Research on technical measures for local preventio

Research and application of local outburst prevention and control technical measures in township coal mines in Lengshuijiang City

at present, the international leading part of the bulge prevention and control technology can be divided into two aspects according to its effect on the bulged coal seams: on the one hand, it is to eliminate or weaken the energy accumulation of coal and gas bulges and prevent the sudden release of this kind of energy, that is, to remove the coal rock pressure and gas pressure. The first part of this kind of method includes gas drainage, drainage drilling Advance drilling, hydraulic punching, deep hole loose blasting, etc; On the other hand, it is to strengthen the stability of the coal body, increase the fracture resistance of the coal body, and make it difficult to produce coal and gas bulges. The main methods belonging to this kind of methods are metal skeleton, front detection support, outburst prevention baffle, making half face and leaving half face, etc. When the accuracy of the resistance strain gauge inside the sensor is not high, the anti-aging ability of the glue used to fix the strain gauge is not good, and the material of the sensor is not good, which will affect the accuracy of the sensor and the implementation of some bulge prevention methods, because the bulge mechanism is relatively large, and there are many disturbing factors in the construction task, the results of various methods to prevent bulge are different in the utilization of each mine. At the same time, due to the different nature of coal, the results of the methods adopted will also vary from place to place, so, The primary parameters of the bulge prevention and control measures adopted in each bulge mine must go through three stages: selection, experimental measurement and point channeling. Only after testing the friction coefficient of plastic packaging materials can we effectively deal with the problems encountered by a wide range of users and obtain better outburst prevention results. Tuzhu coal mine has stopped experimenting on the implementation results of various prevention and control methods since 1990, and began to examine and determine the primary implementation technical parameters of some prevention and control methods since 1994, and affirmed some prevention and control methods and their primary technical parameters suitable for the characteristics of the raised coal seams in this mine

outline of bulge

Tuzhu mine is located in the southwest of Jinzhushan mining area in Lianshao coalfield, at the southwest end of Qiaotou River syncline, starting from shiziling fault in the southwest and adjacent to a adit mine 200 meters west of survey line 1; The northwest wing to 39 survey line is connected with Tuoshan mine, and the mine design production capacity is 400000 tons/year. Due to the huge mining technology premise, the provincial coal department approved the production capacity of 210000 tons/year in 1977, and the approved production capacity of 300000 tons/year in 2006 after the process of reform and expansion in recent years. The coal bearing stratum of the mine is the lower section of the water measuring group, and the coal bearing stratum of the mine field is the lower section of the water measuring group, with a total of seven coal layers. Among them, coal seams 2, 3 and 4 are non convex coal seams, and coal seams 5, 6, 7 and 5 branch coal seams have the risk of coal and gas bulge. At the end of 2006, coal and gas bulges were produced 22 times, of which the largest bulge intensity was 1100t. The coal trademark of each coal seam is anthracite. The hydrogeology in the mining area is huge, and there is no risk of coal dust explosion and no spontaneous combustion of coal seams

Tuzhu coal mine has produced 23 coal and gas outbursts since 1974. Statistics according to the raised foundation environment are shown in the table; The environmental statistics implemented according to the outburst prevention measures are shown in the table

