Practice Of Scour Prevention In Safe Mining Of Isolated Pillar Under Thick And Hard Roof In Barapukuria Coal Mine

Affected by geological conditions or mining technology,island coal pillars are often formed during coal mining and mining.Due to the mining around the coal pillars,the stress on the working face is concentrated by the overlying strata,and the geological structures such as hard roof and faults are affected.The mining pressure is often threatened by the mining pressure.This paper takes the island coal pillar of 1210 D working face under the thick hard roof of Barapukuria coal mine in Bangladesh as the research object.Through theoretical analysis and field test,the safe mining control scheme of island coal pillar is put forward and practiced on site.Based on the principle of dynamic and static loading superposition,combined with the evolution of overlying strata structure of the island coal pillar,the static load stress characteristics of the coal pillar are analyzed,and it is concluded that the thick hard roof overburden is easy to form a “T” structure,resulting in high stress concentration on the island working face;The cantilever beam model is established,and the dynamic load formed by the breaking of the thick and hard roof during the coal pillar mining process and its influence on the coal pillar are calculated.It is concluded that the thick hard roof has a large suspension top length,and the accumulated elastic energy is more and more broken.When released,the dynamic load is stronger.The pre-seismic impact risk assessment of the 1210 D working face was carried out.The influence of mining depth,coal rock impact tendency,roof rock stratum structure characteristics and roof overburden activity on the recovery of the island coal pillar was analyzed.The comprehensive index method was used to evaluate the impact risk of the working face.State and divide the hazardous area by multi-factor coupling.According to the evaluation results of the impact risk of the island coal pillar in the 1210 D working face,the pre-pressure relief measures were designed and constructed for the island coal pillar area.The elastic wave CT detection technology was used to test the stress of the island coal pillar after pre-pressure relief measures,and the stress distribution law and pre-pressure relief effect in the island coal pillar were further grasped.The results of two CT detections and the location of the high stress region in the early stage of dynamic display are analyzed.It is proved that the elastic wave CT detection technology can effectively evaluate the risk of impact ore pressure in the island coal pillar area of the 1210 D working face,and it is concluded that the coal pillar area is not in the overall High stress,strong impact and dangerous state.Comparing the two detection results,it can be seen that the deep hole blasting pressure relief of the roof can reduce the impact risk of the high stress area,so that the high stress area is further transferred rather than disappeared.According to the results of elastic wave CT detection in the island coal pillar area of 1210 D working face,combined with the microseismic monitoring system,the prevention and control scheme of impact rock pressure in the island mining process is proposed.The field practice effect is good,ensuring safe recovery.This thesis has 100 figures,27 tables and 93 references.