| As the largest coal producer in the world,China has witnessed frequent mine disasters,in which rock burst has become a major disaster threatening safety in production.Under the impact of various factors,rock burst can easily lead to roadway collapse and pillar breakage,resulting in causalities and economic losses.Various anti-surge measures are available at present but reasonable anti-surge measures still need to be determined so as to improve resource recovery rate as much as possible when safe and efficient production is safeguarded.Such determination of reasonable anti-shock measures is of great significance to safe and efficient production.Based on the engineering background of the 8204 working face of a mine,this paper takes advantage of theoretical analysis methods in revealing the energy dissipation mechanism in the process of coal and rock mass crushing,and evaluates the impact tendency;based on the existing anti-scour coal pillar scour prevention measures,an elastoplastic model of coal pillars was established,and a reasonable coal pillar leaving width was optimized.Based on the above research results,numerical simulation was used to study the stress distribution characteristics in coal pillars of different widths,and the stability of the roadway stability was analyzed.Through field measurement,the deformation of narrow coal pillar roadway,the force of anchor cable and the deep displacement of surrounding rock were analyzed,and the surrounding rock control effect of wide and narrow coal pillar roadway was compared.Main conclusions of this article are as follows:(1)Using the method of theoretical calculation,energy dissipation in the process of coal and rock mass destruction is analyzed,the mechanism of coal and rock loss is explained,and the comprehensive index method is used to evaluate the risk of coal seam impact tendency,concluding that rock burst risk index is 0.71 in 8204 work face.It is believed that certain shock risk exists in this mine.(2)By analyzing the existing aanti-scouring measures of the mine,it is proposed to use narrow coal pillars to prevent roadway impact;based on the criterion of maximum connection degree,the danger of rock burst under different coal pillar widths is determined,and economic benefits are considered and the calculations are compared.Two coal pillar retention schemes were optimized and the reasonable narrow coal pillar width was determined to be5 m.(3)Using FLAC3 D to simulate and analyze the vertical stress distribution and yield failure characteristics under different coal pillar widths,it is obtained that when the coal pillar width is 5m,the roadway stress peak is farther,and it is located above the solid coal side of the roadway,and on the side of the coal pillar.When yielding occurs,the excess load will be transferred to the solid coal of the working face,which proves that the 5m narrow coal pillar can effectively reduce the impact risk of the roadway.By simulating different advance support distances,when a 5m narrow coal pillar is obtained,the 30 m advance support roadway has better stability.(4)A narrow coal pillar test was conducted on the 8204 working face of a certain mine.By setting up the measurement area,the two sides of the narrow coal pillar roadway,the approaching amount of roof and floor and the approaching rate were observed,the anchor cable force of the roadway and the deep displacement of the surrounding rock were analyzed,and the surrounding rock control effect of the wide and narrow coal pillar roadway was compared.It was demonstrated on the spot that the 5m narrow coal pillar with reasonable support methods can effectively maintain the roadway and prevent rock bursts. |
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