Study On The Stability Of Water-bearing Section Coal Pillar Under Mining Action

As the mining depth of underground coal seams increases,the difficulty of rock formation control increases,and the coal pillars in sections are subject to the physical and chemical action of water,which is prone to instability under mining disturbances,resulting in loss of life and property.Therefore,it is of great significance to the safety production of coal mines to carry out research on the stability of the water-bearing section coal pillar under the action of mining.Taking the actual coal mining working face as the background,the uniaxial compression and Brazilian splitting experiments were carried out on the briquette specimens with different water contents.The main work and results are as follows:(1)Four kinds of briquette specimens with different water contents were prepared through laboratory experiments,uniaxial compression experiments and Brazilian splitting experiments were carried out to obtain the mechanical parameters of briquette under different water contents,and the stress-strain of briquette with different water contents was analyzed from the perspective of energy.The basic characteristics of the curve are established to establish the functional relationship between water content and peak stress,elastic modulus and Poisson’s ratio.(2)Based on the cusp catastrophe theory,the compression amount in the vertical direction of the section coal pillar is taken as the state variable,and the water-induced weakening function is introduced to establish the potential function expression of the water-bearing section coal pillar,and convert it into the cusp catastrophe model standard After the form,the influence of control variables and mutation eigenvalues on the stability of the water-bearing section coal pillar is analyzed;the displacement criterion and the strain energy criterion are selected as the indicators for analyzing the stability of the water-bearing section coal pillar.(3)The elastic-plastic finite element model of surrounding rock-coal pillar is established by ANSYS software,and the distribution law of stress field,strain field,displacement field and strain energy field of the water-bearing section coal pillar is obtained by analysis: the vertical stress peak value and plastic strain peak value of the water-bearing section coal pillar decrease,and the proportion of stress concentration area decreases;the displacement peak value and plastic strain peak value occur at the top of the side near the goaf,where instability is most likely to occur;Criteria monitoring points were set up in the goaf area,and the stability of the water-bearing section coal pillar was deeply analyzed.(4)The cusp catastrophe theory is used to analyze the stability of the water-bearing section coal pillar.In judging the overall stability of the water-bearing section coal pillar,the strength criteria are compared,and the results are consistent;the displacement criterion and the strain energy criterion can also be used to analyze the location of the local instability of the water-bearing section coal pillar.Using the displacement mutation criterion,it is concluded that local instability occurs at the edge of the coal pillar first;using the strain energy mutation criterion,it is concluded that local instability occurs 2-3m away from the outer wall of the water-bearing section coal pillar when the working face is excavated for the first time;Using the displacement mutation criterion and the energy mutation criterion obtained by the catastrophe theory,the position of the local instability of the water-bearing section coal pillar can be well determined.There are 53 figures,10 tables and 103 references in this paper.