Experimental study on the influence of width-height ratio on coal pillar type rock burst
The deep coal mining in China is becoming more and more complicated.Under the influence of mining,struc-ture or hard roof and floor,the section coal pillar is easy to induce coal pillar type rock burst.The prevention and control of coal pillar type rock burst has become a difficult problem in coal mine safety and efficient mining.It is of positive signi-ficance to study the mechanical properties and impact failure characteristics of section coal pillars under different width-height ratio for the prevention and control of coal pillar type rock burst.Uniaxial compression experiments were carried out on the"rock-coal-rock"combination of coal samples with different width-height ratio.The influence of width-height ratio on the impact failure of coal pillars was studied by analyzing the impact tendency,dynamic failure characteristics,fractal dimension and acoustic emission characteristic parameters of the combination.The results show that:① The width-height ratio of coal pillar has a significant effect on the impact tendency of the combination.When the width-height ratio is not less than 2∶1,the impact energy index KE is 1.82-2.65,and the impact tendency has no obvious change.When is less than 2∶1,the impact tendency increases first and then decreases.When is 1∶1,KE is the largest,reaching 15.43.② With the decrease of width-height ratio,the failure characteristics of the composite body are as follows:tension-compression failure-compression-shear failure-tension-shear failure.When the width-height ratio of the coal pillar is 5∶1-3∶1,the damage of the combination is relatively slow.When the width-height ratio is 2∶1,the flake coal chips begin to pop out,and the degree of impact damage is low.When the width-height ratio is 1∶1 and 0.75∶1,it has obvious impact failure characteristics.When the width-height ratio is 0.5∶1,the overall stability of the combination decreases,and the severity of the coal pillar failure of the 0.75∶1 sample combination decreases.③ The energy release rate of post-peak acoustic emission is similar to that of fractal dimension D,which increases first and then decreases with the decrease of width-height ratio.When the width-height ratio is not less than 2∶1,the energy release time is longer during the failure process of the combination,and the coal pillar failure is gentle.When the width-height ratio is 1∶1,the energy release rate and D value increase significantly.Compared with the energy release rate of the combination with a width-height ratio of not less than 2∶1,the energy release rate increases by about 4 times,and the D value increases by 0.18-0.23.The impact damage of coal pillar is the most severe.The energy release rate and D value of the 0.75∶1 combination were reduced by about 10％and 0.01,respectively,and the damage severity was similar to that of the 1∶1 combination.When the width-height ratio is reduced to 0.5∶1,the reduction of the relevant parameters is about 6 times that of the 0.75∶1 combination,and the degree of damage is relatively small.The results show that the width-height ratio has a significant effect on the impact failure of coal pillars.On the whole,the intensity of impact failure of coal pillars increases first and then decreases gradu-ally with the decrease of width-height ratio(5∶1-0.5∶1).When the width-height ratio of coal pillar is greater than 3∶1,the rock burst risk is relatively small.When the width-height ratio of coal pillar is 1∶1 and 0.75∶1,the rock burst risk is larger,followed by 0.5∶1.
coal pillar type rock burstwidth-height ratio of coal pillarcoal-rock assemblageacoustic emissionfractal dimension
万方数据
维普
