Study on working resistance distribution of support and resistance increasing characteristics of support partition in longwall face with ultra-large length

The effect of the increase of inclined length of fully mechanized mining face on roof breaking and stress evolution is complex, which leads to regional differences in the support characteristics of support in mining face. In order to deeply understand the interaction between support and surrounding rock in super-long working face, taking the 450 m super-long working face in Xiaobaodang Coal Mine as the engineering background, the mechanical model of elastic foundation rock beam is constructed, and the mathematical statistics and homogenization cycle analysis method are used to analyze the end-cycle resistance, working resistance distribution frequency and increasing resistance characteristics of support in working face. Clarify the characteristics of roof movement and support working resistance distribution in the inclined direction of working face with different face lengths, and explore the resistance increasing characteristics of support in the inclined zone of super-long working face. The results show that with the increase of the inclination length of the working face, the support of the coal body in the two roadways to the central roof is weakened, the peak area of the middle working face moves closer to the two roadways, and the distribution trend of working resistance of support in super-long working face is M-type three-peak distribution. When the support in the upper, middle and lower parts of the super-long working face shows a logarithmic resistance increase, the homogenization curve is still a logarithmic function, which shows that the resistance increases rapidly at first and then tends to smooth. The resistance increase of the support reflects that the roof of the working face gradually changes from rapid subsidence to slow subsidence during the pressure period. In the case of logarithmic-exponential drag increase, the resistance increase homogenization curve in the middle and upper region is a logarithmic function, and the middle and lower homogenization curve is a logarithmic-exponential compound function, which shows the characteristics that the resistance increases rapidly at first, then tends to smooth and finally increases rapidly. When the working cycle time of the support exceeds a certain value, the logarithmic-exponential compound resistance increasing support will rapidly increase the resistance, which is not conducive to the roof control. By optimizing the coal cutting speed of the working face and reducing the working cycle time of the support, the resistance increase of the support can be reduced, and the instantaneous resistance increase of the support in the state of high resistance can be avoided and the supporting effect of the support in the working face can be improved.