statistical table of uplift foundation environment of Tuzhu mine

before 1988, in the handling of some outburst prevention measures for the self built mine, the safety protection measures such as vibratory blasting and long-distance blasting were directly taken to stop the handling of crosscut coal uncovering and coal roadway excavation. After the Ministry of coal issued the "detailed rules for the prevention and control of coal and gas outbursts" in 1988, the "four in one" comprehensive outburst prevention method was quickly implemented and utilized in our mine from 1989. During the period from 1991 to 2013, a total of 1521 bulge lookouts were stopped along the coal heading face, 352 bulge risks were predicted on the face, and 352 bulge prevention measures were adopted. Among them, the deep hole loosening blasting method has been implemented for 46 times (along the coal roadway), and the advance drilling method has been implemented for 323 times (among them, the Miji drilling method with a hole diameter of 42mm has been implemented for 300 times, and the advance drilling method with a hole diameter of 89mm has been implemented for 23 times). 107 crosscuts were exposed, 395 times of bulge observation on the task face (including the observation through the coal gate) were stopped, and 39 times of bulge risk on the task face were predicted, including 13 times of gas drainage, 2 times of hydraulic punching method, 35 times of drainage drilling method, and 19 times of metal skeleton method. The crosscut exposed the coal bulge for 15 times, of which the bulge was effectively removed for 5 times after the bulge prevention method was adopted, and the bulge prevention method was not adopted for 7 times (6 times of coal seam bulge by mistake and 1 time of true bulge by looking at the bulge). See table and table for prevention and control measures and utilization environment

the outburst prevention method of the surface crosscut task plane uses the environment

the deep hole loosening blasting method and the hydraulic punching method have not been implemented and utilized. The main reason is that the method is huge in technology, strong in craftsmanship, and difficult for workers to grasp. At the same time, because the 5 coal seam (including the 5 coal mechanism bifurcation coal seam) is extremely cracked into powdered coal, the result of adopting the deep hole loosening blasting method is very ignored, It is impossible to achieve the goal of "boring blasting" to produce excessive cracks and release gas to strengthen the hardness of the coal body and form the forward movement of mining concentrated stress. Even after the deep hole loose blasting method is adopted, the advance drilling method must be adopted. Hydraulic punching has strict requirements on water pressure, and the amount and range of coal washed out by the signs of easy shrinkage of the coal seam itself are difficult to meet the requirements of the regulations and detailed rules. Therefore, these two methods have not been implemented and utilized in the raised coal seams. At present, the mine mainly adopts the method of advance drilling along the raised coal seam roadway, and the method of drainage drilling and metal skeleton should be adopted first in the task of coal uncovering at the crosscut. However, because the advance drilling method and the drainage drilling method show that this material has certain advantages over similar materials, the technical parameters have not been measured and confirmed, and it is difficult to accurately control the effective emission range during implementation. Therefore, after the implementation of the method, there are still secondary failures, and coal and gas bulges are produced

determination of the main technical parameters of some prevention and treatment methods

4.1 Determine the effective discharge radius and effective discharge time of the advance drilling method

4.1.1 Measurement style and positive standard

two methods are mainly used to measure the effective discharge radius and discharge of the advance drilling method: first, the borehole gas flow method is used to measure the effective discharge radius of the advance drilling, that is, three mutually parallel measurement boreholes are drilled along the task surface in soft layers, with a hole diameter of 42mm, a hole length of 5 ~ 7m, and a spacing of 0.2 ~ 0.5m. After the hole is sealed, the gas emission of each borehole is measured immediately, and measured every 2 ~ 10min, Then drill a hole to be examined parallel to the measuring hole at a certain interval from the middle of the measuring hole at the most edge. After drilling, measure the gas emission of each measuring hole every 2-10min for 2 hours. The affirmation standard is based on the requirements of selecting qualified industries to try out the detailed rules for the prevention and control of coal and gas bulge: if the gas emission of the measuring hole is continuously measured for three times, it will be confirmed that the measuring hole is within the effective discharge radius of the advanced drilling hole, which is greater than 10% before the advance drilling; The second is to adopt the drilling cuttings target method to measure the effective discharge radius and discharge time of the advance drilling, that is, in the mining task surface with bulge risk, first drill a test hole in its soft layer, measure the drilling cuttings target per meter, and then confirm the discharge according to the construction requirements. When the time comes, drill a test hole at a certain angle to the hole at a certain interval from the test hole, and measure the drilling cuttings target value per meter. The positive standard is based on the measured data within the same depth range of the two boreholes and the spacing between the two points. After a certain time, when the measured data of the inspection hole is less than the critical target value of the bulge, the maximum annual night distance between the two points is the effective influence radius of the method, and that time is the effective discharge time of the radius