been formed for many years, but since the block is small, it has been idle and has not been recovered. After the completion of the residual team in Houjingkou, it was handed over to the disabled team. When the working face is recovered, the return air lane has been blocked, although the ventilation can be guaranteed, but the personnel can not pass. At about 6:40 on the 7th of August, the middle and lower sections of the working face to the nose section were crushed by the vibrating top plate due to the pressure. When the gun was dropped on the working surface, the friction pillar was pushed down (about 8m long), and the working surface shovel Six coal workers were trapped in distress. After the accident, the safety officer reported to the wellhead and the mine in time, and the relevant personnel at the wellhead organization took the following rescue measures:

1) Contact the people in distress by shouting, knowing that they are avoiding the gap between the bracket and the coal wall, telling them to calm down, let them take the smashing stone code, idle support to control the top, to prevent the range And the degree of intensification is self-rescue and to be saved.

2) Through the above means, the trapped person takes self-prevention on the spot and avoids the influence of the slippery surface of the work surface, and cleans up the obstruction in the slipper as much as possible.

3) The wellhead organizes the on-site personnel from the outside to the inside, and on the working surface, the column is controlled upwards along the head to control the roof, the plane is cut off, the side is rafted, the side is swayed, and the swaying step is moved gradually. After 40 minutes of fighting, When the ambulance team arrived at the scene, the top section of the ambulance was restored until the person in distress could climb out. After the rescue with the ambulance team, all the people in distress were rescued before the second time.

Through this successful war case, we can realize that the key to the success of the rescue accident is that the rescue personnel are not surprised, the measures are decisive and proactive, and the local resources are taken, and the initiative of the rescuers and the people in distress and the initiative of the disaster prevention and disaster prevention are fully exerted.

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