The influence of complex topography on the stress of underlying coal strata

Abstract

To master the influence law of complex landform such as the surface mountain and the valley area between the mountains on the underlying coal rock stress, this study constructed a calculation model of the vertical stress of the coal strata under the mountain through theoretical analysis.Taking the 50205 working face of Hecaogou coal mine as example for analysis, This paper studied the complex landform on the underlying coal rock load characteristics and stress transfer law.Results show that: mountain load has significant stress effect on shallow coal seam.In the horizontal direction, the influence range is negatively correlated with the mountain slope, and the coefficient of influence range is positively related to the mountain slope.The effect of mountain on the vertical stress of the underlying coal seam can be divided into three stages: initial effect, intense growth effect and slow growth effect.The vertical stress superposition value of the underlying coal strata in the gully region firstly increases and then decreases with the change of depth.Moreover, when the distance between two adjacent mountains increases to more than.1.25 times of the width of the mountain bottom, the effect of stress superposition is very small and can be ignored.As the distance between adjacent mountains gradually increases, an inverted triangle area with insignificant stress superposition is formed in the coal strata under the gully area.

Keywords

• surface mountain load
• calculation model
• numerical simulation
• vertical stress
• coefficient of superposition