Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Master of Science in Mining Engineering (MSMIE)

Document Type

Master's Thesis




Mining Engineering

First Advisor

Dr. Zach Agioutantis

Second Advisor

Dr. Jhon Silva


Pillars are used as the primary support structures for underground mining to maintain stability by supporting the over laying strata. In the case of horizontal seams, the pillars are typically subjected to axial loading due to the weight of the overburden and/or abutment stresses, while in the case of inclined seams they are subjected to oblique loading due to both the vertical and horizontal in-situ stress. Over the years numerous studies have been completed on square and rectangular pillars in horizontal seams that have resulted in several pillar stability equations and criteria. However very few studies are available with respect to pillars in inclined seams. Inclined pillars are subject not only to high normal stresses, but they are also subject to higher shear stresses that depend on the inclination of the seam, the ratio of the horizontal to vertical in-situ stress as well as the physical and mechanical properties of the material. This work presents a parametric numerical investigation of pillars in inclined seams using the finite element method (FEM) by evaluating different geometrical parameters such as seam inclination, pillar rib geometry as well as different pillar strength parameters. The major principal stress was examined at mid height of the center pillar whereas the rotational shear stress was taken at the roof-pillar interface of the center pillar. It is concluded that under Hoek & Brown conditions, high shear stress is developed at the pillar-roof interface for inclined pillars and such stress increase as pillar inclination increases. The shear stress developed in the pillar roof interface for the Hoek & Brown models does not peak at the uphill pillar rib, compared to the elastic models. The shear stress is slightly higher on the uphill side of inclined pillars than on the downhill side. Finally, the major principal stress at the ribs is higher for the elastic models than the Hoek & Brown models.

Digital Object Identifier (DOI)