Prediction Model of Abutment Pressure Affected by Far-Field Hard Stratum Based on Elastic Foundation Theory

In view of the three-dimensional dynamic abutment pressure, the influence of the far-field hard stratum (FHS) in deep, thick coal seams is indeterminant. Based on elastic foundation theory, a three-dimensional dynamic prediction model of the abutment pressure was established. Using this model, the dynamic change in the coal seam abutment pressure caused by the movement of the FHS was studied, and a method for determining the dynamic change range of the abutment pressure was developed. The results of the new prediction model of the abutment pressure are slightly higher than the measured values, with an error of 0.51%, which avoids the shortcomings of the results because the Winkler foundation model results are lower than the measured values and have an error of 9.98%. As time progresses, the abutment pressure and its distribution range are affected by the FHS movement, which has the characteristics of gradually increasing dynamic change until the FHS fractures. The peak value of the abutment pressure increases linearly with time, and the influence range increases with time following a power function with an exponent of less than 1. The influence range of the FHS movement on the abutment pressure ahead of the working face, behind the working face, and along the working face is 10 times, 25 times, and 17 times the mining thickness, respectively. According to the actual geological parameters, the dynamic change range of the coal seam abutment pressure was determined by drawing an additional stress curve and by determining the threshold value. These research results are of great significance to the partition optimization of the roadway support design of deep, thick coal seams.