Study On Strata-Pressure Behavior In Fully-Mechanized Face Of Hanjiawan Coal Mine

Hanjiawan coal locates in the area of Shi Ge tai of Shen Fu mining field, thecharacteristics of coal seam are shallow buria l depth, thin roof bedrock, thick windblownsands unconsolida ted la yers, which is the typica l shallow seam. The mining practice formining in the thick unconsolida ted la yers show that the strata behaviors of long-wall miningin shallow seam performs strongly, which needs super resista nce support to bala nce the loadsof overlying stratas and unconsolida ted la yers and to prevent the integral breaking of thewhole overlying strata. This thesis researches deeply the strata behaviors in fully-mecha nizedface of Hanjiawan coal by mea ns of field observation, theoretica l research and numerica lsimulation.Using the KJ216 monitoring system, the thesis monitors dynamica lly the roof of 2303workface and two mining gateways. The analysis of monitor data shows that the setting loadsof face supports are serious sma ll and some support has offset load, which are caused by theuneven settlement of work-face roof and the non-sta ndard support injection. It obtains that theimmed iate roof first caving interval is 20.3m, while the ma in roof first weighting interval is38m and the avera ge period ic weighting length is 9m. It also indica tes that the convergencebetween roof and floor of the air return gate and haula ge gate are 64mm, 52mm separately,and the roadway surface displacement changing rate is 3.0mm/h, which show that the tunnelpressure is little and the present support pattern is reasonable. The numerica l simulation ofwork-face shows that with face advancing the gob roof deformation and its dama ge rangeenlarges gradua lly, which causes large-scale destroy to the unconsolida ted la yers and extend sto surface to perform step subsidence. The ma in influencing dama ge of plastic zone is in therange of roof and overburdens. The coal walls near work-face have serious plastic dama ge.The lead abutment pressure tends to increase, and the peak is 3~9m ahead of coal wall with25~35m influence scope. The analysis of roof to floor convergence and pressure distribution characteristicsindica tes that in order to improve the recovery rate and reduce cost the section coal pilla rs areallowed to reduce. Meanwhile, the thesis simulates the roadway displacement deformationand its stability when the size of section coal pilla rs is 10~16m, which shows that the size canbe reduced from origina l 20m to 12~14m.The results have guiding significa nces for improving the coal production capacity,technical and economic benefits and recovery coefficient of Hanjiawan coal, and also forguara nteeing its safety production. The research la ys a foundation for the coal to build a minewith safe production and high yield and efficiency.