Study On The Stability Of Coal Pillal Under Propulsion Velocity Effect

The stability of coal pillar is one of major issues for the safety and high efficiency production of coal mine,which is of great significance for coal mining,tunneling and development.With the development of mine equipment,the impel speed of working face getting faster and faster,which have an effect on the stability of coal pillar.Based on the research results of related researchers,firstly from the theoretical point,this thesis analyzed the influencing factors of coal pillar stability,the failure mechanism and the force of coal pillar.Then,the mechanical properties of coal and rock under different loading rates were tested and the corresponding laws were studied.Finally,taking the 21103 working face of Gaoyang coal mine as the engineering background,the numerical simulation software is used to study the related research and conclusions obtained are as follows:(1)The mechanical properties of coal and rock under different loading rates are obtained by the experiment of the mechanical properties of coal and rock under different loading rates.The compressive and tensile strength of coal androck increases with the increase of loading rate.The relationship curves between compressive strength and tensile strength and loading rate of coal are fitted by the experimental data,and the fitting formula is obtained.The peak shear strength of coal rock increases with the normal stress increase and keep the trend of linear growth.The change of shear angle of coal and rock also changes the trend of shear strength.When the shear angle is 45 ? and 55 ?,the relationship between shear peak strength and shear rate is decreasing.When the shear angle is 65 ?,the shear strength shows an increasing trend with the increase of loading rate.The stress-strain curves of coal and rock during shear test show different characteristics that those of hard rock.(2)When accelerate impel speed of working face,it will reduce the plastic area of the trend direction of working face along and the peak value of the main stress in the vertical direction of the coal is increased.The acceleration of the working face has little influence on the plastic zone of the lateral coal body,and the position of peak stress in the coal body moves from about 10 m to 6m around the coal wall.The results of this thesis have a significance and guiding value for scientific understanding the mechanical properties of coal and rock and high-output and high-efficiency development of the coal industry.