Considering Behind Limit Deformation for Calculation of Coal Pillars Parameters by Finite Element Method

Abstract

-The paper presents the steps of calculating the stress-strain state of coal pillars by finite element method. The estimated area included the following blocks: the rock of roof and soil, coal pillar, broken-down rock, and the area of complete roof displacement. All the blocks were taken linearly deformable with natural deformation characteristics. The distribution of the bearing pressure on the pillar obtained on the first stage was used to determine the length of behind limit deformation zone and its deformation characteristics. On the second stage, the behind limit deformation zone was additionally calculated on the edge of the pillar. The analytical dependence of the length of the pillar's behind limit deformation zone (the distance to the maximum pressure) on the compressive strength of coal, depth and lateral thrust rate was established. This result allows us to find the minimum width of the stable pillars.Keywords -coal pillars, finite element method, behind limit coal deformation, maximum bearing pressure.