Determination of working resistance of support parameter variation of large mining height support: the case of Caojiatan coal mine

Abstract

AbstractAiming at the problem that it is difficult to determine the reasonable working resistance of support in fully-mechanized top coal caving face with large mining height, this paper discusses it from the perspective of preventing rib spalling of coal wall, and holds that the support resistance of working face should not only maintain the stability of roof structure of working face, but also prevent rib spalling of coal wall. Taking Caojiatan 122,107 working face as the engineering background. Using theoretical analysis, numerical simulation, orthogonal test, and similar simulation, it is concluded that reducing the end distance b, reducing the distance l between the action point of the support force and the coal wall, increasing the vertical force Pv and the horizontal force Ph of the support are beneficial to the integrity and stability of the coal wall. The proportion index η of the plastic zone of coal wall is established, and the fitting relationship between η and support parameters is: $$\eta { = } - 0.21{\text{g}}P_{v} + 0.04{\text{g}}P_{h} + 0.551{\text{g}}b - 0.039{\text{g}}l + 0.665$$ η = - 0.21 g P v + 0.04 g P h + 0.551 g b - 0.039 g l + 0.665 . Taking η as the index, the calculation formula of the lower limit value of support strength is constructed, and the lower limit value of support strength required to prevent coal wall spalling in 122,107 working face is 12,369 kN. On-site monitoring and adjustment have achieved good results.