Coal Pillar Strength Formula in Indonesian coal mines

Ratih Hardini Kusuma Putri

doi:10.31284/j.jemt.2020.v1i1.1147

Ratih Hardini Kusuma Putri

Open Access

https://doi.org/10.31284/j.jemt.2020.v1i1.1147

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Abstract

In underground coal mines, coal pillars play a major rule in sustaining the weight of the overburden and protecting the stability of the entries and crosscut during mine development and production, allowing the miners to safely extract the coal¹. The determination of a coal pillar size is adjusted to the expected load and strength of the coal seam. It needs to consider several factors such as pillar load (stress within the pillar), pillar strength, and safety factors. In this determination, an analysis will be conducted using five similar coal pillar strengths including; Obert-Duvall Equation (1967), Holland Equation (1964), Holland-Gaddy Equation (1956), Salamon-Munro Equation (1967), and Bieniawski (1983). Using AirLaya seam as an example, we can combine the results of various equations. The coal used in the Airlaya research area has a value of k = 425.75, thus the strength of Airlaya insitu seam coal is estimated to be 161,607 Psi.

Highlights

In underground coal mines, coal pillars play a major rule in sustaining the weight of the overburden and protecting the stability of the entries and crosscut during mine development and production, allowing the miners to safely extract the coal [1]
The determination of the dimensions of the Barrier pillar is very important in the design of coal underground mines because the barrier pillar is a coal pillar whose main function is to protect from the effects of deformation and excessive subsidence [3]
Another function of the barrier pillar is as a dividing zone between the two work areas to limit the voltage that works in each area and is a barrier to fight incoming air currents, gas migration, and spontaneity combustion

Summary

Introduction

Coal pillars play a major rule in sustaining the weight of the overburden and protecting the stability of the entries and crosscut during mine development and production, allowing the miners to safely extract the coal [1]. Due to these vital functions, the coal pillar has become one of the most fascinating subjects in the field of rock mechanics, in the field of ground control. An analysis will be conducted using five similar pillar strengths including; Obert-Duvall Equation, Holland Equation, Holland-Gaddy Equation, Salamon-Munro Equation, and Bieniawski by paying attention to stress factors [1], physical properties and mechanical properties of intact rock, rock mass characteristics, pillar size (scale effect) and pillar shape (shape effect) and coal condition (depth, slope, and thickness of coal) [4]

Discussion

Conclusion