Fine numerical simulation of mining stress distribution in coal pillar based on strain softening model

Based on the engineering geological conditions of 3-corner 08 working face of Shanxi Jingfang coal industry, the in-situ borehole stress measurement of mining stress of coal pillar protecting roadway in working face is carried out.On this basis, the numerical calculation models based on the Moore Coulomb (MC) constitutive model and the strain softening (SS) constitutive model are established respectively, and the spatial distribution and evolution law of mining stress on coal pillars in fully mechanized caving face are studied in detail.The results of in-situ borehole stress monitoring and numerical simulation show that compared with the traditional MC model, the refined numerical simulation based on the SS model can accurately obtain the spatial distribution of mining stress of coal pillar in fully mechanized caving face, and the results are closer to the in-situ borehole stress monitoring results.The peak position of the abutment pressure on the coal pillar based on the SS model is 40-50 m behind the working face, while the peak position of the mining stress on the coal pillar based on the MC model is always in the middle of the goaf, which cannot reflect the influence of the caving and breaking of the goaf roof on the distribution law of the mining stress.The lateral abutment pressure on the coal pillar and the advance abutment pressure in front of the working face based on the SS model are 43.3% and 26.2% smaller than those based on the MC model, respectively.The research results have certain theoretical and engineering significance for guiding the size of coal pillar and roadway layout and support design in fully mechanized caving face.