Evaluation On The Retaining Of Waterproof Coal Pillar In The South Wing Of 87 Mining Area Of Zou Zhuang Coal Mine

The paper is based on the South Shallow Face of 87 Mining Area of Zou Zhuang Coal Mine,the main coal seam is overlaid with the fourth aquifer（referred to as“Sihan”）at the bottom of the thick water-bearing loose layer,and the limestone water of Taiyuan Formation is influenced by the Tertiary red bed water and the F25 fault water.Coal seam mining affected by many floods.Therefore,it is very necessary to evaluate and study the watertight coal pillars on the south wing of the 87 mining area.Based on the research results of rational setting of coal and rock pillars in shallow coal seams under the threat of multiple water sources at home and abroad,this thesis collects data on geological engineering conditions and discusses the macro,micro factors.Through rock and mineral analysis and hydraulic property experiments,the combined characteristics of the overlying rock structure,the ability to resist water inrush and sand-breaking damage,and the water blocking characteristics of the overlying rock layer are studied,it reveals the water content of the coal strata in the 87 mining area and determines the level of the coal strata under the water source strata.The maximum development height of water-passing fissures is obtained by the standard calculation formulas and the results of the calculation formula in the"Coal Mine Water Control Rules".FLAC^3Dwas used to simulate the excavation process of the coal seam,and the evolution law of the plastic zone of the surrounding rock was obtained.Maximum range of coal mining in the south wing of the 87 mining area has been comprehensively determined,and the research results obtained are as follows:（1）The hydrogeological data of 87 mining area shows that the threat of multiple water sources in the shallow working face of the south wing is:there is a certain thickness of aquifer in the rock layer above the coal seam,and the bottom of this layer has part of the"Sihan"water and it is also affected by the red layer in the third group of Taiyuan,the number of faults F25 and limestone water,and based on the shallow borehole data,the contour maps of the“three separations”and the fourth containment were drawn,and the“four containment”was obtained."The law of distribution in the shallow part of the South Wing.（2）According to the comprehensive geological conditions of the 87 mining area,drill holes for geological inspection are arranged and planned and the pumping test was carried out.The hydrogeological parameters of the"Sihan"were calculated,the calculated permeability coefficient and unit water inflow indicate that the"Sihan"belong to weak aquifers.Rock,soil and water experiments were conducted on the"Sihan"and its overlying rock samples to study the roof lithology,the measurement of the water content of the rock formation in the bedrock weathering zone and the water resistance.The results show that the"Sihan"is mainly composed of cohesive soil,weak water richness and poor fluidity;the overlying rock composition contains clay minerals with good water absorption capacity,which makes the overlying rock have better water barrier properties.（3）According to the analysis of the water immersion test of the rock,the rock in the bedrock weathered zone will collapse and combine with water to form a water barrier after being immersed in water,reducing the water permeability;the dry saturated water absorption rate test also shows that the higher the degree of weathering,the higher the level of siltation.the more water the rock absorbs,the stronger the water blocking ability and growth water blocking ability of the rock formation.（4）Based on the influence of multiple factors such as red bed water,limestone water,according to the water content of the fault in the south wing of 87 mining area,and according to the characteristics of the watery rock layer above the coal seam in the south wing,the coal mining level is determined to be level II;and the first mining surface is considered comprehensively.Large mining height and mining safety and reliability,raise the water mining level by one level and determine it as Class I,the type of coal pillar is used to prevent water damage.（5）Use the drilling holes for water inspection in construction to make a geological model,use FLAC^3Dto evolve the coal excavation process,and observe the changes of surrounding rock formation.Conclusions have been drawn from the study of the force change of the surrounding rock,the change of displacement,and the deformation and failure mode of the surrounding rock:the vertical stress and displacement of the overlying rock gradually increase and gradually reach a stable level;as the excavation progresses,the overlying rock will form two drop zones and cracks with flowing water performance,and their height will eventually be an exact value.As a result,the power generation height in the collapsed area obtained by numerical simulation is 12.4 m,the maximum deployment height in the water conduction failure area is 44.9 m,The confirmed size of the waterproof coal pillar is 64.9m.（6）According to the calculation formula of the"Sanxia",the thickness of the protected area is 15 m,and the height of the water diversion area is 48.7 m.and the maximum limit for mining is-352.7 m.According to the actual measurement results of the project,the coal pillar size is 71.55m,and the highest elevation of the coal seam is-355.55m.Combine simulation and consider safety factors,south of the mine area 87 is 80 m,and the mining upper limit is determined to be-360m.The mining area was originally designed to leave a160m waterproof coal and rock pillar,with 1.865 million tons of coal compressed.After research,the waterproof coal rock pillar can be reduced by 80m and more than 930,000tons of coal resources will be liberated.（7）Safety control techniques,such as controlling mining height in the initial mining and fault zone,speeding up the advance speed and improving the drainage system,have been formulated.Figure 35 table 14 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